# GCN_circulars

GRB_name: GRB170208A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20641
SUBJECT: Konus-Wind observation of GRB 170208A
DATE:    17/02/09 14:34:23 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170208A
(Swift-BAT detection: Cholden-Brown et al., GCN Circ. 20631;
Fermi-GBM detection: Roberts and Meegan, GCN Circ. 20633)
triggered Konus-Wind at T0=65479.756 s UT (18:11:19.756).

The burst light curve shows a multipeaked structure
started at ~T0-0.4 s with a total duration of ~8 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170208_T65479/

As observed by Konus-Wind, the burst
had a fluence of 2.62(-0.31,+0.37)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0-0.012 s,
of 1.94(-0.65,+0.67)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.52(-0.46,+0.56)
and Ep = 153(-24,+36) keV (chi2 = 67/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 67/59 dof)

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170207A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20642
SUBJECT: GRB 170207A: AstroSat CZTI detection
DATE:    17/02/09 14:36:07 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IITB), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed a clear detection of GRB170207A (IPN Triangulation detection: D. Svinkin et al., GCN Circ. 20628) in the 40-200 keV energy range. The light curve shows multiple peaks. The first peak occurred at 21:45:08.67 UT, 5 s after the Fermi trigger (Fermi GBM detection: O.J. Roberts., GCN circular 20630) and a second group of peaks was detected 18 s after the trigger. An interval of ~ 5 s between these two showed no detectable emission. The measured peak count rate is 345 counts/s above the background in combined data of four quadrants, with a total 2332.5 counts. The local mean background count rate was 352 counts/s. Using cumulative rates, we measure a T90 of 36.5 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170208B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20643
SUBJECT: Konus-Wind observation of GRB 170208B
DATE:    17/02/09 14:39:18 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170208B
(Swift-BAT detection: Siegel et al., GCN Circ. 20632)
triggered Konus-Wind at T0=81222.750 s UT (22:33:42.750).

The burst light curve shows a single emission episode
started at ~T0-5 s with a total duration of ~11 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170208_T81222/

As observed by Konus-Wind, the burst
had a fluence of 8.17(-0.44,+0.46)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.072 s,
of 2.55(-0.82,+0.82)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.78(-0.23,+0.25)
and Ep = 105(-7,+8) keV (chi2 = 40/51 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.0
(chi2 = 39/50 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170208A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20644
SUBJECT: GRB 170208A: Swift/UVOT Upper Limits
DATE:    17/02/09 14:45:54 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and A. Cholden-Brown (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170208A
125 s after the BAT trigger (Cholden-Brown et al., GCN Circ. 20631).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 20634)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           125          275          148         >21.4
u_FC               337          587          246         >20.7
white              125         1365          373         >21.9
v                  667         1415           97         >19.3
b                  593         1503           87         >19.4
u                  337         1489          324         >20.2
w1                 717         1464           78         >19.4
w2                 642         1390           97         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.13 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170207A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20645
SUBJECT: GRB 170207A: POLAR Observation
DATE:    17/02/09 14:46:15 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Yi Zhao (IHEP), Yuanhao Wang (IHEP), Hancheng Li (IHEP)
report on behalf of the POLAR collaboration:


At 2017-02-07T21:45:04.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170207A, 
which was also detected by the 
Fermi/GBM (trigger 508196708/170207906, O.J. Roberts et al,
Circ 20630), IPN Triangulation(D. Svinkin et al, Circ 20628)
and Konus-Wind (D. Svinkin et al, Circ 20629).


The POLAR light curve consists of multiple peaks,
with a duration (T90) of 39.47 s measured from T0+0.82 s.
The 1-s peak rate measured from T0+17.00 s is 6318.2 cnts/s.
The total counts is about 63182 cnts. The above measurements
are in the energy range of about 20-500 keV.


LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170207A/lc/POLAR_lc_grb170207A.png


Using the best location from the IPN Triangulation, which is (J2000):
RA:     315.704   [deg]
Dec:    +55.690   [deg]
Err:    4.66      [sq. deg]


the incident angle in POLAR coordinate at T0 is:
theta:  70.6      [deg]
phi:    -2.2      [deg]


All analysis results presented above are preliminary.


POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170208B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20646
SUBJECT: GRB 170208B: Fermi GBM Detection   
DATE:    17/02/09 15:19:35 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA) and C. Meegan (UAH) 
report on behalf of the Fermi GBM Team:

"At 22:33:36.53 UT on the 8th of February 2017, 
the Fermi Gamma-Ray Burst Monitor triggered and 
located GRB 170208B (trigger 508286021 / 170208940), 
which was also detected by Konus-Wind 
(Svinkin et al. 2017, GCN 20643) and Swift 
(Siegel et al. 2017, GCN 20632). The GBM on-ground 
location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM 
trigger time using the Swift-XRT position is 54 degrees.

The GBM light curve consists of a long GRB with 
overlapping episodes of bright emission over a 
duration (T90) of about 22 s (50-300 keV). The 
time-averaged spectrum from T0-8.0 s to T0+14.0 s is 
adequately fit by a Band function with 
Epeak = 104.1 +/- 5.5 keV, alpha = -0.83 +/- 0.05, and 
beta = -2.33 +/- 0.09

The event fluence (10-1000 keV) in this time interval is 
(1.13 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux
measured starting from T0-7.9 s in the 10-1000 keV band
is 12.1 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170208B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20647
SUBJECT: GRB 170208B WHT nIR candidate afterglow
DATE:    17/02/09 16:50:56 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

K. Wiersema, N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick),
R. Karjalainen, F. Riddick (ING) report on behalf of a larger collaboration:

We observed the field of Swift GRB 170208B (Siegel et al. GCN 20632)
with the 4.2m William Herschel Telescope on La Palma.
Images were obtained in the Y,J,H,K filters with LIRIS.

In the K-band exposure, for which the mid-time was 2.54 hr post-burst,
we find a source with magnitude K(AB)=21.1+/-0.1 within the revised
X-ray error circle (Goad et al. GCN 20635).

The source is absent (or very marginally present) in the other infrared
filters, which were observed somewhat earlier, to AB mag limits of
about 22.5 in each band.

The position of this source is:
RA(2000)=08:28:34.55
dec(2000)=-9:01:47.8

This is about 1.8 arcsec south of the steady optical source
seen by GROND and Pan-STARRS (Kruehler GCN 20640; 
we note there was a typo in the declination coordinate 
reported in GCN 20640, Kruehler priv. comm.).  

We suggest that the K-band source is most likely the 
afterglow of the GRB, and is not seen in bluer filters 
due to dust extinction, while the optical source may be the 
host galaxy.


GRB_name: GRB170208A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20649
SUBJECT: GRB 170208A: Swift-XRT refined Analysis
DATE:    17/02/09 18:27:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B. Sbarufatti (INAF-OAB/PSU), K.L. Page (U. Leicester), B. Mingo (U.
Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU) and A.
Cholden-Brown report on behalf of the Swift-XRT team:

We have analysed 5.5 ks of XRT data for GRB 170208A (Cholden-Brown et
al. GCN Circ. 20631), from 105 s to 13.0 ks after the  BAT trigger. The
data comprise 56 s in Windowed Timing (WT) mode (the first 8 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by Evans
et al. (GCN Circ. 20634).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.075 (+0.030, -0.029).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.97 (+/-0.17). The
best-fitting absorption column is  4.5 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.1 x 10^-11 (6.4 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.5 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^21 cm^-2
Excess significance: 6.2 sigma
Photon index:      1.97 (+/-0.17)

If the light curve continues to decay with a power-law decay index of
1.075, the count rate at T+24 hours will be 6.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x
10^-13 (4.2 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00737438.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170208B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20651
SUBJECT: Correction to GCN 20640: GRB 170208B: GROND observations
DATE:    17/02/09 22:12:53 GMT
FROM:    Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>

T. Kruehler (MPE Garching) reports:

The declination of the source mentioned in my original
GCN 20640 contained an error. The correct position is:

RA (J2000): 08:28:34.55
Dec (J2000): -09:01:46.1

I thank N. R. Tanvir for pointing out the error.


GRB_name: GRB170209A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20652
SUBJECT: GRB 170209A: Fermi GBM Detection
DATE:    17/02/09 22:26:43 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 01:08:38.08 UT on the 9th of February 2017,
the Fermi Gamma-Ray Burst Monitor triggered and
located GRB 170209A (trigger 508295323 / 170209048),
for which MASTER reported an OT in follow-up 
observations of the reported GBM location region
(Podesta et al. 2017, GCN 20650). The on-ground 
calculated location using the GBM trigger data is,

RA = 113.40, DEC = -49.64 (J2000 degrees), equivalent
to J2000 7h 33m, -49d 38',

with an uncertainty of 3.22 degrees (radius, 1-sigma
containment, statistical only; there is additionally
a systematic error which we have characterized as a
core-plus-tail model, with 90% of GRBs having a 3.7 deg.
error and a small tail suffering a larger than 10 deg.
systematic error [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight at the GBM trigger
time is 120 degrees.

The GBM light curve consists of a long GRB with two bright
episodes of emission over a duration (T90) of about 40 s
(50-300 keV). The time-averaged spectrum from T0+0 s to
T0+40.0 s is best fit by a power law function with an
exponential high-energy cutoff.  The power law index is
-0.95 +/- 0.07 and the cutoff energy, parameterized as
Epeak is 132 +/- 9 keV.

The event fluence (10-1000 keV) in this time interval is
(9.34 +/- 0.37)E-06 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+1.9 s in the 10-1000 keV band
is 12.6 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170208A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20653
SUBJECT: GRB 170208A: Swift-BAT refined analysis
DATE:    17/02/09 22:51:04 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
A. Cholden-Brown (PSU), J. R. Cummings (CPI),
N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 170208A (trigger #737438)
(Cholden-Brown, et al., GCN Circ. 20631). The BAT ground-calculated
position is
RA, Dec = 166.544, -46.786 deg which is
   RA(J2000)  =  11h 06m 10.5s
   Dec(J2000) = -46d 47' 08.8"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 17%.

The mask-weighted light curve shows a pulse from ~T0 to ~T+1.5 s,
followed by some weaker emissions that last till ~T+8 s. T90 (15-350 keV)
is 7.45 +- 0.54 sec (estimated error including systematics).

The time-averaged spectrum from T-0.04 to T+8.06 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.04 +- 0.13.  The fluence in the 15-150 keV band is 1.5 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.04 sec in the 15-150 keV band
is 5.4 +- 0.6 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/737438/BA/


GRB_name: GRB170208B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20654
SUBJECT: GRB 170208B: Swift-BAT refined analysis
DATE:    17/02/09 22:55:28 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. H. Siegel (PSU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170208B (trigger #737463)
(Siegel et al., GCN Circ. 20632).  The BAT ground-calculated position is
RA, Dec = 127.145, -9.027 deg which is
   RA(J2000)  =  08h 28m 34.7s
   Dec(J2000) = -09d 01' 36.1"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a bright pulse structure with
several overlapping peaks that starts at ~T-5 s and ends at ~T+15 s,
followed by a weaker pulse from ~T+100 s to ~T+160 s. There are also some
weak emissions that start at ~T-20 s, prior to the first bright pulse. The short
spike with duration of ~ 4 ms seen in 15-25 keV at ~T+191.3 s is due to
instrumental noise. T90 (15-350 keV) is 128.07 +- 5.75 sec (estimated error
including systematics).

The time-averaged spectrum from T-18.20 to T+159.30 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.18 +- 0.21,
and Epeak of 97.8 +- 27.4 keV (chi squared 57.4 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.1 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+0.42 sec in the 15-150 keV band is
8.4 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.62 +- 0.05 (chi squared 71.7 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/737463/BA/


GRB_name: GRB170208B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20655
SUBJECT: GRB 170208B: RATIR Optical and NIR Observations
DATE:    17/02/09 23:48:46 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Neil Gehrels (GSFC), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy
(UMD) report:

We observed the field of GRB 170208B (Siegel, et al., GCN 20632) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/02 9.11 to 2017/02 9.47 UTC (3.98 to
12.65 hours after the BAT trigger), obtaining a total of 6.02 hours
exposure in the r and i bands and 2.52 hours exposure in the Z and Y bands.

We do not detect either the GROND (Kruehler, et al., GCN 20640) source or
the WHT (Wiersema, et al., GCN 20647) source.  In comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

r > 23.56
i > 23.43
Z > 22.64
Y > 22.55

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  The lack of detection of the WHT
source is consistent with this source being reddened due to dust or due to
a high-z origin if the GROND source is not the GRB host galaxy.  The first
possibility is also suggested by the significant X-ray column density
relative to the Galactic value (Kennea, et al., GCN 20637).

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170209A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20656
SUBJECT: IPN Triangulation of GRB 170209A
DATE:    17/02/09 23:58:53 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 170209A
(Fermi GBM Detection: Roberts & Meegan, GCN Circ. 20652)
has been  detected by Fermi (GBM), Konus-Wind, INTEGRAL (SPI-ACS),
and Mars-Odyssey (HEND), so far, at about 4118 s UT (01:08:38).

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  110.686 (07h 22m 45s) -51.959 (-51d 57' 34")
 Corners:
  111.873 (07h 27m 29s) -55.694 (-55d 41' 38")
  111.366 (07h 25m 28s) -55.308 (-55d 18' 29")
  109.742 (07h 18m 58s) -48.166 (-48d 09' 58")
  110.149 (07h 20m 36s) -48.575 (-48d 34' 30")
 ---------------------------------------------
The error box area is 1.66 sq. deg, and its maximum
dimension is 7.64 deg (the minimum one is 13.1 arcmin).
The Sun distance was 105 deg.

This box may be improved.

The distance between the narrowest annulus (GBM-HEND annulus with
3 sigma half width of 0.109 deg) center line and the optical transient
J072307.30-521446.6 (Podesta et al., GCN Circ. 20650) is 1 arcmin,
supporting the association of the transient and the GRB.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170209_T04120/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170208B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20657
SUBJECT: GRB 170208B: Swift/UVOT Upper Limits
DATE:    17/02/10 01:47:01 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170208B
127 s after the BAT trigger (Siegel et al., GCN Circ. 20632).
No optical afterglow consistent with the enhanced XRT position
(Goad et al. GCN Circ. 20635) or the GROND position
(Kruehler et al., GCN Circ. 20640)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC               127          377          246         >20.7
v                  432         2146          214         >19.6
b                  382         2096          233         >20.3
u                  127         2211          598         >21.3
w1                 482         2195          214         >20.1
m2                 457         2171          214         >19.9
w2                 408         2122          234         >19.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170209A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20658
SUBJECT: GRB 170209A: Swift ToO observations
DATE:    17/02/10 14:42:18 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the IPN GRB 170209A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020739

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the IPN event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170209A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20659
SUBJECT: Konus-Wind observation of GRB 170209A
DATE:    17/02/10 15:04:10 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170209A
(Fermi-GBM detection: Roberts and Meegan, GCN Circ. 20652;
IPN triangulation: Hurley et al., GCN Circ. 20656)
triggered Konus-Wind at T0=4120.061 s UT (01:08:40.061).

The burst light curve shows two multipeaked episodes
started at ~T0-2 s with a total duration of ~40 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170209_T04120/

As observed by Konus-Wind, the burst
had a fluence of 8.35(-0.69,+0.76)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.904 s,
of 2.75(-0.80,+0.84)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+41.216 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.59(-0.30,+0.35)
and Ep = 126(-13,+18) keV (chi2 = 68/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 68/59 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
with  alpha = -0.92(-0.31,+0.35)
and Ep = 164(-28,+47) keV (chi2 = 60/60 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 60/59 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170210A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20660
SUBJECT: GRB 170210A: Fermi GBM observation
DATE:    17/02/10 17:54:44 GMT
FROM:    Bagrat Mailyan at UAH  <bm0054@uah.edu>

O.J. Roberts (USRA/NASA) and B. Mailyan (UAH)
report on behalf of the Fermi GBM Team:

"At 02:47:36.58 UT on February 10th 2017, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 170210A (trigger 508387661 / 170210116). The
on-ground calculated location using the GBM trigger
data is,

RA = 232.56, DEC = -58.59 (J2000 degrees), equivalent to
J2000 15h 30m, -58d 35',

with an uncertainty of 1 degree (radius, 1-sigma
containment, statistical only; there is additionally
a systematic error which we have characterized as a
core-plus-tail model, with 90% of GRBs having a 3.7 deg.
error and a small tail suffering a larger than 10 deg.
systematic error [Connaughton et al. 2015, ApJS, 216, 32]).

The initial angle from the Fermi-LAT boresight to the GBM
ground-location is 109 degrees.

The GBM light curve shows a long burst with multiple
episodes of bright emission over a duration (T90) of about
79 s (50-300 keV). The time-averaged spectrum from T0+9 s
to T0+84 s is best fit by a Band function with
alpha= -0.90 +/- 0.02, beta= -2.28 +/- 0.08 and Epeak
is 361.5 +/- 14.1 keV.

The event fluence (10-1000 keV) in this time interval is
(1.10 +/- 0.2) E-04 erg/cm^2. The 1s peak photon flux
measured starting from T0+41.7 s in the 10-1000 keV band is
32.8 +/- 0.6 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170210A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20661
SUBJECT: IPN Triangulation of GRB 170210A
DATE:    17/02/10 23:46:11 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:


The long-duration GRB 170210A (Roberts and Mailyan, GCN Circ. 20660) has 
been detected by Fermi(GBM), Konus-Wind, Mars-Odyssey (HEND), and Swift 
(BAT), so far, at about 10056 s UT (02:47:36).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
    RA(2000), deg                 Dec(2000), deg
   ---------------------------------------------
   Center:
    226.055 (15h 04m 13s) -65.101 (-65d 06' 02")
   Corners:
    228.764 (15h 15m 03s) -63.914 (-63d 54' 51")
    228.302 (15h 13m 12s) -64.342 (-64d 20' 31")
    223.147 (14h 52m 35s) -66.193 (-66d 11' 35")
    223.706 (14h 54m 49s) -65.801 (-65d 48' 04")
   ---------------------------------------------
The error box area is 1731 sq. arcmin, and its maximum
dimension is 3.28 deg (the minimum one is 10.1 arcmin).
The Sun distance was 80 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170210_T10092/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170209A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20662
SUBJECT: GRB 170209A: Swift-XRT observations
DATE:    17/02/11 02:09:50 GMT
FROM:    Aaron Cholden-Brown at PSU/Swift  <aaronb@swift.psu.edu>

B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows
(PSU), A. Cholden-Brown (PSU), S. J. LaPorte (PSU) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 170209A (Roberts et al. GCN Circ. 20652), collecting 5.0 ks
of Photon Counting (PC) mode data between T0+134.5 ks and T0+153.7 ks. 


No X-ray sources have been detected consistent with being within 16
arcsec of the MASTER-OAFA position. The 3-sigma upper limit in the
field ranges from ~0.002 to ~0.005 ct s^-1, corresponding to a 0.3-10
keV observed flux of 8.6e-14 to 2.0e-13 erg cm^-2 s^-1 (assuming a
typical GRB spectrum).

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020739.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170208C
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20664
SUBJECT: GRB 170208C: POLAR Observation
DATE:    17/02/12 01:08:15 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Yi Zhao (IHEP), Yuanhao Wang (IHEP), Hancheng Li (IHEP)
report on behalf of the POLAR collaboration:


At 2017-02-08T13:16:33.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170208C, 
which was also detected by the 
Fermi/GBM (trigger 508252598/170208553)
and INTEGRAL/SPIACS (trigger 7684).


The POLAR light curve consists of multiple peaks,
with a duration (T90) of 47.87 s measured from T0+2.15 s.
The 1-s peak rate measured from T0+47.00 s is 1842.1 cnts/s.
The total counts is about 20354 cnts. The above measurements
are in the energy range of about 20-500 keV.


LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170208C/lc/POLAR_lc_grb170208C.png


Using the best location from the Fermi/GBM, which is (J2000):
RA:     284.420   [deg]
Dec:    -0.110    [deg]
Err:    2.52      [deg]


the incident angle in POLAR coordinate at T0 is:
theta:  93.2      [deg]
phi:    -50.0     [deg]


All analysis results presented above are preliminary.


POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170210A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20665
SUBJECT: GRB 170210A: POLAR observation
DATE:    17/02/12 02:55:11 GMT
FROM:    Yuanhao Wang at IHEP/CAS  <wangyuanhao@ihep.ac.cn>

Y.H. Wang (IHEP), M.Z. Feng (IHEP), Y. Zhao (IHEP), 
report on behalf of the POLAR collaboration:

At 2017-02-10T02:47:37 UT (T0), during a routine on-ground 
search of data, POLAR detected the long-duration GRB 170210A, 
which was also reported by the 
Fermi/GBM (O.J. Roberts et al, GCN Circ. 20660) and 
IPN Triangulation(K. Hurley et al, GCN Circ. 20661), and also 
detected by Konus-Wind.

The POLAR light curve shows a long burst consists of multiple peaks,
with a duration (T90) of 62.27 s measured from T0+13.12 s.
The 1-s peak rate measured from T0+41.0 s is 6673.75cnts/s.
The total counts is about 106099 cnts.
LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170210A/lc/POLAR_lc_grb170210A.png

The above results are not dead time corrected. The above 
measurements are in the energy range of about 20-500 keV.

Using the best location from the IPN Triangulation, which is (J2000):
RA:     226.055   [deg]
Dec:    -65.101   [deg]
Err:    1731      [sq. arcmin](3 sigma)

the incident angle in POLAR coordinate at T0 is:
theta:  80.6      [deg]
phi:    130.9     [deg]

The Minimum Detectable Polarization(MDP) for this burst is
estimated to be ~7.3% [1-sigma, statistical only]. 

All analysis results presented above are preliminary.

POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170202A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20666
SUBJECT: GRB 170202A: 15 GHz upper limits from AMI
DATE:    17/02/12 19:20:00 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170202A (Racusin et al., GCN 20575) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Feb 02.87, Feb 04.00, Feb 
06.04, Feb 07.01 and Feb 09.00 (UT) do not reveal any radio source at 
the XRT location (Osborne et al., GCN 20586), with 3sigma upper limits 
of 451 uJy, 69 uJy, 81 uJy, 352 uJy and 105 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170203A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20667
SUBJECT: GRB 170203A: 15 GHz upper limits from AMI
DATE:    17/02/12 19:22:31 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170203A (Racusin et al., GCN 20583) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Feb 03.37, Feb 04.56, Feb 
06.56 and Feb 10.55 (UT) do not reveal any radio source at the BAT 
location (Cummings et al., GCN 20597), with 3sigma upper limits of 183 
uJy, 84 uJy, 75 uJy and 171 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170210A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20668
SUBJECT: Konus-Wind observation of GRB 170210A
DATE:    17/02/13 13:19:12 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, bright GRB 170210A
(Fermi-GBM detection: Roberts and Mailyan, GCN Circ. 20660;
IPN Triangulation: Hurley et al., GCN Circ. 20661;
POLAR detection: Wang et al., GCN Circ. 20665)
triggered Konus-Wind at T0=10092.18 s UT (02:48:12.180).

The burst light curve shows a multipeaked structure which
starts at ~T0-41 s and has a total duration of ~124 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170210_T10092/

As observed by Konus-Wind, the burst
had a fluence of 1.40(-0.16,+0.16)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+7.152 s,
of 1.83(-0.33,+0.33)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+86.528 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.99(-0.06,+0.07),
the high energy photon index beta = -2.55(-0.68,+0.26),
the peak energy Ep = 392(-40,+45) keV
(chi2 = 105/97 dof)

The spectrum near the maximum count rate
(measured from T0+5.888 to T0+7.680 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.63(-0.14,+0.17),
the high energy photon index beta = -2.30(-0.39,+0.21),
the peak energy Ep = 410(-76,+90) keV
(chi2 = 70/65 dof)

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170209A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20670
SUBJECT: GRB 170209A: AstroSat CZTI detection
DATE:    17/02/13 20:10:05 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IITB), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed a clear detection of GRB 170209A (Fermi GBM detection: O.J. Roberts et al., GCN Circ. 20652) in the 40-200 keV energy range. The light curve showed multiple peaks emission. The first emission peak occurred at 01:08:40.08 UT, 2 s after the Fermi trigger and a second group of emission peaked at ~34 s after the trigger. An interval of ~9 s between these two showed no detectable emission. The measured peak count rate was 245.1 counts/s above the background in combined data of four quadrants, with a total 1453.0 counts. The local mean background count rate was 343.9 counts/s. Using cumulative rates, we measured a T90 of 40.4 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170208A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20671
SUBJECT: GRB 170208A: AstroSat CZTI detection
DATE:    17/02/14 06:33:23 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IITB), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB 170208A (Swift detection: A. Cholden-Brown et al., GCN Circ. 20631) in the 40-200 keV energy range. The light curve shows multiple peaks structure with maximum counts at 18:11:16.0 UT peak, which coincides with Swift trigger. The measured peak count rate is 316.9 counts/sec above the background in combined data of four quadrants, with a total of 1106.2 counts. The local mean background count rate was 425.1 counts/sec. Using cumulative rates, we measure a T90 of 10.7 secs.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170208A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20672
SUBJECT: GRB 170208A: IRSF upper limits
DATE:    17/02/14 07:27:20 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

K. L. Murata (Nagoya U), L. Townsend (UCT), I. Monageng (SAAO), Y. Moritani
(Kavli IPMU), M. Jian (U of Tokyo), S. Chimasu (Tokai U), A. Kawachi (Tokai
U), A. Okazaki (Hokkai-Gakuen U) and T. Nagayama (Kagoshima U)

We observed the field of GRB 170208A (Cholden-Brown et al., GCN Circular
#20631) with the near-infrared (J, H, Ks) simultaneous imaging camera
SIRIUS attached to 1.4 m telescope IRSF (InfraRed Survey Facility) in
Sutherland observatory, South Africa.

The observations started on 2017-02-08 18:56:55 UT (~ 43 min. after the
burst). We could not detect the afterglow within the enhanced XRT error
circle (Evans et al., GCN Circular #20634) in the three bands. We have
obtained the following preliminary upper limits (Vega magnitude system):

 J > 16.50
 H > 16.25
 Ks > 15.92

Given magnitudes were calibrated against 2MASS point sources in this field.
The upper limits were determined as the magnitudes of the faintest star
within 1 arcmin from the enhanced XRT position.

This observation was carried out by IRSF and OISTER collaboration.


GRB_name: GRB170208B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20673
SUBJECT: GRB 170208B: IRSF upper limits
DATE:    17/02/14 07:28:56 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

K. L. Murata (Nagoya U), L. Townsend (UCT), I. Monageng (SAAO), Y. Moritani
(Kavli IPMU), M. Jian (U of Tokyo), S. Chimasu (Tokai U), A. Kawachi (Tokai
U), A. Okazaki (Hokkai-Gakuen U) and T. Nagayama (Kagoshima U)

We observed the field of GRB 170208B (Siegel et al., GCN Circular #20632)
with the near-infrared (J, H, Ks) simultaneous imaging camera SIRIUS
attached to 1.4 m telescope IRSF (InfraRed Survey Facility) in Sutherland
observatory, South Africa.

The observations started on 2017-02-08 22:49:41 UT (~ 15 min. after the
burst). We could not detect the afterglow within the enhanced XRT error
circle (Goad et al., GCN Circular #20635) in the three bands. We have
obtained the following preliminary upper limits (Vega magnitude system):

 J > 16.83
 H > 16.31
 Ks > 16.30

Given magnitudes were calibrated against 2MASS point sources in this field.
The upper limits were determined as the magnitudes of the faintest star
within 1 arcmin from the enhanced XRT position.

This observation was carried out by IRSF and OISTER collaboration.


GRB_name: GRB170208B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20674
SUBJECT: GRB 170208B: SMARTS optical/IR observations
DATE:    17/02/14 19:48:17 GMT
FROM:    Bethany Cobb at GWU  <bcobb@gwu.edu>

B. E. Cobb (GWU) reports:

Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 170208B
(GCN 20632, Siegel et al.) with a mid-exposure time of about
5.1 hours post-burst (2017-02-09 03:38 UT). Total summed exposure
times amounted to 36 minutes in I and 30 minutes in J.

No source is detected at the position of the X-ray afterglow
(GCN 20635, Goad et al.) to approximate limiting magnitudes
of I > 20.9 and J > 19.4. Magnitudes are calibrated using
Landolt standard stars in I and 2MASS stars in J.


GRB_name: GRB170214A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20675
SUBJECT: GRB 170214A: Fermi GBM detection
DATE:    17/02/14 22:26:42 GMT
FROM:    Bagrat Mailyan at UAH  <bm0054@uah.edu>

B. Mailyan and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 15:34:26.92 UT on 14 February 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170214A (trigger 508779271 / 170214649).

The on-ground calculated location, using the GBM trigger
data, is RA = 255.61, DEC = -5.78 (J2000 degrees), equivalent to
J2000 17h 02m, -05d 46',
with an uncertainty of 1 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 29 degrees.

The GBM light curve shows multiple overlaping peaks
with a duration (T90) of about 123 s (50-300 keV).
The time-averaged spectrum from T0+12.8 s to T0+136.7 s is
best fit by a Band function with Epeak = 408.50 +/- 9.09 keV,
alpha = -0.84 +/- 0.01, and beta = -2.34 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(1.8 +/- 0.002)E-4 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+61.7 s in the 10-1000 keV band
is 17.8 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170214A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20676
SUBJECT: GRB 170214A: Fermi-LAT detection
DATE:    17/02/15 00:13:48 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin@nasa.gov>

J. L. Racusin (NASA/GSFC), G. Vianello (Stanford), and J. Perkins (NASA/GSFC), 
report on behalf of the Fermi-LAT team:

At 15:34:26.92 on February 14, 2017, Fermi-LAT detected high-energy 
emission from GRB 170214A, which was also detected by Fermi-GBM 
(trigger 508779271 / 170214649, Mailyan et al., GCN 20675). 

The best LAT on-ground location is found to be
RA, Dec:  256.33, -1.88 (degrees, J2000)
with an error radius of 0.08 deg (90% containment, statistical error only). 

This was 33 deg from the LAT boresight at the time of the trigger, and 
triggered an autonomous repoint of the spacecraft.

The data from the Fermi-LAT show a significant increase in the event rate 
that is spatially and temporally correlated with the GBM emission with high 
significance.  More than 160 photons above 100 MeV and more than 13 
photons above 1 GeV are observed within 1000 seconds. The highest-
energy photon is a 7.8 GeV event which is observed ~105 seconds after 
the GBM trigger.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is 
Judith Racusin (judith.racusin@nasa.gov).

The Fermi-LAT is a pair conversion telescope designed to cover the energy 
band from 20 MeV to greater than 300 GeV. It is the product of an international 
collaboration between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.


GRB_name: GRB170214A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20677
SUBJECT: GRB 170214A: Swift ToO observations
DATE:    17/02/15 02:17:33 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Fermi/LAT GRB 170214A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020740

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170214A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20678
SUBJECT: Konus-Wind observation of GRB 170214A
DATE:    17/02/15 14:44:18 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 170214A (Fermi-GBM detection: Mailyan & Meegan, GCN 20675;
Fermi-LAT detection: Racusin et al., GCN 20676)
triggered Konus-Wind at T0=56076.276 s UT (15:34:36.276)

The light curve shows count rate increase around ~T0-50 s
followed by a bright, multi-peaked structure
which starts at ~T0-14 s and has a total duration of ~150 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(2.41 Â± 0.17)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+52.480, of (8.77 Â± 0.13)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+147.968 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.70 (-0.06,+0.07),
the high energy photon index beta = -2.61 (-0.27,+0.16),
the peak energy Ep = 330 (-19,+21) keV,
chi2 = 96/97 dof.

The spectrum near the peak count rate (measured from T0+47.360
to T0+56.248 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.75 (-0.12,+0.15),
the high energy photon index beta = -2.56 (-1.15,+0.33),
the peak energy Ep = 412 (-68,+73) keV,
chi2 = 110/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170214_T56076/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.

[GCN OPS NOTE(15feb17): Per author's request, the value for the
peak energy flux was changed from "10^-5" to "10^-6".]


GRB_name: GRB170214A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20679
SUBJECT: GRB 170214A: Swift-XRT observations
DATE:    17/02/15 14:47:44 GMT
FROM:    Andy Beardmore at U Leicester  <ab271@leicester.ac.uk>

A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), A. Cholden-Brown (PSU), S. J.
LaPorte (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 170214A (Racusin et al. GCN Circ. 20676),
collecting 4.9 ks of Photon Counting (PC) mode data between T0+38.6 ks
and T0+65.3 ks. 

Two uncatalogued X-ray sources have been detected, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:

Source 1:
  RA (J2000):  256.34147  =  17:05:21.95
  Dec (J2000): -1.88746  =  -01:53:14.9
  Error: 2.4 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0131 +/- 0.0021 ct s^-1   
  Distance: 49 arcsec from Fermi/LAT position.
  Flux: (4.88 +/- 0.78)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000):  256.3873  =  17:05:32.95
  Dec (J2000): -2.0113  =  -02:00:40.8
  Error: 8.8 arcsec (radius, 90% conf.)
  Count-rate: (1.94 [+0.96, -0.74])e-3 ct s^-1  
  Distance: 515 arcsec from Fermi/LAT position.

A catalogued source was also detected.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020740.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170209A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20680
SUBJECT: GRB 170209A: GROND confirmation of MASTER afterglow
DATE:    17/02/15 16:29:28 GMT
FROM:    Jochen Greiner at MPI  <jcg@mpe.mpg.de>

P. Schady, J. Greiner (both MPE Garching), and S. Steinmassl (TU Munich),
report:

We observed the field of the optical transient reported by MASTER 
(Podesta et al. 2017, GCN #20650) of GRB 170209A (Fermi/GBM trigger 508295323;
Roberts & Meegan 2017, GCN #20652) simultaneously in g'r'i'z'JHK with GROND 
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at 
ESO La Silla Observatory (Chile).

Observations started at 03:16 UT on 2017-02-10, 26 hrs after the GRB trigger,
resulting in 36 min of total exposures in g'r'i'z' and  30 min in JHK.
They were performed at an average seeing of 2.3" and at an airmass of 1.1.
A second epoch observation was started at 03:03 UT on 2017-02-15, around 6 days
after the GRB trigger, resulting in 72  min of total exposures in g'r'i'z' and 
60 min in JHK. Seeing conditions were better, around 1.3".

We detect two sources close to the MASTER position: the fainter one, to the
North-West, has faded by more than 1.2 mag, while the second source (to the
South-West) stayed constant within the errors.

The position of the fading object is
RA  (2000.0)  =  07:23:07.19 
Decl.(2000.0) = -52:14:45.5
with an error of +-0.3", and about 1.5 arcsec from the MASTER position.

We find the following magnitudes of the fading object:
     epoch 1               epoch 2
g'  > 23.5 mag            > 24.6 mag
r'  = 23.4 +- 0.1 mag     > 24.6 mag
i'  = 23.3 +- 0.3 mag     > 24.2 mag
z'  = 23.1 +- 0.3 mag     > 24.2 mag
J   > 21.3 mag            > 21.7 mag
H   > 21.0 mag            > 21.3 mag
K   > 19.3 mag            > 19.7 mag

The close match with the MASTER object, the fading and the powerlaw-like 
r'i'z colors confirm the nature of this object as the afterglow of 
GRB 170209A, as suggested also by Hurley et al. 2017, GCN #20656 based 
purely on the positional coincidence.

Given magnitudes are calibrated against GROND zeropoints and 2MASS field stars
and are not corrected for the Galactic foreground extinction corresponding to
a reddening of E(B-V)= 0.12 mag in the direction of the burst (Schlafly & 
Finkbeiner 2011).

We thank the support astronomer, S. Ciceri, for the support of the observations.


GRB_name: GRB170214A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20681
SUBJECT: GRB170214A: RATIR Optical and NIR Observations
DATE:    17/02/15 21:59:15 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer
(UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:


We observed the field of GRB 170214A (Mailyan, et al., GCN 20675;
Racusin, et al., GCN 20676) with the Reionization and Transients
Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson
Telescope at the Observatorio AstronÃ³mico Nacional on Sierra San Pedro
MÃ¡rtir from 2017/02 15.44 to 2017/02 15.50 UTC (10.58 to 11.99 hours
after the GBM trigger). We performed a series of tiled observations
partially covering the LAT error circle, obtaining a total of 0.40
hours exposure in the r and i bands and 0.32 hours exposure in the Z
and Y bands.

At the position of the first Swift/XRT source (source 1; Beardmore,
et al., GCN 20679), in comparison with the SDSS DR9 and 2MASS catalogs,
we obtain the following detections:

   r    21.06 +/- 0.11
   i    20.89 +/- 0.13
   Z    20.54 +/- 0.18
   Y    20.34 +/- 0.32

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We did not detect any significant fading during our observations, so
at present we cannot confirm the nature of this source. Further
observations are planned.

The second, fainter XRT source (source 3; Beardmore, et al., GCN 20679)
falls outside our set of frames.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170214A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20682
SUBJECT: GRB 170214A: Swift/UVOT Upper Limits
DATE:    17/02/16 07:17:01 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and A.P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170214A
38603 s after the LAT trigger (Mailyan and Meegan, GCN Circ. 20675).
No optical afterglow consistent with the XRTâ€™s source 1 position
(Beardmore et al., GCN Circ. 20679, Troja et al., GCN Circ. 20681)
is detected in the initial UVOT exposures. The source 3 position is just 
off the edge of the field of view.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for source 1 in the 
initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

w1               38603        65287         4856         >21.0

The magnitude in the table is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.36 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20683
SUBJECT: GRB 170214A: NOT optical afterglow confirmation
DATE:    17/02/16 07:38:43 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DARK/NBI), Jens-Kristian Krogager (IAP and DARK/NBI), 
and Adarsh Ranjan (IAP), report on behalf of a larger collaboration:

We observed the candidate optical counterpart of GRB 170214A (Mailyan & 
Meegan , GCN 20675; Racusin et al., GCN 20676; Beardmore et al., GCN 
20679; Troja et al., GCN 20681) with the Nordic Optical Telescope (NOT), 
equipped with the AlFOSC camera. Three observations by 300 s each were 
taken in the SDSS r band, under a seeing of 0.7", starting on 2017 Feb 
16.263 UT (38.90 hr after the Fermi/GBM trigger). We note that our 
pointing only covers XRT source #1 from Beardmore et al. (GCN 20679).

Within the XRT error circle (Beardmore et al., GCN 20679), we detect a 
single object at coordinates (0.5" error):

RA(J2000) = 17:05:21.90
Dec(J2000) = -01:53:15.7

We assume that this is the same object reported by Troja et al. (GCN 
20681). Calibrating against nearby SDSS stars, we measure r = 22.45 +- 
0.07 AB. The fading by more than 1 mag compared to the RATIR measurement 
(Troja et al., GCN 20681), as well as the spatial association with an 
X-ray source (Beardmore et al., GCN 20679), confirm this object to be 
the optical afterglow of GRB 170214A.


GRB_name: GRB170214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20684
SUBJECT: GRB 170214A: GROND detection in all bands
DATE:    17/02/16 14:07:29 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

Patricia Schady and Thomas Kruehler (MPE Garching) report:

We observed the field of the Fermi GRB 170214A (trigger 508779271/170214649, Mailyan et al., GCN #20675) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).

Observations started at 08:53 UT on 2017-02-15, 17.3 hrs after the GRB trigger, and they were performed at an average seeing of 1.5" and at an average airmass of 1.6. We detect an uncatalogued source within the XRT error circle of Source 1 (Beardmore et al., GCN #20679), at the same position reported by Malesani et al., (GCN #20683).

Based on combined images with 16 min of total integration time in griz and 19 min in JHK at a mid-time of 09:05 UT on 2017-02-15, this source has the following preliminary magnitudes (all in the AB system):

g' = 22.6 +/- 0.3 mag
r = 21.3 +/- 0.1 mag
i = 20.8 +/- 0.1 mag
z' = 20.3 +/- 0.1 mag
J = 19.6 +/- 0.1 mag
H = 19.3 +/- 0.1 mag
K = 18.8 +/- 0.3 mag

We re-observed the target on 2017-02-16 at a mid-time of 08:45 UT, and the r-band magnitude has decayed by a further 0.1 mag compared to the NOT measurement (Malesani et al., GCN #20683).

The given magnitudes are derived based on calibrating the images against SDSS in the optical and 2MASS field stars in the NIR bands. They are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.30 in the direction of the burst (Schlafly & Finkbeiner 2011).

We acknowledge the excellent help provided by the observer on the 2.2 m telescope at La Silla, Simona Ciceri, in obtaining these data.


GRB_name: GRB170214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20685
SUBJECT: GRB170214A: RATIR Optical and NIR Afterglow Confirmation
DATE:    17/02/16 15:00:45 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer
(UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara (UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºniga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:

We observed the field of GRB 170214A (Mailyan, et al., GCN 20675;
Racusin, et al., GCN 20676) with the Reionization and Transients
Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson
Telescope at the Observatorio AstronÃ³mico Nacional on Sierra San
Pedro MÃ¡rtir from 2017/02 16.46 to 2017/02 16.54 UTC (43.4
to 45.4 hours after the GBM trigger), obtaining a total of 1.42
hours exposure in the r and i bands and 0.60 hours exposure in the
Z and Y bands.

Source 1 (Beardmore, et al., GCN 20679; Troja, et al., GCN 20681) is
still detected in our observations at a position consistent with the
NOT source (Malesani, et al., GCN 20683). In comparison with the
SDSS DR9 and 2MASS catalogs, we obtain the following detections:

   r    22.78 +/- 0.08
   i    22.40 +/- 0.15
   Z    21.54 +/- 0.17
   Y    21.22 +/- 0.17

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

Compared to our first night of observations (Troja, et al., GCN 20681)
the source significantly faded in all filters, confirming that it is the
optical (Malesani, et al., GCN 20683) and NIR afterglow of GRB170214A.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20686
SUBJECT: GRB 170214A: VLT/X-shooter spectroscopy and tentative redshift
DATE:    17/02/16 16:41:59 GMT
FROM:    Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>

T. Kruehler, P. Schady, J. Greiner (all MPE Garching) and
N. R. Tanvir (U. Leicester) report:

We observed the optical counterpart (Troja et al. GCN 20681,
Malesani et al. GCN 20683, Schady et al. GCN 20684) of GRB 170214A
(Mailyan and Meegan, GCN 20675, Racusin et al. GCN 20676)
with the ESO Very Large Telescope UT 2 (Kueyen) equipped
with the X-shooter spectrograph, covering the wavelength range
3200-20000 AA. Observations started at 08:18 UT on 2017-02-16,
roughly 40.7 hours after the burst and consisted of 6 exposures
of 600 s each.

Our spectrum has a low signal-to-noise ratio with no signal being
detected bluewards of around 5800 AA due to a combination of
high background from the bright moon and faint afterglow.
In the red part, the spectrum exhibits four marginal absorption
features, which are consistent with coming from various FeII
transitions at a common redshift of z=2.53.

We acknowledge excellent support from the ESO observing staff
in Paranal, in particular Marcela Espinoza, Cedric Ledoux,
and Stephane Brillant.


GRB_name: GRB170214A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20687
SUBJECT: GRB 170214A: Mondy optical upper limit
DATE:    17/02/16 17:10:55 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI),
report on behalf of larger GRB follow-up collaboration:

We observed the field of  GRB 170214A   (Mailyan et al., GCN 20675; Racusin
et al., GCN 20676) with AZT-33IK telescope of Sayan observatory (Mondy)
starting on Feb., 15 (UT) 20:58:01. We obtained several images in R-filter.
The optical counterpart of  GRB 170214A (Troja et al., GCN 20681; Malesani
et al., GCN 20683; Schady et al., GCN 20684) is not detected in our stacked
image.

Preliminary photometry of the field is following

Date              UT start    t-T0        Filter  Exp.       OT      UL
                      (mid, days)                       (s)

2017-02-15 20:58:01  1.24558  R     120*30    n/d      21.4


Photometry is based on nearby SDSS-DR9 stars
SDSS-DR9_id            R(Lupton)
J170525.39-015302.5 17.50
J170522.63-015255.8 17.31
J170519.90-015220.7 18.47
J170517.04-015226.0 15.51
J170515.90-015250.9 17.81
J170518.92-015435.6 17.44
J170512.43-015325.4 16.54
J170511.57-015336.2 18.05


GRB_name: GRB170214A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20691
SUBJECT: GRB 170214A: Swift-XRT afterglow detection
DATE:    17/02/18 02:47:32 GMT
FROM:    Andy Beardmore at U Leicester  <ab271@leicester.ac.uk>

A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), A. Cholden-Brown (PSU), S. J.
LaPorte (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
Fermi/LAT-detected burst GRB 170214A. The observations now extend from
T0+38.6 ks to T0+274.4 ks. 

Of the sources previously reported, "Source 1" is above the RASS limit
and fading with 3-sigma significance, and is therefore likely the GRB
afterglow. Using 4445 s of PC mode data and 4 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 256.34147, -1.88746
which is equivalent to:

RA (J2000): 17h 05m 21.95s
Dec(J2000): -01d 53' 14.9"

with an uncertainty of 2.4 arcsec (radius, 90% confidence). This
position is 49 arcsec from the Fermi/LAT position.  The source is
fading with alpha >0.7.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00020740/index_1.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020740.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170219A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20702
SUBJECT: IPN Triangulation of GRB 170219A (short/hard)
DATE:    17/02/19 16:48:45 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:

The short-duration, hard-spectrum GRB 170219A has been detected by Fermi 
(GBM trigger 509155392), Konus-Wind, and INTEGRAL (SPI-ACS), so far, at 
about 187 s UT (00:03:07).

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    54.843 (03h 39m 22s) +50.072 (+50d 04' 20")
  Corners:
    55.105 (03h 40m 25s) +49.403 (+49d 24' 11")
    55.314 (03h 41m 15s) +49.435 (+49d 26' 04")
    54.571 (03h 38m 17s) +50.741 (+50d 44' 27")
    54.356 (03h 37m 25s) +50.708 (+50d 42' 28")
  ---------------------------------------------
The error box area is 696 sq. arcmin, and its maximum
dimension is 1.41 deg (the minimum one is 8.4 arcmin).
The Sun distance was 94 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170219_T00186/IPN/

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB170219A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20703
SUBJECT: Konus-Wind observation of GRB 170219A (short/hard)
DATE:    17/02/19 18:00:38 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The short/hard GRB 170219A (IPN triangulation: Svinkin et al.,
GCN 20702) triggered Konus-Wind at T0=186.125 s UT (00:03:06.125).

The light curve shows a single, bright pulse with a
duration of ~0.25s. The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst had a fluence of
(1.6 Â± 0.6)x10^-6 erg/cm2 and a 16-ms peak energy flux,
measured from T0, of (2.8 Â± 0.9)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The spectrum, measured from T0 to T0+0.064 s,
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.24 (-0.15,+0.17), Ep = 1620 (-660,+1920) keV,
Cstat=47/56 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170219_T00186/

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.


GRB_name: GRB170219A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20706
SUBJECT: GRB 170219A: Fermi GBM observation
DATE:    17/02/19 21:08:46 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA), M. Stanbro and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 00:03:07.12 UT on February 19th 2017, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 170219A (trigger 509155392 / 170219002), which
was also detected by Konus-Wind
(Frederiks et al. 2017, GCN 20703) and for which a
triangulated position was reported by IPN
(Svinkin et al. 2017, GCN 20702). The GBM localisation 
is within about 2.5-sigma of the triangulated IPN position.

The initial angle from the Fermi-LAT boresight to the GBM
ground-location using the centre of the IPN triangulated
position is 133 degrees.

The GBM light curve shows a bright, short burst a duration
(T90) of about 0.08 s (50-300 keV). The time-averaged spectrum
from T0-0.03 s to T0+0.05 s is best fit by a power law function
with an exponential high-energy cutoff.  The power law index is
-0.59 +/- 0.10 and the cutoff energy, parameterized as Epeak
is 1165 +/- 182 keV

A Band function fits the spectrum equally well with
alpha= -0.56 +/- 0.11, beta= -3.25 +/- 1.19 and Epeak
is 1093 +/- 202 keV.

The event fluence (10-1000 keV) in this time interval is
(9.52 +/- 0.49)E-07 erg/cm^2. The 64 ms peak photon flux
measured starting from T0+0 s in the 10-1000 keV band is
29.4 +/- 1.9 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170219A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20710
SUBJECT: GRB 170219A: CALET Gamma-Ray Burst Monitor detection
DATE:    17/02/21 09:29:37 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The short-duration GRB 170219A (Roberts et al., GCN Circ. 20706; Frederiks et al.,
GCN Circ. 20703; INTEGRAL-SPI/ACS trigger #7701) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 00:03:06.76 on 19 February 2017.  The burst signal was seen
by all CGBM instruments.  Because of a problem in one of the ground alert processing
script, the GCN notice was not distributed automatically for this event.

The light curve of the SGM shows a single peak.  The peak starts and peaks
at T0-0.2 sec and ends at T+0.5 sec.  The T90 duration measured by
the SGM data is 0.25 +- 0.18 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1171497500/index.html

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170219A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20719
SUBJECT: GRB 170219A: POLAR Observation
DATE:    17/02/22 08:18:10 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Minzi Feng (IHEP), Yi Zhao (IHEP), Yuanhao Wang (IHEP)
report on behalf of the POLAR collaboration:


At 2017-02-19T00:03:07.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170219A, 
which was also detected by the 
Fermi/GBM (trigger 509155392/170219002, Circ 20706),
CALET/GBM (Cherry et al. 2017, GCN 20710)
INTEGRAL/SPIACS (trigger 7701), Konus-Wind
(Frederiks et al. 2017, GCN 20703) and for which a triangulated
position was reported by IPN (Svinkin et al. 2017, GCN 20702).


The POLAR light curve consists of a single peak,
with a duration (T90) of 0.15 s measured from T0+0.08 s.
The 10-ms peak rate measured from T0+0.12 s is 16148.3 cnts/s.
The total counts is about 964 cnts. 


LC_URL:
http://polar.ihep.ac.cn/grb/2017/02/GRB170219A/lc/POLAR_lc_grb170219A.png


The above results are not dead time corrected. The above
measurements are in the energy range of about 20-500 keV.


Using the best location from the Fermi/GBM, which is (J2000):
RA:     72.730     [deg]
Dec:    +49.980    [deg]
Err:    2.88       [deg]


the incident angle in POLAR coordinate at T0 is:
theta:  59.8       [deg]
phi:    -90.2      [deg]


All analysis results presented above are preliminary.


POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170222A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20722
SUBJECT: IPN Triangulation of GRB 170222A (short/hard)
DATE:    17/02/22 13:52:53 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The short-duration, hard-spectrum GRB 170222A has been detected by Fermi 
(GBM trigger 509432464), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey 
(HEND), Swift (BAT), and CALET (GBM), so far, at about 18059 s UT 
(05:00:59).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   292.956 (19h 31m 49s) +28.211 (+28d 12' 40")
  Corners:
   292.896 (19h 31m 35s) +27.812 (+27d 48' 44")
   292.864 (19h 31m 27s) +28.266 (+28d 15' 59")
   293.017 (19h 32m 04s) +28.608 (+28d 36' 28")
   293.048 (19h 32m 12s) +28.156 (+28d 09' 22")
  ---------------------------------------------
The error box area is 254 sq. arcmin, and its maximum
dimension is 0.8 deg (the minimum one is 9.36 arcmin).
The Sun distance was 56 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170222_T18056/IPN/

A Swift ToO request has been approved.

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB170222A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20725
SUBJECT: GRB 170222A: Swift ToO observations
DATE:    17/02/22 14:32:19 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the IPN GRB 170222A. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020741

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the IPN event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170222A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20726
SUBJECT: GRB 170222A: Tiled Swift observations
DATE:    17/02/22 15:27:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
IPN GRB 170222A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00064

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the IPN event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170222A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20728
SUBJECT: GRB 170222A: Fermi GBM observation
DATE:    17/02/22 22:52:42 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (UAH), E. Bissaldi (Politecnico & INFN Bari), and C. Meegan
(UAH)
report on behalf of the Fermi GBM Team:

"At 05:00:59.08 UT on 22 February 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170222A (trigger 509432464 / 170222209),
which was also reported by IPN (Hurley et al. 2017, GCN 20722).

The on-ground calculated location, using the GBM trigger
data, is RA = 312.10, DEC = +12.45 (J2000 degrees,
equivalent to 20h 48m, 12d 27'), with an uncertainty
of 3.6 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

Although the GBM localization is not consistent within 3 sigma
of the IPN localization, the GBM localization places this event
in the same part of the sky and is the same event as that reported by IPN.
The angle from the Fermi LAT boresight at the GBM trigger time using
the IPN position is 120 degrees.

The GBM light curve shows a single multi-peaked emission episode
with a duration (T90) of about 1.7 s (50-300 keV).
The time-averaged spectrum from T0-0.64 s to T0+2.43 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.70 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 862 +/- 118 keV.

The event fluence (10-1000 keV) in this time interval is
(5.31 +/- 0.19)E-06 erg/cm^2. The 0.64-sec peak photon flux measured
starting from T0+1.15 s in the 10-1000 keV band
is 17.4 +/- 1.9 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170222A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20729
SUBJECT: GRB 170222A: Swift-XRT observations
DATE:    17/02/23 16:51:35 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>

A. D'Ai (IASF-PA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 170222A in a series of observations tiled on the sky and
covering the entire IPN error box. The total exposure time is 5.3 ks,
distributed over 3 tiles; the maximum exposure at a single sky location
was 3.2 ks. The data were collected between T0+33.8 ks and T0+38.9 ks,
and are entirely in Photon Counting (PC) mode.

Three uncatalogued X-ray sources are detected:

Source 1:
   RA (J2000):    292.95293 = 19h 31m 48.70s
   Dec (J2000):   28.04614  = +28:02:46.1
   Error: 5.0 arcsec
   Count-rate:  1.01 (+0.21, -0.20) Ã— 10-2 ct/s

Source 2:
   RA (J2000):    292.68930 = 19h 30m 45.43s 
   Dec (J2000):    27.96842 = +27:58:06.3
   Error: 5.7 arcsec
   Count-rate: 2.4 (+0.9, -0.7) Ã— 10-2 ct/s

Source 3:
   RA (J2000):    293.02439 = 19h 32m 05.85s 
   Dec (J2000):    28.26746 = +28:16:02.9
   Error: 3.1 arcsec
   Count-rate: 8.0 (+2.8, -2.3) Ã—10-3 ct/s

However, none of these is a credible afterglow candidate.
Source 2 is outside the IPN errorbox, while sources 1 and 3 match
Simbad sources NVSS J193148+280248 and CCDM J19321+2816BC. Sources 2
and 3 are affected by optical loading and might be spurious detections.

The Swift XRT observations did not cover the Fermi GBM error circle
reported by Hamburg et al. (GCN #20728).

The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00064.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170222A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20731
SUBJECT: Konus-Wind observation of GRB 170222A
DATE:    17/02/24 12:52:25 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A.Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 170222A
(IPN triangulation: Hurley et al., GCN 20722;
Fermi GBM observation: Hamburg et al., GCN 20728)
triggered Konus-Wind at T0=18056.528 s UT (05:00:56.528).

The burst light curve shows a multi-peaked structure
which starts at ~T0-0.1 s and has a total duration of ~1.9 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
9.10(-2.43,+3.61)x10^-6 erg/cm2, and a 64-ms peak flux,
measured from T0+1.104 s, of 1.23(-0.46,+0.76)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.72(-0.26,+0.36)
and Ep = 1210(-418,+830) keV (chi2 = 73/88 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.28
(chi2 = 73/87 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170222_T18056/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170220A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20733
SUBJECT: GRB 170220A: POLAR Observation
DATE:    17/02/24 14:50:14 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

R. Marcinkowski (PSI), H.L. Xiao (PSI) and W. Hajdas (PSI) report on behalf of the POLAR collaboration:

At 2017-02-20 18:48:01.00 UT(T0), during a routine on-ground search of data, 
POLAR detected short GRB 170220A, which was also observed by Konus at 18:47:58.467 UT.
 

The POLAR light curve consists of 1 peak with duration (T90) of 0.3 +/- 0.1 s measured from T0. 
The 50 ms peak flux at T0 + 0.7 s is equal to 7300 +/- 100 counts/sec. 
POLAR recorded 1230 events from the burst. 
Above measurements are in the energy range of about 50 - 500 keV.
 
LC_URL: http://polar.psi.ch/triggers/GRB_170220A_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170220A

 
The analysis results presented above are preliminary.   POLAR is a dedicated 
Gamma-Ray Burst polarimeter which was launched on-board the Chinese space
 laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range
 of POLAR is ~ 50-500 keV. 

More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .
 
This message is quotable in publications.


GRB_name: GRB170222A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20749
SUBJECT: GRB 170222A: CALET Gamma-Ray Burst Monitor detection
DATE:    17/02/26 10:06:52 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, Y. Kawakubo,
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The short-duration GRB 170222A (Hamburg et al., GCN Circ. 20728;
Kozlova et al., GCN Circ. 20731; INTEGRAL-SPI/ACS trigger #7705)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:00:58.48
on 22 February 2017.  The burst signal was only seen by the SGM
instruments.

The light curve of the SGM shows several peaks.  The entire burst
episode starts at T0+0.5 sec, peaks at T0+0.8 sec and ends at T0+2 sec.
The T90 duration measured by the SGM data is 1.2 +- 0.1 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1171774567/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170228A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20785
SUBJECT: GRB 170228A: Fermi-LAT detection
DATE:    17/03/01 11:50:23 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari), F. Longo (University & INFN Trieste),
E. Moretti (MPI Munich), M. Yassine (LUPM) and Z. Acuner (KTH Stockholm)
report on behalf of the Fermi-LAT team:


At 19:03:00.71 UT on February, 28, 2017, Fermi-LAT detected high-energy emission
from GRB 170228A, which was also detected by Fermi-GBM (trigger 170228794/510001385).

The best LAT on-ground location is found to be

RA, Dec = 239.55, -3.59 (J2000)

with an error radius of 0.3 deg (90 % containment, statistical error only).

This was about 70 deg from the LAT boresight at the time of the trigger.
The burst entered the LAT FoV about 80 s post trigger and exited about 800 s post trigger.
The data from the Fermi-LAT show a significant increase in the event rate that
is spatially correlated with the trigger with high significance.
In total, LAT detected about 20 photons with an energy greater than 100 MeV.
The highest-energy photon is a 5 GeV event, which is observed 130
seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Zeynep Acuner (acuner@kth.se).


The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration
between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.


GRB_name: GRB170228A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20786
SUBJECT: GRB 170228A: Fermi GBM observation
DATE:    17/03/01 16:32:05 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres, M. Stanbro and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 19:03:00.71 UT on 28 February 2017, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 170228A (trigger 510001385 /
170228794) which was also detected by Fermi/LAT (Bissaldi et al., GCN
20785). The GBM on-ground location is consistent with the LAT
position.


The GBM light curve shows a single pulse followed by weaker emission
with a duration (T90) of about 62 s (50-300 keV).
The time-averaged spectrum from T0 to T0 + 18.8 s is
best fit by a Band function with Epeak = 755 +/- 76 keV,
alpha = -0.50 +/- 0.07, and beta = -2.35 +/- 0.17.

The event fluence (10-1000 keV) in this time interval is
(2.23 +/- 0.06)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.0 s in the 10-1000 keV band
is 10.2 +/- 0.2 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170206B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20787
SUBJECT: GRB 170206B: 15 GHz upper limits from AMI
DATE:    17/03/01 16:43:13 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array observed the Swift GRB 170206B (Lien et al., GCN 
20618) as part of the 4pisky program; follow up observations were 
obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 
Feb 08.37, Feb 09.38, Feb 14.43 and Feb 15.46 (UT) do not reveal any 
radio source at the XRT location (Evans et al., GCN 20619), with 3sigma 
upper limits of 123 uJy, 108 uJy, 108 uJy and 108 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170228A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20788
SUBJECT: GRB 170228A: AstroSat CZTI detection
DATE:    17/03/01 18:14:23 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, V. Bhalerao (IITB) and D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB170228A (Fermi-LAT detection: E. Bissaldi et al., GCN Circ. 20785) in the 40-200 keV energy range. The light curve shows single peak structure with main peak at 19:03:02.71 UT, 2 s after the Fermi trigger. The measured peak count rate is 541.9 counts/sec above the background in combined data of four quadrants, with a total 3569 counts. The local mean background count rate was 349.1 counts/s. Using cumulative rates, we measure a T90 of 14.1 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170228B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20792
SUBJECT: GRB 170228B: POLAR Observation
DATE:    17/03/02 12:28:20 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

H.L. Xiao (PSI) , W. Hajdas (PSI) and R. Marcinkowski (PSI)  report on behalf of the POLAR collaboration:

At 2017-02-28 18:32:56 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170228B,
which was also observed by  Fermi GBM (trigger #509999585).

The POLAR lightcurve consists of two peaks with duration (T90) of 35.00 +/- 1.00 s measured from T0.
The 1.0 s peak flux at T0 + 24.5 s  is equal to 390 +/- 50 counts/sec.
POLAR five modules recorded 4680 events from the burst.
Above measurements are in the energy range of about 80 - 500 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170228B_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170228B

Using the best location from Fermi GBM, which is (J2000):
RA : 355.94 [deg]
Dec: 15.73 [deg]
the incident angle in the POLAR coordinate at T0 is:
Theta: 24.09 [deg]
Phi: 264.49 [deg]

The analysis results presented above are preliminary. POLAR is a dedicated Gamma-Ray Burst polarimeter which was launched
on-board the Chinese space laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV.

More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .

This message is quotable in publications.


GRB_name: GRB170228B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20803
SUBJECT: GRB 170228B CALET Gamma-Ray Burst Monitor detection
DATE:    17/03/03 06:13:49 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

P. S. Marrocchesi (U of Siena)  A. Yoshida, T. Sakamoto, Y. Kawakubo,
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence),
and the CALET collaboration:

The long-duration GRB 170228B (Fermi GBM trigger #509999585;
Xiao et al, GCN Circ. 20792) triggered the CALET Gamma-ray Burst
Monitor (CGBM) at 18:32:58.03 on 28 February 2017.  The burst signal
was seen by the HXM2 and SGM instrument.

The light curve of the SGM shows two peaks.  The first peak starts at T0,
peaks at T+5 sec and ends at T+18 sec.  The second peak starts at T+20 sec,
peaks at T+25 sec and ends at T+35 sec.  The T90 duration measured by
the SGM data is 32.2 +- 1.2 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1172341676/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170228A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20806
SUBJECT: Konus-Wind observation of GRB 170228A
DATE:    17/03/03 13:49:20 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, hard-spectrum GRB 170228A
(Fermi-LAT detection: Bissaldi et al., GCN 20785;
Fermi GBM observation: Veres et al., GCN 20786;
AstroSat CZTI detection: Sharma et al., GCN 20788)
triggered Konus-Wind at T0=68584.788 s UT (19:03:04.788).

The burst light curve starts with a bright FRED-like pulse having a
duration of ~20 s, followed by a weaker emission,
which is detectable until ~T0+100 s.
The emission is seen up to ~3 MeV.

As observed by Konus-Wind, the burst
had a fluence of 4.99(-0.99,+1.51)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.316 s,
of 8.97(-2.47,+2.57)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+98.560 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.03(-0.18,+0.22),
and Ep = 1017(-317,+657) keV (chi2 = 97/98 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -1.98 (chi2 = 97/97 dof).

The spectrum near the peak count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.43(-0.14,+0.17),
the high energy photon index beta = -2.78(-2.28,+0.48),
the peak energy Ep = 675(-92,+112) keV,
chi2 = 95/76 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170228_T68584/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170304A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20813
SUBJECT: GRB 170304A: Fermi GBM observation
DATE:    17/03/04 12:01:08 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:

"At 00:04:26.07 UT on 04 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170304A (trigger 510278671 / 170304003).


The on-ground calculated location, using the GBM trigger
data, is RA = 330.50, DEC = -73.76 (J2000 degrees,
equivalent to 22 h 2 m, 73 d 46 '), with an uncertainty
of 6.7 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 69 degrees.

This burst was also independently detected by INTEGRAL SPI-ACS.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 59 degrees.

The GBM light curve shows a single pulse
with a duration (T90) of about 0.16 s (50-300 keV).
The time-averaged spectrum from T0-0.1 s to T0+0.2 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.02 +/- 0.23 and
the cutoff energy, parameterized as Epeak, is 76.4 +/- 9.8 keV.


The event fluence (10-1000 keV) in this time interval is
(2.1 +/- 0.2)E-7 erg/cm^2. The 64 ms peak photon flux measured
starting from T0 in the 10-1000 keV band is 24.1 +/- 1.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170305A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20818
SUBJECT: GRB170305A: Fermi GBM detection
DATE:    17/03/05 20:28:27 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

M. Stanbro (UAH), A. von Kienlin (MPE), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 06:09:06.78 UT on 05 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170305A (trigger 510386951 / 17035256).

The on-ground calculated location, using the GBM trigger
data, is RA = 38.66, DEC = 12.09, with an uncertainty
of 3.7 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

This burst was also independently detected by INTEGRAL SPI-ACS.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 59 degrees.

The GBM light curve consists of 1 episode
with a duration (T90) of about 0.44 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.384 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.53 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 293 +/- 24 keV

The event fluence (10-1000 keV) in this time interval is
(1.29 +/- 0.07)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 31.0 +/- 1.6 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 233 +/- 35 keV, alpha = -0.42 +/- 0.13 and beta = -2.06 +/-
0.13.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170306A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20819
SUBJECT: GRB 170306A: Swift detection of a burst
DATE:    17/03/06 07:26:32 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

C. B. Markwardt (NASA/GSFC), V. D'Elia (ASDC), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB) and
K. L. Page (U Leicester) report on behalf of the Swift Team:

At 07:06:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170306A (trigger=741220).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 263.082, -44.747 which is 
   RA(J2000) = 17h 32m 20s
   Dec(J2000) = -44d 44' 50"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 20 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 07:08:26.0 UT, 133.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 263.06892, -44.74808 which
is equivalent to:
   RA(J2000)  = 17h 32m 16.54s
   Dec(J2000) = -44d 44' 53.1"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 33 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 3.82
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 139 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. Because of the density of catalogued stars, further
analysis is required to report an upper limit for any afterglow in the
sub-image. The 8'x8' region for the list of sources generated on-board covers
100% of the XRT error circle. Because of the density of catalogued stars,
further analysis is required to report an upper limit for any afterglow in the
region. No correction has been made for the expected extinction corresponding
to E(B-V) of 0.41. 

Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170306A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20820
SUBJECT: GRB 170306A: LCO Cerro Tololo observations
DATE:    17/03/06 09:02:26 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large 
collaboration report:

We observed Swift GRB 170306A (Markwardt et al. GCN 20819) on March 6, 
07:26:06 UT (~20 minutes since the GRB trigger time) with the 1-m LCO 
unit in Cerro Tololo with SDSS r and i filters. Within the Swift XRT 
error circle we detect an uncatalogued source at the following position:

RA(J2000) = 17:32:16.76
Dec(J2000)= -44:44:53.7

with an error radius of 1". We find the following magnitude values as 
calibrated against nearby USNOB-1 objects (R2 and I values):

Mid Time      Exposure       Filter       Magnitude (AB)
(min)           (s)
-------------------------------------------------------
24            5x60           SDSS-I        18.5 +- 0.2
34            5x60           SDSS-R        19.0 +- 0.2
-------------------------------------------------------

At the moment we cannot make any statement on the temporal behaviour of 
the source. The expected Galactic dust extinction is A_r=1~mag, A_i=0.7 
mag (from Schlafly et al. 2011). Given the crowded field, we caution 
that the source might be unrelated to the GRB.


GRB_name: GRB170306A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20822
SUBJECT: GRB 170306A: GROND observations
DATE:    17/03/06 15:17:58 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

Patricia Schady, Phil Wiseman (both MPE) and Jan Bolmer (ESO, Santiago) report:

We observed the field of GRB 170306A (Swift trigger 741220; Markwardt et al., GCN #20819) simultaneously in grizJHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).

Observations started at 07:20 UT on 2017-03-06, 14 minutes after the GRB trigger, and they continued for ~2 hours, until the start of astronomical twilight. They were performed at an average seeing of 1.3" and at an average airmass of 1.5.

Within the 3.7" XRT error circle (Markwardt et al., GCN #20819) we detect two uncatalogued sources in addition to the source reported by Guidorzi et al. (GCN #20820). These two newly identified sources have AB magnitudes r~20.0 mag and r~20.3 mag calibrated against GROND zeropoints and uncorrected for the significant Galactic foreground extinction along the line of sight. None of the sources within the XRT error circle show any significant variability during the 2 hours of GROND observations.

We acknowledge the excellent support provided by the Chilean observer at the telescope, and the support astronomer, Angela Hempel, in obtaining these data.


GRB_name: GRB170306A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20823
SUBJECT: GRB 170306A: Swift/UVOT Upper Limits
DATE:    17/03/06 18:52:02 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and C. B. Markwardt (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170306A
140 s after the BAT trigger (Markwardt et al., GCN Circ. 20819).
No optical afterglow consistent with the XRT position
(Markwardt et al., GCN Circ. 20819)
and the optical positions
(Guidorzi et al., GCN Circ. 20820; Schady et al., GCN Circ. 20822)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           140          290          147         >20.0
u_FC               299          548          246         >18.9
white              140          771          186         >20.4
v                  629          821           39         >18.1
b                  554          747           39         >18.6
u                  299          722          265         >19.0
w1                 678          870           39         >18.1
m2                 653          846           39         >19.0
w2                 604          796           39         >18.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.41 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170305A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20824
SUBJECT: IPN Triangulation of GRB 170305A (short)
DATE:    17/03/06 18:57:17 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The short-duration GRB 170305A (Stanbro at al., GCN Circ. 20818)
has been detected by Fermi (GBM), Konus-Wind, INTEGRAL (SPI-ACS),
Mars-Odyssey (HEND), and Swift (BAT), so far,
at about 22147 s UT (06:09:07).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    39.658 (02h 38m 38s)  +9.901 ( +9d 54' 05")
  Corners:
    39.371 (02h 37m 29s) +11.649 (+11d 38' 56")
    39.926 (02h 39m 42s)  +9.863 ( +9d 51' 47")
    39.796 (02h 39m 11s)  +8.512 ( +8d 30' 43")
    39.391 (02h 37m 34s)  +9.939 ( +9d 56' 21")
  ---------------------------------------------
The error box area is 2881 sq. arcmin, and its maximum
dimension is 3.16 deg (the minimum one is 29.0 arcmin).
The Sun distance was 55 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170305_T22143/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170306B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20825
SUBJECT: GRB 170306B: Tiled Swift observations
DATE:    17/03/06 18:58:17 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 170306B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00065

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170306B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20826
SUBJECT: GRB 170306B: Fermi-LAT detection
DATE:    17/03/06 18:58:37 GMT
FROM:    Nicola Omodei at Stanford U.  <nicola.omodei@slac.stanford.edu>

N. Omodei (Stanford U.), G, Vianello (Stanford U.), D. Tak(U. of 
Maryland) and F. Longo (University and INFN Trieste) report on behalf of 
the Fermi-LAT team:
At 14:07:22.27 on March 06, 2017, Fermi-LAT detected high-energy 
emission from GRB 170306B, which was also detected by Fermi-GBM (trigger 
510502047).
The best LAT on-ground location is found to be RA, Dec 154.62, 51.59 
(degrees, J2000) with an error radius of 0.61 deg (90% containment, 
statistical error only).
This was 55 deg from the LAT boresight at the time of the trigger and 
triggered an autonomous repoint of the spacecraft.
The data from the Fermi-LAT show a significant increase in the event 
rate within 4.3 degree of the GBM location after the GBM trigger that is 
temporally correlated with the GBM emission with high significance.
More than 10 photons above 100 MeV are observed within 300 seconds.
The highest-energy photon is a 500 MeV event which is observed 46 
seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Nicola Omodei 
(nicola.omodei@stanford.edu).

The Fermi-LAT is a pair conversion telescope designed to cover the 
energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between NASA and DOE 
in the U.S. and many scientific institutions across France, Italy, Japan 
and Sweden.


GRB_name: GRB170306B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20827
SUBJECT: GRB 170306B: Fermi GBM detection
DATE:    17/03/06 19:32:55 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres (UAH), C. Meegan (UAH) and A. von Kienlin (MPE)
report on behalf of the Fermi GBM Team:

"At 14:07:22.27 UT on 6 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170306B (trigger 510502047 / 170306588),
which was also detected by Fermi/LAT (Omodei et al., GCN 20826). The
GBM on-ground location is consistent with the LAT position.


The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed
to the GBM in-flight location.

The GBM light curve shows multiple overlapping pulses
with a duration (T90) of about 18.7 s (50-300 keV).
The time-averaged spectrum from T0-3.8 s to T0+26.9 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.73 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 289 +/- 10 keV.


The event fluence (10-1000 keV) in this time interval is
(3.07 +/- 0.06)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+8.7 s in the 10-1000 keV band
is 12.4 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170306A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20828
SUBJECT: GRB 170306A: Swift-XRT refined Analysis
DATE:    17/03/06 21:36:26 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A.
Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), S.L.
Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 6.7 ks of XRT data for GRB 170306A, from 119 s to 28.8
ks after the  BAT trigger. The data comprise 29 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. The refined XRT position is RA,
Dec = 263.0690, -44.7482 which is equivalent to:

RA (J2000): 17 32 16.56
Dec(J2000): -44 44 53.5

with an uncertainty of 3.6 arcsec (radius, 90% confidence).

The light curve can be modelled with an initial power-law decay with an
index of alpha=3.25 (+0.28, -0.21), followed by a break at T+559 s to
an alpha of 0.36 (+0.10, -0.26).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.05 (+0.30, -0.19). The
best-fitting absorption column is  3.98 (+1.64, -0.16) x 10^21 cm^-2,
consistent with the Galactic value of 3.8 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.8 x 10^-11 (6.1 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.98 (+1.64, -0.16) x 10^21 cm^-2
Galactic foreground: 3.8 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.05 (+0.30, -0.19)

If the light curve continues to decay with a power-law decay index of
0.36, the count rate at T+24 hours will be 0.011 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (6.9 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00741220.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170306A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20829
SUBJECT: GRB 170306A, Swift-BAT refined analysis
DATE:    17/03/07 02:59:37 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170306A (trigger #741220)
(Markwardt et al., GCN Circ. 20819).  The BAT ground-calculated position is
RA, Dec = 263.087, -44.765 deg which is
   RA(J2000)  =  17h 32m 20.9s
   Dec(J2000) = -44d 45' 52.5"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 29%.

The mask-weighted light curve shows a pulse that starts at ~T-7 s and ends
at ~T+20 s. In addition, there is a hint of some weak emissions from ~T-100 s
to ~T-80 s. T90 (15-350 keV) is 17.8 +- 6.7 sec (estimated error including systematics).

The time-averaged spectrum from T-7.1 to T+19.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.98 +- 0.28.  The fluence in the 15-150 keV band is 8.3 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+10.93 sec in the 15-150 keV band
is 1.3 +- 0.4 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/741220/BA/


GRB_name: GRB170306B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20830
SUBJECT: GRB 170306B: Swift-XRT observations
DATE:    17/03/07 11:32:04 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU),
D.N. Burrows (PSU), A. Cholden-Brown (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), B. Mingo (U. Leicester), A.
Melandri (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of
the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 170306B in a series of observations tiled
on the sky. The total exposure time is 4.5 ks, distributed over 8
tiles; the maximum exposure at a single sky location was 1.4 ks. The
data were collected between T0+17.4 ks and T0+29.9 ks, and are entirely
in Photon Counting (PC) mode. 

No uncatalogued X-ray sources have been detected. The 3-sigma upper
limit in the field (not including the regions where the tiles overlap)
ranges from ~0.007 to ~0.021 ct s^-1, corresponding to a 0.3-10 keV
observed flux of 2.9e-13 to 8.5e-13 erg cm^-2 s^-1 (assuming a typical
GRB spectrum).

Four previously-catalogued X-ray sources have been detected, however
their status as catalogued objects makes them unlikely to be the
afterglow.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00065.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170306B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20831
SUBJECT: Konus-Wind observation of GRB 170306B
DATE:    17/03/07 11:39:11 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 170306B (Fermi-LAT detection: Omodei et al., GCN 20826;
Fermi-GBM detection: Veres et al., GCN 20827)
triggered Konus-Wind at T0=50850.920 s UT (14:07:30.920)

The light curve shows a multi-peaked structure
with a total duration of ~25 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(3.4 Â± 0.4)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+3.712, of (4.1 Â± 0.6)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+22.528 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.58 (-0.13,+0.16),
the high energy photon index beta = -2.62 (-0.61,+0.28),
the peak energy Ep = 237 (-27,+27) keV,
chi2 = 105/97 dof.

The spectrum near the peak count rate (measured from T0 to T0+6.912 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.40 (-0.11,+0.12),
the high energy photon index beta = -2.70 (-0.84,+0.29),
the peak energy Ep = 214 (-24,+30) keV,
chi2 = 120/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170306_T50850/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB170307A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20832
SUBJECT: Swift Trigger 741528: a possible GRB
DATE:    17/03/07 20:41:30 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), L. M. Z. Hagen (PSU),
J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),
J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU) and
E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift Team:

At 20:24:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located the possible GRB 170307A (trigger=741528).  Swift did not slew
due to an observing constraint.  The BAT on-board calculated location is 
RA, Dec 13.535, +9.537, which is 
   RA(J2000)  =  00h 54m 08s
   Dec(J2000) = +09d 32' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows that Swift was 
emerging from the SAA at this time, giving a quickly-decreasing
count rate that would swamp any variation expected from the source
at the nominal intensity implied by the image strength. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 00:33 UT on 2017 May 24. There will thus be no XRT or
UVOT data for this trigger before this time. 

Because of high and variable background rates from the SAA, and
in the absence of follow-up observations by the XRT, the 
immediately-available data does not determine whether this 
was a true astronomical event or an image fluctuation 
(with a nominal significance of 7.2 sigma). 
A determination of the nature of this source will require the
full downlinked data set. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170307A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20835
SUBJECT: GRB 170307A: Fermi GBM observation   
DATE:    17/03/08 05:44:32 GMT
FROM:    C. Michelle Hui at MSFC/Fermi-GBM  <c.m.hui@nasa.gov>

C.M. Hui (NASA/MSFC) and O.J. Roberts (USRA/NASA)
report on behalf of the Fermi GBM Team:

At 20:25:17.49 UT on 07 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170307A (trigger 510611122 /170307851),
which was also detected by Swift BAT (A. Y. Lien et al., GCN 20832).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time 
using the Swift-BAT location is 98 degrees.

The GBM light curve consists of multiple peaks with a duration (T90) 
of about 57.9s (50-300 keV). The time-averaged spectrum 
from T0-27.6s to T0+28.7 s is adequately fit by a power law function 
with an exponential high-energy cutoff. The power law index 
is -1.18 +/- 0.26 and the cutoff energy, parameterized as Epeak, 
is 83.80 +/- 19.90 keV.

The event fluence (10-1000 keV) in this time interval is 
(1.85 +/- 0.25)E-06 erg/cm^2. The 1-sec peak photon flux measured 
starting from T0+8.3 s in the 10-1000 keV band is 
1.72 +/- 0.25 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.


GRB_name: GRB170305A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20837
SUBJECT: GRB 170305A: POLAR observation
DATE:    17/03/08 09:24:45 GMT
FROM:    Radek Marcinkowski at PSI/POLAR  <radoslaw.marcinkowski@psi.ch>

R. Marcinkowski (PSI), H.L. Xiao (PSI) and W. Hajdas (PSI) report on behalf
of the POLAR collaboration:

At 2017-03-05 06:09:06.8 UT(T0), during a routine on-ground search of data, 
POLAR detected GRB 170305A, which was also observed by Fermi GBM (trigger 
# 510386951; GCN 20818, M. Stanbro) and Konus-Wind, INTEGRAL (SPI-ACS),
Mars-Odyssey (HEND), and Swift (BAT) (GCN 20824, K. Hurley et al.).

The POLAR light curve consists of 1 peak with duration (T90) of 
0.3 +/- 0.05 s measured from T0. The 64ms peak flux at T0 + 0.1 s  
is equal to   9630 +/- 120 counts/sec. POLAR recorded 2400 events from 
the burst. Above measurements are in the energy range of about 20 - 500 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170305A_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170305A

Using the best location from IPN Triangulation (GCN 20824, K. Hurley et al.), 
which is (J2000):
RA : 39.66 deg
Dec:  9.90 deg
the incident angle in the POLAR coordinate at T0 is:
Theta: 31.4 deg
Phi:  239.1 deg

The analysis results presented above are preliminary. POLAR is a dedicated 
Gamma-Ray Burst polarimeter which was launched on-board the Chinese space
laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range 
of POLAR is ~ 50-500 keV. More information about POLAR can be found at 
http://polar.psi.ch/pub , http://polar.ihep.ac.cn/en/ 
and http://isdc.unige.ch/polar/ .

This message is quotable in publications.


GRB_name: GRB170307A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20838
SUBJECT: GRB 170307A (trigger 741528): Swift-BAT refined analysis
DATE:    17/03/08 13:59:24 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-12 to T+963 sec from the recent telemetry downlink,
we determine that BAT trigger #741528 (Lien et al., GCN Circ. 20832) is indeed
a GRB, which also detected by Fermi GBM (Hui et al., GCN Circ. 20835). We report
further analysis of BAT GRB 170307A (trigger #741528).
The BAT ground-calculated position is
RA, Dec = 13.510, 9.538 deg which is
   RA(J2000)  =  00h 54m 02.5s
   Dec(J2000) = +09d 32' 17.9"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.

The mask-weighted light curve shows a weak structure with several overlapping
pulses that starts at ~T+55 s and ends at ~T+125 s. The burst emission might
start before it came into the BAT FOV at ~T-12 s. T90 (15-350 keV) is
56.92 +- 27.40 sec (estimated error including systematics).

The time-averaged spectrum from T+55.33 to T+124.69 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.88 +- 0.23.  The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+69.72 sec in the 15-150 keV band
is 1.4 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/741528/BA/


GRB_name: GRB170306B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20839
SUBJECT: GRB 170306B: POLAR observation
DATE:    17/03/08 14:02:46 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

H.L. Xiao (PSI), R. Marcinkowski (PSI)  and W. Hajdas (PSI) report on behalf of the POLAR collaboration:

At 2017-03-06 14:07:20.0 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170306B,
which was also observed by  Fermi-GBM (trigger # 510502047), Fermi-LAT (trigger #170306588) and SPI ACS at 2017-03-06 14:07:25.

The POLAR light curve consists of multiple peaks with duration (T90) of 25.0 +/- 1.0 s measured from T0.
The 1.00 s peak flux at T0 + 11.50 s  is equal to 2380 +/- 100 counts/sec.
POLAR recorded 31640 events from the burst.
Above measurements are in the energy range of about 15 - 300 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170306B_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170306B

Using the best location from Fermi-LAT, which is (J2000):
RA : 154.650 [deg]
Dec:  51.630 [deg]
Err:  39.00  [arcmin]
the incident angle in the POLAR coordinate at T0 is:
Theta: 87.0 [deg]
Phi: 98.4 [deg]

The analysis results presented above are preliminary. POLAR is a dedicated Gamma-Ray Burst polarimeter which
was launched on-board the Chinese space laboratory Tiangong-2 (TG-2) on Sep 15, 2016. 

More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .

This message is quotable in publications.


GRB_name: GRB170306A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20843
SUBJECT: GRB 170306A: GROND afterglow detection
DATE:    17/03/10 13:15:22 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

Patricia Schady (MPE Garching) reports:

Following on from the GROND (Greiner et al. 2008, PASP 120, 405)
observations of GRB 170306A on the 2017-03-06 (Schady et al., GCN #20819),
I re-observed the field simultaneously in g'r'i'z'JHK with GROND at on
2017-03-10, 4 days after the GRB trigger. Observations were performed at
an average seeing of 1.4" and at an average airmass of 1.7.

One of the three sources detected with GROND (Schady et al., GCN #20819)
within the refined XRT error circle (DAvanzo et al., GCN #20828) is no
longer seen in the latest GROND observations down to the following 3 sigma
limiting magnitudes (all in AB system):

g > 22.6 mag
r >  23.5 mag
i > 22.3 mag
z > 22.4 mag
J > 20.4 mag
H > 19.9 mag
K > 18.9 mag

This source is therefore the likely optical/NIR afterglow of GRB 170306A.
The position of the afterglow candidate is

RA (J2000)    = 17:32:16.69
Dec (J2000) =  -44:44:55.5

with a positional uncertainty of 0.3" in both coordinates.

Based on combined images with 36 min of total integration time in g'r'i'z'
and 30 min in JHK at a mid-time of 09:33 UT on 2017-03-06, the afterglow
candidate had the following preliminary magnitudes (all in AB system):

g' = 21.6 +/- 0.1 mag
r = 20.4 +/- 0.1 mag
i = 20.0 +/- 0.1 mag
z' = 19.9 +/- 0.1 mag
J = 19.1 +/- 0.1 mag
H = 18.4 +/- 0.1 mag
K = 18.5 +/- 0.2 mag

The given magnitudes are derived based on images calibrated against GROND
zero points in the optical and 2MASS field stars in the NIR bands. They
are not corrected for the Galactic foreground extinction corresponding to
a reddening of E_(B-V)= 0.36 in the direction of the burst (Schlafly &
Finkbeiner 2011).

I acknowledge the excellent support provided by the Chilean observer at
the telescope, and the support astronomer, Sam Kim, in obtaining these
data. I also thank David Buckley for some useful email exchanges that in
part led to the second epoch of GROND observations.


GRB_name: GRB170306A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20844
SUBJECT: GRB170306A: SALT observations
DATE:    17/03/10 20:05:16 GMT
FROM:    Soebur Razzaque at U of Johannesburg  <srazzaque@uj.ac.za>

D.A.H. Buckley (SAAO/SALT), A, Martin-Carrillo (U. College Dublin), S. Razzaque (U. Johannesburg) and R. Skelton (SAAO/SALT) report on behalf of a larger collaboration.

We observed the nominal position of GRB 170306A (Markwardt et al. GCN 20819 and Guidorzi et al. GCN 20820) on 2017-03-07 at 01:22:42 UTC using the Southern African Large Telescope (SALT) in Sutherland, South Africa, 18.61 h after the Swift GRB trigger. A 20 sec r'-band image was obtained using SALTICAM just prior to the commencement of attempted low resolution (R ~ 355 at 660 nm) spectroscopy. Two stellar objects at râ€™ ~ 19 and 20 were seen, with FWHM of 1.7 arcsec, near the GRB position and long slit spectroscopy was attempted of both. Only the brighter one provided a detection, which was noisy and showed no obvious spectral features. Subsequent information provided by P. Schady on possible optical candidates from the first GROND observation (Schady et al. GCN 20822) was used to confirm the identification of the râ€™ = 20.4 object identified by Schady (GCN 20843) as the optical counterpart. The SALT image shows a very weak detection of this object, barely above the background, with an estimated brightness of râ€™= 21.4 +/- 0.3, having dimmed approximately one magnitude since detection.

We thank Patricia Schady and Christiano Guidorzi for providing information to assist in the identification of the optical counterpart.

________________________________

This email and all contents are subject to the following disclaimer:

http://disclaimer.uj.ac.za


GRB_name: GRB170309A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20845
SUBJECT: GRB 170309A: POLAR Observation
DATE:    17/03/11 06:10:16 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Yi Zhao (IHEP), Yuanhao Wang (IHEP), Zhengheng Li (IHEP)
report on behalf of the POLAR collaboration:


At 2017-03-09T12:26:42.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170309A, 
which was also detected by CALET/CGBM (TRIGGER_NUM:1173097284).


The POLAR light curve consists of multiple peaks,
with a duration (T90) of 2.51 s measured from T0+0.87 s.
The 1-s peak rate measured from T0+2.00 s is 1778.1 cnts/s.
The total counts is about 4523 cnts. 


LC_URL:
http://polar.ihep.ac.cn/grb/2017/03/GRB170309A/lc/POLAR_lc_grb170309A.png


The above results are not dead time corrected. The above
measurements are in the energy range of about 20-500 keV.


All analysis results presented above are preliminary.


POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170311A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20846
SUBJECT: GRB 170311A: Swift detection of a burst
DATE:    17/03/11 08:25:14 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J. R. Cummings (NASA/UMBC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB/PSU) report on behalf
of the Swift Team:

At 08:08:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170311A (trigger=741965).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 280.563, -30.063 which is 
   RA(J2000) = 18h 42m 15s
   Dec(J2000) = -30d 03' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 15 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 08:10:28.0 UT, 105.1 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 280.5893,
-30.0458 which is equivalent to:
   RA(J2000)  = 18h 42m 21.43s
   Dec(J2000) = -30d 02' 44.8"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 102 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.30
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 109 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. Because of the density of
catalogued stars, further analysis is required to report an upper limit for any
afterglow in the region. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.16. 

Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170311A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20847
SUBJECT: GRB 170311A: MASTER-OAFA  early  optical observations
DATE:    17/03/11 10:01:06 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , 
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, A.V.Krylov, 
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko

Lomonosov Moscow State 
University, Sternberg Astronomical Institut of MSU

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. 
Ershova Irkutsk State University

V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in OAFA was pointed to the  GRB170311A 18 sec after notice time 
and 59 sec after trigger time (Cummings et al.,  GCN 20846)
at 2017-03-11 08:09:45 UT. On our first (10s 
exposure)  set we haven't found optical transient  within SWIFT error-box 
(ra=280.562 dec=-30.0628 r=0.05).
The 5-sigma upper limit has been about 16.2 mag

The observations made on zenit distance = 49 degrees, galaxy latitude b = 
-12 degree.
The moon (98 % bright part) is 15 degrees above the horizon. The distance 
between  moon and  object is 124
The sun  altitude  is -30.1 degree.
The object can be observed till sunrise at 2017-03-11 10:34:12

  The message may be cited.


GRB_name: GRB170311A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20848
SUBJECT: GRB 170311A: GROND upper limits
DATE:    17/03/11 15:45:09 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady and P. Wiseman (both MPE Garching) report:

We observed the field of GRB 170311A (Swift trigger 20846; Cummings et
al., GCN #20846) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 09:45 UT on 2017-03-11, 1.6 hours after the GRB
trigger. They were performed at an average seeing of 1.2" and at an
average airmass of 1.1.

We do not detect a source within the Swift-XRT error circle (Cummings et
al., GCN #20846) down to the following 3 sigma limiting AB magnitudes:

g' > 23.1 mag
r' > 23.4 mag
i' > 22.7 mag
z' > 22.5 mag
J > 20.6 mag
H > 20.2 mag
K > 19.0 mag

The given limits are derived based on images calibrated against
Pan-STARRS/2MASS field stars, and are not corrected for the Galactic
foreground extinction corresponding to a reddening of E_(B-V)= 0.14 in the
direction of the burst (Schlafly & Finkbeiner 2011).


GRB_name: GRB170311A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20850
SUBJECT: GRB 170311A: Enhanced Swift-XRT position
DATE:    17/03/11 22:53:52 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2232 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170311A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 280.58942, -30.04597 which is equivalent
to:

RA (J2000): 18h 42m 21.46s
Dec (J2000): -30d 02' 45.5"

with an uncertainty of 1.5 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170311A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20851
SUBJECT: GRB 170311A: Swift/UVOT Upper Limits
DATE:    17/03/12 02:10:46 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170311A
110 s after the BAT trigger (Cummings et al., GCN Circ. 20846).
No optical afterglow consistent with the XRT position
(Cummings et al. GCN Circ. 20846)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           110          259          147         >20.5
u_FC               269          519          246         >19.7
white              110         7074          645         >21.2
v                  600        11424         1022         >20.3
b                  525         5585          294         >20.1
u                  269         5380          537         >20.1
w1                 650         5175          279         >20.1
m2                 624        13058           82         >20.1
w2                 575         7280          313         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.16 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170311A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20852
SUBJECT: GRB 170311A: Swift-XRT refined Analysis
DATE:    17/03/12 03:29:38 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), A. Cholden-Brown (PSU), S.
J. LaPorte (PSU), K.L. Page (U. Leicester), B. Mingo (U. Leicester),
A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 6.8 ks of XRT data for GRB 170311A, from 108 s to 35.6
ks after the  BAT trigger. The data comprise 64 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.59 (+0.16, -0.17).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.52 (+0.28, -0.26). The
best-fitting absorption column is  2.2 (+1.5, -0.9) x 10^21 cm^-2,
consistent with the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 4.8 x 10^-11 (5.6 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.2 (+1.5, -0.9) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.52 (+0.28, -0.26)

If the light curve continues to decay with a power-law decay index of
1.59, the count rate at T+24 hours will be 6.1 x 10^-5 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.9 x
10^-15 (3.4 x 10^-15) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00741965.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170311A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20853
SUBJECT: GRB 170311A: Further GROND analysis
DATE:    17/03/12 14:20:10 GMT
FROM:    Philip Wiseman at MPE/Swift  <wiseman@mpe.mpg.de>

P. Wiseman and P. Schady (both MPE Garching) report:

We re-inspected the observations of GRB 170311A taken with GROND (Schady &
Wiseman, GCN #20848) with respect to the enhanced XRT position (Osborne et
al., GCN #20850).

There is no credible afterglow consistent with or near to this position.
The upper limits remain the same as those reported in GCN #20848.


GRB_name: GRB170311A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20855
SUBJECT: GRB 170311A: Swift-BAT refined analysis
DATE:    17/03/12 16:08:13 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170311A (trigger #741965)
(Cummings, et al. GCN Circ. 20846).  The BAT ground-calculated position is
RA, Dec = 280.539, -30.041 deg which is
  RA(J2000)  =  18h 42m 09.4s
  Dec(J2000) = -30d 02' 27.1"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.

The mask-weighted light curve shows a complex structure with several
overlapping peaks that starts at ~T-1 s and ends at ~T+6 s. T90 (15-350 keV)
is 6.32 +- 0.96 sec (estimated error including systematics).

The time-averaged spectrum from T-0.92 to T+6.08 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.38 +- 0.32.  The fluence in the 15-150 keV band is 2.5 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.73 sec in the 15-150 keV band
is 0.8 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/741965/BA/


GRB_name: GRB170311A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20858
SUBJECT: GRB 170311A: VLT observations
DATE:    17/03/13 12:54:51 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DARK/NBI), H. Flores (GEPI/Paris obs.), A. J. Levan (Univ. 
Warwick), D. Xu (NAOC/CAS), N. R. Tanvir (Univ. Leicester), and J. P. U. 
Fynbo (DARK/NBI), report:

We observed the field of GRB 170311A (Cummings et al., GCN 20846) with 
the VLT/UT2 (Kueyen), using the acquisition camera of the X-shooter 
spectrograph. Observations started approximately on March 11.366 UT, 
that is around 38 min after the GRB trigger. Imaging was carried out 
using the SDSS z filter.

No source is detected within or close to the UVOT-enhanced XRT position 
(Osborne et al., GCN 20850), down to a 3-sigma limiting magnitude z = 21 
AB, calibrated against nearby stars from the Pan-STARRS catalog 
(Chambers et al. 2016, arXiv: 1612.05560). Our result is consistent with 
other reports (e.g., Wiseman & Schady, GCN 20853).

We acknowledge excellent support from the ESO observing staff at 
Paranal, in particular Marcelo Lopez, Joe Anderson, and George Hau. We 
also acknowledge the team of the Gaia-ESO survey (ESO program 
197.B-1074, PI Gilmore), for generously and consistently accepting to 
carry out ToO observations during their allocated nights.


GRB_name: GRB170311B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20859
SUBJECT: IPN Triangulation of GRB 170311B (long/very intense)
DATE:    17/03/13 18:56:23 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

A long-duration, very intense GRB 170311B
has been detected by Konus-Wind, Mars-Odyssey (HEND),
and Swift (BAT), so far, at about 49490 s UT (13:44:50).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   354.919 (23h 39m 40s) +31.187 (+31d 11' 14")
  Corners:
   355.382 (23h 41m 32s) +31.782 (+31d 46' 54")
   355.104 (23h 40m 25s) +31.806 (+31d 48' 21")
   354.474 (23h 37m 54s) +30.587 (+30d 35' 13")
   354.747 (23h 38m 59s) +30.567 (+30d 34' 01")
  ---------------------------------------------
The error box area is 1076 sq. arcmin, and its maximum
dimension is 1.42 deg (the minimum one is 13.4 arcmin).
The Sun distance was 34 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170311_T49504/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB170311B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20865
SUBJECT: Konus-Wind observation of GRB 170311B
DATE:    17/03/14 09:18:29 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long, very intense GRB 170311B (IPN triangulation:
Hurley et al., GCN 20859) triggered Konus-Wind
at T0=49504.661 s UT (13:45:04.661).

The burst light curve shows a bright, multi-peaked structure,
that is preceded and followed by a weaker emission.
The total duration of the burst is ~30 s.
The emission is seen up to ~8 MeV.

As observed by Konus-Wind, the burst had a fluence of
(8.0 Â± 0.6)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+5.888, of (2.5 Â± 0.3)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+15.360 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.61 (-0.06,+0.06),
the high energy photon index beta = -2.85 (-0.49,+0.25),
the peak energy Ep = 440 (-28,+30) keV,
chi2 = 105/97 dof.

The spectrum near the peak count rate (measured from T0+4.608
to T0+6.114 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.48 (-0.12,+0.13),
the high energy photon index beta = -2.60 (-0.44,+0.23),
the peak energy Ep = 408 (-48,+55) keV,
chi2 = 67/74 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170311_T49504/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB170311B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20872
SUBJECT: GRB 170311B: AstroSat CZTI detection
DATE:    17/03/15 13:58:30 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IITB), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB170311B (IPN Triangulation detection: K. Hurley et al., GCN Circ. 20859) in the 40-200 keV energy range. The light curve shows multiple peak structure with peak counts at 13:45:15.0 UT, ~10 s after Konus-Wind trigger (Konus-Wind observation: D. Frederiks et al., GCN Circ. 20865). For initial few seconds from the trigger time the light curve doesn't show excess counts above the background. The measured peak count rate is 412.9 counts/s above the background in combined data of four quadrants, with a total 1979 counts. The local mean background count rate was 378.1 counts/s. Using cumulative rates, we measure a T90 of 13.4 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170307A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20880
SUBJECT: GRB 170307A: 15 GHz upper limit from AMI
DATE:    17/03/16 15:14:11 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson 
(Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. 
Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. 
Grainge, A. Scaife (Manchester)

We observed the GRB 170307A detected by Swift (Lien et al., GCN 20832, 
Stamatikos et al. GCN 20838) and Fermi (Hui et al. GCN 20835) with the 
AMI Large Array at 15 GHz on 2016 Mar 13.57 (UT). We place a 3sigma 
upper limit of 90 uJy on the radio afterglow.

We thank the AMI staff for scheduling this observation. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170317A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20885
SUBJECT: GRB 170317A: Swift detection of a burst with an optical counterpart
DATE:    17/03/17 10:01:55 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

S. J. LaPorte (PSU), A. P. Beardmore (U Leicester),
B. Mingo (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:

At 09:45:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170317A (trigger=742866).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 93.088, +50.520 which is 
   RA(J2000) = 06h 12m 21s
   Dec(J2000) = +50d 31' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a FRED
structure with a duration of about 10 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 09:47:22.4 UT, 83.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 93.06317, 50.49431 which is equivalent
to:
   RA(J2000)  = 06h 12m 15.16s
   Dec(J2000) = +50d 29' 39.5"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 109 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.53
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 86 seconds after the BAT trigger. There is a candidate afterglow in
the list of sources generated on-board at
  RA(J2000)  = 06:12:14.78 =  93.06160
  DEC(J2000) = +50:29:34.8  =  50.49300
with a 90%-confidence error radius of about 1.10 arc sec. This position is 5.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.05. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.19. 

Burst Advocate for this burst is S. J. LaPorte (extragsam AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20886
SUBJECT: GRB 170317A: ISON-Ussuriysk aferglow confirmation
DATE:    17/03/17 13:06:50 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kochergin (UAFO), A. Volnova 
(IKI),  E. Chornaya  (UAFO),   A. Matkin (UAFO, ISON),  I. Molotov 
(KIAM)  report on behalf of larger GRB follow-up collaboration:

We observed the field of the GRB 170317A (LaPorte et al., GCN  20885) 
with SANTEL-650 (0.65m)  telescope of UAFO/ISON-Ussuriysk observatory 
starting on March, 17 (UT) 10:20:37. We obtained series of unfiltered 
images of 60 s exposure. In a first combined images we  detected optical 
afterglow (LaPorte et al., GCN  20885). Preliminary photometry of some 
initial combined image  is following

Date       UT start  t-T0   Filter  Exp.  OT     err  UL (3sigma)
                      (mid, days)    (s)

2017-03-17 10:20:37  0.0321 none   20*60  18.95  0.08 21.5

In comparison with early reported photometry (LaPorte et al., GCN 
20885) the OT is faded, and we confirm the afterglow of the GRB 170317A.

Photometry is based on nearby USNO-B1.0 stars

USNO_B1_id   R2
1405-0167482 15.08
1405-0167474 15.43
1405-0167493 16.10
1405-0167484 16.14
1404-0169177 15.93
1405-0167639 15.62
1405-0167631 15.69


GRB_name: GRB170317A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20887
SUBJECT: GRB 170317A: Enhanced Swift-XRT position
DATE:    17/03/17 13:22:50 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2369 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 170317A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 93.06206, +50.49305 which is equivalent
to:

RA (J2000): 06h 12m 14.89s
Dec (J2000): +50d 29' 35.0"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20888
SUBJECT: GRB 170317A : Xinglong TNT optical observation
DATE:    17/03/17 13:39:57 GMT
FROM:    L.P. Xin at NAOC  <xlp@nao.cas.cn>

L. P. Xin,  T. M. Zhang,  J. Y. Wei,  Y. L. Qiu,  J. S. Deng, 
J. Wang,  X. H. Hanï¼ŒC. Wu and E. W. Liang  reports:
 
We began to observe GRB 170317A (LaPorte et al., GCN 20885)  
with Xinglong  0.8-m TNT telescope at 2017-03-17,11:39:17 (UT), 
about  1.9 hours after the Swift trigger time. 
 
The optical afterglow reported ( LaPorte et al., GCN 20885; 
Mazaeva et al., GCN 20886)  was  clearly detected  in the 
stacked 11*300 sec R-band image.   
Preliminary analysis shows that  the brightness of the optical afterglow
in R band is about 19.8+/-0.1 mag,  calibrated by nearby USNO B1.0 objects
at the mid time of 2.3 hours after the burst.

This message could be cited. 

We thank the excellent support of the Xinglong 80cm TNT staff, particularly S. Liu


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20889
SUBJECT: GRB 170317A: GMG observation
DATE:    17/03/17 14:58:21 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, Y. Xin and J.-M. Bai (YNAO) report:


We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with the 2.4-meter
optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatories. Observations began
from 13:58:18 UT, about 4.2 hours after the trigger. We detected the afterglow with
R~19.96+/-0.10 mag, calibrated by a nearby USNO-B1.0 star.


GRB_name: GRB170317A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20891
SUBJECT: GRB 170317A: Swift-XRT refined Analysis
DATE:    17/03/17 15:46:59 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), B.
Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia
(ASDC) and  report on behalf of the Swift-XRT team: report on behalf of
the Swift-XRT team:

We have analysed 6.9 ks of XRT data for GRB 170317A, from 68 s to 13.5
ks after the  BAT trigger. The data comprise 8 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode. 

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.8 (+4.2, -1.4). At T+105 s  the decay
flattens to an alpha of 0.58 (+0.07, -0.09) before breaking again at
T+3006 s to a final decay with index alpha=1.4 (+0.4, -0.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.05 (+0.10, -0.07). The
best-fitting absorption column is  consistent with the Galactic value
of 2.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.5 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.5 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.05 (+0.10, -0.07)

If the light curve continues to decay with a power-law decay index of
1.4, the count rate at T+24 hours will be 2.2 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.9 x
10^-14 (1.1 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00742866.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170317A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20892
SUBJECT: GRB 170317A: MITSuME Okayama Ks-band upper-limit
DATE:    17/03/17 16:39:39 GMT
FROM:    Kenshi Yanagisawa at OAO/NAOJ  <yanagi@oao.nao.ac.jp>

K. Yanagisawa, D. Kuroda, Y. Shimizu, H. Izumiura (OAO/NAOJ),
M. Yoshida (Hiroshima), K. Ohta(Kyoto) and N. Kawai (Tokyo Tech.)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 170317A (LaPorte et al., GCN 20885)
in Ks-band with a wide-field near infrared imager at Okayama
Astrophysical Observatory (Japan).  The imager has effective
aperture of 0.91 m.

Observations started from 09:54 UT on 17th March, 8 min after
the BAT trigger, to 10:38 UT. The total exposure of 17.0 min
was successfully obtained.

In our co-add image, we did not find any new point source within
the XRT error circle (Beardmore et al., GCN 20887) down to
the limiting magnitude of Ks=16.1 (Vega, S/N=5). The photometric
calibration was made against 2MASS field stars.

T0+[sec]    MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
   +1,819    10:16      1020.0          >16.1
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20893
SUBJECT: GRB 170317A: Mondy optical observations
DATE:    17/03/17 16:48:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova
(IKI)  report on behalf of larger GRB follow-up collaboration:

We observed the field of  GRB 170317A (LaPorte et al., GCN  20885) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on  March, 17 
(UT) 13:56:13. We obtained 60 of 60 s exposure images in R-filter.
The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN 
20886; Xin et al., GCN 20888; Mao  et al., GCN 20889) is clearly visible 
in stacked images. Preliminary photometry of the afterglow is following

Date       UT start   t-T0    Filter  Exp.     OT     Err.  UL
                      (mid, days)      (s)

2017-03-17 13:56:13  0.18073  R      20*60    20.94  0.10  22.5

The photometry is based on nearby USNO-B.10 stars
Ref.stars
USNO_B1_id   R2
1405-0167493 16.10
1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25


GRB_name: GRB170317A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20894
SUBJECT: GRB 170317A: Swift/UVOT Detection
DATE:    17/03/17 17:00:57 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and S. J. LaPorte (PSU) report on behalf of
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB
170317A 87 s after the BAT trigger (LaPorte et al., GCN Circ.20885).
A fading source consistent with the XRT position (Beardmore et al.
GCN Circ. 20887) is detected in the initial UVOT exposures. The GRB
afterglow was also observed by Mazaeva et al. (GCN Circ. 20886) and
Mao et al. (GCN. Circ. 20889) in the R band.

The preliminary UVOT position is:
    RA  (J2000) =  06:12:14.82 =  93.06173 (deg.)
    Dec (J2000) = +50:29:35.2  =  50.49310 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT
photometric system  (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)
for the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               87          237          147         17.53 +/- 0.04
v                  629         1597          117         18.36 +/- 0.19
b                  554         1349           78         19.12 +/- 0.19
u                  299          549          246         17.75 +/- 0.07
w1                 678         7320          588         20.20 +/- 0.29
m2                 653         7115          398        >19.8
w2                 604         8141          607        >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170317A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20896
SUBJECT: GRB 170317A: Swift-BAT refined analysis
DATE:    17/03/17 21:02:25 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170317A (trigger #742866)
(LaPorte et al., GCN Circ. 20885).  The BAT ground-calculated position is
RA, Dec = 93.087, 50.500 deg which is
  RA(J2000)  =  06h 12m 21.0s
  Dec(J2000) = +50d 30' 00.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The mask-weighted light curve shows a FRED-like pulse that starts at
~T-2 s, peaks at ~ T+2 s, and ends at ~T+18 s. T90 (15-350 keV) is
11.94 +- 4.87 sec (estimated error including systematics).

The time-averaged spectrum from T-0.29 to T+18.29 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.80 +- 0.49,
and Epeak of 58.8 +- 10.5 keV (chi squared 75.18 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+1.28 sec in the 15-150 keV band is
3.5 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.78 +- 0.10 (chi squared 89.59 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/742866/BA/


GRB_name: GRB170317A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20899
SUBJECT: GRB 170317A: MITSuME Okayama Optical Observation
DATE:    17/03/18 00:11:10 GMT
FROM:    Daisuke Kuroda at OAO/NAOJ  <dikuroda@oao.nao.ac.jp>

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME and OISTER collaboration:

We observed the field of GRB 170317A (LaPorte et al., GCNC 20885)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2017-03-17 10:14:19 UT (~28 min after
the burst). We detected the previously reported afterglow (LaPorte
et al., GCNC 20885; Mazaeva et al., GCNC 20886) in Rc and Ic bands.

Three sigma upper limit and photometric results of the OT are
listed below. We used GSC2.3 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'     Rc   Rc_err  Ic   Ic_err
------------------------------------------------------------------
0.06138    11:14:22    6120.0     >20.5  19.3 0.2     19.2 0.3"
------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20901
SUBJECT: GRB 170317A: LCO FTN observations
DATE:    17/03/18 09:56:26 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large 
collaboration report:

We observed Swift GRB 170317A (LaPorte et al. GCN 20885) on March 18, 
06:01 UT (0.84 days since the GRB) with the 2-m LCO Faulkes Telescope 
North with SDSS r and i filters. We marginally detect the optical 
afterglow (LaPorte et al.; Mazaeva et al. GCN 20886, 20893; Xin et al. 
GCN 20888; Mao et al. GCN 20889, 20890; Kuin et al. GCN 20894) in the r 
filter with the following values:

Mid Time      Exposure       Filter       Magnitude (AB)
(days)           (s)
-------------------------------------------------------
0.87          10x120          SDSS-R        22.9 +- 0.3
0.88          10x120          SDSS-I        > 22.0
-------------------------------------------------------

as calibrated against nearby PanSTARRS-1 DR1 objects.


GRB_name: GRB170318A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20904
SUBJECT: GRB 170318A: Swift detection of a burst
DATE:    17/03/18 12:29:49 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

B. Sbarufatti (INAF-OAB/PSU), D. N. Burrows (PSU), J. A. Kennea (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 12:11:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170318A (trigger=743065).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 305.645, +28.409 which is 
   RA(J2000) = 20h 22m 35s
   Dec(J2000) = +28d 24' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 12:13:44.4 UT, 108.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 305.66565,
28.40652 which is equivalent to:
   RA(J2000)  = 20h 22m 39.76s
   Dec(J2000) = +28d 24' 23.5"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 65 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 4.45
x 10^21 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 6.78e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 116 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the large, but uncertain extinction expected. 

Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170318A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20905
SUBJECT: GRB 170318A: Prompt enhanced Swift-XRT position
DATE:    17/03/18 13:00:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 170318A, we find an
enhanced XRT position of the afterglow: RA, Dec: 305.6668, 28.4066
which is equivalent to:
   RA (J2000)  = 20 22 40.03
   Dec (J2000) = +28 24 23.7
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/743065.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170315A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20906
SUBJECT: GRB 170315A: POLAR observation
DATE:    17/03/18 14:09:08 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

H.L. Xiao (PSI), R. Marcinkowski (PSI)  and W. Hajdas (PSI) report on behalf of the POLAR collaboration:

At 2017-03-15 13:57:53.0 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170315A,
which was also observed by Fermi GBM (trigger # 511279081).

The POLAR light curve consists of multiple peaks with duration (T90) of 7.00 +/- 1.00 s measured from T0.
The 1.00 s peak flux at T0 + 4.50 s  is equal to 830 +/- 80 counts/sec.
POLAR recorded 3130 events from the burst.
Above measurements are in the energy range of about 15 - 300 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170315A_raw.png
     or http://polar.psi.ch/pub/lc.php?event=GRB+170315A

Using the best location from Fermi GBM, which is (J2000):
RA : 230.39 [deg]
Dec: 60.34 [deg]
Error: 9.18
the incident angle in the POLAR coordinate at T0 is:
Theta: 49.83 [deg]
Phi: 291.93 [deg]


The analysis results presented above are preliminary. POLAR is a dedicated Gamma-Ray Burst polarimeter which was launched on-board the Chinese space
laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV.
More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .

This message is quotable in publications.


GRB_name: GRB170318A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20907
SUBJECT: GRB 170318A: Enhanced Swift-XRT position
DATE:    17/03/18 15:27:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2006 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170318A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 305.66732, +28.40600 which is equivalent
to:

RA (J2000): 20h 22m 40.16s
Dec (J2000): +28d 24' 21.6"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170318B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20908
SUBJECT: GRB 170318B: Swift detection of a burst
DATE:    17/03/18 15:39:36 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Cholden-Brown (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. A. Kennea (PSU), H. A. Krimm (CRESST/NSF/USRA),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 15:27:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170318B (trigger=743086).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 284.279, +6.269, which is 
   RA(J2000)  =  18h 57m 07s
   Dec(J2000) = +06d 16' 10"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 3 sec.  The peak count rate
was ~1900 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 15:29:06.3 UT, 73.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 284.30606, 6.29833
which is equivalent to:
   RA(J2000)  = 18h 57m 13.45s
   Dec(J2000) = +06d 17' 54.0"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 141 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data does not constrain the column density. 

The initial flux in the 2.5 s image was 5.39e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 84 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the large, but uncertain extinction expected. 

Burst Advocate for this burst is A. Cholden-Brown (aaronb AT swift.psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170318B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20909
SUBJECT: GRB 170318B: Prompt enhanced Swift-XRT position
DATE:    17/03/18 16:17:21 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 170318B, we find an
enhanced XRT position of the afterglow: RA, Dec: 284.3062, 6.2994 which
is equivalent to:
   RA (J2000)  = 18 57 13.49
   Dec (J2000) = +06 17 57.9
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/743086.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170318B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20910
SUBJECT: GRB 170318B: Enhanced Swift-XRT position
DATE:    17/03/18 17:06:50 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 839 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170318B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 284.30611, +6.29924 which is equivalent
to:

RA (J2000): 18h 57m 13.47s
Dec (J2000): +06d 17' 57.3"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170317A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20911
SUBJECT: GRB 170317A: RATIR Optical and NIR Observations
DATE:    17/03/18 17:10:21 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler@gmail.com>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM),  Harvey Moseley
(GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD)
report:

We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/03 18.13 to 2017/03 18.30 UTC (17.37 to
21.38 hours after the BAT trigger), obtaining a total of 2.84 hours
exposure in the r and i bands and 1.19 hours exposure in the Z, Y, J, and H
bands.

For a source within the enhanced Swift-XRT error circle (Beardmore et al.,
GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we obtain
the following detections and 3-sigma upper limits:

  r     22.85 +/- 0.05
  i     22.86 +/- 0.09
  Z     22.92 +/- 0.30
  Y     22.34 +/- 0.26
  J     22.41 +/- 0.35
  H     > 21.95

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170318A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20912
SUBJECT: GRB 170318A: Swift-BAT refined analysis
DATE:    17/03/18 18:57:59 GMT
FROM:    Hans Krimm at NASA-GSFC/NSF  <hans.krimm@nasa.gov>

J. R. Cummings (CPI),S. D. Barthelmy (GSFC), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA),A. Y. Lien (GSFC/UMBC),C. B. Markwardt (GSFC),
D. M. Palmer (LANL),T. Sakamoto (AGU),B. Sbarufatti (INAF-OAB/PSU),
M. Stamatikos (OSU),T. N. Ukwatta (LANL)(i.e. the Swift-BAT team):

Using the data set from T-239 to T+483 sec from the recent telemetry 
downlink,
we report further analysis of BAT GRB 170318A (trigger #743065)
(Sbarufatti, et al., GCN Circ. 20904). The BAT ground-calculated 
position is
RA, Dec = 305.662, 28.408 deg which is
    RA(J2000)  =  20h 22m 38.9s
    Dec(J2000) = +28d 24' 30.5"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.

The mask-weighted light curve shows a single FRED-shaped pulse that starts
approximately T+20 sec, peaks at T+2 sec and decays to background by
T+100 sec.  T90 (15-350 keV) is 133.7 +- 42.8 sec (estimated error 
including systematics).

The time-averaged spectrum from -21.544 to 175.788 sec is best fit by a 
simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.11.  The fluence in the 15-150 keV band is 3.7 +- 0.3 x 
10^-06erg/cm2.
The 1-sec peak photon flux measured from T+1.87 sec in the 15-150 keV band
is 1.2 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/743065/BA/


GRB_name: GRB170318B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20913
SUBJECT: GRB 170318B: Fermi GBM observation
DATE:    17/03/18 20:28:15 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:

"At 15:27:53.09 UT on 18 March 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170318B (trigger 511543678 / 170318644).
which was also detected by the Swift/BAT
(Cholden-Brown et al. 2008, GCN 20908)
The GBM on-ground location is consistent with the Swift position.


The angle from the Fermi LAT boresight at the GBM trigger time is 93 degrees.


The GBM light curve shows  a single peak
with a duration (T90) of about 4 s (50-300 keV).
The time-averaged spectrum from T0-3.3 s to T0+1.8 s is
adequately fit by a simple power law function with index -1.40 +/- 0.10.


The event fluence (10-1000 keV) in this time interval is
(8.0 +/- 1.4)E-7 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.8 s in the 10-1000 keV band
is 1.9 +/- 0.2 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170318A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20914
SUBJECT: GRB 170318A: Swift/UVOT Upper Limits
DATE:    17/03/18 21:27:48 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (INAF-OAB/PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170318A
117 s after the BAT trigger (Sbarufatti et al., GCN Circ. 20904).
No optical afterglow consistent with the XRT position (Evans et al. GCN 
Circ. 20907) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           117          266          147         >20.4
u_FC               329          552          220         >19.6
white              117         6605          363         >20.8
v                 2222         2241           19         >17.0
b                 2147         6400          216         >19.8
u                  329         6195          417         >20.1
w1                5790         5990          197         >19.4
m2                5585         5784          197         >19.3
w2                2197        11766          560         >20.4

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.97 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB170318A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20915
SUBJECT: GRB 170318A: RATIR Optical and NIR Observations
DATE:    17/03/18 22:08:37 GMT
FROM:    Nat Butler at Az State U  <natbutler@asu.edu>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 170318A (Sbarufatti, et al., GCN 20904) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional
on Sierra San Pedro MÃ¡rtir from 2017/03 18.51 to 2017/03 18.53 UTC (3.0 to
27.6 minutes after the BAT trigger), obtaining a total of 0.24 hours
exposure in the r and i bands and 0.11 hours exposure in the Z, Y, J, and H
bands.

We do not detect a source within the Swift-XRT error circle (Evans, et al.,
GCN 20907).  In comparison with the USNO-B1 and 2MASS catalogs, we obtain
the following upper limits (3-sigma):

 r > 23.39
 i > 22.82
 Z > 21.72
 Y > 21.56
 J > 21.12
 H > 20.73

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  We note that this field suffers
large Galactic extinction (A_V~3).

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170318A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20917
SUBJECT: GRB 170318A: Swift-XRT refined Analysis
DATE:    17/03/19 04:03:37 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester),
P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo
(INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti
(INAF-OAB/PSU) and  report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 7.0 ks of XRT data for GRB 170318A, from 98 s to 41.1
ks after the  BAT trigger. The data comprise 94 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The light curve can be modelled with an initial power-law decay with an
index of alpha=1.09 (+0.51, -0.29), followed by a break at T+208 s to
an alpha of 2.74 (+0.76, -0.17).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 0.84 (+0.20, -0.19). The
best-fitting absorption column is  6.3 (+2.7, -1.9) x 10^21 cm^-2,
consistent with the Galactic value of 4.4 x 10^21 cm^-2 (Willingale et
al. 2013). The PC mode spectrum has a photon index of 0.92 (+0.35,
-0.30) and a best-fitting absorption column of 6.4 (+4.6, -1.9) x 10^21
cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 8.3 x 10^-11 (9.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.4 (+4.6, -1.9) x 10^21 cm^-2
Galactic foreground: 4.4 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      0.92 (+0.35, -0.30)

If the light curve continues to decay with a power-law decay index of
2.74, the count rate at T+24 hours will be 4.0 x 10^-7 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x
10^-17 (3.8 x 10^-17) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00743065.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170318B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20918
SUBJECT: GRB 170318B: Swift-XRT refined Analysis
DATE:    17/03/19 05:09:13 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U.
Leicester), J.P. Osborne (U. Leicester), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU),
D.N. Burrows (PSU) and report on behalf of the Swift-XRT team: report
on behalf of the Swift-XRT team:

We have analysed 7.2 ks of XRT data for GRB 170318B, from 64 s to 41.1
ks after the  BAT trigger. The data comprise 95 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The light curve can be modelled with an initial rise, with a power-law
index of alpha=-0.5 (+0.4, -0.5), followed by a break at T+134 s  to an
alpha of 2.96 (+0.16, -0.15).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.6 (+/-0.4). The
best-fitting absorption column is  6.4 (+1.7, -1.4) x 10^22 cm^-2, in
excess of the Galactic value of 1.4 x 10^22 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.3 (+/-0.6) and a
best-fitting absorption column of 6.2 (+2.1, -1.7) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 8.0 x 10^-11 (3.5 x 10^-10) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.2 (+2.1, -1.7) x 10^22 cm^-2
Galactic foreground: 1.4 x 10^22 cm^-2
Excess significance: 4.6 sigma
Photon index:      2.3 (+/-0.6)

If the light curve continues to decay with a power-law decay index of
2.96, the count rate at T+24 hours will be 4.5 x 10^-8 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x
10^-18 (1.6 x 10^-17) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00743086.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170318B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20919
SUBJECT: GRB 170318B: Swift/UVOT Upper Limits
DATE:    17/03/19 08:56:36 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and A. Cholden-Brown (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170318B
84 s after the BAT trigger (Cholden-Brown et al., GCN Circ. 20908).
No optical afterglow consistent with the XRT position (Goad et al. GCN 
Circ. 20910) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            84          234          147         >20.4
u_FC               296          546          246         >19.8
white               84         6145          530         >21.0
v                  626         6557          432         >19.4
b                  552         5940          236         >20.0
u                  296         7172          659         >20.2
w1                 675         6967          432         >19.9
m2                5123         5323          197         >19.3
w2                 601         6352          216         >19.6

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 4.51 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB170317A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20920
SUBJECT: GRB 170317A: RATIR Optical and NIR Observations 
DATE:    17/03/19 15:18:09 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy
(UMD) report:

We observed the field of GRB 170317A (LaPorte et al., GCN 20885) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico
Nacional on Sierra San Pedro MÃ¡rtir from 2017/03 19.13 to 2017/03 19.30
UTC (41.26 to 45.37 hours after the BAT trigger), obtaining a total of
2.84 hours exposure in the r and i bands and 1.19 hours exposure in the
Z, Y, J, and H bands.

For a source within the enhanced Swift-XRT error circle (Beardmore et
al., GCN 20887), in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following detections and 3-sigma upper limits:

 r 23.70 +/- 0.10
 i 23.93 +/- 0.26
 Z > 23.07
 Y > 22.51
 J > 22.27
 H > 21.75

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

The source has faded by about a magnitude in r and i since our earlier
observations (Watson et al., GCN 20911).

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170318B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20921
SUBJECT: GRB 170318B: RATIR Optical and NIR Observations
DATE:    17/03/19 17:09:31 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy
(UMD) report:

We observed the field of GRB 170318B (Cholden-Brown et al., GCN 20908)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir from 2017/03 19.47 to
2017/03 19.51 UTC (19.76 to 20.76 hours after the BAT trigger),
obtaining a total of 0.71 hours exposure in the r and i bands and 0.30
hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT enhanced error circle (Goad et al.,
GCN 20910), in comparison with the USNO-B1 and 2MASS catalogs, we obtain
the following upper limits (3-sigma):

 r    > 25.64
 i    > 24.39
 Z    > 22.65
 Y    > 22.43
 J    > 21.38
 H    > 20.98

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170317A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20922
SUBJECT: GRB 170317A: POLAR observation
DATE:    17/03/19 19:12:35 GMT
FROM:    Haulin Xiao at PSI/POLAR  <hualin.xiao@psi.ch>

H.L. Xiao (PSI), W. Hajdas (PSI) and R. Marcinkowski (PSI)  report on behalf of the POLAR collaboration:

At 2017-03-17 09:45:56.0 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170317A
(Swift BAT (trigger # 742866); LaPorte et al., GCN 20885).


The POLAR light curve consists of one peak with duration (T90) of 6.00  1.00 s measured from T0.
The 1.00 s peak flux at T0 + 5.50 s  is equal to 370  50 counts/sec.
POLAR recorded 1500 events from the burst.
Above measurements are in the energy range of about 15 - 300 keV.

LC_URL: http://polar.psi.ch/triggers/GRB_170317A.png

Using the best location from Swift-BAT, which is (J2000):
RA : 93.087 [deg]
Dec: 50.500 [deg]
the incident angle in the POLAR coordinate at T0 is:
Theta: 81.38 [deg]
Phi: 4.61 [deg]

The analysis results presented above are preliminary. POLAR is a dedicated Gamma-Ray Burst polarimeter which was launched on-board the Chinese space
laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV.
More information about POLAR can be found at http://polar.psi.ch/pub ,
http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ .

This message is quotable in publications.


GRB_name: GRB170318B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20923
SUBJECT: GRB 170318B: Swift-BAT refined analysis
DATE:    17/03/20 01:21:46 GMT
FROM:    Hans Krimm at NASA-GSFC/NSF  <hans.krimm@nasa.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), A. Cholden-Brown (PSU),
J. R. Cummings (CPI), N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry 
downlink,
we report further analysis of BAT GRB 170318B (trigger #743086)
(Cholden-Brown, et al., GCN Circ. 20908).  The BAT ground-calculated 
position is
RA, Dec = 284.229, 6.335 deg which is
    RA(J2000)  =  18h 56m 54.9s
    Dec(J2000) = +06d 20' 04.5"
with an uncertainty of 3.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.

The mask-weighted light curve shows an initial symmetric pulse of 
duration ~20 sec
from about T-15 sec to T+5 sec.  This is followed by low-level extended 
emission from
~T+30 to T+160 sec. T90 (15-350 keV) is 160.0 +- 35.8 sec (estimated 
error including systematics).

The time-averaged spectrum from T-15.33 to T+160.67 sec is best fit by a 
simple
power-law model.  The power law index of the time-averaged spectrum is
1.84 +- 0.59.  The fluence in the 15-150 keV band is 5.5 +- 1.9 x 10^-7 
erg/cm2.
The 1-sec peak photon flux measured from T-7.83 sec in the 15-150 keV band
is 0.1 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/743086/BA/


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20924
SUBJECT: GRB 170317A: Mondy optical observations
DATE:    17/03/20 15:19:06 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Volnova (IKI) 
  report on behalf of larger GRB follow-up collaboration:

We observed the field of  GRB 170317A (LaPorte et al., GCN  20885) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on  March, 18 
(UT) 14:57:48. We several images in R-filter.
The optical afterglow (LaPorte et al., GCN 20885; Mazaeva et al., GCN 
20886; Xin et al., GCN 20888; Mao  et al., GCN 20889) is visible in 
stacked images. Preliminary photometry of the afterglow is following

Date       UT start   t-T0    Filter  Exp.     OT     Err.  UL
                      (mid, days)      (s)

2017-03-18 14:57:48  1.23738  R       30*120   23.25  0.22  23.6

The photometry is based on nearby USNO-B.10 stars
Ref.stars
USNO_B1_id   R2

1405-0167631 15.69
1404-0169027 16.03
1405-0167512 16.85
1404-0169128 16.25


GRB_name: GRB170318A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20925
SUBJECT: GRB 170318A: KAIT Optical Upper Limit
DATE:    17/03/20 19:32:13 GMT
FROM:    Max Genecov at UC Berkeley  <mgenecov@berkeley.edu>

Max Genecov, WeiKang Zhang, and Alex Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:


The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 170318A (Sbarufatti, et al.,
GCN 20904) starting at 12:33:14 UT, ~23 minutes after the burst.
The target was at low elevation but rising. Observations were performed
with an automatic sequence in the clear (roughly R) and I filters, and
the exposure time was 20 s per image. We do not detect any optical
source within the XRT error circle (Evans, et al., GCN 20907).
The limiting magnitude of the co-added clear band image is ~17.6 at
a mid-time of 39.7 minutes after the burst.


GRB_name: GRB170320A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20927
SUBJECT: IPN Triangulation of GRB 170320A (long/intense)
DATE:    17/03/21 21:30:55 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

A long-duration, intense GRB 170320A has been detected by
Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift (BAT),
so far, at about 13359 s UT (03:42:39).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   320.074 (21h 20m 18s) +55.060 (+55d 03' 35")
  Corners:
   320.632 (21h 22m 32s) +57.567 (+57d 34' 00")
   320.255 (21h 21m 01s) +57.396 (+57d 23' 46")
   319.649 (21h 18m 36s) +52.549 (+52d 32' 57")
   319.971 (21h 19m 53s) +52.726 (+52d 43' 35")
  ---------------------------------------------
The error box area is 3245 sq. arcmin, and its maximum
dimension is 5.05 deg (the minimum one is 11.2 arcmin).
The Sun distance was 62 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170320_T13359/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB170320A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20934
SUBJECT: GRB 170320A: POLAR Observation
DATE:    17/03/23 06:15:20 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Yi Zhao (IHEP), Yuanhao Wang (IHEP), Zhengheng Li (IHEP)
report on behalf of the POLAR collaboration:


At 2017-03-20T03:42:39.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170320A, 
which was also detected by INTEGRAL/SPIACS (ID 170320.15474)
and the KONUS-Wind.


The POLAR light curve consists of a single peak,
with a duration (T90) of 5.74 s measured from T0+2.79 s.
The 1-s peak rate measured from T0+3.00 s is 2258.1 cnts/s.
The total counts is about 5844 cnts. 


LC_URL:
http://polar.ihep.ac.cn/grb/2017/03/GRB170320A/lc/POLAR_lc_grb170320A.png


The above results are not dead time corrected. The above
measurements are in the energy range of about 80-500 keV.


All analysis results presented above are preliminary.


POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170320A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20935
SUBJECT: Konus-Wind observation of GRB 170320A
DATE:    17/03/23 11:06:28 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, intense GRB 170320A
(IPN Triangulation: Hurley et al., GCN 20927;
POLAR Observation: Zhao et al., GCN 20934)
triggered Konus-Wind at T0=13359.957 s UT (03:42:39.957).

The burst light curve shows a multipeaked structure with a total
duration of ~30 s.
The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.87(-0.30,+0.34)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.592 s,
of 1.01(-0.19,+0.20)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+35.072 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.35(-0.15,+0.21),
the high energy photon index beta = -2.41(-0.46,+0.22),
the peak energy Ep = 111(-22,+23) keV,
chi2 = 99/97 dof.

The spectrum near the peak count rate
(measured from T0 to T0+2.304 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.52(-0.17,+0.20),
the high energy photon index beta = -2.21(-0.18,+0.13),
the peak energy Ep = 178(-24,+29) keV,
chi2 = 79/69 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170320_T13359/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170325A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20938
SUBJECT: GRB 170325A, Swift-BAT detection of a short GRB
DATE:    17/03/26 04:36:10 GMT
FROM:    David Palmer at LANL  <dmopalmer@gmail.com>

GRB 170325A, Swift-BAT detection of a short GRB
 
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), 
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
GRB 170325A was detected by Swift/BAT at 2017-03-25 07:56:57.95 UTC.  
Because the spacecraft was slewing at that time, there was no onboard triggers, 
and the burst was found later in the ground analysis in response to
Fermi-GBM trigger #512121423.

Using the data set from T-16 to T+92 sec from the recent telemetry downlink,
The BAT ground-calculated position is
RA, Dec = 127.483, 20.526 deg which is 
   RA(J2000)  =  08h 29m 55.9s 
   Dec(J2000) = +20d 31' 32.5" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
 
The mask-weighted light curve shows a single FRED-like pulse that
starts and peaks at ~T0, and ends at ~T+0.4 s. T90 (15-350 keV) is 0.3 +- 0.1 sec 
(estimated error including systematics).
 
The time-averaged spectrum from T+0.0 to T+0.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.06 +- 0.26.  The fluence in the 15-150 keV band is 8.8 +-1.3 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band
is 1.1 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 


GRB_name: GRB170325A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20940
SUBJECT: GRB 170325A: Fermi GBM observation
DATE:    17/03/27 17:35:41 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari), M. Stanbro,
and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 07:56:58.04 UT on 25 March 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170325A (trigger 512121423/170325331),
which was also detected by the Swift/BAT (Palmer et al. 2017, GCN 20938).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 60 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 0.58 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.192 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.7 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 600 +/- 200 keV.

The event fluence (10-1000 keV) in this time interval is
(4.8 +/- 0.6)E-7 erg/cm^2. The 64-ms peak photon flux, measured
starting from T0 in the 10-1000 keV band, is 7.6 +/- 1.1 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170325B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20941
SUBJECT: GRB 170325B: POLAR Observation
DATE:    17/03/29 06:04:37 GMT
FROM:    Wen Xing at POLAR  <wenxing@ihep.ac.cn>

Xing Wen (IHEP), Yi Zhao (IHEP), Yuanhao Wang (IHEP), 
report on behalf of the POLAR collaboration:

At 2017-03-25T21:50:01.00 UT (T0), during a routine on-ground 
search of data, POLAR detected the GRB 170325B, 
which was also detected by KONUS-Wind.

The POLAR light curve consists of a single peak,
with a duration (T90) of 6.47 s measured from T0+2.80 s.
The 500-ms peak rate measured from T0+4.50 s is 557.2 cnts/s.
The total counts is about 1196 cnts. 

LC_URL:
http://polar.ihep.ac.cn/grb/2017/03/GRB170325B/lc/POLAR_lc_grb170325B.png

The above results are not dead time corrected. The above
measurements are in the energy range of about 80-500 keV.

All analysis results presented above are preliminary.

POLAR is a dedicated Gamma-Ray Burst polarimeter (50-500 keV)
on-board the Chinese space laboratory Tiangong-2 launched on
Sep 15,2016. More information about POLAR can be found at 
http://polar.ihep.ac.cn/en/ , http://isdc.unige.ch/polar/
and http://polar.psi.ch/pub/.


GRB_name: GRB170329A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20942
SUBJECT: GRB 170329A: Fermi-LAT detection
DATE:    17/03/29 15:31:29 GMT
FROM:    Manal Yassine at IN2P3/LUPM/CNRS  <manal.yassine@lupm.in2p3.fr>

M. Yassine (LUPM, Montpellier) ,E. Bissaldi (Politecnico & INFN Bari), 
G. Vianello (Stanford), J. L. Racusin (NASA/GSFC),
F. Longo (University and INFN, Trieste) and N. Omodei (Stanford) report 
on behalf of the Fermi-LAT team:

At 09:17:06.94 UT on March 29, 2017, Fermi-LAT detected high-energy 
emission from GRB 170329A, which was also detected by Fermi-GBM 
(170329387/512471831).

The best LAT on-ground location is found to be RA, Dec 356.6, 9.8 
(degrees, J2000) with an error radius of 0.6 deg (90% containment, 
statistical error only).
This was 33 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event 
rate that is spatially and temporally consistent with the GBM emission.
More than 37 photons above 100 MeV  observed within 1 ks.
The highest-energy photon is a 0.8 GeV event which is observed 4 seconds 
after the GBM trigger.

The Fermi-LAT point of contact for this burst is Manal Yassine 
(manal.yassine@lupm.in2p3.fr).

The Fermi-LAT is a pair conversion telescope designed to cover the 
energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between NASA and DOE 
in the U.S. and many scientific institutions across France, Italy, Japan 
and Sweden.


GRB_name: GRB170329A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20943
SUBJECT: GRB 170329A: Fermi GBM detection
DATE:    17/03/30 04:07:55 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

E.Bissaldi (Politecnico & INFN Bari), O.J.Roberts (USRA/MSFC) 
and C.Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 09:17:06.94 UT on 29 March 2017, the Fermi Gamma-Ray Burst Monitor 
triggered and located GRB 170329A (trigger 512471831 / 170329387),
which was also detected by the LAT (Yassine et al. 2017, GCN 20942)
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 33 degrees.

The GBM light curve consists of a bright peak
with a duration (T90) of 33.5 s (50-300 keV).
The time-averaged spectrum from T0+0 s to T0+33.5 s is 
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.61 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 799 +/- 86 keV

The event fluence (10-1000 keV) in this time interval is
(1.45 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.3 s in the 10-1000 keV band
is 5.2 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170330A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20944
SUBJECT: GRB 170330A: Swift detection of a burst
DATE:    17/03/30 22:43:47 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

P. D'Avanzo (INAF-OAB), S. D. Barthelmy (GSFC),
A. Cholden-Brown (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:

At 22:29:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170330A (trigger=744773).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 283.326, -13.437, which is 
   RA(J2000)  =  18h 53m 18s
   Dec(J2000) = -13d 26' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 10 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 22:31:29.6 UT, 98.4 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 283.3323, -13.4301 which is equivalent to:
   RA(J2000)  = +18h 53m 19.75s
   Dec(J2000) = -13d 25' 48.4"
with an uncertainty of 5.9 arcseconds (radius, 90% containment). This
location is 33 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 108 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. Because of the density of catalogued stars, further
analysis is required to report an upper limit for any afterglow in the
sub-image. The 8'x8' region for the list of sources generated on-board covers
100% of the XRT error circle. Because of the density of catalogued stars,
further analysis is required to report an upper limit for any afterglow in the
region. No correction has been made for the expected extinction corresponding
to E(B-V) of 0.45. 

Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170330A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20945
SUBJECT: GRB 170330A: Prompt enhanced Swift-XRT position
DATE:    17/03/30 23:13:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 170330A, we find an
enhanced XRT position of the afterglow: RA, Dec: 283.3308, -13.4310
which is equivalent to:
   RA (J2000)  = 18 53 19.39
   Dec (J2000) = -13 25 51.7
with an uncertainty of 2.0 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/744773.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170331A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20946
SUBJECT: GRB 170331A: Swift detection of a burst
DATE:    17/03/31 01:53:22 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
P. D'Avanzo (INAF-OAB), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL)
and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 01:40:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170331A (trigger=744791).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 323.782, -24.414, which is 
   RA(J2000)  =  21h 35m 08s
   Dec(J2000) = -24d 24' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a complicated set of overlapping
peaks with a total duration of about 25 sec.  The peak count rate
was ~1400 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 01:42:50.6 UT, 124.2 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 323.79260, -24.38604 which
is equivalent to:
   RA(J2000)  = 21h 35m 10.22s
   Dec(J2000) = -24d 23' 09.7"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 105 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (4.65 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.1
(+3.11/-2.65) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 127 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.05. 

Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170327A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20947
SUBJECT: Fermi trigger 512347439/GRB 170327A: MASTER-SAAO possible OT detection
DATE:    17/03/31 02:30:06 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, A.V.Krylov, 
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, V.Vladimirov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU

D.Buckley
South African Astronomical Observatory

R. Rebolo, M. Serra,
The Instituto de Astrofisica de Canarias


R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , 
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina


O.Gress, N.M.Budnev, K.Ivanov 
Irkutsk State University

V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory


MASTER-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was pointed to the  Fermi trigger 512347439/GRB 
170327A (ra=18 26 16 dec=-33 27 00 r=5.3167)  2823 sec after notice time 
and 2870 sec after trigger time at 2017-03-27 23:31:45 UT in inspection 
mode.


MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic  Net",
Advances in Astronomy, 2010, 30L ) discovered OT source
MASTER OT J184546.55-352847.6 
at (RA, Dec) = 18h 45m 46.55s -35d 28m 47.6s on 2017-03-28.06645 UT/

The OT's unfiltered magnitude is 17.0m (mlim=19.0).
There are only 2 images of this area (MASTER inspection mode) and OT is 
seen in both images on
Tstart=2017-03-28 01:35:41UT and
Tstart=2017-03-28 01:42:14UT with exposition duration 60s (each).

There is no minor planet at this place except (208700)_2002_JK with 
Vmag=20.4 and 0.6E,7.0S offset (doesn't have any connection with our OT).

We have reference image on 2016-05-14.93352 UT with unfiltered mlim= 
19.1m, the nearest in time images of this area are in MASTER-IAC database 
on 2016-07-31 23:23:26 with mlim=19.4.
There is no any sources in VIZIER database, it means 22mag limit in 
history

Deep photometry and Spectral observations are required.
The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/MASTEROTJ184546.55-352847.6.jpg


The observations made on zenit distance = 23.91 deg.
The distance to Moon was Dist. to Moon: 85.299167
The sun  altitude  was -58.18 degree.

  The message may be cited.


GRB_name: GRB170331A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20948
SUBJECT: GRB 170331A: Prompt enhanced Swift-XRT position
DATE:    17/03/31 02:31:40 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 170331A, we find an
enhanced XRT position of the afterglow: RA, Dec: 323.7920, -24.3858
which is equivalent to:
   RA (J2000)  = 21 35 10.08
   Dec (J2000) = -24 23 08.9
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/744791.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170331A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20949
SUBJECT: GRB 170331A: LCO Sutherland observations
DATE:    17/03/31 08:30:47 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large 
collaboration report:

We observed Swift GRB 170331A (Melandri et al. GCN 20946) on March 31, 
03:21 UT (1.7 hours since the GRB) with two 1-m LCO units in Sutherland 
(South Africa) with the SDSS i filter. We do not find any object within 
the prompt enhanced Swift-XRT error circle (Evans GCN 20948) down to 
i>17.5 mag (with an exposure of 2x120s) as calibrated against USNOB-1 
nearby stars.


GRB_name: GRB170329A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20951
SUBJECT: GRB 170329A: AstroSat CZTI detection
DATE:    17/03/31 09:31:04 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB170329A (Fermi GBM detection: E.Bissaldi et al., GCN Circ. 20943) in the 40-200 keV energy range. The light curve shows single peak emission with peak counts at 09:17:08.940 UT, 2 s after the Fermi trigger. The measured peak count rate is 161.1 counts/s above the background in combined data of four quadrants, with a total 879 counts. The local mean background count rate was 387.9 counts/s. Using cumulative rates, we measure a T90 of 14.1 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170329A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20952
SUBJECT: Konus-Wind observation of GRB 170329A
DATE:    17/03/31 10:56:46 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A.Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170329A (Fermi-LAT detection: Yassine et al., GCN
20942; Fermi-GBM detection: Bissaldi et al., GCN 20943)
triggered Konus-Wind at T0=33423.095 s UT (09:17:03.095).

The burst light curve shows a single multi-peaked pulse
with a total duration of ~7 s. The emission is seen up to ~6 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.47(-0.18,+0.22)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.346 s,
of 4.74(-1.61,+1.66)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.30(-0.25,+0.30)
and Ep = 688(-109,+153) keV (chi2 = 63/81 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 63/80 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170329_T33423/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170330A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20954
SUBJECT: GRB 170330A: LCO Cerro Tololo observations
DATE:    17/03/31 11:29:20 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large 
collaboration report:

We observed Swift GRB 170330A (D'Avanzo et al. GCN 20944) on March 31, 
07:00 UT (8.5 hours since the GRB) with one 1-m LCO unit in Cerro Tololo 
with the SDSS i filter. Comparing with the PanSTARRS archive data, 
within the XRT error circle we do not find any new/variable source down 
to i>20.5 mag (with a total exposure of 10x120s at 8.7 hours mid time) 
as calibrated against nearby PanSTARRS sources.


GRB_name: GRB170317A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20955
SUBJECT: GRB 170317A: 15 GHz upper limits from AMI
DATE:    17/03/31 13:28:06 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson 
(Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. 
Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. 
Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170317A (LaPorte et al., GCN 20885) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Mar 17.59, Mar 18.78, Mar 
20.79 and Mar 22.78 (UT) do not reveal any radio source at the XRT 
location (Beardmore et al., GCN 20887), with 3sigma upper limits of 126 
uJy, 246 uJy, 84 uJy and 111 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170318A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20956
SUBJECT: GRB 170318A: 15 GHz upper limits from AMI
DATE:    17/03/31 13:30:46 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170318A (Sbarufatti et al., GCN 20904) as part of the 4pisky program, 
and subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Mar 18.55 and Mar 21.50 
(UT) do not reveal any radio source at the XRT location (Evans et al., 
GCN 20907), with 3sigma upper limits of 159 uJy and 93 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170318B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20957
SUBJECT: GRB 170318B: 15 GHz upper limits from AMI
DATE:    17/03/31 13:32:06 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford) , T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170318B (Cholden-Brown et al., GCN 20908) as part of the 4pisky program, 
and subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Mar 19.11, Mar 21.17 and 
Mar 23.24 (UT) do not reveal any radio source at the XRT location (Goad 
et al., GCN 20910), with 3sigma upper limits of 300 uJy, 150 uJy and 315 
uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170325A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20958
SUBJECT: GRB 170325A: 15 GHz upper limits from AMI
DATE:    17/03/31 15:12:54 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

We followed up the short GRB 170325A, detected in the Swift/BAT 
ground-based analysis (Palmer et al., GCN 20938), with the AMI Large 
Array as part of the 4pisky program. We note that this GRB was also 
detected by Fermi/LAT (Bissaldi et al., GCN 20940). Our observations at 
15 GHz on 2016 Mar 27.01, Mar 27.84 and Mar 29.83 (UT; 1.7d, 2.5d and 
4.5d post-burst respectively) do not reveal any transient source in the 
BAT error circle (Palmer et al., GCN 20938), which allows us to place 
3sigma upper limits of 113 uJy, 85 uJy and 117 uJy respectively on the 
radio afterglow of the GRB.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170330A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20959
SUBJECT: GRB 170330A: Swift/UVOT Detection of a Fading Afterglow
DATE:    17/03/31 15:32:32 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170330A
109 s after the BAT trigger (D'Avanzo et al., GCN Circ. 20944).
A fading source consistent with the XRT position
(Evans GCN Circ. 20945)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  18:53:19.36 = 283.33067 (deg.)
    Dec (J2000) = -13:25:51.2  = -13.43090 (deg.)
with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white_FC           109          258          147         18.42 +/- 0.08
u_FC               266          516          246         >19.9
white              547         1368          225         19.94 +/- 0.21
v                  596         1418           97         >18.4
b                  522         1344           78         >19.3
u                  266         1484          336         >20.0
w1                 646         1467           97         >19.0
m2                 621         1442           97         >18.9
w2                 572         1393           78         >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.45 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170331A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20960
SUBJECT: GRB 170331A: Enhanced Swift-XRT position
DATE:    17/03/31 15:54:30 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1885 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170331A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 323.79186, -24.38626 which is equivalent
to:

RA (J2000): 21h 35m 10.05s
Dec (J2000): -24d 23' 10.5"

with an uncertainty of 1.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170330A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20961
SUBJECT: GRB 170330A: Enhanced Swift-XRT position
DATE:    17/03/31 16:39:38 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 3111 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 170330A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 283.33044, -13.43115 which is equivalent
to:

RA (J2000): 18h 53m 19.30s
Dec (J2000): -13d 25' 52.1"

with an uncertainty of 1.5 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170331A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20962
SUBJECT: GRB 170331A: Swift-XRT refined Analysis
DATE:    17/03/31 17:20:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.
Cholden-Brown (PSU) and  report on behalf of the Swift-XRT team: report
on behalf of the Swift-XRT team:

We have analysed 7.4 ks of XRT data for GRB 170331A, from 127 s to 19.2
ks after the  BAT trigger. The data comprise 12 s in Windowed Timing
(WT) mode with the remainder in Photon Counting (PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.99 (+0.12, -0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.5 (+/-0.3). The
best-fitting absorption column is  5.6 (+1.7, -1.5) x 10^21 cm^-2, in
excess of the Galactic value of 4.7 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.3 x 10^-11 (7.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.6 (+1.7, -1.5) x 10^21 cm^-2
Galactic foreground: 4.7 x 10^20 cm^-2
Excess significance: 5.8 sigma
Photon index:      2.5 (+/-0.3)

If the light curve continues to decay with a power-law decay index of
0.99, the count rate at T+24 hours will be 1.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.7 x
10^-14 (8.9 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00744791.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170330A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20963
SUBJECT: GRB 170330A: Swift-XRT refined Analysis
DATE:    17/03/31 18:51:53 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows
(PSU), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), B. Mingo (U.
Leicester) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 7.3 ks of XRT data for GRB 170330A, from 89 s to 53.1
ks after the  BAT trigger. The data comprise 404 s in Windowed Timing
(WT) mode (the first 7 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.71 (+0.07, -0.06), followed by a break at T+439 s to
an alpha of 1.061 (+0.029, -0.025).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.00 (+/-0.10). The
best-fitting absorption column is  4.0 (+0.6, -0.5) x 10^21 cm^-2, in
excess of the Galactic value of 3.0 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.88 (+0.12, -0.11)
and a best-fitting absorption column of 4.0 (+/-0.6) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.2 x 10^-11 (6.1 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.0 (+/-0.6) x 10^21 cm^-2
Galactic foreground: 3.0 x 10^21 cm^-2
Excess significance: 2.6 sigma
Photon index:      1.88 (+0.12, -0.11)

If the light curve continues to decay with a power-law decay index of
1.061, the count rate at T+24 hours will be 0.021 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.7 x
10^-13 (1.3 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00744773.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170331A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20965
SUBJECT: GRB 170331A: Swift/UVOT Upper Limits
DATE:    17/03/31 23:34:37 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field
of GRB 170331A 128 s after the BAT trigger (Melandri et
al., GCN Circ. 20946). No optical afterglow consistent
with the XRT position (Osborne et al. GCN Circ. 20960)
is detected in the initial UVOT exposures. Preliminary
3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for
the first finding chart (FC) exposure and subsequent
exposures are:


Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           128          278          147         >20.4
u_FC               286          536          246         >19.6
white              128         1532          392         >21.0
v                  616         1753          134         >18.5
b                  542         1680          117         >19.1
u                  286         1655          343         >19.7
w1                 665         1631          117         >19.1
m2                1069         1606           58         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170317A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20966
SUBJECT: DOAO 1m telescope V, R, I observation of GRB 170317A
DATE:    17/04/01 02:04:01 GMT
FROM:    Changsu Choi at Seoul Nat U  <changsu@astro.snu.ac.kr>

Changsu Choi(CEOU/SNU), Tae-Woo Kim(DOAO/NYSC), Myungshin Im(CEOU/SNU),  on
behalf of a larger collaboration

We observed the field of GRB 170317A (LaPorte et al., GCN  20885) with 1m
telescope of Deokheung Optical Astronomy Observatory (DOAO) in Korea,
starting from 2017/3/17 10:41:47 to 11:59:41.5 UT which is 0.042 days to
0.093 days after BAT trigger. .

We obtained V, R, I images and clearly detected afterglow on the stacked
images (LaPorte et al., GCN 20885; Mazaeva et al., GCN20886; Xin et al.,
GCN 20888; Mao  et al., GCN 20889; Kuroda et al., GCN20899).

The photometric calibration is based on in APASS catalog in the observed
field. No galactic extinction correction is applied.

Date            UT start         t-T0       Filter     Exp.      Mag
Err.

                            (mid, days)           (s)


2017-03-17 10:41:47        0.042     I           180*3    18.86     0.10

2017-03-17 10:51:01        0.049     R          300*3    19.66     0.07

2017-03-17 11:06:18        0.057     I           300*5    20.29     0.26

2017-03-17 11:31:41        0.079     V          300*3    20.38     0.15

2017-03-17 11:46:59        0.086     R          300*2    19.98     0.15
2017-03-17 11:57:10        0.093     V          300*2    20.77     0.23


GRB_name: GRB170331A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20967
SUBJECT: GRB 170331A: Swift-BAT refined analysis
DATE:    17/04/01 06:15:10 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170331A (trigger #744791)
(Melandri et al., GCN Circ. 20946).  The BAT ground-calculated position is
RA, Dec = 323.778, -24.406 deg which is
  RA(J2000)  =  21h 35m 06.8s
  Dec(J2000) = -24d 24' 22.4"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 18%.

The mask-weighted light curve shows a weak pulse that starts at ~T-3 s,
peaks at ~T+1 s, and ends at ~T+17 s. T90 (15-350 keV) is 17.57 +- 2.57 sec
(estimated error including systematics).

The time-averaged spectrum from T-2.78 to T+17.17 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.37 +- 1.19,
and Epeak of 48.2 +- 12.7 keV (chi squared 61.51 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 9.7 +- 1.6 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+0.42 sec in the 15-150 keV band is
1.2 +- 0.4 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.86 +- 0.21 (chi squared 68.07 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/744791/BA/


GRB_name: GRB170330A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20968
SUBJECT: GRB 170330A: Swift-BAT refined analysis
DATE:    17/04/01 06:16:03 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), P. D'Avanzo (INAF-OAB),
N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170330A (trigger #744773)
(D'Avanzo et al., GCN Circ. 20944).  The BAT ground-calculated position is
RA, Dec = 283.331, -13.458 deg which is
  RA(J2000)  =  18h 53m 19.4s
  Dec(J2000) = -13d 27' 29.2"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The mask-weighted light curve shows a multi-peaked structure that lasts
until ~T+126 s, with the main peak occurs around ~T-135 s. The burst came
into the BAT field of view at ~T-170 s during a pre-planned spacecraft slew.
Therefore, the burst emission might have started before ~T-170 s.
T90 (15-350 keV) is 144.73 +- 3.51 sec (estimated error including systematics).

The time-averaged spectrum from T-143.2 to T+126.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.38 +- 0.09.  The fluence in the 15-150 keV band is 5.6 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-134.71 sec in the 15-150 keV band
is 4.5 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/744773/BA/


GRB_name: GRB170330A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20969
SUBJECT: GRB 170330A: AstroSat CZTI detection
DATE:    17/04/01 12:19:52 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB 170330A (Swift burst detection: P. D'Avanzo et al., GCN Circ. 20944) in the 40-200 keV energy range. The light curve shows multiple peak structure with peak counts at 22:27:36.000 UT, around ~35 s after the Swift trigger time i.e. ~T-170 s (Swift-BAT refined analysis: A. Y. Lien et al., GCN Circ. 20968) and it also coincides with the Swift main peak. The light curve doesn't show excess counts above the background for last ~100 s. The measured peak count rate is 163.2 counts/s above the background in combined data of four quadrants, with a total 1389 counts. The local mean background count rate was 358.8 counts/s. Using cumulative rates, we measure a T90 of 15.6 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170330A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20974
SUBJECT: Konus-Wind observation of GRB 170330A
DATE:    17/04/03 15:28:48 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170330A (Swift-BAT trigger #744773:
D'Avanzo et al., GCN 20944; Lien et al., GCN 20968;
AstroSat CZTI detection: Sharma et al., GCN 20969)
triggered Konus-Wind at T0=80850.946 s UT (22:27:30.946).

The burst light curve shows a single multi-peaked pulse
with a total duration of ~12 s. The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.85(-0.54,+0.42)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+4.912 s,
of 4.91(-2.23,+2.17)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 5 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.22(-0.67,+0.88),
the high energy photon index beta = -1.98(-0.84,+0.17),
the peak energy Ep = 226(-66,+190) keV
(chi2 = 69/76 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170330_T80850/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170403A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20975
SUBJECT: GRB 170403A: Fermi GBM observation
DATE:    17/04/03 23:37:23 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 13:59:17.80 UT on the 3rd of April 2017, the
Fermi Gamma-Ray Burst Monitor triggered and
located GRB 170403A (trigger 512920762 / 170403583).
The on-ground calculated location using the GBM
trigger data is,

RA = 267.08, DEC = +14.53 (J2000 degrees)

with an uncertainty of 7.16 degrees (radius, 1-sigma
containment, statistical only; there is additionally
a systematic error which we have characterized as a
core-plus-tail model, with 90% of GRBs having a 3.7 deg.
error and a small tail suffering a larger than 10 deg.
systematic error [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight at the GBM trigger
time is 88 degrees.

The GBM light curve consists of a short, bright GRB with
emission over a duration (T90) of about 1s
(50-300 keV). The time-averaged spectrum from T0-0.096 s to
T0+0.384 s is best fit by a power law function with an
exponential high-energy cutoff.  The power law index is
-1.01 +/- 0.14 and the cutoff energy, parameterized as
Epeak is 470 +/- 163 keV.

The event fluence (10-1000 keV) in this time interval is
(3.9 +/- 0.2)E-07 erg/cm^2. The 64 ms peak photon flux
measured starting from T0+0 s in the 10-1000 keV band
is 16.6 +/- 1.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170403A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20976
SUBJECT: IPN Triangulation of GRB 170403A (short)
DATE:    17/04/04 14:51:54 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, report:

The short-duration GRB 170403A has been detected by
Fermi (GBM; Roberts and Meegan, GCN Circ. 20975), Konus-Wind, INTEGRAL 
(SPI-ACS), and Swift (BAT), so far, at about 50358 s UT (13:59:18).
The burst was probably outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   259.339 (17h 17m 21s) +18.373 (+18d 22' 24")
  Corners:
   259.284 (17h 17m 08s) +20.795 (+20d 47' 43")
   259.729 (17h 18m 55s) +15.801 (+15d 48' 04")
   259.375 (17h 17m 30s) +16.007 (+16d 00' 24")
   258.911 (17h 15m 39s) +21.035 (+21d 02' 06")
  ---------------------------------------------
The error box area is 1.63 sq. deg, and its maximum
dimension is 5.29 deg (the minimum one is 19.4 arcmin).
The Sun distance was 110 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170403_T50358/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB170403A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20977
SUBJECT: Konus-Wind observation of GRB 170403A (short/hard)
DATE:    17/04/04 15:25:20 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The short GRB 170403A (Fermi-GBM observation: Roberts & Meegan,
GCN 20975; IPN triangulation: Svinkin et al., GCN 20976) triggered
Konus-Wind at T0=50358.544 s UT (13:59:18.544).

The light curve shows a single pulse with a duration of ~0.12s.

As observed by Konus-Wind, the burst had a fluence of
(5.4 Â± 0.8)x10^-7 erg/cm2 and a 16-ms peak energy flux,
measured from T0-0.016, of (7.6 Â± 1.8)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated 3-channel spectrum of the burst, measured from
T0-0.064 s to T0+0.064 s, can be modeled by an exponentially cutoff 
power law with alpha = -0.16 (-0.36, +0.46) and Ep = 357(-58,+90) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170403_T50358/

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.


GRB_name: GRB170325A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20978
SUBJECT: GRB 170325A: optical observations, possible OT/host detection
DATE:    17/04/04 20:20:06 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), P. Minaev 
(IKI),  E. Klunko (ISTP), A. Volnova (IKI), M. Eselevich (ISTP)   report 
on behalf of larger GRB follow-up collaboration:

Ð¦e followed up the short GRB 170325A (Palmer et al., GCN  20938) with 
AZT-33IK telescope of Sayan observatory (Mondy) an ZTSh telescope of 
CrAO observatory. The burst was detected by GBM/Fermi (Bissaldi et al., 
GCN 20940) and also detected as 5.5 sigma non-triggered IBAS event of 
0.1 s duration of SPI-ACS/INTEGRAL (see 
http://grb.rssi.ru/GRB170325A/GRB170325_SPI-ACS.png).

We obtained several images in R-filter  on  March 26, March 29, and 
April 1 and cover all 90% error box of the BAT/Fermi (Palmer et al., GCN 
  20938).  We investigated variability of sources in the BAT/Fermi error 
box between the three epochs. One source exhibits marginal fading 
between first and second epochs. Preliminary photometry of the source is 
following

Date       UT start   t-T0    Filter  Exp.     OT     Err.  UL
                      (mid, days)      (s)

2017-03-26 14:10:51  1.28049  R      3600    21.94   0.15  22.2
2017-03-29 21:00:52  4.56314  R      3240    22.27   0.10  23.6
2017-04-01 15:46:59  7.35072  R      4100    22.45   0.25  22.6

the photometry is based on nearby SDSS-DR9 stars

SDSS-DR9_id         R(Lupton transformations)
J082954.53+203317.9 18.69
J083002.05+203031.2 16.74
J082950.18+203013.8 18.25
J082949.90+203106.9 16.65

Coordinates of the source are  (J2000) 08:29:57.677   +20:30:51.75 with 
uncertainty of  0.7 arcsec in both coordinates. The finding chart can be 
found in
http://grb.rssi.ru/GRB170325A/GRB170325A_Mondy_170326_2.png
http://grb.rssi.ru/GRB170325A/GRB170325A_CrAO_170329.png

The source is not presented in SDSS-DR9, but clearly visible in 
r(=22.59), i(=22.10) filters, barely visible in u-filter (23.1), and not 
detected in g and z of SDSS images.

We suggest the source is an afterglow and host candidates of the short 
GRB 170325A.


GRB_name: GRB170330A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20979
SUBJECT: GRB 170330A CALET Gamma-Ray Burst Monitor detection
DATE:    17/04/04 23:27:52 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170330A (D'Avanzo et al. GCN Circ. 20944;
Sharma et al. GCN Circ. 20969; Kozlova et al. GCN Circ. 20974) triggered
the CALET Gamma-ray Burst Monitor (CGBM) at 22:27:27.91 on 30 March 2017.
The burst signal was seen by all CGBM instruments.

The light curve of the SGM shows several peaks.  The bright burst episode
starts at T-5 sec and ends at T+20 sec.  Two late time emissions at T+120 s
and T+150 s, which triggered Swift/BAT, are barely visible in the HXM data.
The T90 duration measured by the SGM data is 18.5 +- 2.4 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1174947694/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170402A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20980
SUBJECT: GRB 170402A CALET Gamma-Ray Burst Monitor detection
DATE:    17/04/04 23:31:32 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

T. Sakamoto, A. Yoshida, Y. Kawakubo, M. Moriyama, Y. Yamada (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170402A (Fermi GBM trigger #512808659;
Konus-Wind trigger time on 06:50:51.076) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 06:50:52.11 on 2 April 2017.
The burst signal was only seen by the SGM instrument.

The light curve of the SGM shows several peaks.  The entire
burst episode starts at T+2 sec and ends at T+12 sec.  Two bright
emissions peak at T+3 sec and T+5 sec.  The T90 duration measured
by the SGM data is 7.5 +- 0.6 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1175150695/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170405A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20984
SUBJECT: GRB 170405A: Swift detection of a burst with an optical counterpart
DATE:    17/04/05 18:50:16 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

E. Troja (NASA/GSFC/UMCP), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), S. B. Cenko (GSFC), A. Cholden-Brown (PSU),
A. D'Ai (INAF-IASFPA), F. E. Marshall (NASA/GSFC) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 18:39:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170405A (trigger=745797).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 219.810, -25.244, which is 
   RA(J2000)  =  14h 39m 14s
   Dec(J2000) = -25d 14' 36"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple peaks
with a duration of about 180 sec.  The peak count rate
was ~4500 counts/sec (15-350 keV), at ~4 sec after the trigger. 

The XRT began observing the field at 18:41:49.0 UT, 120.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 219.8290, -25.2438 which is equivalent to:
   RA(J2000)  = +14h 39m 18.96s
   Dec(J2000) = -25d 14' 37.7"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 61 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 128 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 14:39:18.72 = 219.82800
  DEC(J2000) = -25:14:35.3  = -25.24315
with a 90%-confidence error radius of about 0.61 arc sec. This position is 3.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.18 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.09. 

Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170405A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20985
SUBJECT: GRB 170405A: Enhanced Swift-XRT position
DATE:    17/04/05 20:38:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 368 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170405A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 219.82767, -25.24368 which is equivalent
to:

RA (J2000): 14h 39m 18.64s
Dec (J2000): -25d 14' 37.3"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170405A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20986
SUBJECT: GRB 170405A: Fermi GBM observation 
DATE:    17/04/05 22:51:57 GMT
FROM:    C. Michelle Hui at MSFC/Fermi-GBM  <c.m.hui@nasa.gov>

C. M. Hui (MSFC) and C. Meegan (UAH) 
report on behalf of the Fermi GBM Team:

At 18:39:22.89 UT on 05 April 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170405A (trigger 513110367/170405777),
which was also detected by Swift (Troja et al. 2017, GCN 20984).
The GBM on-ground location is consistent with the Swift position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux of the GRB.
This ARR was accepted and the spacecraft slewed to the GBM in-flight 
location. The initial angle from the Fermi LAT boresight is 52 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 78.6 s (50-300 keV).
The time-averaged spectrum from T0+7.2 s to T0+86.0 s is 
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.01 +/- 0.01 and
 the cutoff energy, parameterized as Epeak, is 355.2 +/- 8.6 keV.

The event fluence (10-1000 keV) in this time interval is
(7.85 +/- 0.07)E-05 erg/cm^2. The 1s peak photon flux measured
starting from T0+29.5 s in the 10-1000 keV band is 
15.8 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.


GRB_name: GRB170405A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20987
SUBJECT: GRB 170405A: Fermi-LAT detection
DATE:    17/04/06 00:24:15 GMT
FROM:    Giacomo Vianello at SLAC  <giacomov@slac.stanford.edu>

G.Vianello (Stanford), D.Kocevski (NASA/MSFC)

report on behalf of the Fermi-LAT team:

At 18:39:22.89 on April, 05, 2017 Fermi-LAT detected high-energy
emission from GRB 170405A, which was also detected by Swift (Troja et
al., GCN 20984) and Fermi/GBM (trigger 513110367/170405777).

The best LAT on-ground location is found to be:

RA, Dec = 219.37, -25.23 (J2000)

with an error radius of 0.51 deg (90 % containment, statistical error
only). This was 53 deg from the LAT boresight at the time of the
trigger and triggered an autonomous repoint of the spacecraft.  This
position is compatible with the XRT position reported by Evans et al.
(GCN 20985).

The data from the Fermi-LAT show a significant increase in the event
rate that is spatially and temporally correlated with the trigger with
high significance. More than 13 events have been observed above 100
MeV which are spatially and temporally correlated with the GRB. The
highest-energy photon is a 900 MeV event which is observed 445 seconds
after the GBM trigger.

We note that roughly 5 ks of data are currently available.  We will
provide an update, if necessary, as more data become available.

The Fermi-LAT point of contact for this burst is Giacomo Vianello
(giacomov@stanford.edu)

The Fermi-LAT is a pair conversion telescope designed to cover the
energy band from 20 MeV to greater than 300 GeV. It is the product of
an international collaboration between NASA and DOE in the U.S. and
many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20988
SUBJECT: GRB 170405A: NOT optical observations
DATE:    17/04/06 01:22:36 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DARK/NBI), K. E. Heintz (DARK/NBI and Univ. Iceland), 
and Tapio Pursimo (NOT) report on behalf of a larger collaboration:

We observed the optical afterglow of GRB 170405A (Troja et al., GCN 
20984; Hui & Meegan, GCN 20986; Vianello & Kocevski, GCN 20987) with the 
Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. 
Observations were carried out in the SDSS griz filters, with a 
sub-optimal PSF (1.6-2.0").

Inspection of the r-band image (with mean time Apr 6.01 UT, that is 5.47 
hr after the trigger) clearly shows the optical afterglow first 
localized by UVOT (Troja et al., GCN 20984), which has now faded to r = 
21.05 +- 0.08 AB, calibrated against nearby stars from the Pan-STARRS 
catalog. In our images, the afterglow coordinates are perfectly 
consistent with the UVOT values:

RA(J2000) = 14:39:18.72
Dec(J2000) = -25:14:35.3

We also note the presence of a nearby object approximately 2.3" W of the 
afterglow, also visible in the Pan-STARRS archival images (with a 
Pan-STARRS magnitude r = 21.82 +- 0.19 AB). Its relation to the GRB is 
not clear, but its proximity may affect the afterglow photometry.


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20989
SUBJECT: GRB 170405A: TAROT Reunion observatory optical observations
DATE:    17/04/06 02:22:43 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.)
Thierry P. (Auragne Observatory, France),
Klotz A.N.O. (Guitalens Observatory, France)
report:

We imaged the field of GRB 170405A detected by SWIFT
(trigger 745797) with the TAROT robotic telescope (D=18cm)
located at the Reunion observatory, France.

The observations started 3.84h after the GRB trigger.
We detected the OT (Troja et al., GCN 20984;
Hui & Meegan, GCN 20986; Vianello & Kocevski, GCN 20987;
Malesani, GCNC 20988):

t0+3.84h to t0+3.97h : R=19.0 +/- 0.2

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170405A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20990
SUBJECT: GRB 170405A: Redshift from OSIRIS/GTC 
DATE:    17/04/06 03:10:20 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D.A. Kann (IAA-CSIC), 
C.C. Thoene (IAA-CSIC), L. Izzo (IAA-CSIC), N.R. Tanvir (U. Leicester), 
G. Lombardi (GTC, IAC), and A. Marante (GTC) report on behalf of a 
larger collaboration:

We observed the field of GRB 170405A (Troja et al., GCN 20984; Hui 
& Meegan, GCN 20986; Vianello & Kocevski, GCN 20987) using OSIRIS 
on the 10.4m GTC at the Roque de los Muchachos observatory (La Palma, 
Spain). The observation consisted of 3x900s using the R1000B grism, 
covering the range between 3700 and 7800 Ã…. The first spectrum started at 
2:14 UT (7.57 hr after the burst).

On a preliminary reduction based on archival calibrations we detect a 
spectral continuum with strong absorption features, which we identify as 
due to Ly-alpha, SiII, OI, CII, SiIV, CIV, FeII and AlII at a common redshift of 
z = 3.510, which we identify as the redshift of the GRB.


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20991
SUBJECT: GRB 170405A: Watcher optical detection
DATE:    17/04/06 07:36:55 GMT
FROM:    Antonio Martin-Carrillo at UCD,Space Science Group  <antonio.martin-carrillo@ucd.ie>

A. Martin-Carrillo (UCD), D. Murphy (UCD), L. Hanlon (UCD), H. J. van Heerden (UFS), B. van Soelen (UFS) and P. J. Meintjes (UFS)

We observed the field of GRB 170405A (Troja et al, GCN 20984; Hui & Meegan, GCN 20986; Vianello & Kocevski, GCN 20987) using the 40cm UCD Watcher telescope at Boyden Observatory in South Africa.

Due to bad weather observations started at 19:31:13 UT, about 51.4 minutes after the burst trigger (T0=18:39:48 UT). A faint source consistent with the UVOT coordinates reported by Troja et al. is detected on our combined images taken with the SDSS râ€™ filter. At a mid-time of 20:00 UT, we derive a preliminary magnitude of râ€™=18.0 (AB system), confirming that the source has faded since the UVOT detection.

Magnitudes were calibrated using several nearby APASS stars. No correction for Galactic extinction in the direction of the GRB has been applied.


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20992
SUBJECT: GRB 170405A: ISON/Terskol optical observations
DATE:    17/04/06 12:12:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI),  V. Agletdinov (KIAM),  A. Pozanenko (IKI), A. Volnova 
(IKI),   I. Molotov (KIAM)  report on behalf of  larger GRB follow-up 
collaboration:

We observed the field of GRB 170405A (Troja et al., GCN 20984) with 
K-800 (0.8m) telescope  of ISON/Terskol   observatory starting  on 
April, 05 (UT) 19:12:55, i.e. 45 minutes after GRB onset.  We obtained 
several unfiltered images of 15 s exposure. The optical afterglow Troja 
et al., GCN 20984; Malesani et al., GCN 20988; Klotz et al., GCN 20989; 
Ugarte Postigo et al., GCN 20990;    Martin-Carrillo et al., GCN 20991) 
is clearly visible in combined images. Preliminary photometry   of the 
afterglow is following


Date       UT start   t-T0    Filter  Exp.   OT     Err.  UL
                       (mid, days)     (s)

2017-04-05 19:12:55 0.03139 CR 72*15  17.27 0.10 20.1
2017-04-05 19:34:33 0.04300 CR 48*15  17.96 0.13 19.8
2017-04-05 19:49:05 0.06019 CR 110*15 18.39 0.14 20.4
2017-04-05 20:23:55 0.08543 CR 110*15 19.18 0.22 20.2
2017-04-05 21:01:48 0.11099 CR 107*15  n/d n/d   18.9

Photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id     R2
0647-0315771    15.13
0647-0315754    15.45
0647-0315872    15.34
0647-0315921    15.08
0647-0315788    14.92

Preliminary light curve of the afterglow can be found in
http://grb.rssi.ru/GRB170405A/GRB170405A_light_curve.png


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20994
SUBJECT: GRB 170405A: LCO FTN observations
DATE:    17/04/06 13:02:36 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large 
collaboration report:

We observed Swift GRB 170405A (Troja et al. GCN 20984) on April 06, from 
10:23 to 11:01 UT (0.66 to 0.68 days since the GRB) with the 2-m LCO 
Faulkes Telescope North with the SDSS i and r filters. We do not detect 
the optical afterglow (Troja et al; Malesani et al. GCN 20988; Klotz et 
al. GCN 20989; de Ugarte Postigo et al. GCN 20990; Martin-Carrillo et 
al. GCN 20991; Mazaeva et al. GCN 20992) down to the following limits:

Mid Time      Exposure       Filter       Magnitude (AB)
(days)           (s)
-------------------------------------------------------
0.66           5x120          SDSS-R        > 21.6
0.68           4x120          SDSS-I        > 21.6
-------------------------------------------------------

as calibrated against nearby Pan-STARRS objects. The nearby Pan-STARRS 
object mentioned by Malesani et al. is clearly visible in our stacked 
frames.


GRB_name: GRB170405A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20995
SUBJECT: Konus-Wind observation of GRB 170405A
DATE:    17/04/06 14:57:40 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long GRB 170405A (Swift-BAT detection: Troja et al.,GCN 20984;
Fermi-GBM detection: Hui & Meegan., GCN 20986;
Fermi-LAT detection: Vianello & Kocevski, GCN 20987)
triggered Konus-Wind at T0=67181.254 s UT (18:39:41.254)

The light curve shows a multi-peaked structure
with a total duration of ~100 s and a hint of a subsequent
weak/soft emission lasting until ~T0+200 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(1.05 Â± 0.12)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+15.744, of (5.9 Â± 0.9)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+73.984 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.53 (-0.17,+0.19),
the high energy photon index beta = -2.36 (-0.25,+0.15),
the peak energy Ep = 244 (-27,+32) keV,
chi2 = 98/96 dof.

The spectrum near the peak count rate (measured from T0+8.448 s
to T0+24.832 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.54 (-0.22,+0.24),
the high energy photon index beta = -2.56 (-1.02,+0.27),
the peak energy Ep = 265 (-36,+51) keV,
chi2 = 71/96 dof.

Assuming the redshift z=3.510 (de Ugarte Postigo et al., GCN 20990)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.3, and Omega_Lambda = 0.7,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~2.6x10^54 erg,
the peak luminosity L_iso is ~6.6x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~1100 keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170405_T67181/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.

[GCN OPS NOTE(06apr17):  Per author's request, in the first paragraph
the V&K CirNum was changed from "20827" to "20987",  and in the 6th paragraph
the de Ugarte Postigo CircNum was changed from "20104" to "20990".]


GRB_name: GRB170405A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20996
SUBJECT: GRB 170405A: RATIR Optical and NIR Observations
DATE:    17/04/06 15:58:54 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM),
Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara(UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz 
(UCSC),
JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC),
John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 170405A (Troja, et al., GCN 20984) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/04 6.23 to 2017/04 6.48 UTC (10.93
to 16.85 hours after the BAT trigger), obtaining a total of 3.84 hours
exposure in the r and i bands and 1.62 hours exposure in the Z,
Y, J, and H bands.

For a source within the Swift-UVOT error circle (Troja, et al., GCN 20984),
in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following
detections:

   r    22.67 +/- 0.05
   i    21.83 +/- 0.04
   Z    21.26 +/- 0.07
   Y    21.14 +/- 0.07
   J    20.75 +/- 0.07
   H    20.56 +/- 0.08


These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

The nearby object noted by Malesani et al., (GCN 20988) is detected in all
our images and might affect our photometric measurements. The reported
values should be therefore considered as preliminary.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.

Further observations are planned.


GRB_name: GRB170405A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20997
SUBJECT: GRB 170405A: Swift-XRT refined Analysis
DATE:    17/04/06 17:03:32 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A.
D'Ai (INAF-IASFPA), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.A.
Kennea (PSU), B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester)
and  report on behalf of the Swift-XRT team: report on behalf of the
Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 170405A, from 111 s to 57.3
ks after the  BAT trigger. The data comprise 489 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The late-time light curve (from T0+4.5 ks) can be modelled with a
power-law decay with a decay index of alpha=1.66 (+0.14, -0.12).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.592 (+0.027, -0.019). The
best-fitting absorption column is  consistent with the Galactic value
of 8.7 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has
a photon index of 1.84 (+0.09, -0.07) and a best-fitting absorption
column consistent with the Galactic value. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.6 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 8.7 x 10^20 cm^-2
Intrinsic column:    8.7 (+68.1, -0.0) x 10^20 cm^-2 at z=3.51
Photon index:      1.84 (+0.09, -0.07)

If the light curve continues to decay with a power-law decay index of
1.66, the count rate at T+24 hours will be 5.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x
10^-13 (2.3 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00745797.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20998
SUBJECT: GRB 170405A: Etelman observatory optical observations
DATE:    17/04/06 19:41:45 GMT
FROM:    Bruce Gendre at UVI  <bruce.gendre@gmail.com>

B. Gendre (UVI), N. Orange (OrangeWave Innovative Science, LLC), D.
Morris (UVI), A. Cucchiara (UVI), D. Drost (UVI), T. Giblin (USAF
Academy), J. Hakkila (College of Charleston), A. Klotz (IRAP), J. Neff
(NSF), D. Smith (UVI), J. Staff (UVI), P. Thierry (Auragne Observatory),
R. Watlington (UVI), and L. Wentlent (UVI) report:

We observed the field of GRB 170405A (Troja et al, GCN 20984;
Hui & Meegan, GCN 20986; Vianello & Kocevski, GCN 20987) with the
0.5m Virgin Island Robotic Telescope (VIRT) on February the 6th,
starting at 6:15 UT (11.6 hours after the trigger). We
performed a series of exposures in the clear filter. The weather
conditions were good during the observations.

We co-added the exposures taken between 6h15UT (t0+11.6h) and
7h29UT (t0+12.8h), for a total exposure of 3510s. At the position of the 
optical afterglow reported by Malesani et al. (GCN 20988), we do not 
detect any optical emission, with an upper limit of R = 21.3 (Johnson 
system) estimated from nearby NOMAD1 stars.

Magnitudes have not been corrected for Galactic extinction.
The VIRT is still in its commissioning phase.

This message can be cited.


GRB_name: GRB170405A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  20999
SUBJECT: GRB 170405A, Swift-BAT refined analysis
DATE:    17/04/07 03:25:45 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170405A (trigger #745797)
(Troja et al., GCN Circ. 20984).  The BAT ground-calculated position is
RA, Dec = 219.824, -25.236 deg which is
   RA(J2000)  =  14h 39m 17.8s
   Dec(J2000) = -25d 14' 09.7"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 6%.

The burst was outside of the BAT calibrated field of view from T-134.3 s to T+56.7 s.
The mask-weighted light curve using the â€œdetection maskâ€ (which covers a broader
field of view, but is not well calibrated; see detail description in Markwardt et al. 2007)
shows a multi-peaked structure that starts at ~T-30 s and ends at ~T+240 s. The
major peak occurs at ~T+5 s. T90 (15-350 keV) is 164.7 +- 35.4 sec (estimated error
including systematics).

The time-averaged spectrum from T+56.7 to T+242.5 sec (i.e., when the burst is in the
BAT calibrated field of view) is best fit by a simple power-law model.  The power law
index of the time-averaged spectrum is 1.59 +- 0.12.  The fluence in the 15-150 keV
band is 3.7 +- 0.3 x 10^-06 erg/cm2. All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/745797/BA/


GRB_name: GRB170405A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21000
SUBJECT: GRB170405A, Swift-UVOT Detection
DATE:    17/04/07 06:46:05 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 170405A: Swift/UVOT Detection

S. J. LaPorte (PSU) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170405A
129 s after the BAT trigger (Troja et al., GCN Circ. 20984).  Consistent
with previous reports (Malesani et al, GCN Circ. 20988; Martin-Carrillo et al.
GCN Circ. 20991), a fading source consistent with the XRT position
(Evans et al. GCN Circ. 20985) is detected in the initial UVOT exposures at: 

    RA  (J2000) =  14:39:18.73 = 219.82805 (deg.)
    Dec (J2000) = -25:14:35.4  = -25.24317 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

The upper limits in the UV bands are consistent with the reported
redshift of z = 3.51 (de Ugarte-Postigo et al, GCN Circ. 20990).

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white (fc)         129          279          147         16.01 +/- 0.03
white              747          998          143         18.09 +/- 0.07
v                  618          637           20         16.31 +/- 0.14
b                  543          563           20         17.34 +/- 0.13
u                  287          711          265        >20.2
uvw1               667          859           39        >18.9
uvm2               815          835           19        >17.5
uvw2               593          786           39        >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170317A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21001
SUBJECT: GRB 170317A: SAO RAS optical observations
DATE:    17/04/07 20:23:42 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. Moskvitin (SAO RAS),  E. Mazaeva (IKI), A. Pozanenko (IKI),
A. Volnova (IKI), on behalf of larger GRB follow-up collaboration:


We observed the field of GRB 170317A (LaPorte et al. GCN 20885)
with the SAO RAS telescope Zeiss-1000  + CCD photometer on March, 17
(18:12:00--19:58:03 UT). We obtained several images in Rc band.
The optical afterglow (LaPorte et al., GCN 20885;
Mazaeva et al., GCN 20886; Xin et al., GCN 20888;
Mao et al., GCN 20889; Kuroda et al., GCN 20899) is detected
in a stacked frame. Preliminary photometry is following

Date       UT start   t-T0        Filter  Exp.   OT     Err. UL
                      (mid, days)         (s)

2017-03-17 18:12:00   0.38823     Rc     15*300  22.3   0.3  22.6

Photometry is based on nearby USNO-B1.0 stars
previously used in GCN 20886.


GRB_name: GRB170403B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21002
SUBJECT: GRB 170403B CALET Gamma-Ray Burst Monitor detection
DATE:    17/04/08 01:07:38 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Kawakubo, A. Yoshida, T. Sakamoto, M. Moriyama, Y. Yamada (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170403B (Fermi GBM trigger #512931458;
INTEGRAL SPI-ACS trigger #7799; Konus-Wind trigger time on
16:57:35.034) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 16:57:31.18 on 3 April 2017.  The burst signal was only seen by
the SGM instrument.

The light curve of the SGM shows a single peak starting at T0+2 sec,
peaking at T+5 sec and ending at T+10 sec.  The T90 duration measured
by the SGM data is 6.7 +- 0.4 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1175273491/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170405A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21003
SUBJECT: GRB 170405A: SMARTS optical/IR afterglow observations
DATE:    17/04/09 00:35:06 GMT
FROM:    Bethany Cobb at GWU  <bcobb@gwu.edu>

B. E. Cobb (GWU), reports:

Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 170405A
(GCN 20984, Troja et al.) at two epochs (with mid-exposure times
of 2017-04-06 02:51 UT & 06:52 UT). For each epoch, several
dithered images were obtained with total summed exposure times
of 15 min in V and I and 12 min in J and K.

The fading afterglow of GRB 170405A (e.g. GCN 20984, Troja et al.;
GCN 20988, Malesani et al.; GCN 20989, Klotz et al.) was detected
with the preliminary magnitudes (or 3-sigma limits) listed below.
Note that the optical photometry is calibrated against USNO-B1.0
stars in the field, so suffers from a large photometric calibration
error of about +/-0.2 magnitudes, which has not been included in
the errors quoted below. The IR photometry is calibrated against
2MASS stars. Additionally, the nearby source noted by Malesani
et al. (GCN 20988) is seen and is likely affecting the afterglow
photometry due to its proximity.

mid-exposure
time post-burst
(hours)     I mag          J mag     K mag
8.19000    20.4+/-0.1   >18.5     >16.9
12.1975    21.1+/-0.1   >18.8     >16.8


GRB_name: GRB170409A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21004
SUBJECT: GRB 170409A: Fermi-LAT detection
DATE:    17/04/09 15:48:54 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin@nasa.gov>

F. Longo (University and INFN, Trieste), J. L. Racusin (NASA/GSFC), and 
D. Kocesvki (NASA/MSFC)report on behalf of the Fermi-LAT team:

At 02:41:59.49 on April 9, 2017, Fermi-LAT detected high-energy emission 
from GRB 170904A, which was also detected by Fermi-GBM (trigger 
513398525/170409112). 

The best LAT on-ground location is found to be:

RA, Dec = 347.53, -7.16 (degrees, J2000)

with an error radius of 0.15 deg (90% containment, statistical error only). This 
was 82 deg from the LAT boresight at the time of the trigger and triggered an 
autonomous repoint of the spacecraft.

The data from the Fermi-LAT show a significant increase in the event rate that 
is spatially and temporally consistent with the GBM emission. More than 14 
photons above 100 MeV and 2 photons above 1 GeV are observed within 1000 
seconds.  The highest-energy photon is a 10 GeV event which is observed 442 
seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Francesco Longo 
(francesco.longo@ts.infn.it).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band 
from 20 MeV to greater than 300 GeV. It is the product of an international 
collaboration between NASA and DOE in the U.S. and many scientific institutions 
across France, Italy, Japan and Sweden.


GRB_name: GRB170409A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21005
SUBJECT: GRB 170409A: Fermi GBM Observation
DATE:    17/04/09 17:34:02 GMT
FROM:    Eric Burns at U of Alabama  <eb0016@uah.edu>

E. Burns (UAH), E. Bissaldi (Politecnico & INFN Bari),
S. Poolakkil (UAH), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 02:42:00.49 UT on 09 April 2017 , the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170409A (trigger 513398525/170409113)
which was also detected by the Fermi LAT (Longo et al. 2017, GCN 21004).
The GBM on-ground location is consistent with the LAT position.

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight location. The initial angle from the Fermi LAT boresight to
the LAT location is 82 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 68 s (50-300 keV).
The time-averaged spectrum from T0+26.880 s to T0+97.537 s is
best fit by a Band function with Epeak = 1150 +/- 20 keV,
alpha = -0.82 +/- 0.01, and beta = -2.84 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(2.956 +/- 0.009)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+38.0164 s in the 10-1000 keV band
is 61.8 +/- 0.6 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170402A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21006
SUBJECT: GRB 170402A: AstroSat CZTI detection
DATE:    17/04/10 11:09:17 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, V. Bhalerao (IITB) and D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB 170402A (CALET Gamma-Ray Burst Monitor detection: T. Sakamoto et al., GCN Circ. 20980) in the 40-200 keV energy range in the quadrant C and D only. The light curve shows multiple peak emission with main peak at 06:50:57.076 UT, ~5 s after the CALET trigger. The measured peak count rate is 323.4 counts/sec above the background in combined data of four quadrants, with a total 2197 counts. The local mean background count rate was 363.6 counts/s. Using cumulative rates, we measure a T90 of 13 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170409A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21007
SUBJECT: Konus-Wind observation of GRB 170409A
DATE:    17/04/10 12:43:23 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov,
D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline,
on behalf of the Konus-Wind team, report:

The long, very bright GRB 170409A (Fermi-LAT detection: Longo et al.,
GCN 21004; Fermi-GBM detection: Burns et al., GCN 21005)
triggered Konus-Wind at T0=9741.024 s UT (02:42:21.024)

The burst light curve shows multiple partially overlapped
emission peaks in the interval from ~T0-29 s to ~T0+95 s.
A possible precursor is seen as a weak count rate excess in
the same KW detector at ~T0-143 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(5.7 Â± 0.2)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+12.982, of (1.00 Â± 0.06)x10^-4 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+91.648 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.76 (-0.05,+0.05),
the high energy photon index beta = -2.23 (-0.11,+0.09),
the peak energy Ep = 808 (-65,+69) keV,
chi2 = 111/95 dof.

The spectrum near the peak count rate (measured from T0+12.288 s
to T0+13.056 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.60 (-0.06,+0.07),
the high energy photon index beta = -3.52 (-6.48,+0.65),
the peak energy Ep = 1671 (-180,+192) keV,
chi2 = 99/77 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170409_T09741/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB170409A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21008
SUBJECT: GRB 170409A: TAROT Reunion observatory optical observations
DATE:    17/04/10 16:38:25 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.)
Peyrot A., Teng J.P. (Les Makes Observatory, France),
Thierry P. (Auragne Observatory, France),
Klotz A.N.O. (Guitalens Observatory, France)
report:

We imaged the field of GRB 170409A detected by Fermi LAT and GBM
(trigger 513398525/170409112) with the TAROT robotic telescope (D=18cm)
located at the Reunion observatory, France.

The GRB is located at 34 degrees from the sun and is
observable only in the dawn light in the morning.

The observations started 0.95 day after the GRB trigger.
We stacked 13 images of 120s and examined a field of view of 0.2
degree (radius) around the position provided by
Longo et al. (GCNC 21004). We do not see any new source
at the limiting magnitude of:

t0+0.95d to t0+0.96h : Rlim=17.0 +/- 0.2

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170419A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21013
SUBJECT: GRB 170419A: Swift detection of a burst
DATE:    17/04/19 13:52:55 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

B. Sbarufatti (INAF-OAB/PSU), S. D. Barthelmy (GSFC),
A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU),
A. Cholden-Brown (PSU), C. Gronwall (PSU), J. A. Kennea (PSU),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
M. H. Siegel (PSU) and T. N. Ukwatta (LANL) report on behalf of the
Swift Team:

At 13:26:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170419A (trigger=748898).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 79.866, -21.420 which is 
   RA(J2000)  =  05h 19m 28s
   Dec(J2000) = -21d 25' 12"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 5 sec.  The peak count rate
was ~1700 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT settled on the field at 13:28:21.4 UT, 101.2 seconds after
the BAT trigger. XRT data were delayed for about 8 minutes until Swift 
exited the SAA. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 79.8549, -21.4240 which
is equivalent to:
   RA(J2000)  = 05h 19m 25.18s
   Dec(J2000) = -21d 25' 26.4"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 39 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 3.50
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 591 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.05. 

Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170419A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21015
SUBJECT: GRB 170419A: Enhanced Swift-XRT position
DATE:    17/04/19 20:39:01 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2234 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170419A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 79.85468, -21.42386 which is equivalent
to:

RA (J2000): 05h 19m 25.12s
Dec (J2000): -21d 25' 25.9"

with an uncertainty of 1.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170419B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21016
SUBJECT: GRB 170419B: Swift detection of a burst
DATE:    17/04/19 21:59:49 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Cholden-Brown (PSU), S. D. Barthelmy (GSFC), C. Gronwall (PSU),
N. P. M. Kuin (UCL-MSSL), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Swift Team:

At 21:33:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170419B (trigger=748947).  Swift did not slew due to Sun constraint. 
The BAT on-board calculated location is 
RA, Dec 60.498, -15.143, which is 
   RA(J2000)  =  04h 01m 59s
   Dec(J2000) = -15d 08' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single 
with a duration of about 10 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~3 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 05:29 UT on 2017 June 19. There will thus be no XRT or
UVOT data for this trigger before this time. 

Burst Advocate for this burst is A. Cholden-Brown (aaronb AT swift.psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170419A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21018
SUBJECT: GRB 170419A: Swift-BAT refined analysis
DATE:    17/04/20 01:00:29 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-190 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170419A (trigger #748898)
(Sbarufatti et al., GCN Circ. 21013).  The BAT ground-calculated position is
RA, Dec = 79.854, -21.433 deg which is
  RA(J2000)  =  05h 19m 25.1s
  Dec(J2000) = -21d 25' 58.0"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.

The mask-weighted light curve shows a single-pulse structure that starts
and peaks at ~T0. The main emission ends at ~T+3 s, with a tail that
lasts till ~T+9 s. T90 (15-350 keV) is 8.18 +- 2.00 sec (estimated error
including systematics).

The time-averaged spectrum from T-0.39 to T+8.92 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.06 +- 0.26.  The fluence in the 15-150 keV band is 3.1 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.47 sec in the 15-150 keV band
is 1.5 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/748898/BA/


GRB_name: GRB170419B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21019
SUBJECT: GRB 170419B: Fermi GBM observation
DATE:    17/04/20 09:08:01 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

P. Veres and C. Meegan (both UAH)
report on behalf of the Fermi GBM Team:

"At 21:33:46.807 UT on 19 April 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170419B (trigger 514330431 / 170419898).
which was also detected by the Swift/BAT
(Cholden-Brown et al., GCN 21016). The GBM on-ground
location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 41 degrees.

The GBM light curve shows a single pulse
with a duration (T90) of about 24 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+5.1 s is
best fit by a Band function with Epeak = 116 +/- 19 keV,
alpha = -0.03 +/- 0.29, and beta = -2.07 +/- 0.15.

The event fluence (10-1000 keV) in this time interval is
(2.4 +/- 0.2)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.2 s in the 10-1000 keV band
is 3.8 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170412A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21020
SUBJECT: GRB 170412A CALET Gamma-Ray Burst Monitor detection
DATE:    17/04/20 11:38:45 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. Moriyama, A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Yamada,
A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170412A (Fermi GBM trigger #513733380;
INTEGRAL SPI-ACS trigger #7811) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 23:42:54.53 on 12 April 2017.  The burst signal was seen by all CGBM instruments.

The light curve of the SGM shows a single peak starting at T0 sec,
peaking at T+3 sec and ending at T+35 sec.  The T90 duration measured
by the SGM data is 28.5 +- 1.2 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1176075398/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170419A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21021
SUBJECT: GRB 170419A: Swift-XRT refined Analysis
DATE:    17/04/20 12:12:42 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J.
LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), B.
Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 170419A, from 550 s to 59.3
ks after the  BAT trigger. The data are entirely in Photon Counting
(PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.02 (+0.14, -0.12).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.7 (+/-0.3). The
best-fitting absorption column is  1.6 (+1.2, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 3.5 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.1 x 10^-11 (5.0 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.6 (+1.2, -1.0) x 10^21 cm^-2
Galactic foreground: 3.5 x 10^20 cm^-2
Excess significance: 2.1 sigma
Photon index:      1.7 (+/-0.3)

If the light curve continues to decay with a power-law decay index of
1.02, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.3 x
10^-14 (7.7 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00748898.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170419A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21023
SUBJECT: GRB 170419A: Zadko observatory - Gingin optical observations
DATE:    17/04/20 14:00:15 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. 
Coward (UWA),
M. Boer, (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.),
A. Williams (PO-UWA), R. Martin (PO-UWA)
report:

We imaged the field of GRB 170419A detected by SWIFT
(trigger 748898) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 22.3h after the GRB trigger.
The elevation of the field decreased from
49 degrees above horizon and weather conditions
were good.

We co-added a series of exposures but we did not find any
optical transcient in the XRT error box provided by Goad et al.
(GCNC 21015):

t0+22.3h to t0+22.9h : Rlim = 21.0

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170419B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21024
SUBJECT: GRB 170419B: Zadko observatory - Gingin optical observations
DATE:    17/04/20 14:19:03 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. 
Coward (UWA),
M. Boer, (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.),
A. Williams (PO-UWA), R. Martin (PO-UWA)
report:

We imaged the field of GRB 170419B detected by SWIFT
(trigger 748947) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 13.3h after the GRB trigger.
The elevation of the field decreased from
31 degrees above horizon and weather conditions
were good.

We co-added a series of exposures but we did not find any
optical transcient in the BAT error box provided by
Cholden-Brown et al. (GCNC 21016):

t0+13.3h to t0+13.5h : Rlim = 19.2

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170419B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21025
SUBJECT: GRB 170419B, Swift-BAT refined analysis
DATE:    17/04/20 17:02:25 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
A. Cholden-Brown (PSU), J. R. Cummings (CPI),
N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+262 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170419B (trigger #748947)
(Cholden-Brown et al., GCN Circ. 21016).  The BAT ground-calculated position is
RA, Dec = 60.494, -15.121 deg which is
  RA(J2000)  =  04h 01m 58.5s
  Dec(J2000) = -15d 07' 14.3"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 52%.

The mask-weighted light curve shows a single-pulse structure that starts at
~ T0 and peaks at ~T+2. The major part of the pulse ends at ~T+10 s, and
the weaker tail emission lasts till ~T+90 s. T90 (15-350 keV) is
77.2 +- 9.8 sec (estimated error including systematics).

The time-averaged spectrum from T+0.3 to T+88.0 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.47 +- 0.13.  The fluence in the 15-150 keV band is 1.9 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.98 sec in the 15-150 keV band
is 2.4 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/748947/BA/


GRB_name: GRB170423A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21030
SUBJECT: GRB 170423A: Fermi GBM detection
DATE:    17/04/24 00:04:29 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

M. Stanbro and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 17:15:08.35 UT on 23 April 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170423A (trigger 514660513 / 170423719).
The on-ground calculated location, using the GBM trigger
data, is RA = 344.34, DEC = -4.26, with an uncertainty
of 1.17 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight
location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 54 degrees.

The GBM light curve consists of several peaks
with a duration (T90) of about 47 s (50-300 keV).
The time-averaged spectrum from T0+2.05 s to T0+49.15 s is
best fit by a Band function with Epeak = 97 +/- 5 keV,
alpha = -1.04 +/- 0.04, and beta = -2.15 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(2.6 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10.8 s in the 10-1000 keV band
is 18.4 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170419A
Detection_method: LCO
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21031
SUBJECT: GRB 170419A: LCO Observations
DATE:    17/04/24 18:49:16 GMT
FROM:    Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>

A. Cucchiara, D. Morris (U. of Virgin Islands),
C. Guidorzi (U. Ferrara), and B. Gendre  (U. of Virgin
Islands) report on behalf of a larger collaboration:

"On April 19.71 UT  (T_0 +3.6h) we began observing the
field of GRB 170419A (Sbarufatti et al. GCN #21013) using
the Las Cumbres Observatory Global Network 1m Sutherland facility.

We obtained a series of observations in R and I bands for a total
of 5 minutes on target in each filter.
We identified no optical counterpart within the Enhanced Swift-XRT
position (Goad et al. GCN #21015) at the following 3-sigma limits:

R > 20.9 mag
I > 20.8 mag

These values are calibrated against nearby USNO-B1 sources and
are not corrected for Galactic Extinction."


GRB_name: GRB170424A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21032
SUBJECT: GRB 170424A: Fermi-LAT detection
DATE:    17/04/24 22:00:23 GMT
FROM:    Nicola Omodei at Stanford U.  <nicola.omodei@slac.stanford.edu>

N. Omodei, G.Vianello (Stanford University), report on behalf of the Fermi-LAT team:

At 10:12:30.75 on April, 24, 2017 Fermi-LAT detected high-energy emission from GRB 170424A, which was also detected by Fermi-GBM (trigger 514721555 / 170424425).

The best LAT on-ground location is found to be

RA, Dec = 343.7, -45.12 (J2000)

with an error radius of 0.45 deg (90 % containment, statistical error only). 

This was 57 deg from the LAT boresight at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance. 

The highest-energy photon is a 1 GeV event which is observed 56 seconds after the GBM trigger. 

The GRB was also detected using LAT Low Energy (LLE) data selection, with a significance of 6 sigma. 

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Nicola Omodei (nicola.omodei@stanford.edu).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB170424A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21033
SUBJECT: GRB 170424A: Fermi GBM detection
DATE:    17/04/25 01:05:33 GMT
FROM:    Matthew Stanbro at UAH/Fermi  <mcs0001@uah.edu>

M. Stanbro (UAH), A. von Kienlin (MPE) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 10:12:30.75 UT on 24 April 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170424A (trigger 514721555 / 170424425)
which was also detected by the Fermi-LAT (N. Omodei et al. 2017, GCN 21032).
The GBM on-ground location is consistent with the Fermi-LAT position.

 This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of one episode
with a duration (T90) of about 52 s (50-300 keV).
The time-averaged spectrum from T0+1.54 s to T0+55.81 s is
best fit by a Band function with Epeak = 464 +/- 39 keV,
alpha = -0.85 +/- 0.03, and beta = -2.00 +/- 0.09.

The event fluence (10-1000 keV) in this time interval is
(3.07 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+23.5 s in the 10-1000 keV band
is 4.8 +/- 0.2 ph/s/cm^2.

A power law function with an exponential
high-energy cutoff fits the spectrum equally well.
The power law index is -0.89 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 570 +/- 33 keV.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170424A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21034
SUBJECT: GRB 170424A: Tiled Swift observations
DATE:    17/04/25 03:03:17 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 170424A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00066

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170419A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21035
SUBJECT: GRB 170419A: Swift/UVOT Upper Limits
DATE:    17/04/25 17:28:19 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and B. Sbarufatti (INAF-OAB/PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170419A
592 s after the BAT trigger (Sbarufatti et al., GCN Circ. 21013).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 21015)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           592          742          147         >21.1
white              592        13376         1194         >22.0
v                  748        19148          594         >19.6
b                  846         7551          313         >20.4
u                  822        23245         1108         >21.0
w1                 797         7141          313         >20.0
m2                 773         6935          274         >19.9
w2                1027        17141          672         >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170424A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21036
SUBJECT: Konus-Wind observation of GRB 170424A
DATE:    17/04/25 17:33:31 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170424A
(Fermi-LAT detection: Omodei & Vianello, GCN 21032;
Fermi GBM detection: Stanbro, von Kienlin & Meegan, GCN 21033)
triggered Konus-Wind at T0=36769.094 s UT (10:12:49.094).

The burst light curve shows a single pulse  which started
at ~T0-20 s and lasted until ~T0+42 s (the total duration is ~62 s).
The emission is seen up to ~5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 3.46(-0.32,+0.44)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0-0.046 s,
of 2.81(-1.05,+1.11)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+41.216 s)
is best fit in the 20 keV - 18 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.91(-0.19,+0.23),
and Ep = 353(-70,+111) keV (chi2 = 82/98 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.01 (chi2 = 82/97 dof).

The spectrum near the peak count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 18 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.77(-0.23,+0.33),
the high energy photon index beta = -3.30(-6.70,+1.17),
the peak energy Ep = 446(-127,+170) keV,
chi2 = 108/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170424_T36769/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170424A
Detection_method: LCO
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21037
SUBJECT: GRB 170424A: LCO Observations
DATE:    17/04/25 20:23:46 GMT
FROM:    Antonino Cucchiara at UVI  <antonino.cucchiara@uvi.edu>

A. Cucchiara, D. Morris (U. of Virgin Islands), C. Guidorzi
(U. Ferrara), B. Gendre  (U. of Virgin Islands),
reports on behalf of a larger collaboration:


"On April 25.12 UT  (T_0 +14.5h) we began observing the center
of the field of LAT GRB 170424A (Omodei et al. GCN #21032)
using the Las Cumbres Observatory 1m Sutherland facility.
We covered 30% of the LAT error region and we obtained a series
of observations in R and I band for a total of 6 minutes on sky in
each filter.

We identified no optical counterpart within the center of Swift-XRT
tile #20753  (Evans et al. GCN #21034), out to a radius of ~13 arcmin,
at the following 3-sigma limits:

R > 21.2 mag
I > 20.8 mag

These magnitude are calibrated against nearby USNO-B1 sources,
and are not corrected for Galactic Extinction."




Antonino Cucchiara, PhD
Assistant Professor
Physics and Astronomy
University of the Virgin Islands

Phone: 340-693-1688
College of Science and Mathematics
#2 Brewers Bay road
St. Thomas, USVI 00802


GRB_name: GRB170428A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21042
SUBJECT: GRB 170428A: Swift detection of a short burst
DATE:    17/04/28 09:38:15 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. P. Beardmore (U Leicester), N. P. M. Kuin (UCL-MSSL),
K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU) and R. L. C. Starling (U Leicester)
report on behalf of the Swift Team:

At 09:13:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170428A (trigger=750298).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 330.063, +26.918 which is 
   RA(J2000) = 22h 00m 15s
   Dec(J2000) = +26d 55' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of about 0.25 sec.  The peak count rate
was ~22000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 09:15:06.9 UT, 84.6 seconds after
the BAT trigger. Swift then passed into the SAA, during which time no
data are collected.  No source was detected in 208 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of  84 seconds with the U filter starting
866 seconds after the BAT trigger. No credible afterglow candidate has been
found in the initial data products. The 2.7'x2.7' sub-image covers 25% of the
BAT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The
8'x8' region for the list of sources generated on-board covers 100% of the BAT
error circle. The list of sources is typically complete to about 18.0 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.06. 

Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21044
SUBJECT: GRB 170428A: MASTER-OAFA  early  optical observations 
DATE:    17/04/28 15:19:42 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , 
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, 
A.V.Krylov,  I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko

Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova 
Irkutsk State University

V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in OAFA was pointed to the  GRB170428.38 17 sec after notice time 
and 31 sec after trigger time at 2017-04-28 09:14:14 UT. On our first (10s 
exposure)  set we haven't found optical transient  within SWIFT error-box 
(ra=330.062 dec=26.9172 r=0.05).
The 5-sigma upper limit has been about 16.5 mag

The observations made on zenit distance = 72 degrees, galaxy latitude b = 
-22 degree.
The moon ( 5 % bright part) below the horizon (The altitude of the Moon is 
-49 degree ).
The sun  altitude  is -24.2 degree.
The object can be observed till sunrise at 2017-04-28 11:06:50

The message may be cited.


GRB_name: GRB170428A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21045
SUBJECT: Konus-Wind observation of GRB 170428A
DATE:    17/04/28 18:30:50 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
P. Oleynik, M. Ulanov, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration, bright GRB 170428A
(Swift-BAT detection: Beardmore et al., GCN Circ. 21042)
triggered Konus-Wind at T0=33218.719 s UT (09:13:38.719).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.02 s and has a total duration of ~0.14 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170428_T33218/

As observed by Konus-Wind, the burst
had a fluence of 4.20(-0.90,+0.91)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.056 s,
of 5.00(-1.52,+1.53)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.128 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.47(-0.21,+0.28),
the high energy photon index beta = -2.46(-7.54,+0.52),
the peak energy Ep = 982(-355,+394) keV (chi2 = 31/37 dof).

Fitting this spectrum by a power law with exponential cutoff model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields
alpha = -0.53(-0.18,+0.21) and
Ep = 1134(-268,+368) keV (chi2 = 33/38 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170428A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21046
SUBJECT: GRB 170428A: Swift-BAT refined analysis
DATE:    17/04/28 21:04:52 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

S. D. Barthelmy (GSFC),  A. P. Beardmore (U Leicester), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-119 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170428A (trigger #750298)
(Beardmore, et al., GCN Circ. 21042).  The BAT ground-calculated position is
RA, Dec = 330.051, 26.913 deg which is 
  RA(J2000)  =  22h 00m 12.3s 
  Dec(J2000) = +26d 54' 47.9" 
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.

The mask-weighted light curve shows a complex of three peaks within a period 
from T+0.15 to T+0.35 sec.   There is no sign of extended emission.
T90 (15-350 keV) is 0.20 +- 0.07 sec (estimated error including systematics).

The time-averaged spectrum from T+0.15 to T+0.45 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.76 +- 0.12.  The fluence in the 15-150 keV band is 2.8 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.20 sec in the 15-150 keV band
is 2.8 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/750298/BA/


GRB_name: GRB170428A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21047
SUBJECT: GRB 170428A: Swift-XRT refined Analysis
DATE:    17/04/28 21:19:32 GMT
FROM:    Andy Beardmore at U Leicester  <ab271@leicester.ac.uk>

A.P. Beardmore and  P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

We have analysed 4.2 ks of XRT data for GRB 170428A, from 697 s to 17.2
ks after the  BAT trigger. The data are entirely in Photon Counting
(PC) mode. Using 1475 s of PC mode data and 2 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 330.07813, +26.91580
which is equivalent to:

RA (J2000): 22h 00m 18.75s
Dec(J2000): +26d 54' 56.9"

with an uncertainty of 2.3 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.03 (+0.32, -0.29).

If the light curve continues to decay with a power-law decay index of
1.03, the count rate at T+24 hours will be 7.5 x 10^-4 count s^-1

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00750298.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21048
SUBJECT: GRB 170428A: Xinglong 2.16-m upper limit and host galaxy candidate
DATE:    17/04/29 00:31:01 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu (NAOC), Y. Qin (Geneva Obs.), Y. Zhao, J.J. Jia, H.X. Feng, Z.P. 
Zhu (NAOC),  Y.D. Hu (IAA-CSIC), S. Feng, M.T. Ju (SHAO) report

We observed the field of short GRB 170428A (Beardmore et al., GCN 21042) 
using the 2.16-m telescope located at Xinglong, Hebei, China. We 
obtained 6x300s R-band frames, starting at 19:23:21 UT on 2017-04-28 
(i.e., 10.16 hr after the burst).

No optical source is detected at the XRT position (Beardmore & Evans, 
GCN 21047) in the stacked R-band image, down to a limiting magnitude of 
m(R)>21.0.

We note that in the SDSS and Pan-STARRS archival data there already 
exists a singe source within the XRT error circle, seemingly extended in 
the northeast - southwest direction. It is localised at

R.A (J2000) =   22:00:18.687
Dec. (J2000) = +26:54:56.51

with a brightness of m(r)~22.2 mag, and thus might be the host galaxy of 
this short burst.


GRB_name: GRB170428A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21049
SUBJECT: GRB 170428A: Swift/UVOT Upper Limits
DATE:    17/04/29 00:40:35 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. P. Beardmore (U. Leicester) report
on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170428A
740 s after the BAT trigger (Beardmore et al., GCN Circ. 21042).
No optical afterglow consistent with the XRT position (Beardmore
et al., GCN Circ. 21047) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

v                  740        16576         1101         >20.0
b                  838        10823         1101         >21.0
u                  813         5412          299         >19.5
w1                 789         5207          216         >19.5
m2                 764        17481         1102         >20.1
w2                4392        11731         1082         >20.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21050
SUBJECT: GRB 170428A: GROND detection of the afterglow
DATE:    17/04/29 01:15:09 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan@bolmer.de>

Jan Bolmer (ESO, Chile), Helmut Steinle and Patricia Schady (both MPE Garching) report:

We observed the field of GRB 170428A (trigger=750298, Beardmore et al., GCN #21042)
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at
the 2.2 m MPG telescope at the ESO La Silla Observatory (Chile).

Observations started at 09:57 UT on 2017-04-28, 43 min after the GRB trigger, and they
were performed at an average seeing of 1.2'' and at an average airmass of 2.2. We detect an
uncatalogued source within the XRT error circle reported by Beardmore et al. (GCN #21047) 
at the position of RA, Dec = 330.07823, 26.91584, which is equivalent to:

RA (J2000): 22h 00m 18.78s
Dec (J2000): +26d 54' 57.0''

with an uncertainty of 0.3 arcsec.

Based on combined images with 17 min of total integration time in g'r'i'z' and 19 min in JHK
at a mid-time of 10:15 UT on 2017-04-28, this source has the following preliminary
magnitudes (all in the AB system):

g' = 21.4 +/- 0.1 mag
r' = 21.3 +/- 0.1 mag
i' = 21.1 +/- 0.1 mag
z' = 21.1 +/- 0.1 mag
J = 20.7 +/- 0.2 mag
H = 20.9 +/- 0.4 mag
K > 20.0 mag

The given magnitudes are derived based on calibrating the images against SDSS in the optical
and 2MASS field stars in the NIR bands. They are not corrected for the Galactic foreground
extinction corresponding to a reddening of E_(B-V)= 0.05 in the direction of the burst (Schlafly
& Finkbeiner 2011).

As noted by Xu et al. (GCN #21048), there already exists a single source with a brightness of
r ~ 22.2 mag, presumably the host galaxy, in the SDSS and Pan-STARRS archival data. We
therefore likely observed the NIR/optical afterglow of the short GRB 170428A.


GRB_name: GRB170428A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21051
SUBJECT: GRB 170428A: RATIR Afterglow Confirmation
DATE:    17/04/29 18:40:36 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer
(UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB),
Antonino Cucchiara(UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), JesÃºs GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki
Toy (UMD) report:

We observed the field of GRB 170428A (Beardmore, et al., GCN 21042)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir from 2017/04 29.41 to
2017/04 29.48 UTC (24.69 to 26.25 hours after the BAT trigger), obtaining
a total of 0.90 hours exposure in the r and i bands and 0.35 hours
exposure in the Z, Y, J, and H bands.

For a source at the candidate afterglow position (Bolmer, et al., GCN 
21050),
in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
detection and upper limits (3-sigma):

   r    > 22.3
   i    22.1 +/- 0.4
   Z    > 20.9
   Y    > 20.6
   J    > 20.1
   H    > 19.9

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

Our observations show that the source reported by Bolmer, et al., (GCN 
21050)
significantly faded, and is therefore the afterglow of the short 
GRB170428A.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21052
SUBJECT: GRB 170428A: TAROT La Silla observatory optical observations
DATE:    17/04/30 02:01:18 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 170428A detected by SWIFT
(trigger 750298) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 25s after the GRB trigger
(15s after the notice). The elevation of the field increased from
18 degrees above horizon and weather conditions
were good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT in the GROND position provided
by Bolmer et al. (GCNC 21050) with a limiting magnitude of:
t0+25s to t0+85s : Rlim = 17.5

The second image is 30.0s exposure in tracking mode:
t0+98s to t0+128s : Rlim = 18.2

We co-added a series of exposures:
t0+98s to t0+388s : Rlim = 19.2

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21053
SUBJECT: GRB 170428A: DCT Imaging
DATE:    17/04/30 02:40:13 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

S. B. Cenko, E. Troja (NASA GSFC), E. Golden-Marx, E. Blanton (BU) report on behalf of a larger collaboration:

We imaged the location of the optical afterglow (Bolmer et al., GCN 21050) of the short GRB170428A (Beardmore et al., GCN 21042) with the Large Monolithic Imager mounted on the 4.3m Discovery Channel Telescope in Happy Jack, AZ.  Observations were obtained in the i-band filter beginning at 10:52 UT on 2017 April 29 (1.1 days after the GRB trigger).  We detect emission at the reported afterglow position, and measure a magnitude of i = 22.2 +/- 0.2 mag (calibrated with respect to nearby point sources from SDSS), consistent with the measurement reported by Troja et al. (GCN 21051).  We caution, however, that the candidate host galaxy (Bolmer et al., GCN 21050)  is blended with this location due to poor seeing conditions - accurate afterglow photometry may require removing this host contamination.


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21054
SUBJECT: Short GRB 170428A: MASTER-OAFA  final reduction  of the optical observations 
DATE:    17/05/01 11:13:25 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov,
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU

R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) , 
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova 
Irkutsk State University

V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in 
OAFA was pointed to the  GRB170428A (Beardmore et al., GCN 21042) 17 sec 
after notice time and 31 sec after 
trigger time at 2017-04-28 09:14:14 UT (Podesta et al., GCN 21044).

Our unfiletred limits are:

     Date time         Exp  Proc.type  Lim.
                         (s)

2017-04-28 09:14:14 10  Alert (SWIFT)  16.6 
2017-04-28 09:15:04     20  Alert (SWIFT)  17.1 
2017-04-28 09:16:07     30  Alert (SWIFT)  17.6
2017-04-28 09:17:19     40  Alert (SWIFT)  17.9
2017-04-28 09:18:42     60  Alert (SWIFT)  18.2 
2017-04-28 09:20:24     80  Alert (SWIFT)  18.6
2017-04-28 09:17:19    180    SumAlert(SWIFT)  19.1 
2017-04-28 09:22:28    110  Alert (SWIFT)  18.9
2017-04-28 09:24:59    140  Alert (SWIFT)  19.0
2017-04-28 09:28:01    170  Alert (SWIFT)  19.2 
2017-04-28 09:22:28    420    SumAlert(SWIFT)   19.7
2017-04-28 09:31:33    180  Alert (SWIFT)  19.3
2017-04-28 09:35:16    180  Alert (SWIFT)  19.4 
2017-04-28 09:38:59    180  Alert (SWIFT)  19.5
2017-04-28 09:31:33    540    SumAlert (SWIFT)  19.9 
2017-04-28 09:42:42    180  Alert (SWIFT)  19.5
2017-04-28 09:48:50    180  Alert (SWIFT)  19.5 
2017-04-28 09:55:02    180  Alert (SWIFT)  19.5
2017-04-28 09:42:42    540    SumAlert (SWIFT)  20.1
2017-04-28 09:58:46    180  Alert (SWIFT)  19.4
2017-04-28 10:02:26    180  Alert (SWIFT)  19.1 
2017-04-28 10:06:07    180  Alert (SWIFT)  18.8
2017-04-28 09:58:46    540    SumAlert (SWIFT)  19.3
2017-04-28 10:09:49    180      Alert (SWIFT)   18.3 
2017-04-28 09:31:33   1800    SumAlert (SWIFT)  20.3
2017-04-28 10:02:26   1440    SumAlert (SWIFT)  19.8


The message may be cited.


GRB_name: GRB170428A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21055
SUBJECT: GRB 170428A: TNG optical observations
DATE:    17/05/01 14:24:23 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo (INAF-OAB), V. D'Elia (INAF/OAR & ASI/ASDC), Daniele Malesani (DARK/NBI), S. Campana, G. Tagliaferri (INAF/OAB), 
G. Andreuzzi, D. Carosati (INAF-TNG) report on behalf of the CIBO collaboration: 

We observed the field of GRB 170428A (Beardmore et al., GCN 21042) with the 3.6m Telescopio Nazionale Galileo (TNG) 
equipped with DOLoRes. Observations were carried out in the i-sdss and z-sdss filters. Observations started on May 01 at 
03:55:46 UT (~2.78 days after the burst) under a seeing of ~ 1.5". 

We clearly detect the candidate host galaxy reported by Xu et al. (GCN 21048). Some emission is also visible at the position 
of the optical afterglow (Bolmer et al., GCN 21050; Troja et al., GCN 21051; Cenko et al., GCN 21053), blended with the 
candidate host galaxy light. For the whole complex (afterglow and candidate host galaxy) we measure the following magnitudes: 

i(AB) = 22.1 +/- 0.1 at t-t0 = 2.79 d
z(AB) = 21.9 +/- 0.1 at t-t0 = 2.81 d

(calibrated against nearby SDSS stars). It is not possible, at this stage, to evaluate the afterglow contribution to the observed 
optical emission. Further observations are planned. 


GRB_name: GRB170428A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21058
SUBJECT: GRB 170428A: 15 GHz upper limits from AMI
DATE:    17/05/02 17:27:34 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson 
(Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. 
Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. 
Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for short 
GRB 170428A (Beardmore et al., GCN 21042) as part of the 4pisky program, 
and subsequent follow up observations were obtained up to 3 days 
post-burst. Our observations at 15 GHz on 2016 Apr 28.42 and Apr 30.34 
(UT) do not reveal any radio source at the XRT location (Beardmore et 
al., GCN 21047), with 3sigma upper limits of 117 uJy and 96 uJy 
respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.


GRB_name: GRB170428A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21059
SUBJECT: GRB 170428A: GTC spectroscopic redshift of candidate host galaxy
DATE:    17/05/02 17:43:47 GMT
FROM:    Zach Cano at U of Iceland  <zewcano@gmail.com>

â€‹â€‹L. Izzo, Z. Cano (IAA-CSIC), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI),
D. A. Kann, C. Thoene (IAA-CSIC), and S. Geier (IAC, GRANTECAN) report on
behalf of a larger collaboration:

We observed the field of short-duration GRB 170428A (Beardmore et al., GCN
Circ. 21042) with OSIRIS mounted on the 10.4-m GTC telescope on La Palma
(Spain) starting at 04:31:49 UT on 01 May 2017, at a mean time of +2.82
days from the GRB detection. The observations consisted of 4 x 900 s
spectra using grism R1000R, which covers the wavelength range between 5100
and 10000 AA.

In our r-band acquisition image, (30 second exposure time), we see the host
candidate of Xu et al. (GCN Circ. 21048), which is also slightly visible in
the r-band Pan-STARRS image.  The slit was centred on the host galaxy
candidate, and in the faint trace we detect emission lines corresponding to
Halpha, [OIII] 5007, Hbeta, and [OII] 3726,3729, all at a common redshift
of z=0.454.  The angular separation between the candidate host and the GRB
position determed by GROND (Bolmer et al., GCN Circ. 21050) is 1.2'' +-
0.3'', which at this redshift implies an offset of 6.9 kpc +- 1.7 kpc.

GTC finder chart of the AG position and candidate host:
http://www.iaa.es/~deugarte/GRBs/170428A/GTC.jpeg


GRB_name: GRB170428A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21067
SUBJECT: GRB 170428A CALET Gamma-Ray Burst Monitor detection
DATE:    17/05/04 08:47:22 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Yamada, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The short-duration GRB 170428A (Beardmore et al., GCN Circ. 21042; Tsvetkova
et al., GCN Circ. 21045) was detected the CALET Gamma-ray Burst Monitor (CGBM)
by the ground process pipeline at 09:13:42.36 on 28 April 2017 at 5.1 sigma which
is below the trigger threshold of the on-board trigger.  The burst signal was seen
only by the SGM instrument.

Because there was no on-board trigger, no event data were stored for this
event.  The continuous light curve data recorded in 0.125 s time resolution are
not fine enough to investigate the temporal structure and the duration of this event.

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1177405621/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170424A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21074
SUBJECT: Swift XRT observations of GRB 170424A 
DATE:    17/05/06 16:23:20 GMT
FROM:    Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>

B. Sbarufatti (INAF-OAB/PSU), P. A. Evans (U. Leicester) report on behalf of the Swift XRT team.

We report on Swift XRT observations of the field of the Fermi-LAT discovered GRB 170424A (N. Omodei et al. 2017, GCN 21032).
Swift performed an initial tiled observation of the LAT error circle (27 arcmin) using a 7-tile pattern (7-tile pattern 100% coverage radius: 24 arcmins, maximal coverage radius: 33 arcmins), 700 s of exposure/tile, on April 25th (P. A. Evans 2017, GCN 21034). 

Three uncatalogued sources were detected:

Source# RA             Dec          Rate              Exposure time 
2       22h 52m 53.04s -45d10m43.5s 1.5+/-0.5E-2 cps  684s
3       22h 53m 10.51s -45d29m11.5s 1.9+/-0.6E-2 cps  677s
5       22h 52m 09.64s -45d02m43.3s 1.5+/-0.7E-2 cps  684s

On May 3rd and 4th further observations were performed to check for fading of the sources.
Source 2 was still detected without showing any evidence of fading.
Sources 3 and 5 were no more detected, but the 3-sigma upper limits are consistent with the earlier detections, within errors.

Source# Rate              Exposure time 
2       1.1+/-0.2E-2 cps  2.8 ks
3       < 1.4E-2  cps     3.1 ks      
5       < 7.1E-3  cps     3.1 ks

We conclude that Source 2 is not the GRB afterglow, while the nature of Sources 3 and 5 remains uncertain.

All the quoted errors are at the 90% confidence level.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170423A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21076
SUBJECT: GRB 170423A: TAROT Reunion observatory optical observations
DATE:    17/05/07 15:47:33 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.),
Peyrot A., Teng J.P. (Les Makes Observatory, France),
Thierry P. (Auragne Observatory, France),
report:

We imaged the field of GRB 170423A detected by Fermi GBM
(trigger 514660513 / 170423719) with the TAROT robotic telescope (D=18cm)
located at the Reunion observatory, France.

The observations started 7.41h after the GRB trigger.
We stacked 6 images of 120s and examined a field of view of 1.2
degree (radius) around the position provided by
Stanbro et al. (GCNC 21030). We do not see any new source
at the limiting magnitude of:

t0+7.41h to t0+7.62h : Rlim=17.8 +/- 0.2

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB170510A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21080
SUBJECT: GRB 170510A: Fermi-LAT detection
DATE:    17/05/10 10:55:57 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari), M. Axelsson (Stockholm Univ. & KTH),
and F. Longo (University & INFN, Trieste) report on behalf of the Fermi-LAT team:


At 05:12:25.73 UT on May 10, 2017 Fermi-LAT detected high-energy emission
from GRB 170510A, which was also detected by Fermi-GBM (trigger 516085950/170510217).
The best LAT on-ground location is found to be

RA, Dec = 159.91, -39.32 (J2000)

with an error radius of 0.34 deg (90 % containment, statistical error only).
This was ~67 deg from the LAT boresight at the time of the trigger
and triggered an autonomous repoint of the spacecraft.

The data from the Fermi-LAT show a significant increase in the event rate
that is spatially and temporally correlated with the trigger with high significance.
The highest-energy photon is a 1.8 GeV event which is observed 410 seconds
after the GBM trigger.
A total of 15 photons were detected in the first 500 seconds after the trigger,
after which time the spacecraft entered the SAA.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is
Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it).


The Fermi-LAT is a pair conversion telescope designed to cover the energy band
from 20 MeV to greater than 300 GeV. It is the product of an international
collaboration between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
  


GRB_name: GRB170510A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21081
SUBJECT: GRB 170510A: Fermi-LAT detection
DATE:    17/05/10 11:01:32 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari), M. Axelsson (Stockholm Univ. & KTH),
and F. Longo (University & INFN, Trieste) report on behalf of the Fermi-LAT team:


At 05:12:25.73 UT on May 10, 2017 Fermi-LAT detected high-energy emission
from GRB 170510A, which was also detected by Fermi-GBM (trigger 516085950/170510217).
The best LAT on-ground location is found to be

RA, Dec = 159.91, -39.32 (J2000)

with an error radius of 0.34 deg (90 % containment, statistical error only).
This was ~67 deg from the LAT boresight at the time of the trigger
and triggered an autonomous repoint of the spacecraft.

The data from the Fermi-LAT show a significant increase in the event rate
that is spatially and temporally correlated with the trigger with high significance.
The highest-energy photon is a 1.8 GeV event which is observed 410 seconds
after the GBM trigger.
A total of 15 photons were detected in the first 500 seconds after the trigger,
after which time the spacecraft entered the SAA.

A Swift ToO has been approved for this burst.

The Fermi-LAT point of contact for this burst is
Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it).


The Fermi-LAT is a pair conversion telescope designed to cover the energy band
from 20 MeV to greater than 300 GeV. It is the product of an international
collaboration between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.


GRB_name: GRB170510A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21082
SUBJECT: GRB 170510A: Tiled Swift observations
DATE:    17/05/10 11:58:15 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 170510A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00067

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170510A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21085
SUBJECT: GRB 170510A: Fermi GBM observation
DATE:    17/05/10 17:47:13 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA), E. Bissaldi (Politecnico & INFN Bari)  
and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 05:12:25.73 UT on 10 May 2017, the Fermi Gamma-Ray Burst 
Monitor triggered and located GRB 170510A 
(trigger 516085950 / 170510217), which was also detected by the 
Fermi/LAT (Bissaldi et al. 2017, GCN 21081).

The GBM on-ground location is consistent with the LAT position.

The trigger resulted in an Autonomous Repoint Request (ARR) by 
the GBM Flight Software owing to the high peak flux of the GRB.
This ARR was accepted and the spacecraft slewed to the GBM 
in-flight location. 

The angle from the Fermi LAT boresight is 67 degrees.

The GBM light curve consists of multiple peaks with a 
duration (T90) of about 128 s (50-300 keV). The time-averaged
spectrum from T0+2.0 s to T0+130.0 s is best fit by a power law
function with an exponential high-energy cutoff. The power law 
index is -0.82 +/- 0.03 and the cutoff energy, parameterized as 
Epeak, is 302 +/- 13 keV.

A Band function fits the spectrum equally well with 
Epeak= 264 +/- 17 keV, alpha = -0.77 +/- 0.04 and 
beta = -2.33 +/- 0.16.

The event fluence (10-1000 keV) in this time interval is
(4.78 +/- 0.11)E-05 erg/cm^2. The 1-sec peak photon flux 
measured starting from T0+21.8 s in the 10-1000 keV band 
is 17.0 +/- 0.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21086
SUBJECT: GRB 170510A: Swift-XRT observations
DATE:    17/05/10 22:22:51 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>

A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows
(PSU), A. Cholden-Brown (PSU), S.L. Gibson (U. Leicester), J.P. Osborne
(U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans
(U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 170510A (Bissaldi et al. GCN Circ. 21080)
in a series of observations tiled on the sky. The total exposure time
is 4.7 ks, distributed over 7 tiles; the maximum exposure at a single
sky location was 1.4 ks. The data were collected between T0+24.3 ks and
T0+36.2 ks, and are entirely in Photon Counting (PC) mode. 

One uncatalogued X-ray source has been detected, it is below the RASS
limit and shows no definitive signs of fading. Therefore, at the
present time we cannot confirm this as the afterglow. Details of this
source are given below:

Source 1:
  RA (J2000):  160.15394  =  10:40:36.95
  Dec (J2000): -39.21244  =  -39:12:44.8
  Error: 2.3 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0630 [+0.0091, -0.0090] ct s^-1   
  Distance: 794 arcsec from Fermi/LAT position.
  Flux: (1.76 [+0.26, -0.25])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Two catalogued sources were also detected.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00067.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21087
SUBJECT: GRB 170510A: LCO possible counterpart
DATE:    17/05/11 04:14:49 GMT
FROM:    Bruce Gendre at UVI  <bruce.gendre@gmail.com>

A. Cucchiara, D. Morris (U. of Virgin Islands),
C. Guidorzi (U. Ferrara), B. Gendre  (U. of
Virgin Islands), reports on behalf of a larger
collaboration:

"On May 10 at 16:46 UT (T_0 +11.4h) we began observing the center
of the field of LAT GRB 170510A (Bissaldi et al. GCN #21080)
using the Las Cumbres Observatory 1m Sutherland facility.
We covered 50% of the LAT error region and we obtained a series
of 5x120s observations in R band, for a total of 10 minutes on sky.

We identified a possible optical counterpart of GRB170510A located
at the same position of candidate #1 from the Swift-XRT tiled
observations (Evans et al. GCN #21082, Melandri et al. GCN #21086).

Our preliminary photometry for this source is:

R = 19.6 +/- 0.2 mag

At the moment we cannot establish the temporal variability of this source.
This magnitude is calibrated against nearby USNO-B1 sources,
and is not corrected for Galactic Extinction."


GRB_name: GRB170510A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21090
SUBJECT: Konus-Wind observation of GRB 170510A
DATE:    17/05/12 14:07:37 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 170510A
(Fermi-LAT detection: Bissaldi, et al., GCN Circ. 21080;
Fermi-GBM detection: Roberts, et al., GCN Circ. 21085)
triggered Konus-Wind at T0=18750.788 s UT (05:12:30.788).

The burst light curve shows a multipeaked structure
which starts at ~T0-2 s and has a total duration of ~141 s.
The emission is seen up to ~18 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170510_T18750/

As observed by Konus-Wind, the burst
had a fluence of 5.70(-0.70,+1.51)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+20.688 s,
of 5.60(-1.12,+1.63)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+137.216 s)
is best fit in the 20 keV - 18 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.84(-0.14,+0.17),
the high energy photon index beta = -3.12(-6.88,+0.73),
the peak energy Ep = 261(-36,+42) keV
(chi2 = 76/96 dof).

The spectrum near the maximum count rate
(measured from T0+16.640 to T0+22.528 s)
is best fit in the 20 keV - 18 MeV range
by a power law with exponential cutoff model (CPL):
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.72(-0.09,+0.10)
and Ep = 331(-25,+29) keV (chi2 = 89/92 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.56
(chi2 = 88/91 dof).

In this (and only this) time interval, a prominent count excess
over the Band (and CPL) function is seen in the ~2-18 MeV range,
suggesting a presence of a hard spectral component.
Fitting this spectrum by a CPL + power law (PL) model
yields alpha = -0.48(-0.31,+0.44),
Ep = 301(-31,+50) keV, and
PL photon index of about -1.6 (chi2 = 85/90 dof),
with the component energy flux ratio (PL to CPL) of ~ 0.6
(20 keV - 10 MeV).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB170510A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21091
SUBJECT: GRB 170510A: Global MASTER Net possible OT observations 
DATE:    17/05/12 14:36:50 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov, 
I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University, Sternberg Astronomical Institut

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) ,
National University of San Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),
San Juan, Argentina


K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova 
Irkutsk State University

V.Yurkov, Yu.Sergienko
Blagoveschensk Educational State University, Blagoveschensk

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias


MASTER-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) located 
in SAAO was starting survey on the LAT  GRB170510.22 error-box (Bissaldi et 
al., GCN #21080)   22480 sec after notice time and 41530 sec after trigger time 
at 2017-05-10 16:44:36 UT. The 5-sigma upper limit on our first (180s exposure) 
set is about 18.9 mag

  We marginaly see   optical candidate (Cucchiara  et al. GCN 21087) at XRT 
(Evans  et al. GCN #21082, Melandri et al. GCN #21086)  position with 
unfiltered mag ~ 19  m .

Ra, Dec = 10 40 36.76 -39 12 43.8 (+/-1 arcsec)

We did not see object 2.5 hours late with limit 19.5 .

So X-ray Source 1 (Melandri et al. GCN #21086) is possible OT.

The message may be cited.


GRB_name: GRB170510A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21093
SUBJECT: GRB 170510A: AstroSat CZTI(Veto) detection
DATE:    17/05/14 18:59:22 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

The bright long GRB170510A (Bissaldi E. et al., GCN Circ. 21080) was detected using the CsI veto detectors on Astrosat CZTI (Bhalerao et al., arXiv:1608.03408). 

The source was clearly detected in the 125-250 keV energy range. The light curve shows a multiple peak structure. The peak count rate in the CsI detectors was 940.2 counts/sec above the background (four quadrants summed together), with a total of 699536 counts. The local mean background count rate was 1365.7 counts/sec. Using cumulative rates, we measure a T90 of 67.8 secs.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb . CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.


GRB_name: GRB170514A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21094
SUBJECT: GRB 170514A: Fermi GBM detection
DATE:    17/05/15 09:27:16 GMT
FROM:    Elisabetta Bissaldi at U.Innsbruk/IAPP  <Elisabetta.Bissaldi@uibk.ac.at>

E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:


"At 04:18:38.88 UT on 14 May 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 170514A (trigger 516428323 / 170514180).
The on-ground calculated location, using the GBM trigger
data, is

RA, Dec = 122.10, -25.30

(J2000 degrees, equivalent to 08h 08m, -25d 18'),
with an uncertainty of 2.2 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight at the GBM trigger time is 58 degrees.

The GBM light curve shows two distinct emission episodes
with a duration (T90) of about 104 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+30 s
and from T0+75 s to T0+100 s is adequately fit by
a power law function with an exponential
high-energy cutoff. The power law index is -1.53 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 150 +/- 7 keV.

The event fluence (10-1000 keV) in this time interval is
(2.26 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+83.4 s in the 10-1000 keV band
is 13.0 +/- 0.3 ph/s/cm^2.


The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."


GRB_name: GRB170516A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21097
SUBJECT: GRB 170516A: Swift detection of a burst
DATE:    17/05/16 13:06:41 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA),
P.A. Evans (U Leicester), C. Gronwall (PSU), J. A. Kennea (PSU),
H. A. Krimm (NSF/USRA), N. P. M. Kuin (UCL-MSSL),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
R. L. C. Starling (U Leicester) report on behalf of the Swift Team:

At 12:49:20 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170516A (trigger=753110).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 41.598, -55.899, which is 
   RA(J2000)  =  02h 46m 24s
   Dec(J2000) = -55d 53' 54"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a couple peaks
with a total duration of about 35 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 12:50:41.1 UT, 80.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 41.5663, -55.9092 which is equivalent to:
   RA(J2000)  = +02h 46m 15.91s
   Dec(J2000) = -55d 54' 33.1"
with an uncertainty of 6.4 arcseconds (radius, 90% containment). This
location is 73 arcseconds from the BAT onboard position, within the BAT
error circle. 

The initial flux in the 2.5 s image was 4.96e-10 erg cm^-2 s^-1 (0.2-10
keV). 

Automated UVOT data processing is currently not working, but manual
inspection of the UVOT image shows no GRB afterglow counterpart. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170516A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21098
SUBJECT: GRB 170516A: Enhanced Swift-XRT position
DATE:    17/05/16 19:11:18 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2335 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 170516A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 41.56858, -55.90968 which is equivalent
to:

RA (J2000): 02h 46m 16.46s
Dec (J2000): -55d 54' 34.8"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170516A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21099
SUBJECT: GRB 170516A: Swift/UVOT Upper Limits
DATE:    17/05/16 22:02:21 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report
on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field
of GRB 170516A 87 s after the BAT trigger (Lien et al., GCN Circ.
21097). No optical afterglow consistent with the XRT position
(Lien et al. GCN Circ. 21097) is detected in the initial
UVOT exposures. Preliminary 3-sigma upper limits using
the UVOT photometric system (Breeveld et al. 2011, AIP
Conf. Proc. 1358, 373) for the first finding chart (FC)
exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            87          237          147         >20.1
white               87         5703          541         >21.1
v                 4478         6113          393         >19.8
b                 3863         5498          393         >20.6
u                  299         5293          379         >19.4
w1                4888         5088          197         >19.4
m2                4683         6222          299         >20.5
w2                4274         5909          393         >20.5

The magnitudes in the table are not corrected for the
Galactic extinction due to the reddening of E(B-V) = 0.03
in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB170516A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21101
SUBJECT: GRB 170516A: Swift-XRT refined Analysis
DATE:    17/05/17 00:12:43 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), A. Cholden-Brown (PSU), S. J. LaPorte (PSU), S.L.
Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA) and A.Y. Lien report on behalf of the Swift-XRT team:

We have analysed 7.2 ks of XRT data for GRB 170516A (Lien et al. GCN
Circ. 21097), from 69 s to 34.9 ks after the  BAT trigger. The data
comprise 7 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Osborne et al. (GCN Circ.
21098).

The light curve can be modelled with an initial power-law decay with an
index of alpha=3.78 (+4.22, -0.29), followed by a break at T+232 s to
an alpha of 0.55 (+/-0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.07 (+0.25, -0.23). The
best-fitting absorption column is  9.1 (+6.2, -5.2) x 10^20 cm^-2, in
excess of the Galactic value of 3.1 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.2 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9.1 (+6.2, -5.2) x 10^20 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: 1.9 sigma
Photon index:      2.07 (+0.25, -0.23)

If the light curve continues to decay with a power-law decay index of
0.55, the count rate at T+24 hours will be 0.015 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.9 x
10^-13 (6.0 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00753110.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB170516A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21102
SUBJECT: GRB 170516A: Swift-BAT refined analysis
DATE:    17/05/17 01:07:14 GMT
FROM:    Hans Krimm at NASA-GSFC/NSF  <hans.krimm@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),  H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry 
downlink,
we report further analysis of BAT GRB 170516A (trigger #753110)
(Lien, et al., GCN Circ. 21097). The BAT ground-calculated position is
RA, Dec = 41.543, -55.929 deg which is
    RA(J2000)  =  02h 46m 10.4s
    Dec(J2000) = -55d 55' 44.2"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.

The mask-weighted light curve shows two fairly symmetrical triangular 
peaks.  The first
starts at T-5 s, peaks at T+2 s and decays by T+10 s.  The second peak 
starts
at T+10 s, has a broad peak from T+15 to T+20 and decays by T+28 s.   The
spacecraft slewed away from the burst position at about T+550 sec.
T90 (15-350 keV) is 36.78 +- 11.61 sec (estimated error including 
systematics).

The time-averaged spectrum from T-19.86 to T+31.22 sec is best fit by a 
power law
with an exponential cutoff.  This fit gives a photon index 1.13 +- 0.87,
and Epeak of 19.1 +- 12.4 keV (chi squared 37.46 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 8.5 +- 0.9 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+1.27 sec in the 15-150 keV band is
1.3 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.67 +- 0.17 (chi squared 47.73 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/753110/BA/


GRB_name: GRB170510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21103
SUBJECT: GRB 170510A: Swift-XRT afterglow detection
DATE:    17/05/18 15:59:27 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>

A. Cholden-Brown (PSU), S. J. LaPorte (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), B. Mingo (U. Leicester), V.
D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), J.A.
Kennea (PSU) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 170510A (Bissaldi et al. GCN Circ. 21080).
The observations now extend from T0+24.7 ks to T0+713.5 ks, and are
entirely in Photon Counting (PC) mode. The source previously reported
by Melandri et al. (GCN Circ. 21086), "Source 1", is fading with
3-sigma significance, and is therefore likely the GRB afterglow.

Using 1264 s of PC mode data and 4 UVOT images, we find an enhanced XRT
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 160.15394, -39.21244 which is
equivalent to:

RA (J2000): 10h 40m 36.95s
Dec(J2000): -39d 12' 44.8"

with an uncertainty of 2.3 arcsec (radius, 90% confidence). This
position is 13.2 arcmin from the Fermi/LAT position.  The source is
fading with alpha >0.9.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.8 (+0.8, -0.4). The
best-fitting absorption column is  consistent with the Galactic value
of 6.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.2 x 10^-11 (3.5 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6 (+/-24) x 10^20 cm^-2
Galactic foreground: 6.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.8 (+0.8, -0.4)

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00067/Source1.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00067.

Swift/UVOT observed "Source 1" at T0+696 ks. We did not find an optical
counterpart. We measured a 3 sigma upper limit >21 mag in the UVW1
filter, using an exposure of 1671 s.

This circular is an official product of the Swift-XRT and UVOT teams.


GRB_name: GRB170510A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21105
SUBJECT: GRB 170510A CALET Gamma-Ray Burst Monitor detection
DATE:    17/05/19 02:55:29 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Tezuka, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170510A (Roberts et al., GCN Circ. 21085;
Bissaldi et al., GCN Circ. 21080; Svinkin et al. GCN Circ. 21090;
Sharma et al. GCN Circ. 21093; INTEGRAL SPI-ACS trigger #7841)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:12:23.19 on
10 May 2017.  The burst signal was seen by all CGBM instruments.

The light curve of the SGM shows multiple peaks.  The emission
starts from T+5 sec, peaks at T+25 sec and ends at T+35 sec.
The T90 duration measured by the SGM data is 24.9 +- 1.0 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1178427921/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.


GRB_name: GRB170519A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21106
SUBJECT: GRB 170519A: Swift detection of a burst with an optical counterpart
DATE:    17/05/19 05:24:17 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

T. N. Ukwatta (LANL), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC)
and K. L. Page (U Leicester) report on behalf of the Swift Team:

At 05:10:02 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170519A (trigger=753445).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 163.450, +25.378 which is 
   RA(J2000) = 10h 53m 48s
   Dec(J2000) = +25d 22' 41"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 05:11:23.2 UT, 80.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 163.42823, 25.37377 which
is equivalent to:
   RA(J2000)  = 10h 53m 42.78s
   Dec(J2000) = +25d 22' 25.6"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 72 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 3.58e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 91 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 10:53:42.46 = 163.42693
  DEC(J2000) = +25:22:27.4  =  25.37429
with a 90%-confidence error radius of about 0.75 arc sec. This position is 1.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.07 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB170519A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21107
SUBJECT: GRB 170519A: Enhanced Swift-XRT position
DATE:    17/05/19 08:49:25 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2439 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 170519A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 163.42699, +25.37417 which is equivalent
to:

RA (J2000): 10h 53m 42.48s
Dec (J2000): +25d 22' 27.0"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB170519A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21108
SUBJECT: GRB 170519A: optical observations
DATE:    17/05/19 10:10:58 GMT
FROM:    Luca Izzo at IAA-CSIC  <Luca.Izzo@ICRA.it>

L. Izzo, A. de Ugarte Postigo, Z. Cano, D.A. Kann (IAA-CSIC) report on behalf of a larger collaboration,

We observed the field of GRB 170519A (Ukwatta et al., GCN 21106) with the T24 (Plane Wave CDK 0.61m) of the iTelescope.Net (http://www.itelescope.net) located at Auberry, CA.  
A single image of 300 s was taken in the V filter, starting at 07:18:04 UT, 2.13 hr after the GRB trigger. The GRB optical afterglow is clearly detected with a preliminary photometry estimate of V ~ 18, as compared to field stars of the GSC2.3 catalog.  

An image of the field can be seen at http://goo.gl/GScY4H


GRB_name: GRB170519A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21109
SUBJECT: GRB 170519A: RATIR Optical and NIR Observations
DATE:    17/05/19 13:08:22 GMT
FROM:    Nat Butler at UC berkeley  <natxbutler@gmail.com>

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora
Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:

We observed the field of GRB 170519A (Ukwatta, et al., GCN 21106) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio AstronÃ³mico Nacional on
Sierra San Pedro MÃ¡rtir from 2017/05 19.22 to 2017/05 19.32 UTC (1.8
minutes to 2.44 hours after the BAT trigger), obtaining a total of 1.41
hours exposure in the r and i bands and 0.60 hours exposure in the Z, Y, J,
and H bands.

The optical transient (GCN 21106; Izzo, et al., GCN 21108) is clearly
detected.  In comparison with the SDSS DR9 and 2MASS catalogs, we obtain:

  r 16.72 +/- 0.01
  i 16.50 +/- 0.01
  Z 16.34 +/- 0.01
  Y 16.25 +/- 0.01
  J 16.15 +/- 0.01
  H 15.87 +/- 0.01

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  The lightcurve rises in all bands
initially, peaking at i~16 at about 15 minutes after the GRB trigger, then
fading as t^(-0.8).

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.


GRB_name: GRB170510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21110
SUBJECT: GRB 170510A: LCO Siding Springs early observations
DATE:    17/05/19 13:47:40 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc 
(U. Nova Gorica), C.G. Mundell (U. Bath), A. Cucchiara, D. Morris, B. 
Gendre (U. of Virgin Islands) on behalf of a large collaboration report:

We began observing Fermi GRB 170510A (Bissaldi et al. GCN 21081) on May 
10, 12:14 UT (7.0 hours since the GRB) with a 1-m LCO unit with the SDSS 
i filter.  Within the Swift-XRT error circle (Cholden-Brown et al. GCN 
21103) we clearly detect the optical afterglow candidate (Cucchiara et 
al. GCN 21087; Lipunov et al. GCN 21091) at the following position:

RA(J2000) =  10:40:36.89
DEC(J2000)= -39:12:45.2

with an error radius of 1.0", with the following value:

Mid Time     Exposure       Filter       Magnitude (AB)
(hours)        (s)
-------------------------------------------------------
7.1           5x120         SDSS-I        18.60 +- 0.07
-------------------------------------------------------

as calibrated against nearby UCAC4 stars.


GRB_name: GRB170519A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21111
SUBJECT: GRB 170519A: Weihai optical observations
DATE:    17/05/19 14:41:03 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu, Z.P. Zhu, H.X. Feng (NAOC), C.M. Zhang, S.M. Hu (SDU), Y.D. Hu 
(IAA-CSIC), Y. Qin (Geneva Observatory) report:

We observed the field of GRB 170519A (Ukwatta et al., GCN 21106) using 
the 1-m telescope located at Weihai, Shandong, China. We obtained 4x360s 
frames in the Sloan r-filter, starting at 11:52:54 UT on 2017-05-19, 
i.e., 6.71 hr after the burst.

The optical afterglow (Ukwatta et al., GCN 21106; Izzo et al., GCN 
21108) is clearly detected in our stacked image, and it has decayed to 
m(r) = 18.92 +/- 0.06 at 6.94 hr post-burst, calibrated with nearby SDSS 
stars.


GRB_name: GRB170519A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21112
SUBJECT: GRB 170519A: Swift-BAT refined analysis
DATE:    17/05/19 15:26:19 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+630 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170519A (trigger #753445)
(Ukwatta, et al., GCN Circ. 21106).  The BAT ground-calculated position is
RA, Dec = 163.429, 25.374 deg which is 
  RA(J2000)  =  10h 53m 42.9s 
  Dec(J2000) = +25d 22' 26.6" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows an initial peak starting around T-30 s, peaking
at T+0 s, and decaying by T+15 s.  Then there is a second, weaker peak from about
T+180 s to T+220 s. T90 (15-350 keV) is 216.4 +- 49.4 sec (estimated error including 
systematics).

The time-averaged spectrum from T-28.5 to T+255.6 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.94 +- 0.26.  The fluence in the 15-150 keV band is 1.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.84 sec in the 15-150 keV band
is 0.7 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/753445/BA/


GRB_name: GRB170519A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  21113
SUBJECT: GRB 170519A: iTelescope T11 optical observations
DATE:    17/05/19 15:42:57 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95  <veli-pekka.hentunen@kassiopeia.net>

Veli-Pekka Hentunen and Markku Nissinen (Taurus Hill Observatory (A95),
Varkaus, Finland) report:

We have detected GRB 170519A optical afterglow at iTelescope observatory
T11 (Mayhill, New Mexico) using 0.51-m/6.8 Planewave CDK telescope and
FLI ProLine PL11002M CCD camera. The observations were started at
2017-05-19 05:25:24 (UT). Eleven unfiltered images and seven photometric
R filter images with 120 sec exposure time were taken.

The optical afterglow was detected at the position RA 10:53:42.46
and DEC +25:22:27.4.

The following magnitudes were obtained from the observations using
NOMAD1  1153-0183949 (R = 12.650) as a comparison star:

Tmid(s)+T0    Filter          Exp. time     Mag                 Mag err.
1119              unfiltered    3x120         15.52CR           0.03
1452              unfiltered    2x120         15.63CR           0.03
1906              R               3x120         15.98R              0.10
2324              R               2x120         16.08R              0.11
2806              unfiltered    4x120         16.07CR           0.05
3327              unfiltered    2x120         16.17CR           0.05
3795              R               2x120         16.50R              0.16


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