# GCN_circulars

GRB_name: GRB180331A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22574
SUBJECT: GRB 180331A: Swift-BAT refined analysis
DATE:    18/03/31 16:01:42 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), 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 180331A (trigger #820347)
(Markwardt et al., GCN Circ. 22568).  The BAT ground-calculated position is
RA, Dec = 66.005, 13.386 deg which is
  RA(J2000)  =  04h 24m 01.1s
  Dec(J2000) = +13d 23' 09.2"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 81%.

The mask-weighted light curve shows a weak pulse that starts at ~T0,
peaks at ~T+9 s, and ends at ~T+50 s. T90 (15-350 keV) is 48.0 +- 22.6 sec
(estimated error including systematics).

The time-averaged spectrum from T+0.58 to T+48.58 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.11 +- 1.04,
and Epeak of 66.1 +- 28.3 keV (chi squared 57.70 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.1 +- 1.0 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+8.08 sec in the 15-150 keV band is
0.5 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.46 +- 0.19 (chi squared 64.59 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/820347/BA/


GRB_name: GRB180331B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22575
SUBJECT: GRB 180331B: Enhanced Swift-XRT position
DATE:    18/03/31 19:14:44 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 1501 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 180331B, 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 = 196.78337, +61.72625 which is equivalent
to:

RA (J2000): 13h 07m 8.01s
Dec (J2000): +61d 43' 34.5"

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: GRB180331B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22576
SUBJECT: GRB 180331B: Swift-BAT refined analysis
DATE:    18/03/31 23:43:44 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
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),
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 180331B (trigger #820513)
(Lien et al., GCN Circ. 22573).  The BAT ground-calculated position is
RA, Dec = 196.781, 61.735 deg which is
  RA(J2000)  =  13h 07m 07.6s
  Dec(J2000) = +61d 44' 05.9"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 30%.

The mask-weighted light curve shows a double-peaked structure that starts
at ~T-20 s and ends at ~T+140 s. The two peaks occur at ~T-20 s and ~T+1 s,
respectively. T90 (15-350 keV) is 147.0 +- 33.1 sec (estimated error including systematics).

The time-averaged spectrum from T-22.03 to T+142.97 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.48 +- 0.22.  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+0.97 sec in the 15-150 keV band
is 2.8 +- 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/820513/BA/


GRB_name: GRB180331B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22577
SUBJECT: GRB 180331B: AbAO optical observations
DATE:    18/04/01 03:30:42 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova  (IKI), A. Pozanenko (IKI),  E. Mazaeva (IKI), R. Inasaridze 
(AbAO),  V. Ayvazian  (AbAO),  O. Kvaratskhelia (AbAO), G. Kapanadze 
(AbAO),  I. Molotov (KIAM), report on behalf of larger GRB follow-up 
collaboration:

We observed the field of GRB 180331B  (Lien  et al., GCN 22573) with 
AS-32 (0.7m) telescope of Abastumani Observatory starting on Mar. 31 
(UT) 17:49:41.   We do not detect any object within enhanced XRT 
position (Goad et al., GCN 22575). Preliminary photometry of the field 
is following.

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

2018-03-31  17:49:41   0.11370   CR     38*60  n/d   n/d  22.3

The photometry is based on nearby USNO-B1.0 stars (R2 magnitude).


GRB_name: GRB180331B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22578
SUBJECT: GRB 180331B: Swift-XRT refined Analysis
DATE:    18/04/01 04:53:44 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.6 ks of XRT data for GRB 180331B, from 671 s to 25.2
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=0.30 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.80 (+0.13, -0.12). The
best-fitting absorption column is  8.7 (+3.5, -3.2) x 10^20 cm^-2, in
excess of the Galactic value of 1.6 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 3.7 x 10^-11 (4.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.7 (+3.5, -3.2) x 10^20 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 3.7 sigma
Photon index:      1.80 (+0.13, -0.12)

If the light curve continues to decay with a power-law decay index of
0.30, the count rate at T+24 hours will be 0.082 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x
10^-12 (3.5 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/00820513.

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


GRB_name: GRB180331B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22579
SUBJECT: GRB 180331B: Swift/UVOT Upper Limits
DATE:    18/04/01 09:38:55 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
180331B 668 s after the BAT trigger (Lien et al., GCN Circ. 22573).
No optical afterglow consistent with the XRT position Goad er al.,
(GCN Circ. 22575) is detected in the initial UVOT exposures,
consistent with the report of Volnova et al.  (GCN Circ. 22577).
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           668          818          147         >21.2
white              668         2066          412         >21.8
v                 1056         2115          136         >19.2
b                 1156         2041          117         >20.3
u                 1130         2016          117         >20.3
w1                 849         1992           78         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180402A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22580
SUBJECT: GRB 180402A: Swift detection of a possibly short burst
DATE:    18/04/02 10:08:54 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

A. Y. Lien (GSFC/UMBC), A. P. Beardmore (U Leicester),
J.D. Gropp (PSU) and K. L. Page (U Leicester) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 09:44:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180402A (trigger=821103).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 251.905, -14.963 which is 
   RA(J2000) = 16h 47m 37s
   Dec(J2000) = -14d 57' 48"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a short peak
with a duration of about 0.3 sec.  The peak count rate
was ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger. 
There are some additional variation in the light curve, however, 
this variation is also consistent with the presence of the 
currently-active black hole transient MAXI J1820+070 in the FOV. 
Further analysis of the full downlinked data will be required
to determine the cause of the variation. 

The XRT began observing the field at 09:46:19.2 UT, 79.9 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 251.9335,
-14.9683 which is equivalent to:
   RA(J2000)  = 16h 47m 44.05s
   Dec(J2000) = -14d 58' 05.8"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 100 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 2.94
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 250 seconds with the U 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 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 18.0 mag. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.77. 

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: GRB180402A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22581
SUBJECT: GRB 180402A: LCO McDonald observations
DATE:    18/04/02 12:25:42 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

The LCO 1-m unit at McDonald Observatory (Texas) began observing Swift 
possibly short GRB 180402A (Lien et al. GCN 22580) on April 2, 10:02 UT 
(17.3 minutes since the GRB) with the SDSS-I filter. Within the XRT 
error circle we do not detect any uncatalogued optical afterglow down to 
i'>19.3 mag (5x120 s exposure, at a mid time of 23.7 min post GRB) as 
calibrated against nearby Pan-STARRS objects.


GRB_name: GRB180402A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22582
SUBJECT: GRB 180402A: RATIR Upper Limits
DATE:    18/04/02 15:51:46 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),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and
Vicki Toy (UMD) report:

We observed the field of GRB 180402A (Lien, et al., GCN 22580) 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 2018/04 2.41 to 2018/04 2.50 UTC (1.8 minutes
to 2.33 hours after the BAT trigger), obtaining a total of 1.76 hours
exposure in the r and i bands.

For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 catalog, we obtain the following upper limits (3-sigma):

  r > 23.3
  i > 23.3

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: GRB180402A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22583
SUBJECT: GRB 180402A: KAIT Optical Upper Limit
DATE:    18/04/02 17:40:39 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alexei V. 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 180402A (Lien et al.,
GCN 22580 starting at 09:47:14 UT, 135 s after the burst.
Observations were performed with an automatic sequence in the
clear (roughly R), V, and I filters, and the exposure time was 20 s
per image. We do not detect any optical afterglow candidate within
the XRT position error circle (Lien et al., GCN 22580).
The typical limiting magnitude of our single clear image is about
18.5 mag calibrated to the APASS catalog.


GRB_name: GRB180402A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22584
SUBJECT: GRB 180402A, Swift-BAT refined analysis
DATE:    18/04/02 19:58:51 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
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) (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 180402A (trigger #821103)
(Lien et al., GCN Circ. 22580).  The BAT ground-calculated position is
RA, Dec = 251.923, -14.928 deg which is
  RA(J2000)  =  16h 47m 41.6s
  Dec(J2000) = -14d 55' 41.6"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.

The mask-weighted light curve shows a single short pulse that starts
at ~T0, peaks at ~0.1 s, and ends at ~0.3 s T90 (15-350 keV) is 0.18 +- 0.03 sec
(estimated error including systematics). The ground analysis confirmed
that the additional variation seen in the raw light curve are indeed from
MAXI J1820+070 (Lien et al., GCN Circ. 22580).

The time-averaged spectrum from T+0.05 to T+0.26 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.52 +- 0.30.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.34 sec in the 15-150 keV band
is 1.8 +- 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/821103/BA/


GRB_name: GRB180402A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22585
SUBJECT: GRB 180402A: Fermi GBM detection
DATE:    18/04/02 21:52:22 GMT
FROM:    Christian Malacaria at U of Alabama/MSFC  <christian.malacaria@nasa.gov>

C. Malacaria (NASA-MSFC/USRA) reports on behalf of the Fermi GBM Team:

"At 09:44:59.37 UT on 02 April 2018, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 180402A
(trigger 544355104 / 180402406).

The event was also detected by the Swift/BAT
(Lien et al. 2018, GCN 22580).
The GBM on-ground location is consistent with the Swift position.

The LAT boresight angle is 90 degrees.

The duration (T90) is 0.448 +/- 0.326 s (8-1000 keV).
The time-averaged spectrum from T0-0.1 s to T0+0.2 s is best fit
by a Band function.
The best-fit parameters are: Alpha = 2.23 +/- 2.03,
Beta = -1.35 +/- 0.04, Epeak = 123.80 +/- 44.00 keV.

The event fluence (8-1000 keV) in this time interval is
(8.69 +/- 0.62)E-07 erg/cm^2.
The 1-sec peak photon flux measured starting from T0+0 s in the
10-1000 keV band is 17.5 +/- 1.4 ph/s/cm^2.

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


GRB_name: GRB180402A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22586
SUBJECT: GRB 180402A: Swift-XRT refined Analysis
DATE:    18/04/03 10:09:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 5.4 ks of XRT data for GRB 180402A (Lien et al. GCN
Circ. 22580), from 83 s to 18.3 ks after the  BAT trigger. The data
comprise 24 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The best available XRT position  (using the
promptly downlinked event data, the XRT-UVOT alignment and matching
UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 251.9336,
-14.9686 which is equivalent to:

RA (J2000): 16 47 44.06
Dec(J2000): -14 58 06.9

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.94 (+/-0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.46 (+0.28, -0.26). The
best-fitting absorption column is  4.6 (+2.2, -1.7) x 10^21 cm^-2,
consistent with the Galactic value of 2.9 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 5.6 x 10^-11 (7.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.6 (+2.2, -1.7) x 10^21 cm^-2
Galactic foreground: 2.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.46 (+0.28, -0.26)

If the light curve continues to decay with a power-law decay index of
1.94, the count rate at T+24 hours will be 1.3 x 10^-5 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.3 x
10^-16 (9.1 x 10^-16) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00821103.

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


GRB_name: GRB180402A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22587
SUBJECT: GRB 180402A: Swift/UVOT Upper Limits
DATE:    18/04/03 15:38:17 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (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 180402A
140 s after the BAT trigger (Lien et al., GCN Circ. 22580).
No optical afterglow consistent with the XRT position
(D'Elia et al., GCN Circ. 22586)
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          4328         4478          147         >20.8
u_FC               140          390          246         >19.7
white             4328         6805          407         >20.6
v                  423         5916          286         >19.2
b                 5101         6736          393         >20.2
u                  140         6531          845         >20.3
w1                4691         6326          393         >20.4
w2                5512         5712          197         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.77 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180402A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22588
SUBJECT: Konus-Wind observation of GRB 180402A
DATE:    18/04/03 16:59:32 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The short-duration, hard-spectrum GRB 180402A
(Swift-BAT detection: Lien et al., GCN Circ. 22580;
Fermi-GBM detection: Malacaria, GCN Circ. 22585)
triggered Konus-Wind at T0=35100.353 s UT (09:45:00.353).

The burst light curve shows bright, multi-peaked emission episode,
which starts at T0-64 ms and has a total duration of ~180 ms,
preceded by a weaker pulse at ~T0-340 ms.

As observed by Konus-Wind, the burst
had a fluence of 2.14(-0.33,+0.53)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.086 s,
of 2.03(-0.45,+0.60)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Since the most intense part of the burst was detected before
the trigger, the spectral analysis was performed using
the KW 3-channel light curve data.

Modeling the KW 3-channel spectrum of the main episode
(from T0-0.064 s to T0+0.116 s)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -0.01(-0.43,+0.64), and Ep = 703(-161,+276) keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180402_T35100

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.


GRB_name: GRB180404A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22589
SUBJECT: GRB 180404A: Swift detection of a burst with an optical afterglow
DATE:    18/04/04 00:54:52 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), D. N. Burrows (PSU), A. Deich (PSU),
C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 00:45:35 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180404A (trigger=821881).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 83.564, -37.170 which is 
   RA(J2000) = 05h 34m 15s
   Dec(J2000) = -37d 10' 10"
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 50 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 00:47:02.1 UT, 86.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 83.54900, -37.16824 which is equivalent
to:
   RA(J2000)  = 05h 34m 11.76s
   Dec(J2000) = -37d 10' 05.7"
with an uncertainty of 4.2 arcseconds (radius, 90% containment). This
location is 43 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. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 89 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 05:34:11.63 =  83.54846
  DEC(J2000) = -37:10:03.9  = -37.16774
with a 90%-confidence error radius of about 0.65 arc sec. This position is 2.3
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.40 with a 1-sigma error of about  0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.04. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT 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: GRB180404B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22590
SUBJECT: GRB 180404B: Swift detection of a burst with an optical counterpart
DATE:    18/04/04 02:23:56 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. J. LaPorte (PSU), C. Gronwall (PSU), J.D. Gropp (PSU),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU) and
A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 02:11:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180404B (trigger=821902).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 53.384, -50.195 which is 
   RA(J2000) = 03h 33m 32s
   Dec(J2000) = -50d 11' 41"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 50 sec.  The peak count rate
was ~9000 counts/sec (15-350 keV), at ~9 sec after the trigger. 

The XRT began observing the field at 02:12:53.9 UT, 69.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 53.3967, -50.2151 which is equivalent to:
   RA(J2000)  = +03h 33m 35.21s
   Dec(J2000) = -50d 12' 54.4"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 78 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 81 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 03:33:34.24 =  53.39265
  DEC(J2000) = -50:12:54.1  = -50.21504
with a 90%-confidence error radius of about 0.76 arc sec. This position is 9.3
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.61 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01. 

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: GRB180404A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22591
SUBJECT: GRB 180404A: VLT/X-shooter redshift
DATE:    18/04/04 03:15:44 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

J. Selsing (DARK/NBI), D. Malesani (DAWN/NBI and DARK/NBI), D.A. Kann 
(HETH/IAA-CSIC), N.R. Tanvir (Univ. Leicester) report on behalf of the 
Stargate consortium:

We observed the optical counterpart of GRB 180404A (Gropp et al., GCN  
22589) using the ESO Very Large Telescope (VLT) UT2 equipped with the 
X-shooter spectrograph. Observations were carried out in robotic "rapid 
response mode" (RRM), initiated automatically following the X-ray 
localization notice.

In the 15-s r-band acquisition image, taken on 2018 Apr 4.0423 UT (15.3  
min after the trigger), the afterglow is clearly detected, at 
coordinates (J2000):

RA = 05:34:11.67
Dec = -37:10:04.1

We measure a magnitude R = 18.64 +- 0.1 (Vega), calibrated against 
nearby USNO stars, where the error is dominated by the calibration scatter.

Several spectra were acquired. We report here on the exposure with mid 
epoch Apr 4.0495 UT (that is, 25.6 min after the GRB), with 600 s 
exposure time, and covering the wavelength range 3000-25000 AA. The 
afterglow continuum trace is clearly detected. Superposed on it, several 
absorption features are visible, which we identify as Al III, Fe II, Mg 
II, and Mg I, all at a common redshift redshift of z = 1.000.

We acknowledge excellent support from the observing staff at Paranal, in 
particular Stephane Brillant, Luca Sbordone, Andrea Mehner, and Jose 
Velasquez.


GRB_name: GRB180404A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22592
SUBJECT: GRB 180404A: Enhanced Swift-XRT position
DATE:    18/04/04 04:57:12 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 646 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180404A, 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 = 83.54906, -37.16807 which is equivalent
to:

RA (J2000): 05h 34m 11.77s
Dec (J2000): -37d 10' 05.1"

with an uncertainty of 2.0 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: GRB180404A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22593
SUBJECT: GRB 180404A: MASTER-OAFA OT observation
DATE:    18/04/04 05:30:33 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov,  N.Tyurina,
A.Kuznetsov, V.Chazov, I. Gorbunov, D. Vlasenko, D.Kuvshinov, P.Balanutsa
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

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

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

O. Gres, N.M. Budnev, O. Chuvalaev, Yu.Ishmuhametova
Irkutsk State University

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

D. Buckley, S. Potter
South African Astronomical Observatory


MASTER-OAFA  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Argentina was pointed to the  GRB180404A (Gropp et al. GCN 
22589) 21 sec after notice time and 43 sec after trigger time at 
2018-04-04 00:46:18 UT.
On our first 10s exposure  set we haven't found optical transient with 
17.4 5-sigma upper limit in
SWIFT XRT error-box (ra=83.549 dec=-37.17 r=4.2").

MASTER auto-detection system detected OT with RA,Dec=5h 34m 11s.66, -37d 
10m 03s.5 with unfiltered m_OT=19.8
on the summary image with 660s exposition started 2018-04-04 00:46:18.938UT,
that was discovered by Swift (Gropp et al. GCN 22589) and confirmed by 
VLT (Selsing et al. GCN 22591)

====================================================================

The observations made on zenit distance = 42 degrees, galaxy latitude b = 
-30 degree.
The moon (87 % bright part) below the horizon (The altitude of the Moon is 
-1 degree ).
The sun  altitude  is -29.7 degree.

The message may be cited.



1


GRB_name: GRB180404B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22594
SUBJECT: GRB 180404B: Enhanced Swift-XRT position
DATE:    18/04/04 08:18:28 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 305 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180404B, 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 = 53.39268, -50.21550 which is equivalent
to:

RA (J2000): 03h 33m 34.24s
Dec (J2000): -50d 12' 55.8"

with an uncertainty of 2.9 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: GRB180404B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22596
SUBJECT: GRB 180404B: MASTER-OAFA OT observation
DATE:    18/04/04 09:39:48 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, 
A.Kuznetsov, V.V.Chazov, A.V. Krylov, I. Gorbunov, D. Vlasenko, 
D.Zimnukhov, D.Kuvshinov, P.Balanutsa
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Podesta, F. Podesta, C. Lopez, C.Francile
Observatorio Astronomico Felix Aguilar (OAFA)

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

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

D. Buckley
South African Astronomical Observatory

O. Gres, N.M. Budnev, Yu.Ishmuhametova
Irkutsk State University

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

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


MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Argentina was pointed to the  GRB180404B (LaPorte et al. GCN 
22590; Beardmore et al. GCN 22594) 27 sec after notice time and 45 sec 
after trigger time at 2018-04-04 02:12:29 UT.
On our first 10s exposure  image with unfiltered mlim=16.5 (5-sigma) we 
don't found optical transient  within SWIFT error-box (ra=53.3792 
dec=-50.195 r=0.05 LaPorte et al. GCN 22590)

MASTER auto-detection system detected OT with RA,Dec=53.392900; 
-50.214903
and unfiltered m_OT = 18.4 (automatic reduction)
on the summary image with 670s exposition started on 2018-04-04 02:12:29 
(mlim=19.7)

The message may be cited.


====================================================================


The observations started at zenit distance = 73 degrees, galaxy latitude b 
= -51 degree.
The moon (86 % bright part) is 16 degrees above the horizon. The distance 
between  moon and  object is 115
The sun  altitude was -46.8 degree.


GRB_name: GRB180404B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22597
SUBJECT: GRB 180404B: Fermi GBM observation
DATE:    18/04/04 10:04:46 GMT
FROM:    Andreas von Kienlin at MPE  <azk@mpe.mpg.de>

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 02:11:38.64 UT on 04 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180404B (trigger 544500703 / 180404091),
which was also detected by the Swift/BAT (LaPorte et al. 2018, GCN 22590).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 61.3 degrees.

The GBM light curve shows a single bright peak followed by
a secondary emission episode with a duration (T90) of about 80 s (50-300 keV).
The time-averaged spectrum from T0+0.003 s to T0+33.281 s is well fit by
a power law function with an exponential
high-energy cutoff.  The power law index is -0.40 +/- 0.04 and
the cutoff energy, parameterized as Epeak, is 209 +/- 6 keV.

The event fluence (10-1000 keV) in this time interval is
(3.3 +/- 0.4)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+12.86 s in the 10-1000 keV band
is 8.0 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 204 +/- 8 keV, alpha = -0.38 +/- 0.04 and beta = -3.3 +/- 0.6.

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


GRB_name: GRB180404B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22598
SUBJECT: GRB 180404B: Swift-XRT refined Analysis
DATE:    18/04/04 13:51:34 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 8.4 ks of XRT data for GRB 180404B (LaPorte et al. GCN
Circ. 22590), from 63 s to 30.6 ks after the  BAT trigger. The data
comprise 349 s in Windowed Timing (WT) mode (the first 5 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 Beardmore
et al. (GCN Circ. 22594).

The late-time light curve (from T0+5.2 ks) can be modelled with a
power-law decay with a decay index of alpha=1.52 (+0.14, -0.13).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.61 (+/-0.04). The
best-fitting absorption column is  3.00 (+0.25, -0.23) x 10^21 cm^-2,
in excess of the Galactic value of 1.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.06 (+/-0.14) and a
best-fitting absorption column of 4.2 (+/-0.7) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.8 x 10^-11 (6.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.2 (+/-0.7) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^20 cm^-2
Excess significance: 10.0 sigma
Photon index:      2.06 (+/-0.14)

If the light curve continues to decay with a power-law decay index of
1.52, the count rate at T+24 hours will be 4.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-13 (2.8 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/00821902.

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


GRB_name: GRB180404A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22599
SUBJECT: GRB 180404A: Swift-BAT refined analysis
DATE:    18/04/04 14:33:36 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

S. D. Barthelmy (GSFC), J. R. Cummings (CPI), J. D. Gropp (PSU),
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-239 to T+654 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180404A (trigger #821881)
(Gropp, et al., GCN Circ. 22589).  The BAT ground-calculated position is
RA, Dec = 83.540, -37.168 deg which is
    RA(J2000)  =  05h 34m 09.5s
    Dec(J2000) = -37d 10' 05.0"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 82%.
  
The mask-weighted light curve shows a weak emission that starts at T-25 sec,
followed by a bright peak which peaks at T+3 sec and ends at T+30 sec.
T90 (15-350 keV) is 35.2 +- 5.3 sec (estimated error including systematics).
  
The time-averaged spectrum from T-20.7 to T+24.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.95 +- 0.12.  The fluence in the 15-150 keV band is 1.3 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.99 sec in the 15-150 keV band
is 1.3 +- 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/821881/BA/


GRB_name: GRB180402A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22600
SUBJECT: GRB 180402A: Fermi GBM refined spectral analysis
DATE:    18/04/04 18:32:57 GMT
FROM:    Christian Malacaria at U of Alabama/MSFC  <christian.malacaria@nasa.gov>

C. Malacaria (NASA-MSFC/USRA) reports on behalf of the Fermi GBM Team:

"We report the refined spectral analysis of the
short-duration GRB 180402A
(Swift-BAT detection: Lien et al., GCN Circ. 22580;
Fermi-GBM detection: Malacaria, GCN Circ. 22585;
Konus-Wind observation: Svinkin, GCN Circ. 22588).

The time-averaged spectrum from T0-0.064 s to T0+0.192 s
is well fit by a power-law function
with an exponential high-energy cutoff.

The best-fit parameters are:
Alpha = -0.36 +/- 0.10, Epeak = 1319 +/- 161 keV.
The fluence (10-1000 keV) in this time interval is
(1.21 +/- 0.06)E-06 erg/cm^2.

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


GRB_name: GRB180404B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22601
SUBJECT: GRB 180404B: Swift-BAT refined analysis
DATE:    18/04/04 20:39:26 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (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 180404B (trigger #821902)
(LaPorte et al., GCN Circ. 22590).  The BAT ground-calculated position is
RA, Dec = 53.390, -50.213 deg which is
  RA(J2000)  =  03h 33m 33.6s
  Dec(J2000) = -50d 12' 47.4"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 84%.

The mask-weighted light curve shows a major pulse that starts at ~ T-6 s and peaks
at ~ T+ 10 s. Another weaker pulse arises at the end of the major pulse at ~ T+40 s.
The second pulse peaks at ~ T+50 s and lasts until ~ T+200 s. T90 (15-350 keV)
is 111.5 +- 7.1 sec (estimated error including systematics).

The time-averaged spectrum from T-5.91 to T+195.64 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.04.  The fluence in the 15-150 keV band is 1.20 +- 0.02 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+8.88 sec in the 15-150 keV band
is 5.2 +- 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/821902/BA/


GRB_name: GRB180404A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22602
SUBJECT: GRB 180404A: Swift-XRT refined Analysis
DATE:    18/04/05 00:55:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Tohuvavohu (PSU), S. J. LaPorte (PSU), K.L. Page (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), J.A. Kennea (PSU)
and J.D. Gropp report on behalf of the Swift-XRT team:

We have analysed 3.9 ks of XRT data for GRB 180404A (Gropp et al. GCN
Circ. 22589), from 90 s to 52.0 ks after the  BAT trigger. The data
comprise 26 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Osborne et al. (GCN Circ. 22592).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.5 (+nan, -nan).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.62 (+0.27, -0.22). The
best-fitting absorption column is  consistent with 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 4.1 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.1 (+/-5.1) x 10^20 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.62 (+0.27, -0.22)

If the light curve continues to decay with a power-law decay index of
0.5, 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 (4.5 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/00821881.

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


GRB_name: GRB180404A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22603
SUBJECT: GRB 180404A: LCO FTS observations
DATE:    18/04/05 09:36:04 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

We began observing Swift GRB180404A (Gropp et al. GCN 22589) on April 4, 
09:30 UT (0.36 days post burst) with the LCO 2-m Faulkes Telescope South 
unit in Siding Springs in the SDSS-R filter. We marginally detect the 
optical afterglow (Gropp et al.; Selsing et al. GCN 22591) with the 
following magnitude:

Mid time since GRB Exp Filter Magnitude
(days) (s)
-------------------------------------------------------------
0.37 5x120 SDSS-R 21.3 +- 0.3
-------------------------------------------------------------

as calibrated against nearby USNO UCAC4 objects.


GRB_name: GRB180404A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22605
SUBJECT: GRB 180404A: Swift/UVOT Detection
DATE:    18/04/05 17:04:53 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180404A
90 s after the BAT trigger (Gropp et al., GCN Circ. 22589).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 22592)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
   RA  (J2000) =  05:34:11.64 =  83.54850 (deg.)
   Dec (J2000) = -37:10:03.9  = -37.16774 (deg.)
with an estimated uncertainty of 0.50 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)          90          240          147         19.47 +/- 0.09
white               90          770          180         19.34 +/ -0.10
white             45830       52026         1028        >21.66
v                  632         5179           99        >18.9
b                  558          750           39        >19.4
u (fc)              302         552          246         18.95 +/- 0.12
u                  303          726          265         18.95 +/ -0.14
w1                 682          701           19        >17.8
m2                 656          676           19        >17.4
w2                 607         5094          216         19.45 +/- 0.28

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180404C
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22607
SUBJECT: GRB 180404C CALET Gamma-Ray Burst Monitor detection
DATE:    18/04/06 01:23:16 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, V. Pal'shin,
Y. Kawakubo, 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,
and the CALET collaboration:

The long-duration, hard-spectrum, bright GRB 180404C triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 21:42:08.587 UTC on 4 April 2018.
The burst signal was seen by all CGBM detectors.  This GRB is also clearly
seen by the publicly available INTEGRAL SPI-ACS light curve.

The burst light curve shows a single pulse which starts at T+1.7 sec, peaks at
T+5.5 sec and ends at T+34.1 sec.  The T90 and the T50 durations measured
by the SGM data are 25.4 +- 3.1 sec and 9.5 +- 1.4 sec (40-1000 keV), respectively.
CGBM HV was turned off at ~T+65 sec due to entering the radiation belts, so
no CGBM data are available from that time until ~T+1000 sec.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1206913306/

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


GRB_name: GRB161219B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22608
SUBJECT: Chandra observations of GRB161219B 400 days after the explosion
DATE:    18/04/06 02:38:08 GMT
FROM:    Aprajita Hajela at Northwestern U  <AprajitaHajela2015@u.northwestern.edu>

A. Hajela, R. Margutti (Northwestern University), C. Guidorzi (U Ferrara),
A. Kamble (Harvard), A. MacFadyen (NYU), D. Milisavljevic (Purdue), J.
Parrent (Harvard), A. Zauderer (NSF) report:

"We started deep X-ray follow-up observations of GRB161219B with the
Chandra X-ray Observatory on 2017, August 8 UT (dt ~ 232 days after
explosion, exposure time of 15 ks), PI Margutti, program 18500396. An X-ray
source is detected at the location of GRB161219B with count-rate of ~
0.0024 cts/s (0.5 - 8 keV) and significance of 16 - sigma. The spectrum is
well modeled with an absorbed simple power law with best-fitting photon
index, Gamma = 1.95 +/- 0.38 and Galactic absorption, N_h = 2.8e+20 cm-2.
We do not find any evidence of intrinsic absorption. For these parameters,
the unabsorbed flux is (3.41 +/- 0.76) x 10^-14 ergs cm-2 s-1 (0.3 - 10
keV).

A second Chandra observation was acquired between 2018, January 16th and
January 18th (dt ~ 393-395 days since explosion, exposure time of 32 ks).
GRB161219B is detected with the count-rate of ~ 0.0013 cts/s (0.5 - 8 keV)
and a significance of 9 -sigma. The best-fitting photon-index is Gamma =
2.05 +/- 0.34 . The corresponding unabsorbed flux is (1.72 +/- 0.28) x
10^-14 ergs cm-2 s-1 (0.3 - 10 keV).

We find that GRB161219B continues to decay following a power-law with
index, alpha = 1.22 +/- 0.04 , which is consistent with the decay
inferred from XRT data at t < 115 days.

We thank the entire Chandra team for making these observations possible."

[GCN OPS NOTE(06apr18):  Per author's request, the last two paragraphs
were added.]


GRB_name: GRB180404B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22609
SUBJECT: Konus-Wind observation of GRB 180404B
DATE:    18/04/06 13:33:29 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 180404B
(Swift-BAT detection: LaPorte et al., GCN Circ. 22590;
Fermi-GBM observation: von Kienlin, GCN Circ. 22597)
triggered Konus-Wind at T0=7898.049 s UT (02:11:38.049).

The burst light curve shows the bright pulse
which starts at ~T0-3.4 s and has a total duration of ~29 s
followed by a weaker pulse seen up to ~T0+100 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180404_T07898/

As observed by Konus-Wind, the burst
had a fluence of 2.60(-0.16,+0.18)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+8.832 s,
of 2.07(-0.66,+0.66)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+73.984 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.65(-0.15,+0.16)
and Ep = 205(-17,+21) keV (chi2 = 82/73 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 = 82/72 dof).

The spectrum near the maximum count rate
(measured from T0+8.448 to T0+16.640 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
with  alpha = -0.19(-0.16,+0.17)
and Ep = 186(-11,+12) keV (chi2 = 90/73 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.2
(chi2 = 90/72 dof).

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


GRB_name: GRB180404C
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22610
SUBJECT: IPN Triangulation of GRB 180404C (long)
DATE:    18/04/06 18:02:49 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,

A. Ursi, N. Parmiggiani, F. Verrecchia, A. Bulgarelli,
A. Trois, M. Marisaldi, C. Pittori, M. Tavani, Y. Evangelista,
I. Donnarumma, M. Cardillo, G. Piano, G. Minervini, A. Argan,
F. Lucarelli, A. Zoli, V. Fioretti, F. Fuschino, M. Pilia,
F. Longo, A. Giuliani on behalf of the AGILE 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 180404C (Marrocchesi et al., GCN Circ. 22607)
was detected by Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS),
CALET (CGBM), and AGILE (MCAL) at about 78128 s UT (21:42:08).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    92.302 (06h 09m 13s)  +7.811 ( +7d 48' 38")
  Corners:
    94.505 (06h 18m 01s)  +6.262 ( +6d 15' 44")
    90.162 (06h 00m 39s)  +8.179 ( +8d 10' 43")
    90.059 (06h 00m 14s)  +9.822 ( +9d 49' 21")
    94.425 (06h 17m 42s)  +7.688 ( +7d 41' 17")
  ---------------------------------------------
The error box area is 6.37 sq. deg, and its maximum
dimension is 5.66 deg (the minimum one is 80 arcmin).
The Sun distance was 75 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180404_T78131/IPN

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


GRB_name: GRB180404B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22611
SUBJECT: GRB 180404B: Swift/UVOT Detection
DATE:    18/04/06 18:14:06 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and S. J. LaPorte (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180404B
82 s after the BAT trigger (LaPorte et al., GCN Circ. 22590).
A fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 22594)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
   RA  (J2000) =  03:33:34.23 =  53.39262 (deg.)
   Dec (J2000) = -50:12:54.2  = -50.21506 (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)          82          231          147         18.66 +/- 0.09
white               82         1720          411         19.39 +/- 0.09
white             6421         6620          196        >20.7
v                  624         7031          510        >19.5
b                  550         7661          322        >20.3
u (fc)             295          545          245         19.49 +/- 0.31
u                  295         1670          343         19.70 +/- 0.29
u                 6011         7648          393        >20.1
w1                 674         7442          510        >20.6
m2                1600         7236          413        >20.5
w2                 600         6826          452        >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180407A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22612
SUBJECT: GRB 180407A: Swift detection of a burst
DATE:    18/04/07 02:04:34 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Deich (PSU), C. Gronwall (PSU), S. J. LaPorte (PSU),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL) and A. Tohuvavohu (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 01:54:49 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180407A (trigger=823001).  Swift could not slew to the
location due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 35.241, +33.499 which is 
   RA(J2000) = 02h 20m 58s
   Dec(J2000) = +33d 29' 56"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex structure
structure with a duration of about 70 sec.  The peak count rate
was ~1600 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 12:55 UT on 2018 June 19. There will thus be no XRT or
UVOT data for this trigger before this time. 

Burst Advocate for this burst is A. Deich (aud375 AT 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: GRB180407A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22614
SUBJECT: GRB 180407A: COATLI Upper Limits
DATE:    18/04/07 04:37:08 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC), report:

We observed the field of GRB 180407A (Deich et al., GCN 22612) with the
COATLI 50-cm telescope and interim imager
(http://coatli.astroscu.unam.mx) at the Observatorio AstronÃ³mico
Nacional on the Sierra de San Pedro MÃ¡rtir from 2018-04-07 02:26:12 to
03:01:38 (0.52 to 1.12 hours after trigger) obtaining a total of 510
seconds of exposure in the w filter.

The images were obtained at high airmass (above 3.1) and during
twilight.

For a source within the Swift/BAT error circle, in comparison with the
USNO-B1 catalog, we obtain the following 10-sigma upper limit:

w > 16.53

This magnitude is in the USNO system and is not corrected for Galactic
extinction in the direction of the GRB.

We thank the COATLI technical team (Fernando Ãngeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, RosalÃ­a Langarica,
Fernando QuirÃ³s, and Carlos Tejada) and the staff of the Observatorio
AstronÃ³mico Nacional.


-- 
Dr. Alan M. Watson
Instituto de AstronomÃ­a
Universidad Nacional AutÃ³noma de MÃ©xico


GRB_name: GRB180407A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22616
SUBJECT: GRB 180407A: Swift-BAT refined analysis
DATE:    18/04/07 19:09:11 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), A. Deich (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+144 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180407A (trigger #823001)
(Deich et al., GCN Circ. 22612). Note that due to the Sun constraint, Swift could
not slew to the burst location, and no data were collected for the burst after ~ T+144 s.
The BAT ground-calculated position is
RA, Dec = 35.236, 33.513 deg which is
  RA(J2000)  =  02h 20m 56.6s
  Dec(J2000) = +33d 30' 48.4"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 52%.

The mask-weighted light curve shows a weak pulse that starts at ~ T-20 s and
ends at ~ T+110 s. The pulse consists of several overlapping peaks. The largest
peak occurs at ~ T+2 s. T90 (15-350 keV) is 95.9 +- 29.8 sec (estimated error including
systematics). Note that because the burst went out of the BAT field of view at T+144 s,
T90 reported here might not capture the entire burst duration.

The time-averaged spectrum from T-20.58 to T+107.48 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.94 +- 0.20.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.18 sec in the 15-150 keV band
is 0.9 +- 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/823001/BA/


GRB_name: GRB180402A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22617
SUBJECT: GRB 180402A: ISON-NM early optical limits
DATE:    18/04/08 20:40:42 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI),  L. Elenin (KIAM),  A. Pozanenko (IKI), A. Volnova 
(IKI), I. Molotov (KIAM)  report on behalf of larger GRB  follow-up 
collaboration:

We observed the field of the Swift  short burst GRB 180402A (Lien et 
al., GCN 22580) with 0.4-m telescope of ISON-NM observatory starting on 
Apr., 02 (UT) 09:45:39, i.e. 40 seconds after the burst trigger. We 
obtained 4 unfiltered images of 30 s exposure each. We do not detect any 
source within XRT error circle (Lien et al., GCN 22580). Upper limits 
are following.

Date      start (Ut)   t-T0         Exp.     UL (3sigma)
                       (mid.,sec)    (s)
2018-04-02 09:45:39   55            1*30     14.5
2018-04-02 09:45:39  133            4*30     15.0

The photometry is based on nearby USNO-B1.0 stars (R2 magnitudes).


GRB_name: GRB180409A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22618
SUBJECT: GRB 180409A: Tiled Swift observations
DATE:    18/04/09 23:09:15 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
IPN GRB 180409A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00069

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: GRB180409A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22619
SUBJECT: IPN Triangulation of GRB 180409A
DATE:    18/04/10 05:36:22 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:

A long-duration GRB 180409A was detected by Fermi (GBM), Konus-Wind,
INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT) at about 29899 s
UT (08:18:19).
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:
  175.842 (11h 43m 22s) +36.308 (+36d 18' 30")
 Corners:
  175.961 (11h 43m 51s) +35.973 (+35d 58' 21")
  176.118 (11h 44m 28s) +36.645 (+36d 38' 43")
  175.721 (11h 42m 53s) +36.644 (+36d 38' 37")
  175.567 (11h 42m 16s) +35.969 (+35d 58' 10")
 ---------------------------------------------
The error box area is 772 sq. arcmin, and its maximum
dimension is 49 arcmin (the minimum one is 19 arcmin).
The Sun distance was 131 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180409_T29904/IPN/

Swift ToO has been approved (Evans, GCN Circ. 22618).

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


GRB_name: GRB180410A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22620
SUBJECT: GRB 180410A: Swift detection of a burst or a Galactic transient. 
DATE:    18/04/10 08:27:45 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

J.D. Gropp (PSU), A. Deich (PSU), P. A. Evans (U Leicester),
C. Gronwall (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 08:02:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180410A or a Galactic transient (trigger=824063).  
Swift slewed immediately to the source. 
The BAT on-board calculated location is 
RA, Dec 95.981, +12.808 which is 
   RA(J2000) = 06h 23m 56s
   Dec(J2000) = +12d 48' 28"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex structure
structure with a duration of about 100 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~26 sec after the trigger. 

The XRT began observing the field at 08:05:49.8 UT, 170.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
95.9570, 12.8110 which is equivalent to:
   RA(J2000)  = 06h 23m 49.68s
   Dec(J2000) = +12d 48' 39.4"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 84 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 6.56
x 10^21 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 1.55e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 179 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. 

Given the source's proximity (0.17 degrees) to the Galactic Plane, and
the fact that this is a BAT image trigger, we cannot rule out that
this may be a new Galactic Transient, rather than a GRB. If it is a
transient, we name it Swift J0623.9+1248. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT 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: GRB180409A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22621
SUBJECT: Konus-Wind observation of GRB 180409A
DATE:    18/04/10 10:00:09 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long GRB 180409A (IPN Triangulation: Hurley et al., GCN 22619)
triggered Konus-Wind at T0=29904.770 s UT (08:18:24.770)

The burst light curve shows a multi-peaked structure,
which started at ~T0-3 s and peaked at ~T0+9.4 s.
The total duration of the burst is ~20 s.
The emission is seen up to ~3 MeV.

As observed by Konus-Wind, the burst had a fluence of
(8.8 Â± 1.3)x10^-6 erg/cm2 and a 64-ms peak energy flux,
measured from T0+9.408, of (9.9 Â± 1.5)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+17.920 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 = -0.96 (-0.09,+0.10),
the high energy photon index beta = -3.1 (-6.9,+0.42),
the peak energy Ep = 180 (-14,+15) keV,
chi2 = 67/97 dof.

The spectrum near the peak count rate (measured from T0+7.936
to T0+9.728 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 = -0.50 (-0.13,+0.20),
the high energy photon index beta = -3.5 (-6.5,+0.8),
the peak energy Ep = 266 (-35,+26) keV,
chi2 = 81/78 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180409_T29904/

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


GRB_name: GRB180410A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22622
SUBJECT: GRB 180410A: Enhanced Swift-XRT position
DATE:    18/04/10 11:09:33 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 1707 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180410A, 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 = 95.95717, +12.81143 which is equivalent
to:

RA (J2000): 06h 23m 49.72s
Dec (J2000): +12d 48' 41.1"

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: GRB180410A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22623
SUBJECT: GRB 180410A: MITSuME Akeno optical upper limits
DATE:    18/04/10 12:31:10 GMT
FROM:    Ryosuke Itoh at Tokyo Institute of Tech.  <itoh@hp.phys.titech.ac.jp>

R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, T. Ozawa, H. Mamiya,
K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 180410A (J. D. Gropp et
al., GCN Circular #22620)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the MITSuME 50cm telescope
of Akeno Observatory, Yamanashi, Japan.
The observation started on 2018-04-10 10:02:24 UT.
We did not find any point source at the position of the XRT error
circle (P. A. Evans et al., GCN Circular #22622)
in all three bands. We obtained following limits for the magnitudes.

T0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~2.0           10:27:25       2,700         >18.8   >18.7   >18.0
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.


GRB_name: GRB180404C
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22624
SUBJECT: Konus-Wind observation of GRB 180404C
DATE:    18/04/10 14:05:04 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 180404C
(CATET-GBM detection: Marrocchesi et al., GCN Circ. 22607;
IPN triangulation: Hurley et al., GCN Circ. 22610)
triggered Konus-Wind at T0=78131.929 s UT (21:42:11.929).

The burst light curve shows a multi-peaked structure
which starts at ~T0-88 s and has a total duration of ~200 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/GRB180404_T78131/

As observed by Konus-Wind, the burst
had a fluence of 1.33(-0.18,+0.19)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+2.672 s,
of 2.11(-0.37,+0.37)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+116.736 s)
is best fit in the 20 keV - 19 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.00(-0.10,+0.12),
the high energy photon index beta = -2.40(-0.56,+0.24),
the peak energy Ep = 342(-49,+58) keV
(chi2 = 91/97 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+4.864 s)
is best fit in the 20 keV - 19 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.58(-0.11,+0.13),
the high energy photon index beta = -2.00(-0.12,+0.09),
the peak energy Ep = 517(-71,+86) keV
(chi2 = 86/94 dof).

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


GRB_name: GRB180409A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22625
SUBJECT: GRB 180409A: Swift-XRT observations
DATE:    18/04/10 14:35:14 GMT
FROM:    Aaron Tohuvavohu at PSU/Swift  <aaronb@swift.psu.edu>

A. Tohuvavohu (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U.
Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/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 180409A in a series of observations tiled on the sky. The
total exposure time is 3.5 ks, distributed over 4 tiles; the maximum
exposure at a single sky location was 2.4 ks. The data were collected
between T0+53.5 ks and T0+71.6 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):  175.8434  =  11:43:22.42
  Dec (J2000): +36.2335  =  +36:14:00.6
  Error: 3.6 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0258 +/- 0.0068 ct s^-1   
  Distance: 268 arcsec from IPN position.
  Flux: (8.3 +/- 2.2)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

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_GRB00069.

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


GRB_name: GRB180409A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22626
SUBJECT: GRB 180409A: Fermi GBM observation
DATE:    18/04/10 18:11:51 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

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


"At 08:18:18.67 UT on 9 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180409A (trigger 544954703 / 180409346),
which was triangulated by IPN (Hurley et al., GCN 22619) and was also
detected by Konus (Frederiks et al., GCN 22621).

The on-ground calculated location, using the GBM trigger data, is

RA = 178.18, DEC = +36.050 (J2000 degrees),

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 angle from the Fermi LAT boresight at the GBM trigger time is 71 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 13 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+15 s is
best fit by a Band function with Epeak = 151 +/- 5 keV,
alpha = -0.85 +/- 0.03, and beta = -2.33 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(2.87 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+10.1 s in the 10-1000 keV band
is 41 +/- 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: GRB180410A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22627
SUBJECT: GRB 180410A: Swift/UVOT Upper Limits
DATE:    18/04/10 18:18:04 GMT
FROM:    Frank Marshall at Swift/UVOT  <marshall@milkyway.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180410A
179 s after the BAT trigger (Gropp et al., GCN Circ. 22620).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 22622)
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           179          329          147         >20.6
u_FC               338          587          246         >20.0
white              179         2068          450         >20.9
v                  669         1943          156         >19.2
b                  594         2043          156         >20.1
u                  338         2017          382         >20.4
w1                 718         1993          136         >20.1
m2                 693         1968          136         >20.3
w2                 644         2093          175         >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.92 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180410A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22628
SUBJECT: GRB 180410A: Swift-BAT refined analysis
DATE:    18/04/10 21:03:41 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), J. D. Gropp (PSU),
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 180410A (trigger #824063)
(Gropp et al., GCN Circ. 22620).  The BAT ground-calculated position is
RA, Dec = 95.974, 12.804 deg which is
  RA(J2000)  =  06h 23m 53.7s
  Dec(J2000) = +12d 48' 15.2"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.

The mask-weighted light curve shows a weak-long pulse that starts and peak
at ~ T+25 s, and ends at ~T+150 s. T90 (15-350 keV) is 100.7 +- 13.8 sec
(estimated error including systematics).

The time-averaged spectrum from T+25.16 to T+153.67 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.46 +- 0.13.  The fluence in the 15-150 keV band is 2.2 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+25.70 sec in the 15-150 keV band
is 0.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The spectral and temporal behaviors are consistent with those of a GRB. However,
due to the proximity to the Galactic plane (0.17 degrees), we cannot rule out the
possibility that this is a Galactic transient.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/824063/BA/


GRB_name: GRB180410A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22629
SUBJECT: GRB 180410A: Swift-XRT refined Analysis
DATE:    18/04/10 23:40:51 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), Z. Liu (NAOC /
U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N.
Burrows (PSU) and J.D. Gropp report on behalf of the Swift-XRT team:

We have analysed 6.8 ks of XRT data for GRB 180410A (Gropp et al. GCN
Circ. 22620), from 176 s to 45.6 ks after the  BAT trigger. The data
comprise 201 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN Circ. 22622).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.39 (+0.22, -0.28). At T+321 s  the decay
steepens to an alpha of 2.9 (+0.4, -0.3) before breaking again at T+866
s to a final decay with index alpha=1.48 (+0.15, -0.13).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.87 (+0.07, -0.05). The
best-fitting absorption column is  consistent with the Galactic value
of 6.6 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has
a photon index of 1.45 (+0.21, -0.19) and a best-fitting absorption
column of 7.7 (+2.3, -1.2) x 10^21 cm^-2. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 6.2 x 10^-11 (8.1 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.7 (+2.3, -1.2) x 10^21 cm^-2
Galactic foreground: 6.6 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.45 (+0.21, -0.19)

If the light curve continues to decay with a power-law decay index of
1.48, the count rate at T+24 hours will be 6.1 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.7 x
10^-14 (4.9 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/00824063.

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


GRB_name: GRB180411A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22630
SUBJECT: GRB 180411A: Swift detection of a burst
DATE:    18/04/11 12:48:19 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

Z. Liu (NAOC/U. Leicester), A. P. Beardmore (U Leicester),
A. A. Breeveld (UCL-MSSL), A. Deich (PSU), J.D. Gropp (PSU),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 12:27:43 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180411A (trigger=824451).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 356.829, +66.791 which is 
   RA(J2000) = 23h 47m 19s
   Dec(J2000) = +66d 47' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 100 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~53 sec after the trigger. 

The XRT began observing the field at 12:28:50.4 UT, 66.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 356.85453,
66.77831 which is equivalent to:
   RA(J2000)  = 23h 47m 25.09s
   Dec(J2000) = +66d 46' 41.9"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 58 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 (8.31 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 1.2
(+0.97/-0.75) x 10^22 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.35e-08 erg cm^-2 s^-1 (0.2-10
keV). 

There are no UVOT data available at the present time. 

Burst Advocate for this burst is Z. Liu (zl182 AT leicester.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: GRB180410A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22631
SUBJECT: GRB 180410A: RATIR Optical Observations 
DATE:    18/04/11 16:03:38 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 (U. Wash.), and
Vicki Toy (UMD) report:

We observed the field of GRB 180410A (Gropp et al., GCN 22620) 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 2018/04 11.13 to 2018/04 11.25 UTC (19.10
to 21.87 hours after the BAT trigger), obtaining a total of 2.13 hours
exposure in the r and i bands.

For a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following upper limits (3-sigma):

 r > 24.20
 i > 23.90

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

The XRT error region is only 2.8 arcsec from a previously cataloged star with r = 18.1 and i = 17.4. Thus, our formal upper limits given above may be optimistic.

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


GRB_name: GRB180411A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22632
SUBJECT: GRB 180411A: Swift-XRT refined Analysis
DATE:    18/04/11 22:51:42 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S.L. Gibson (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. Tohuvavohu (PSU), J.P. Osborne (U. Leicester) and Z.
Liu report on behalf of the Swift-XRT team:

We have analysed 9.3 ks of XRT data for GRB 180411A (Liu et al. GCN
Circ. 22630), from 72 s to 29.8 ks after the  BAT trigger. The data
comprise 200 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The refined XRT position is RA, Dec =
356.8540, +66.7785 which is equivalent to:

RA (J2000): 23 47 24.97
Dec(J2000): +66 46 42.5

with an uncertainty of 3.5 arcsec (radius, 90% confidence).

The late-time light curve (from T0+4.4 ks) can be modelled with a
power-law decay with a decay index of alpha=1.09 (+/-0.07).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.68 (+/-0.10). The
best-fitting absorption column is  1.54 (+0.16, -0.15) x 10^22 cm^-2,
in excess of the Galactic value of 8.3 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.01 (+/-0.16) and a
best-fitting absorption column of 1.91 (+0.25, -0.23) x 10^22 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 5.9 x 10^-11 (1.3 x 10^-10) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.91 (+0.25, -0.23) x 10^22 cm^-2
Galactic foreground: 8.3 x 10^21 cm^-2
Excess significance: 7.7 sigma
Photon index:      2.01 (+/-0.16)

If the light curve continues to decay with a power-law decay index of
1.09, the count rate at T+24 hours will be 0.032 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x
10^-12 (4.1 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/00824451.

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


GRB_name: GRB180411A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22633
SUBJECT: GRB 180411A: Swift-BAT refined analysis
DATE:    18/04/12 00:51:06 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), Z. Liu (NAOC/U. Leicester),
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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180411A (trigger #824451)
(Z. Liu, et al., GCN Circ. 22630).  The BAT ground-calculated position is
RA, Dec = 356.840, 66.790 deg, which is 
   RA(J2000)  =  23h 47m 21.6s 
   Dec(J2000) = +66d 47' 25.2" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.
 
The mask-weighted light curve show two major episodes of overlapping peaks
with the first starting at ~T-15 sec, peaking at ~T+5 sec, and second episode
starting at ~T+42 sec, peaking at ~T+52 sec, and returning to zero ~T+180 sec.
T90 (15-350 keV) is 77.5 +- 0.9 sec (estimated error including systematics).
 
The time-averaged spectrum from T-7.02 to T+92.38 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.46 +- 0.03.  The fluence in the 15-150 keV band is 1.2 +- 0.0 x 10^-05 erg/cm2.
The 1-sec peak photon flux measured from T+51.74 sec in the 15-150 keV band
is 6.1 +- 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/824451/BA/


GRB_name: GRB180411A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22634
SUBJECT: GRB 180411A: Fermi GBM detection
DATE:    18/04/12 02:41:57 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 12:27:40.97 UT on 11 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180411A (trigger 545142465 / 180411519),
which was also detected by the Swift/BAT (Liu et al. 2018, GCN 22630).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 150 degrees.

The GBM light curve shows two peaks
with a duration (T90) of about 77.6 s (50-300 keV).
The time-averaged spectrum from T0-3.1 s to T0+79.8 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.18 +/- 0.05 and
the cutoff energy, parameterized as Epeak, is 358 +/- 30 keV.

The event fluence (10-1000 keV) in this time interval is
(3.276 +/- 0.085)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+54.27 s in the 10-1000 keV band
is 10.5 +/- 0.79 ph/s/cm^2.

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


GRB_name: GRB180409A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22635
SUBJECT: GRB 180409A CALET Gamma-Ray Burst Monitor detection
DATE:    18/04/12 05:09:52 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo, A. Tezuka, S. Matsukawa,
H. Onozawa (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 GRB 180409A (IPN triangulation: Hurley et al., GCN circ. 22619;
Konus-Wind detection: Frederiks et al., GCN circ. 22621;
Fermi-GBM detection: Bissaldi and Meegan GCN circ. 22626) triggered
the CALET Gamma-ray Burst Monitor (CGBM) at 08:18:17.669 UTC on 9 April 2018.
The burst signal was seen by all CGBM detectors.

The burst light curve shows several partially overlapped short pulses
which start at T+3.0 sec, peaks at T+12.3 sec and ends at T+14.9 sec.
The T90 and the T50 durations measured by the SGM data are 10.6 +- 0.7 sec
and 5.9 +- 1.8 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1207297067/

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


GRB_name: GRB180410A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22636
SUBJECT: GRB 180410A: Fermi GBM observation
DATE:    18/04/12 08:27:16 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 08:03:27.79 UT on 10 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180410A (trigger 545040212 / 180410336),
which was also detected by the Swift/BAT
(Gropp et al. 2018, GCN 22620, Lien et al., GCN 22628).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 108 degrees.

The GBM light curve consists of an initial peak followed by a weaker
emission episode with a duration (T90) of about 100 s (50-300 keV).
The time-averaged spectrum from T0-3 s to T0+47 s is
adequately fit by a simple power law function with index -1.53 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(3.1 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.5 s in the 10-1000 keV band
is 1.51 +/- 0.27 ph/s/cm^2.


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


GRB_name: GRB180411A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22637
SUBJECT: GRB 180411A: Tautenburg observations
DATE:    18/04/12 09:04:07 GMT
FROM:    Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>

B. Stecklum, S. Klose, and C. Hoegner (Thueringer Landessternwarte 
Tautenburg) report:

We imaged the field of GRB 180411A (Liu et al., GCN 22630) in the Rc band 
using the Tautenburg Schmidt telescope equipped with the prime focus CCD 
camera. Observations started at 19:49 UT, about 7.5 hr after the burst.

Inside the XRT error circle (radius 3.5 arcsec; Gibson et al., GCN 22632) 
we do not find any source. At a mean time of 19:53 UT we constrain the 
magnitude of any optical transient to R>22 mag.


GRB_name: GRB180411A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22638
SUBJECT: GRB 180411A: Swift/UVOT Upper Limit
DATE:    18/04/12 10:53:05 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

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

The Swift/UVOT began observations of the field of GRB 180411A 64 s after 
the BAT trigger (Liu et al., GCN Circ. 22630) with a settling exposure 
in the V filter. The UVOT safety circuit tripped 3.4s into the following 
UV grism exposure, most likely due to the bright star HD223128, 5.08 
arcmin from the burst position.

No optical afterglow consistent with the enhanced XRT position (Gibson 
et al. GCN Circ. 22632) is seen in the 9.3s V settling exposure to a 
preliminary 3-sigma upper limit of 16.8 mag using the UVOT photometric 
system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373).

The magnitude is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.104 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180411A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22639
SUBJECT: Konus-Wind observation of GRB 180411A
DATE:    18/04/12 11:45:17 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long GRB 180411A (Swift/BAT detection: Liu et al., GCN 22630;
Markwardt et al., GCN 22633; Fermi-GBM detection: Poolakkil, GCN 22634)
triggered Konus-Wind at T0=44862.530 s UT (12:27:42.530).

The KW light curve shows two multipeaked pulses with
a total duration of ~90 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(4.01 Â± 0.91)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+50.496, of (3.3 Â± 0.7)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+82.368 s)
is best fit in the 20 keV - 15 MeV range by by the GRB (Band)
function with the following model parameters:
the low-energy photon index alpha = -1.17 (-0.12,+0.15),
the high energy photon index beta = -2.39 (-0.90,+0.31),
the peak energy Ep = 239 (-49,+55) keV,
chi2 = 90/97 dof.

The spectrum near the peak count rate (measured from T0+41.408
to T0+57.792 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 = -0.89 (-0.13,+0.16),
the high energy photon index beta = -2.49 (-0.77,+0.31),
the peak energy Ep = 255 (-40,+44) keV,
chi2 = 96/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180411_T44862/

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

[GCN OPS NOTE(12apr18): The Subject line was corrected from "180113A"
to "180411A".]


GRB_name: GRB180411A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22640
SUBJECT: Konus-Wind observation of GRB 180411A
DATE:    18/04/12 12:00:31 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long GRB 180411A (Swift/BAT detection: Liu et al., GCN 22630;
Markwardt et al., GCN 22633; Fermi-GBM detection: Poolakkil, GCN 22634)
triggered Konus-Wind at T0=44862.530 s UT (12:27:42.530).

The KW light curve shows two multipeaked pulses with
a total duration of ~90 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(4.01 Â± 0.91)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+50.496, of (3.3 Â± 0.7)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+82.368 s)
is best fit in the 20 keV - 15 MeV range by by the GRB (Band)
function with the following model parameters:
the low-energy photon index alpha = -1.17 (-0.12,+0.15),
the high energy photon index beta = -2.39 (-0.90,+0.31),
the peak energy Ep = 239 (-49,+55) keV,
chi2 = 90/97 dof.

The spectrum near the peak count rate (measured from T0+41.408
to T0+57.792 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 = -0.89 (-0.13,+0.16),
the high energy photon index beta = -2.49 (-0.77,+0.31),
the peak energy Ep = 255 (-40,+44) keV,
chi2 = 96/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180411_T44862/

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


GRB_name: GRB180411B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22641
SUBJECT: GRB 180411B: CALET Gamma-Ray Burst Monitor detection
DATE:    18/04/12 12:22:46 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

T. Sakamoto, A. Yoshida, V. Pal'shin, Y. Kawakubo, A. Tezuka, S. Matsukawa,
H. Onozawa (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, soft-spectrum, bright GRB 180411B (Konus-Wind trigger time on 08:38:56.08)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 08:37:29.769 UTC on 11 April 2018.
The burst signal was seen by all CGBM detectors.

The burst light curve shows several multi-peaked pulses which start at T0, peak at T+82 sec
and end at T+123 sec.  The T90 and the T50 durations measured by the SGM data are
99.0 +- 1.8 sec and 43.8 +- 1.7 sec (40-1000 keV), respectively.  Despite its brightness,
the burst signal is seen only below ~300 keV indicating the soft spectrum.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1207471016/

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


GRB_name: GRB180411A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22642
SUBJECT: GRB 180411A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/04/12 12:30:59 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

V. Pal'shin, A. Yoshida, T. Sakamoto, Y. Kawakubo, A. Tezuka, S. Matsukawa,
H. Onozawa (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 180411A (Swift-BAT trigger #824451: Liu, et al., GCN Circ. 22630,
Markwardt et al., GCN Circ. 22633; Fermi-GBM detection: Poolakkil, von Kienlin and
Meegan, GCN Circ. 22634) triggered the CALET Gamma-ray Burst Monitor (CGBM) at
12:28:26.665 UTC on 11 April 2018.  The trigger occurred at the exit from the SAA,
44 sec after the BAT trigger.  The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure which starts at T-35 sec, peaks at
T+9 sec and ends at T+36 sec. The T90 and the T50 durations measured by the SGM data are
60.0 +- 6.7 sec and 20.4 +- 9.0 sec (40-1000 keV), respectively.  Since CGBM missed the
initial part of the burst, these values underestimate the real burst durations.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1207484873/

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


GRB_name: GRB180409A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22643
SUBJECT: GRB 180409A: Swift-XRT afterglow detection
DATE:    18/04/15 03:23:31 GMT
FROM:    Aaron Tohuvavohu at PSU/Swift  <aaronb@swift.psu.edu>

A. Tohuvavohu (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U.
Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU) 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
IPN-detected burst GRB 180409A (Yoshida et al. GCN Circ. 22635). The
observations now extend from T0+53.4 ks to T0+455.1 ks. The source
previously reported by Tohuvavohu et al. (GCN Circ. 22625), "Source 1",
is fading with 3-sigma significance, and is therefore likely the GRB
afterglow. Using 1887 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 = 175.84306, +36.23354
which is equivalent to:

RA (J2000): 11h 43m 22.33s
Dec(J2000): +36d 14' 00.8"

with an uncertainty of 3.1 arcsec (radius, 90% confidence). This
position is 4.5 arcmin from the IPN position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.0 (+/-0.3).

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00069/Source1.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00069.

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


GRB_name: GRB180416A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22644
SUBJECT: GRB 180416A: Fermi GBM detection
DATE:    18/04/16 15:46:33 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 08:09:26.47 UT on 16 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180416A (trigger 545558971 / 180416340).
The on-ground calculated location, using the GBM trigger data, is

RA = 113.65, Dec = -49.12 (J2000 degrees)

with an uncertainty of 1.0 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 21 degrees.

The GBM light curve consists of multiple separated peaks
with a duration (T90) of about 103 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+100 s is
adequately by a power law function with an exponential
high-energy cutoff. The power law index is -1.19 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 153 +/- 4 keV.

The event fluence (10-1000 keV) in this time interval is
(3.61 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+87.2 s in the 10-1000 keV band
is 22.2 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak = 145 +/- 5 keV, alpha = -1.16 +/- 0.02 and
beta = -2.89 +/- 0.26.


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


GRB_name: GRB180404B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22645
SUBJECT: GRB 180404B: AstroSat CZTI detection
DATE:    18/04/16 17:52:13 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long GRB 180404B, which was also detected by Swift (Palmer D. et al., GCN 22590), Fermi-GBM (Kienlin A. V. et al., GCN 22597) and Konus-Wind (Svinkin D. et al., GCN 22609).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 02:11:53.5 UT, ~9.5 s after the Swift trigger. The measured peak count rate is 281.6 cts/s above the background in combined data of four quadrants, with a total of 3662 cts. The local mean background count rate was 541 cts/s. Using cumulative rates, we measure a T90 of 44 s. 

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180418A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22646
SUBJECT: GRB 180418A: Swift detection of a short burst
DATE:    18/04/18 06:55:40 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), P. A. Evans (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU),
M. Stamatikos (OSU/NASA/GSFC) and A. Tohuvavohu (PSU) report on behalf
of the Neil Gehrels Swift Observatory Team:

At 06:44:06 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180418A (trigger=826428).  Swift could not immediately slew
to the burst due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 170.112, +24.956 which is 
   RA(J2000) = 11h 20m 27s
   Dec(J2000) = +24d 57' 22"
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 1.5 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+49.6
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.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: GRB180418A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22647
SUBJECT: GRB 180418A: KAIT Optical Afterglow Candidate
DATE:    18/04/18 07:18:14 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

GRB 180418A: KAIT Optical Afterglow Candidate

WeiKang Zheng and Alexei V. 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 180418A (D'Elia et al.,
GCN 22646 starting at 06:46:41 UT, 125 s after the burst.
Observations were performed with an automatic sequence in the
clear (roughly R), V, and I filters, and the exposure time was 20 s
per image. Inside the Swift/BAT position error circle we
detected an afterglow candidate at position:
RA:  11:20:29.20 (j2000)
Dec: 24:55:58.8  (j2000)
The clear band magnitude declined from Mag ~15.8 to ~17.2 during our
observations.
Observation are on going, multi-band follow-ups are encouraged.


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22648
SUBJECT: GRB 180418A: LCO FTN afterglow confirmation
DATE:    18/04/18 07:47:13 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

The LCO 2-m Faulkes Telescope North (Hawaii) began observing Swift short 
GRB 180418A (D'Elia et al. GCN 22646) on April 18, 07:18:19 UT (34 
minutes since the GRB) with the SDSS-I filter. We clearly detect the 
optical afterglow (Zheng et al. GCN 22647) with the following magnitude:

Mid time since GRB Exp Filter Magnitude
(hrs) (s)
------------------------------------------------------------
0.62 5x60 SDSS-I 19.2 +- 0.1
------------------------------------------------------------

as calibrated against nearby SDSS objects.


GRB_name: GRB180418A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22649
SUBJECT: GRB 180418A: Swift-XRT observations
DATE:    18/04/18 08:12:24 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), G.
Cusumano (INAF-IASF PA), M. Perri (ASDC) and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 180418A at 07:35:27.5 UT,
3081.4 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 170.12059,
24.93276 which is equivalent to:
   RA(J2000)  = 11h 20m 28.94s
   Dec(J2000) = +24d 55' 57.9"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 88 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 1.07
x 10^20 cm^-2 (Willingale et al. 2013). 


GRB_name: GRB180418A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22650
SUBJECT: GRB 180418A: Enhanced Swift-XRT position
DATE:    18/04/18 10:19:03 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 1679 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 180418A, 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 = 170.12153, +24.93309 which is equivalent
to:

RA (J2000): 11h 20m 29.17s
Dec (J2000): +24d 55' 59.1"

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: GRB180418A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22652
SUBJECT: GRB 180418A: RATIR Optical Observations
DATE:    18/04/18 12:45:53 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 (U. Wash.), and
Vicki Toy (UMD) report:

We observed the field of GRB 180418A (D'Elia, et al., GCN 22646) 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 2018/04 18.28 to 2018/04 18.43 UTC
(1.8 minutes to 3.64 hours after the BAT trigger), obtaining a total of
2.57 hours exposure in the r and i bands.

At the position of the optical afterglow (Zheng & Filippenko, GCN 22647),
in comparison with the SDSS DR9 catalog, we obtain the following
detection:

   r    = 19.95 +/- 0.01

This magnitude is in the AB system and is 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.

Further observations are planned.


GRB_name: GRB180416B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22653
SUBJECT: GRB 180416B: CALET Gamma-Ray Burst Monitor detection
DATE:    18/04/18 12:47:28 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

Y. Kawakubo, A. Yoshida, T. Sakamoto, V. Pal'shin, A. Tezuka, S. Matsukawa,
H. Onozawa (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 180416B (Fermi-GBM trigger #545609416; Konus-Wind trigger
time on 22:10:10.60 UT) triggered the CALET Gamma-ray Burst Monitor (CGBM) at
22:10:09.279 UTC on 16 April 2018. The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse which starts at T+1.6 sec, peaks at
T+3.1 sec and ends at ~T+14 sec, followed by a weak tail seen up to ~T+62 sec.
The T90 and the T50 durations measured by the SGM data are 51.6 +- 12.7 sec
and 17.4 +- 8.4 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1207951766/

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


GRB_name: GRB180418A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22655
SUBJECT: GRB 180418A: Swift-XRT refined Analysis
DATE:    18/04/18 19:38:07 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

Z. Liu (NAOC / U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte
(PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and V.
D'Elia report on behalf of the Swift-XRT team:

We have analysed 6.7 ks of XRT data for GRB 180418A (D'Elia et al. GCN
Circ. 22646), from 3.1 ks to 31.9 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN Circ. 22650).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.09 (+0.18, -0.16).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.02 (+0.28, -0.26). The
best-fitting absorption column is  8.0 (+7.1, -5.8) x 10^20 cm^-2, in
excess of the Galactic value of 1.1 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 (3.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.0 (+7.1, -5.8) x 10^20 cm^-2
Galactic foreground: 1.1 x 10^20 cm^-2
Excess significance: 2.0 sigma
Photon index:      2.02 (+0.28, -0.26)

If the light curve continues to decay with a power-law decay index of
1.09, the count rate at T+24 hours will be 3.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-13 (1.3 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/00826428.

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


GRB_name: GRB180418A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22656
SUBJECT: GRB 180418A: Fermi GBM observation
DATE:    18/04/18 20:00:05 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

E. Bissaldi (Politecnico & INFN Bari) and P. Veres (UAH)
report on behalf of the Fermi GBM Team:


"At 06:44:06.28 UT on 18 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180418A (trigger 545726651 / 180418281),
which was also detected by the Swift/BAT (D'Elia et al. 2018, GCN 22646).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 78 degrees.

The GBM light curve consists of a signle FRED-like peak,
with a duration (T90) of about 2.5 s (50-300 keV).
The time-averaged spectrum from T0-0.06 s to T0+0.77 s is
adequately fit by a simple power law function with index -1.52 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(7.6 +/- 0.4)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.26 s in the 10-1000 keV band
is 7.56 +/- 1.13 ph/s/cm^2.


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


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22657
SUBJECT: GRB 180418A: 1.5m OSN optical observations
DATE:    18/04/18 20:57:12 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

A. Sota, Y. Hu, J. C. Tello, I. Carrasco and A. J. Castro-Tirado 
(IAA-CSIC), on behalf of a larger collaboration, report: "Following the 
detection of GRB 180418A with the Neil Gehrels Swift Observatory (D'Elia 
et al. GCNC 22646), I-band observations at the 1.5m telescope at 
Observatorio de Sierra Nevada (Granada, Spain) have been gathered on Apr 
18 starting at 19:49 UT (13 hr post burst). At the position of the 
optical afterglow (Zheng and Filippenko, GCNC 22647; Guidorzi et al., 
GCNC 22648; Troja et al., GCNC 22652), no counterpart is detected down 
to I = 21.0 in the coadded image (5x300s)."


GRB_name: GRB180418A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22658
SUBJECT: GRB 180418A: Swift-BAT refined analysis 
DATE:    18/04/18 22:09:29 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), V. D'Elia (ASDC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), J. P. Norris (BSU),
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 180418A (trigger #826428)
(D'Elia et al., GCN Circ. 22646).  The BAT ground-calculated position is
RA, Dec = 170.132, 24.925 deg which is
  RA(J2000)  =  11h 20m 31.6s
  Dec(J2000) = +24d 55' 28.9"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a single FRED-like pulse that starts
at ~T0, peaks at ~T+0.4 s, and ends at ~T+3.5 s. T90 (15-350 keV)
is 2.29 +- 0.83 sec (estimated error including systematics).

The time-averaged spectrum from T+0.10 to T+3.50 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.44 +- 0.12.  The fluence in the 15-150 keV band is 3.2 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.23 sec in the 15-150 keV band
is 3.0 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The duration and hardness of this burst show it to be intermediate between the
short and long burst populations.

Using a 16-ms binned light curve, the lag analysis finds a lag of 0.1000 +/- 0.026 s
for the 100-350 keV to 25-50 keV band, and 0.088 +/- 0.026 s for the 50-100 keV
to 15-25 keV band. These values are also intermediate between canonical short and
long GRBs.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/826428/BA/


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22659
SUBJECT: GRB 180418A: Gemini-North imaging and spectroscopy 
DATE:    18/04/18 22:46:13 GMT
FROM:    Wen-fai Fong at Northwestern U  <wfong@northwestern.edu>

W. Fong (Northwestern Univ.), N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), and R. Chornock (Ohio Univ.) report on behalf of a larger collaboration:

"We observed the location of the short-duration GRB 180418A (D'Elia et al., GCN 22646) with the Gemini Multi-Object Spectrograph (GMOS) mounted on the Gemini-North 8-meter telescope. We obtained 4x120-sec each in the griz-bands at a mid-time of 2018 April 18.451 UT (4.09 hr post-burst) in 0.7-1" seeing over an airmass range of 1.2-1.5. We detect the optical afterglow (Zheng et al., GCN 22647, Guidorzi et al., GCN 22648, Troja et al., GCN 22652) in all bands with the following preliminary magnitudes:

g = 22.0 +/- 0.1
r = 21.6 +/- 0.2
i = 21.2 +/- 0.2
z = 21.9 +/- 0.4

All magnitudes are reported in the AB system, calibrated to SDSS, and not corrected for Galactic extinction. Notably, the most nearby source in projection is 13.3" from the optical afterglow position, although it is difficult to tell whether the source is point-like or extended in our images. There are otherwise no clearly-extended sources within 30" of the optical afterglow position (corresponding to 185 kpc at z~0.5) to 3-sigma limits of g>23.4 AB mag, r>22.5 AB mag.

In addition, we obtained 4x900-sec of GMOS spectroscopy of the optical afterglow at a mid-time of 2018 April 18.382 UT (2.44 hr post-burst) at an airmass of 1.1. No prominent features can be identified, beyond a blue continuum. Analysis is ongoing.

Further observations are planned. We thank the Gemini staff, and in particular observers Jason Chu and Michael Hoenig, for their assistance with these observations."


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22660
SUBJECT: GRB 180418A: NOT optical observations
DATE:    18/04/19 00:20:53 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele Malesani (DAWN/NBI and DARK/NBI), Kasper Elm Heintz (Univ. 
Iceland and DAWN/NBI), Maria Stone (Univ. Turku), and James Stone, 
report on behalf of a larger collaboration:

We observed the optical afterglow (Zheng & Filippenko, GCN 22647; 
Guidorzi et al., GCN 22648; Troja et al., GCN 22652; Fong et al., GCN 
22659) of GRB 180418A (D'Elia et al., GCN 22646) with the 2.5-m Nordic 
Optical Telescope (NOT) equipped with StanCam.

Observations were carried out in the Bessel R filter, but calibrated 
against SDSS r-band Pan-STARRS local photometry. A low S/N source is 
detected at a position consistent with previous reports.

At a mid time of April 18.936 UT (15.72 hr after the trigger), we 
measure for the counterpart r = 22.70 +- 0.15 AB.

Compared to the Gemini-North measurement (Fong et al., GCN 22659), we 
infer a decay slope alpha = 0.75 +- 0.17, assuming F(t) propto t^-alpha.


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22661
SUBJECT: GRB 180418A: Xinglong TNT optical upper limit
DATE:    18/04/19 02:51:03 GMT
FROM:    L.P. Xin at NAOC  <xlp@nao.cas.cn>

L. P. Xin,   J. Z. Yan,  J. Y. Wei,  Y. L. Qiu, J. S. Deng,  
J. Wang,  X. H. Han, X. M. Meng, C. Wu, D. TURPIN, H. L. Li report:

We began to observe GRB 180418A  (D'Elia et al., GCN 22646)  
with Xinglong  0.8-m TNT telescope, China,  at 2018-04-18, 14:23:11(UT),
about 7.8 hours after the burst.

We obtained 10  R-band images with an exposure time of 300 sec for each frame.  
The optical afterglow (Zheng & Filippenko, GCN 22647; 
Guidorzi et al., GCN 22648; Troja et al., GCN 22652; Fong et al., GCN 
22659; Malesani et al., GCN 22660 ) was not detected in our stacked image with 10*300 sec.
The 3 sigma upper limit is estimated to be about R~20 mag  calibrated 
by USNO B1.0 R2 mag at about 8.2 hours after the burst,

We acknowledge the excellent support from Xinglong staff YunPeng Wang.


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22662
SUBJECT: GRB 180418A GROND observations
DATE:    18/04/19 10:03:15 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

The field of GRB 180418A (Swift trigger 826428; D'Elia et al., GCN #22646)
was observed 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 01:27 UT on 19th April, 18.7 hours after the GRB
trigger. They were performed at an average seeing of 1.5" and at an
average airmass of 1.7.

A source is detected in the g'r'i' bands at a position consistent with the
X-ray and optical afterglow (Zheng et al., GCN #22647; Goad et al., GCN
#22650). The source is not clearly point-like, and it is therefore
possible that some host galaxy light is contributing to the flux. Based on
22 min of exposure in g'r'i'z' and 20 min in JHK, the estimated AB
magnitudes are:

g' = 23.60 +/- 0.14 mag
r' = 23.24 +/- 0.13 mag
i' = 22.88 +/- 0.21 mag
z' > 22.96 mag
J > 21.16 mag
H > 20.67 mag
K > 18.82 mag

Given magnitudes are calibrated against SDSS for g'r'i'z' and 2MASS field
stars for JHK, and they are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E(B-V)=0.01 mag in
the direction of the burst (Schlafly & Finkbeiner 2011).

I thank Sam Kim for his excellent support from La Silla.


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22663
SUBJECT: GRB 180418A:  Imaging of the optical afterglow with the 1.3 m DFOT and 3.6 m DOT in ARIES, India
DATE:    18/04/19 10:24:49 GMT
FROM:    Kuntal Misra at ARIES,India  <kuntal@aries.res.in>

Kuntal Misra, Abhishek Paswan, Mridweeka Singh, S. B. Pandey, T. S. Kumar, Amitesh Omar (ARIES, Nainital, India) report

We observed the field of GRB 180418A (Dâ€™Elia et al. GCN 22646) with the facilities at the Devasthal Observatory, operated by ARIES India,   located in the Central Himalayan region.  Observations were triggered around 2018-04-18T14:41 UT (nearly 8 hours after the burst) with the 1.3 m Devasthal Fast Optical Telescope (DFOT) in r and i bands and with the newly commissioned 3.6 m Devasthal Optical Telescope (DOT) in griz bands.  The afterglow is not detected in co-added images in r and i bands of 3x300 sec each taken with DFOT.  However,  we detect a faint source consistent with the position of the optical afterglow (Zheng et al. GCN 22647, Guidorzi et al. GCN 22648, Troja et al. GCN 22652, Fong et al. GCN 22659, Malesani et al. 22660) at a magnitude of 22.3+/-0.1 in r band with the ARIES Devasthal Faint Object Spectrograph Camera (ADFOSC) mounted on the 3.6 m DOT.    The magnitudes are calibrated with respect to the nearby stars and are not corrected for Galactic extinction. 

Further analysis is in progress and more observations are planned to get deeper images.

We thank the DOT operation team for successfully conducting the observations.


GRB_name: GRB180418A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22664
SUBJECT: GRB 180418A: Continued RATIR Optical Observations
DATE:    18/04/19 13:35:19 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 (U. Wash.), and
Vicki Toy (UMD) report:

We re-observed the field of GRB 180418A (D'Elia, et al., GCN 22646) 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 2018/04 19.13 to 2018/04 19.41 UTC
(20.47 to 27.09 hours after the BAT trigger), obtaining a total of
4.17 hours exposure in the r and i bands.

The optical afterglow (Zheng & Filippenko, GCN 22647) is detected in all
bands and significantly faded with respect to our first night of
observations (Troja et al., GCN 22652). In comparison with the
SDSS DR9 catalog, we obtain the following detections:

   r = 23.63 +/- 0.22
   i = 23.14 +/- 0.16

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: GRB180418A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22665
SUBJECT: GRB 180418A: Swift/UVOT Detection
DATE:    18/04/19 22:05:17 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180418A
3086 s after the BAT trigger (D'Elia et al., GCN Circ. 22646).
A fading source consistent with the XRT position
(Goad et al. GCN Circ. 22650)
is detected in the initial UVOT exposures, confirming the previously
reported optical afterglows (Zheng & Filippenko, GCN Circ. 22647; Guidorzi
et al., GCN Circ. 22648; Troja et al., GCN Circ. 22652; Fong et al., GCN
Circ. 22659; Malesani et al., GCN Circ. 22660; Schady et al., GCN Circ. 22662;
Misra et al., GCN Circ. 22663).

The preliminary UVOT position is:
   RA  (J2000) =  11:20:29.21 = 170.12172 (deg.)
   Dec (J2000) = +24:55:59.2  =  24.93311 (deg.)
with an estimated uncertainty of 0.49 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)        3087         3236          147         19.19+-0.11
white             3087         4470          344         19.45+-0.09
white            49806        72093         4850        >22.62
v                 3243         4835          347        >19.53
b                 4064         4264          196        >20.19
b                15510        16114          590        >20.82
u (fc)            3859         4059          196         19.35+-0.24
u                14598        31858          894        >20.73
uvw1              3655         3855          196         19.19+-0.28
uvw1              9720        27635         1206         20.02+-0.21
uvm2              3450         3649          196         18.93+-0.27
uvm2              8814        26975         2165         20.65+-0.26
uvw2              4476         4676          196        >19.69

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180418A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22666
SUBJECT: GRB 180418A: Further GROND observations
DATE:    18/04/20 14:14:21 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady and T.-W. Chen (both MPE Garching) report:

We re-observed the field of GRB 180418A (Swift trigger 826428; D'Elia et
al., GCN #22646) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) on 20th April, at a mid-time of 02UT. Observations
were performed at an average seeing of 1.2" and at an average airmass of
1.7.

Compared to the previous night of GROND observations (Schady, GCN #22662),
the target has decayed by ~0.8dex in the r'-band. Based on around 60
minutes of data, the estimated AB magnitudes from the second epoch of
GROND observations are:

g' = 24.5 +/- 0.2 mag
r' = 24.0 +/- 0.1 mag
i' = 23.4 +/- 0.2 mag
z' > 23.5 mag
J > 21.7 mag
H > 21.1 mag
K > 19.5 mag

Given magnitudes are calibrated against SDSS and 2MASS field stars, and
they are not corrected for the expected Galactic foreground extinction
corresponding to a reddening of E(B-V)=0.01 mag in the direction of the
burst (Schlafly & Finkbeiner 2011).

We thank Sam Kim for his excellent support from La Silla.


GRB_name: GRB180418A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22668
SUBJECT: GRB 180418A : SQUEAN observations
DATE:    18/04/21 15:57:47 GMT
FROM:    Changsu Choi at Seoul Nat U  <changsu@astro.snu.ac.kr>

Changsu Choi (CEOU/SNU), Yongjung Kim (CEOU/SNU), Woojin Park (KHU), Suhyun
Shin (CEOU/SNU) and Myungshin Im (CEOU/SNU),  on behalf of a larger
collaboration

We observed the field of GRB 180418A (Swift BAT trigger 826428; D'Elia et
al., GCN #22646) using SQUEAN installed at 2.1m Otto Struve telescope of
McDonald Observatory in US, on 18th and 19th April (UT).

The optical counter part of GRB180418A was clearly detected by observation
on 18th April, starting from 2018-04-18T08:18:27 to 08:31:38 UT which is
0.065 days to 0.0742 after BAT trigger.
No obvious source is found in the images taken on 2018-04-19 (UT).

The preliminary photometry results are given below.

All magnitudes are reported in AB magnitudes. The photometric calibration
is based on the stars in SDSS catalog in the observed field. No galactic
extinction correction is applied.

Date           t-T0      Filter Exp.      Magnitude Error
(UT, start)  (mid, days)            (s)     (3" aperture)
2018-04-18T08:18:27 0.065 r       60*3    20.44 0.07
2018-04-18T08:22:53 0.068 i 60*3 20.34 0.04
2018-04-18T08:25:02 0.070 r 60*6 20.47 0.06
2018-04-18T08:27:48 0.072 z 60*3 20.61 0.12
2018-04-18T08:31:38 0.075 r 60*3 20.57 0.08


GRB_name: GRB180418A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22670
SUBJECT: GRB 180418A: MITSuME Ishigakijima Optical Observation
DATE:    18/04/24 02:00:28 GMT
FROM:    Ryosuke Itoh at Tokyo Institute of Tech.  <itoh@hp.phys.titech.ac.jp>

T. Horiuchi,  H. Hanayama, M. Honma (IAO, NAOJ),
R. Itoh, K. Shiraishi, K. Murata, Y. Tachibana and  N. Kawai (Tokyo Tech)
report on behalf of the MITSuME and OISTER collaboration:

We observed the field of GRB 180418A (D'Elia et al.,GCN 22646)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

The observation started on 2018-04-18 13:55:32 UT, (~7 hours after
the burst). We detected the previously reported afterglow
(W. Zheng and A. Filippenko, GCNC22647) in the R band.

The photometric results of the OT are listed below.
We used UCAC-4 catalog for flux calibration.

#T0+[hour]  MID-UT    T-EXP[sec] g'   Rc   Ic
-------------------------------------------------------------------
8.6    15:22:01      10380  >22.8  22.4+/-0.5 >22.0
-------------------------------------------------------------------
T0+ : Elapsed time after the burst [hour]
T-EXP: Total Exposure time [sec]


GRB_name: GRB180418A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22671
SUBJECT: GRB 180418A: TAROT La Silla observatory early optical observations
DATE:    18/04/25 00:27:40 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Noysena.K., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Eymar, L. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 180418A detected by SWIFT
(trigger 826428) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 28s after the GRB trigger
(15s after the notice). The elevation of the field decreased from
6 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).
Despite the very elevation we can measure the very
early optical light variation of the OT reported by
Zheng & Filippenko (GCNC 22647). We used NOMAD-1 1149-0186465
as reference star r(AB)=15.23 (according SDSS DR9).
Preliminary analysis gives:

start end  r(AB) 1sig
(sec) (sec)
   28   36  14.30 0.04
   36   43  14.24 0.03
   43   51  14.40 0.03
   51   58  14.61 0.04
   58   66  14.98 0.05
   66   73  15.42 0.06
   73   81  15.52 0.09
   81   88  15.83 0.15

The following images are taken in tracking mode.
We used the same reference star for PSF fitting:

start end  r(AB) 1sig
(sec) (sec)
  100  130  15.96 0.06
  141  171  16.50 0.11
  181  211  16.58 0.13
  221  251  17.10 0.31
  262  292  16.90 0.25
  302  392  17.00 0.29

Magnitudes are not corrected for galactic dust extinction.

We note that the maximum brightness of the OT
seems to occured at 40s r(AB)=14.24 followed by
a decay of about alpha=2.7 until 70s. Then the decay
is compatible with alpha=1.1 until 6 min (end of TAROT
observations because the elevation was too low).


GRB_name: GRB180425A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22672
SUBJECT: GRB 180425A: Swift detection of a burst
DATE:    18/04/25 07:01:11 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

F. E. Marshall (NASA/GSFC), P. D'Avanzo (INAF-OAB),
P. A. Evans (U Leicester), H. A. Krimm (NSF/USRA),
A. Melandri (INAF-OAB), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 06:46:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180425A (trigger=828672).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 64.469, -32.956 which is 
   RA(J2000) = 04h 17m 53s
   Dec(J2000) = -32d 57' 20"
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 ~1800 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 06:47:40.0 UT, 78.2 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 64.4517,
-32.9519 which is equivalent to:
   RA(J2000)  = 04h 17m 48.41s
   Dec(J2000) = -32d 57' 06.9"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 54 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 (2.90 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2
(+2.26/-2.02) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 5.37e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 87 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
0.03. 

Burst Advocate for this burst is F. E. Marshall (marshall 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: GRB180425A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22673
SUBJECT: GRB 180425A: Enhanced Swift-XRT position
DATE:    18/04/25 09:07:46 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 1083 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 180425A, 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 = 64.45159, -32.95216 which is equivalent
to:

RA (J2000): 04h 17m 48.38s
Dec (J2000): -32d 57' 07.8"

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: GRB180425A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22674
SUBJECT: GRB 180425A: Swift/UVOT Upper Limits
DATE:    18/04/25 14:10:33 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and F. E. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180425A
88 s after the BAT trigger (Marshall et al., GCN Circ. 22672).
No optical afterglow consistent with the XRT position
(Osborne et al., GCN Circ. 22673)
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 early exposures are:

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

white               88         1201          353         >21.0
u                  302         1152          285         >20.5
v                  631         1250           78         >18.5
b                  557         1176           58         >19.4
uvw1               680         1299           78         >19.0
uvm2               827         1275           58         >18.5
uvw2               606         1226           58         >19.0

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: GRB180425A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22675
SUBJECT: GRB 180425A: Swift-BAT refined analysis 
DATE:    18/04/25 14:53:09 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), 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 180425A (trigger #828672)
(Marshall, et al., GCN Circ. 22672).  The BAT ground-calculated position is
RA, Dec = 64.450, -32.949 deg which is
  RA(J2000)  =  04h 17m 48.1s
  Dec(J2000) = -32d 56' 58.1"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 27%.

The mask-weighted light curve shows a single triangular shaped peak beginning
at T-2 sec, peaking at T+3 sec and declining to background by T+14 sec.
T90 (15-350 keV) is 11.2 +- 2.6 sec (estimated error including systematics).

The time-averaged spectrum from T+0.06 to T+12.73 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.13.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.33 sec in the 15-150 keV band
is 2.2 +- 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/828672/BA/


GRB_name: GRB180425A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22676
SUBJECT: GRB 180425A: Swift-XRT refined Analysis
DATE:    18/04/25 15:32:33 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), A.
Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester)
and F.E. Marshall report on behalf of the Swift-XRT team:

We have analysed 6.7 ks of XRT data for GRB 180425A (Marshall et al.
GCN Circ. 22672), from 84 s to 23.0 ks after the  BAT trigger. The data
comprise 132 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Osborne et al. (GCN Circ. 22673).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.20 (+0.11, -0.12). At T+446 s  the decay
steepens to an alpha of 2.09 (+0.33, -0.28) before breaking again at
T+2630 s to a final decay with index alpha=0.34 (+/-0.30).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.02 (+0.15, -0.14). The
best-fitting absorption column is  8.0 (+3.8, -3.4) x 10^20 cm^-2, in
excess of the Galactic value of 2.9 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.98 (+0.19, -0.18)
and a best-fitting absorption column of 1.2 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.4 x 10^-11 (4.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.2 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 2.9 x 10^20 cm^-2
Excess significance: 3.0 sigma
Photon index:      1.98 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
0.34, the count rate at T+24 hours will be 0.016 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.3 x
10^-13 (6.6 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/00828672.

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


GRB_name: GRB180427A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22678
SUBJECT: GRB 180427A: Fermi GBM detection
DATE:    18/04/27 18:18:10 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 10:37:03.04 UT on 27 April 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180427A (trigger 546518228 / 180427442).
The on-ground calculated location, using the GBM trigger data, is

RA = 283.33, Dec = +70.30

(J2000 degrees), 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 angle from the Fermi LAT boresight at the GBM trigger time is 136 degrees.

The GBM light curve shows a single FRED-like emission episode
with a duration (T90) of about 26 s (50-300 keV).
The time-averaged spectrum from T0 to T0+26 s is
best fit by a Band function with Epeak = 108 +/- 3 keV,
alpha = -0.28 +/- 0.04, and beta = -2.81 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(4.92 +/- 0.06)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+5.3 s in the 10-1000 keV band
is 29.2 +/- 0.8 ph/s/cm^2.


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


GRB_name: GRB180427A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22679
SUBJECT: IPN Triangulation of GRB 180427A
DATE:    18/04/28 15:35:23 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,

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, 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 180427A (Bissaldi, GCN Circ. 22678)
was detected by Fermi (GBM; trigger 546518228), Konus-Wind, Mars-Odyssey 
(HEND), INTEGRAL (SPI-ACS), and Swift (BAT) at about 38223 s UT (10:37:03).
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:
   271.012 (18h 04m 03s) +68.454 (+68d 27' 14")
  Corners:
   277.258 (18h 29m 02s) +68.858 (+68d 51' 30")
   265.504 (17h 42m 01s) +67.232 (+67d 13' 56")
   265.042 (17h 40m 10s) +67.831 (+67d 49' 51")
   277.094 (18h 28m 23s) +69.480 (+69d 28' 49")
  ---------------------------------------------
The error box area is 2.88 sq. deg, and its maximum
dimension is 4.82 deg (the minimum one is 36.96 arcmin).
The Sun distance was 86 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180427_T38222/IPN

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


GRB_name: GRB180427A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22680
SUBJECT: Konus-Wind observation of GRB 180427A
DATE:    18/05/04 10:41:56 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration GRB 180427A
(Fermi GBM detection: Bissaldi, GCN Circ. 22678,
IPN triangulation: Hurley et al., GCN Circ. 22679)
triggered Konus-Wind at T0=38222.928 s UT (10:37:02.928).

The burst light curve shows a single pulse
which starts at ~T0-0.4 s and has a total duration of ~34.5 s.
The emission is seen up to ~2 MeV.

As observed by Konus-Wind, the burst
had a fluence of 5.09(-0.19,+0.21)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+5.024 s,
of 4.93(-0.81,+0.81)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+33.536 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.59(-0.07,+0.08),
the high energy photon index beta = -3.10(-0.24,+0.17),
the peak energy Ep = 116(-4,+4) keV
(chi2 = 78/61 dof).

The spectrum near the maximum count rate
(measured from T0+3.840 to T0+7.424 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = 0.49(-0.13,+0.14),
the high energy photon index beta = -3.78(-0.51,+0.30),
the peak energy Ep = 135(-5,+5) keV
(chi2 = 78/60 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180427_T38222/

There are no data available for the triggered mode 300-1200 keV band.

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


GRB_name: GRB180416B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22681
SUBJECT: GRB 180416B: AstroSat CZTI detection
DATE:    18/05/04 17:30:55 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long GRB 180416B, which was also detected by CALET (Kawakubo Y. et al., GCN 22653) along with Fermi-GBM (trigger #545609416) and Konus-Wind trigger time on 22:10:10.60 UT.

The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission with peak at 22:10:12.50 UT. The measured peak count rate is 388 cts/s above the background in combined data of four quadrants, with a total of 5491 cts. The local mean background count rate was 526.8 cts/s. Using cumulative rates, we measure a T90 of 56.3 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180504A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22682
SUBJECT: GRB 180504A: Swift detection of a burst
DATE:    18/05/04 20:03:11 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J.D. Gropp (PSU),
J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),
A. Tohuvavohu (PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 19:46:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180504A (trigger=830822).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 331.134, -14.655 which is 
   RA(J2000) = 22h 04m 32s
   Dec(J2000) = -14d 39' 17"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 50 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

Using promptly downlinked data we find a bright, uncatalogued X-ray
source located at RA, Dec 331.14235, -14.65988 which is equivalent to:
   RA(J2000)  = 22h 04m 34.16s
   Dec(J2000) = -14d 39' 35.6"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). 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 3.50
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 9.57e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 117 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
0.04. 

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: GRB180504A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22683
SUBJECT: GRB 180504A: Prompt enhanced Swift-XRT position
DATE:    18/05/04 20:28:42 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 180504A, we find an
enhanced XRT position of the afterglow: RA, Dec: 331.1442, -14.6583
which is equivalent to:
   RA (J2000)  = 22 04 34.61
   Dec (J2000) = -14 39 30.0
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/830822.

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: GRB180504A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22684
SUBJECT: GRB 180504A: NOT afterglow candidate
DATE:    18/05/05 07:05:30 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. Malesani (DAWN/NBI and DARK/NBI) and Illa R. Losada (NOT, Nordita, 
Stockholm Univ.) report on behalf of a larger collaboration:

We observed the field of GRB 180504A (Lien et al., GCN 22682) with the 
Nordic Optical Telescope equipped with the AlFOSC camera. The field has 
a bad visibility from La Palma, and observations were carried out at 
large airmass (~2) and straddling twilight. The average seeing was 1.5".

Coincident with the UVOT-enhanced position reported by Evans (GCN 
22683), we note the presence of a faint source, at a position (J2000; 
0.5" error):

RA = 22:04:34.61
Dec = -14:39:30.0

We note that the automatically reported un-enhanced XRT position 
(available from http://www.swift.ac.uk/xrt_positions/) is at the time of 
writing significantly different from the one quoted in the GCN, and 
would not include our afterglow candidate.

Photometry of the candidate against nearby stars from the Pan-STARRS 
survey yields r = 22.5 +/- 0.3 (AB) at a mean time 2018 May 5.222 UT 
(9.57 hr after the trigger)

Further observations are planned.


GRB_name: GRB180504A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22685
SUBJECT: GRB 180504A: Swift-XRT refined Analysis
DATE:    18/05/05 08:09:42 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte (PSU), J.A.
Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri
(INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT team:

We have analysed 12 ks of XRT data for GRB 180504A (Lien et al. GCN
Circ. 22682), from 98 s to 30.5 ks after the  BAT trigger. The data
comprise 163 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 best available XRT position  (using the promptly downlinked
event data, the XRT-UVOT alignment and matching UVOT field sources to
the USNO-B1 catalogue) is RA, Dec = 331.1442, -14.6583 which is
equivalent to:

RA (J2000): 22 04 34.61
Dec(J2000): -14 39 30.0

with an uncertainty of 2.0 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.7 (+nan, -nan).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.80 (+/-0.11). The
best-fitting absorption column is  6.9 (+3.2, -2.8) x 10^20 cm^-2, in
excess of the Galactic value of 3.5 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.86 (+0.25, -0.23)
and a best-fitting absorption column of 1.5 (+0.8, -0.7) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.7 x 10^-11 (4.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.5 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 3.5 x 10^20 cm^-2
Excess significance: 2.7 sigma
Photon index:      1.86 (+0.25, -0.23)

If the light curve continues to decay with a power-law decay index of
0.7, the count rate at T+24 hours will be 7.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.8 x
10^-13 (3.4 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/00830822.

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


GRB_name: GRB180504A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22686
SUBJECT: Correction to Swift-XRT light curve fit for GRB 180504A in GCN 22685
DATE:    18/05/05 08:20:13 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

The fit results to the Swift-XRT light curve provided in GCN 22685 were
incomplete. The correct fit is as follows:

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha= 1.47 (+0.16, -0.17). At T+222 s the decay
steepens to an alpha of 2.81 (+0.20, -0.14) before breaking again at
T+1078 s to a final decay with index alpha=0.83 (+/- 0.13).

If the light curve continues to decay with a power-law decay index of 0.83
, the count rate at T+24 hours will be 2.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x 10^-13
(1.3 x 10^-13) erg cm^-2 s^-1.

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

[GCN OPS NOTE(05may18): Per author's request, the GRB name
was added to the Subject-line.]


GRB_name: GRB180504A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22687
SUBJECT: GRB 180504A: ePESSTO NTT NIR observations
DATE:    18/05/05 15:09:36 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. Clark (QUB), O. McBrien (QUB), D. Malesani (DAWN, DARK), P. D'Avanzo (INAF-OAB), E. Kankare (QUB), 
M. T. Botticella (INAF Capodimonte), K. Maguire (QUB), M. Dennefeld (IAP, Paris), C. Inserra (Southampton), 
S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), I. Manulis (Weizmann) report:

We observed the field of GRB 180504A (Lien et al., GCN Circ. 22682) under the extended Public ESO Spectroscopic 
Survey for Transient Objects (ePESSTO; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org <http://www.pessto.org/> ). The observations 
were performed on the ESO New Technology Telescope at La Silla with the SofI instrument in imaging mode starting from 
2018-05-05 at 08:37:49 UT (i.e. about 12.9 hours from the burst) and consisted of 15 images obtained with the J filter, 
each one lasting 90s.

The afterglow candidate reported by Malesani et al. (GCN Circ. 22684) is clearly detected. From preliminary photometry, 
we estimate a magnitude of J ~ 21.3 (Vega, calibrated against the 2MASS catalogue). 


GRB_name: GRB180416A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22688
SUBJECT: GRB 180416A: AstroSat CZTI detection
DATE:    18/05/05 15:15:57 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

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

Analysis of Astrosat CZTI data showed the detection of a long GRB 180416A, which was also detected by Fermi-GBM (Bissaldi E. et al, GCN # 22644).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 08:10:54.5 UT, ~87 s after GBM trigger. The measured peak count rate is 420.5 cts/s above the background in combined data of four quadrants, with a total of 3904 cts. The local mean background count rate was 508.5 cts/s. Using cumulative rates, we measure a T90 of 92.6 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180505A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22689
SUBJECT: GRB 180505A: Fermi GBM detection
DATE:    18/05/05 19:33:04 GMT
FROM:    Christian Malacaria at U of Alabama/MSFC  <christian.malacaria@nasa.gov>

C. Malacaria (NASA-MFSC/USRA) and E. Bissaldi (Politecnico & INFN Bari)
report on behalf of the Fermi GBM Team:

"At 12:57:09.91 UT on 5 May 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180505A (trigger 547217834 / 180505540).
The on-ground calculated location, using the GBM trigger data, is

RA = 4.51, Dec = -59.89

(J2000 degrees), with an uncertainty of 1.2 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 124 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 22 s (50-300 keV).
The time-averaged spectrum from T0-3.5 s to T0+31 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.38 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 235 +/- 19 keV

The event fluence (10-1000 keV) in this time interval is
(2.38 +/- 0.07)E-05 erg/cm^2. The 1-s peak photon flux measured
starting from T0+20.99 s in the 10-1000 keV band
is 29.2 +/- 0.8 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 233 +/- 25 keV, alpha = -1.38 +/- 0.04 and beta = -3.09 +/- 1.32.


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


GRB_name: GRB180504A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22690
SUBJECT: GRB 180504A: Swift-BAT refined analysis
DATE:    18/05/05 23:31:08 GMT
FROM:    Hans Krimm at NASA-GSFC/NSF  <hans.krimm@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),  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), 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 180504A (trigger #830822)
(Lien, et al., GCN Circ. 22682).  The BAT ground-calculated position is
RA, Dec = 331.144, -14.665 deg which is
    RA(J2000)  =  22h 04m 34.7s
    Dec(J2000) = -14d 39' 53.6"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 61%.

The mask-weighted light curve shows a triangular shaped profile, 
beginning at
~T-60 sec, peaking at ~T+20 sec, and decaying by T+80 sec.
T90 (15-350 keV) is 88.3 +- 44.4 sec (estimated error including 
systematics).

The time-averaged spectrum from T-25.03 to T+113.85 sec is best fit by a 
simple
power-law model.  The power law index of the time-averaged spectrum is
1.50 +- 0.13.  The fluence in the 15-150 keV band is 2.2 +- 0.2 x 
10^-6erg/cm2.
The 1-sec peak photon flux measured from T+16.80 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/830822/BA/


GRB_name: GRB180504A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22691
SUBJECT: GRB 180504A: Swift/UVOT Upper Limits
DATE:    18/05/07 14:52:23 GMT
FROM:    Jeffrey Gropp at PSU  <jdg44@psu.edu>

J. D. Gropp (PSU), S. J. LaPorte (PSU), 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 180504A
118 s after the BAT trigger (Lien et al., GCN Circ. 22682).
No optical afterglow consistent with the enhanced XRT position
(Evans GCN Circ. 22683)
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

b                     5159           6793           116      >19.04
uvm2              5978            7606          136      >18.81
u_FC                302            6588          688      >19.53
u                       705            1869          381      >19.47
v                        631              651         136      >18.20
uvw1               6183            6383         136       >18.58
uvw2               5569             7204         136      >18.87
white_FC          143             6998          557     >20.67
white                 582             1746          393    >20.46

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180427A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22694
SUBJECT: GRB 180427A: AstroSat CZTI detection
DATE:    18/05/09 13:34:15 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

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

Analysis of AstroSat CZTI data showed the detection of a bright GRB 180427A, which was also detected by Fermi-GBM (Bissaldi E. et al., GCN 22678), IPN Triangulation (Hurley K. et al., GCN 22679) and Konus-Wind (Kozlova A. et al., GCN 22680).

The source was clearly detected in the 40-200 keV energy range. The light curve shows a double-peaked structure in overall FRED-like emission, with strongest emission at 10:37:04.5 UT. The measured peak count rate is 1717 cts/s above the background in combined data of four quadrants, with a total of 18897 cts. The local mean background count rate was 494.8 cts/s. Using cumulative rates, we measure a T90 of 22.4 s. In Preliminary analysis, we find that 981.3 compton events are associated with this event.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180510A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22695
SUBJECT: GRB 180510A: Swift detection of a burst
DATE:    18/05/10 19:47:25 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60@psu.edu>

J.D. Gropp (PSU), A. Deich (PSU), J. A. Kennea (PSU),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 19:24:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180510A (trigger=831810).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 276.318, -31.911 which is 
   RA(J2000) = 18h 25m 16s
   Dec(J2000) = -31d 54' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 70 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 19:26:02.5 UT, 88.3 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 276.3303, -31.9069 which is equivalent to:
   RA(J2000)  = +18h 25m 19.27s
   Dec(J2000) = -31d 54' 24.8"
with an uncertainty of 5.5 arcseconds (radius, 90% containment). This
location is 40 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. 

The initial flux in the 2.5 s image was 1.09e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 96 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. Results from the list of sources generated on-board are not
available at this time. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.26. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT 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: GRB180510B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22696
SUBJECT: GRB 180510B: Swift detection of a burst with an optical counterpart
DATE:    18/05/10 21:22:21 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60@psu.edu>

A. Tohuvavohu (PSU), A. Deich (PSU), J.D. Gropp (PSU),
J. A. Kennea (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 20:15:42 UT, the Swift Burst Alert Telescope (BAT) triggered and
located possible GRB 180510B (trigger=831816). Due to an observing constraint
Swift did not slew immediately to the burst. 

The BAT on-board calculated location is 
RA, Dec 77.989, -62.335 which is 
   RA(J2000) = 05h 11m 57s
   Dec(J2000) = -62d 20' 05"
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 ~800 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 21:04:52.4 UT, 2950.1 seconds
after the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 77.96962, -62.32356 which
is equivalent to:
   RA(J2000)  = 05h 11m 52.71s
   Dec(J2000) = -62d 19' 24.8"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 52 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 (2.54 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.8
(+3.31/-2.67) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 2953 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 05:11:52.64 =  77.96932
  DEC(J2000) = -62:19:26.3  = -62.32396
with a 90%-confidence error radius of about 0.76 arc sec. This position is 4.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.25 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is A. Tohuvavohu (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: GRB180418A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22697
SUBJECT: GRB 180418A: 15 GHz upper limits from AMI
DATE:    18/05/10 21:43:58 GMT
FROM:    Kunal Mooley at NRAO,Caltech  <kmooley@caltech.edu>

J. Bright (Oxford), K. P. Mooley (NRAO, Caltech; Jansky Fellow), R. P. 
Fender (Oxford)

We observed the field of GRB 180418A (D'Elia et al., GCN 22646) with the 
AMI Large Array at 15.5 GHz. Our observations on 2018 Apr 18.88, Apr 
20.89 and Apr 22.86 (UT) (0.61 d, 2.61 d and 4.58 post-burst) do not 
reveal any radio source at the XRT location (Goad et al., GCN 22650), 
with preliminary 3sigma upper limits of 99 uJy, 81 uJy and 93 uJy 
respectively.

We thank the MRAO staff for scheduling these observations. Results from 
the AMI short-GRB program are posted on the AMI-GRB database available 
at http://4pisky.org/ami-grb/.


GRB_name: GRB180510B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22698
SUBJECT: GRB 180510B: Enhanced Swift-XRT position
DATE:    18/05/11 00:21:41 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 2476 s of XRT Photon Counting mode data and 7 UVOT
images for GRB 180510B, 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 = 77.96901, -62.32411 which is equivalent
to:

RA (J2000): 05h 11m 52.56s
Dec (J2000): -62d 19' 26.8"

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: GRB180510B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22700
SUBJECT: GRB 180510B: TAROT La Silla observatory optical observations
DATE:    18/05/11 09:01:11 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Noysena.K., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Eymar, L. (CNRS-ARTEMIS),
Gendre B. (UWA - Univ. Western Australia) report:

We imaged the field of GRB 180510B detected by SWIFT
(trigger 831816) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 2.88h after the GRB trigger
just after the dusk. The elevation of the field
decreased from 38 degrees above horizon weather conditions
were good.

We co-added a series of exposures but we we cannot
detect the OT reported by Tohuvavohu et al. (GCNC 22696)
Preliminary analysis gives:

start  end    rlim(AB)
(hour) (hour)
2.88   3.62   19.0

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.


GRB_name: GRB180510B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22701
SUBJECT: GRB 180510B: GROND detection in all bands
DATE:    18/05/11 11:12:06 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady (MPE, Garching) reports:

We observed the field of GRB 180510B (Swift trigger 831816; Tohuvavohu et
al., GCN #22696) 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 23:14 UT on 10th May, 3.0 hours after the GRB
trigger. They were performed at an average seeing of 1.3" and at an
average airmass of 1.8.

A single point source is present within the 1.5" Swift-XRT error circle
reported by Beardmore et al. (GCN #22698) at

RA (J2000) = 05:11:52.66
DEC (J2000) = -62:19:26.4

with an uncertainty of 0.2" in each coordinate.

Based on 6.6 min of total exposures in g'r'i'z' and 6 min in JHK, the
estimated AB magnitudes are

g' = 20.5 +/- 0.1 mag
r' = 20.0 +/- 0.1 mag
i' = 19.8 +/- 0.1 mag
z' = 19.6 +/- 0.1 mag
J = 18.8 +/- 0.1 mag
H = 18.5 +/- 0.1 mag
K = 18.0 +/- 0.1 mag

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.02 in the direction
of the burst (Schlafly & Finkbeiner 2011).

I would like to thank Markus Rabus for his excellent support from La Silla.


GRB_name: GRB180510B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22702
SUBJECT: GRB 180510B: VLT/X-shooter observations
DATE:    18/05/11 11:34:10 GMT
FROM:    Andrea Rossi at INAF  <a.rossi@iasfbo.inaf.it>

J. Palmerio (IAP, Paris), A. Rossi (INAF-OAS), D. Malesani (DAWN/NBI and 
DARK/NBI), N. R. Tanvir (Univ. Leicester), V. D'Elia (ASI-SSDC), A. de 
Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), S. D. Vergani (GEPI/Obs. 
Paris), D. Xu (NAOC), D. A. Kann (HETH/IAA-CSIC), J.P.U. Fynbo 
(DAWN/NBI), and B. Sbarufatti (PSU), report on behalf of the Stargate 
Consortium:

We observed the optical afterglow of GRB 180510B (Tohuvavohu et al., GCN 
22696; Schady et al., GCN 22701) with the ESO VLT/X-shooter 
spectrograph, covering the wavelength range 3000-21000 AA.
The afterglow is clearly detected in the 10s acquisition images taken 
starting at 23:09 UT (~3.7 hours after the GRB trigger) with brightness 
R~19.8 (Vega), calibrated against USNO-B1 stars in the field. 
Spectroscopy started at 23:19 UT on 2018-05-10 (~3.9 hours after the GRB 
trigger) and consisted of 2 exposures of 600 s.

Preliminary analysis of the spectrum reveals continuum flux down to 3600 
AA, which sets an upper limit to the redshift z <~ 2 via the lack of any 
obvious DLA feature. In addition, we identify several absorption lines 
at a common redshift of z=1.305, the most prominent being ZnII/CrII, 
FeII, MgII, and MgI. Moreover, we also identify another absorption 
system at z=0.63 based on the detection of the MgII doublet. Therefore, 
we propose the most probable redshift of the GRB to be z=1.305, with an 
intervening system at 0.638.

We acknowledge the excellent support from the ESO staff, particularly 
Boris Haeussler, Karleyne Silva and Emanuela Pompei in obtaining these 
observations.


GRB_name: GRB180510B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22705
SUBJECT: GRB 180510B: Swift-BAT refined analysis
DATE:    18/05/11 14:30:53 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), 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),
A. Tohuvavohu (PSU), 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 180510B (trigger #831816)
(Tohuvavohu et al. GCN Circ. 22696).  The BAT ground-calculated position is
RA, Dec = 77.965, -62.320 deg which is
  RA(J2000)  =  05h 11m 51.6s
  Dec(J2000) = -62d 19' 13.0"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 41%.

The mask-weighted light curve shows a weak pulse that starts at ~T-20 s and peaks
at ~T+1 s. The main pulse ends at ~ T+40 s, and there is some low-level emission
that lasts until ~T+140 s. T90 (15-350 keV) is 134.3 +- 48.2 sec (estimated error including systematics).

The time-averaged spectrum from T-19.92 to T+137.10 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.00 +- 0.17.  The fluence in the 15-150 keV band is 2.1 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.96 sec in the 15-150 keV band
is 1.2 +- 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/831816/BA/


GRB_name: GRB180510A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22707
SUBJECT: GRB 180510A: Swift-XRT refined Analysis
DATE:    18/05/11 19:47:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), S.L. Gibson (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB) and J.D. Gropp report on behalf of the Swift-XRT
team:

We have analysed 4.9 ks of XRT data for GRB 180510A (Gropp et al. GCN
Circ. 22695), from 77 s to 40.5 ks after the  BAT trigger. The data
comprise 228 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The refined XRT position is RA, Dec = 276.3314, -31.9081 which is
equivalent to:

RA (J2000): 18 25 19.54
Dec(J2000): -31 54 29.1

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

The late-time light curve (from T0+15.8 ks) can be modelled with a
power-law decay with a decay index of alpha=1.2 (+/-0.4).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.94 (+0.08, -0.07). The
best-fitting absorption column is  5.2 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 2.1 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.01 (+0.30, -0.28)
and a best-fitting absorption column of 3.5 (+1.4, -1.2) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.8 x 10^-11 (5.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.5 (+1.4, -1.2) x 10^21 cm^-2
Galactic foreground: 2.1 x 10^21 cm^-2
Excess significance: 1.9 sigma
Photon index:      2.01 (+0.30, -0.28)

If the light curve continues to decay with a power-law decay index of
1.2, the count rate at T+24 hours will be 0.016 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.2 x
10^-13 (9.4 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/00831810.

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


GRB_name: GRB180510B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22708
SUBJECT: GRB 180510B: Swift-XRT refined Analysis
DATE:    18/05/11 21:22:02 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), P.A. Evans (U.
Leicester), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester),
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and A.
Tohuvavohu report on behalf of the Swift-XRT team:

We have analysed 2.6 ks of XRT data for GRB 180510B (Tohuvavohu et al.
GCN Circ. 22696), from 3.0 ks to 10.2 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Beardmore et al. (GCN Circ.
22698).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.48 (+/-0.12).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.83 (+/-0.12). The
best-fitting absorption column is  1.3 (+0.4, -0.3) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 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 3.7 x 10^-11 (4.5 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.3 (+0.4, -0.3) x 10^21 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index:      1.83 (+/-0.12)

If the light curve continues to decay with a power-law decay index of
1.48, the count rate at T+24 hours will be 9.2 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x
10^-13 (4.1 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/00831816.

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


GRB_name: GRB180510A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22709
SUBJECT: GRB 180510A: Swift/UVOT followup observations
DATE:    18/05/12 07:21:32 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL), S. R. Oates (U.Warwick) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180510A 97 
s after the BAT trigger (Gropp et al., GCN Circ. 22695).
A source is detected at the edge of the refined XRT position (Dâ€™Ai et 
al. GCN Circ. 22707) but this is consistent with the position of a 
USNO-B1.0 source (at 276.332, -31.908), and it is not clear if we see 
any fading. Preliminary detections and 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            97          247          147         20.0 Â± 0.3
white            28989        29010          21          >19.2
v   22961        23272         301          >19.4
b                28076        28983         885          20.2 Â± 0.2
u                  310          322          12          >17.6
uvw1             15854        16753         886          >20.6
uvw2             22055        22955         886          >20.5

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.26 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB180512A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22710
SUBJECT: GRB 180512A: Swift detection of a burst
DATE:    18/05/12 23:01:48 GMT
FROM:    Alex Deich at Penn State U  <aud375@psu.edu>

A. Deich (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J.D. Gropp (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC) and
F. E. Marshall (NASA/GSFC) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 22:01:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180512A (trigger=832119).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 201.953, +21.406 which is 
  RA(J2000) = 13h 27m 49s
  Dec(J2000) = +21d 24' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 550 sec.  The main pulse starts at
~T+400 s and ends at ~T+550 s. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~500 sec after the trigger. 

The XRT began observing the field at 22:05:20.1 UT, 213.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 201.93846, 21.40271 which is equivalent
to:
  RA(J2000)  = 13h 27m 45.23s
  Dec(J2000) = +21d 24' 09.8"
with an uncertainty of 4.4 arcseconds (radius, 90% containment). This
location is 50 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 1.73
x 10^20 cm^-2 (Willingale et al. 2013). 

No UVOT data are available at this time. 

Burst Advocate for this burst is A. Deich (aud375 AT 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: GRB180512A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22711
SUBJECT: GRB 180512A: Upper limits from OSN
DATE:    18/05/12 23:37:11 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, Dark/NBI), L. Izzo, D. A. Kann 
(both HETH/IAA-CSIC), and A. Sota (IAA/CSIC) report on behalf of HETH:

We observed the field of GRB 180512A  (Deich et al.; GCN Circ. 22710) 
with the 1.5-m OSN telescope in Granada, Spain

Observations started at 22:15:35 UT (827 s after the GRB trigger) for 
OSN, and we obtained 8x60s images in the Rc band and 6x300s images in 
the Ic band. Observations were obtained in inclement conditions (bad 
seeing of ~3").

In our stacked images, we find no source inside the Swift-XRT error 
circle down to a 3-sigma limit of Ic (Vega) > 21. The calibration was 
performed using nearby stars in the SDSS catalog.


GRB_name: GRB180512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22712
SUBJECT: GRB 180512A: OASDG optical observations
DATE:    18/05/12 23:39:22 GMT
FROM:    Luca Izzo at IAA-CSIC  <Luca.Izzo@ICRA.it>

L. Izzo (HETH/IAA-CSIC) reports:

We observed the field of GRB 180512A (Deich et al., GCN Circ. 22710) with the 0.5m telescope of the Osservatorio Astronomico S. Di Giacomo located in Agerola, Italy ( http://acgo.it/oa )

We began observing at 22:31:54 UT (~30 min after the GRB trigger), and obtained 7x180s images in the Rc band. In our stacked image, we find no source inside the Swift-XRT error box down to a 3-sigma limit of Rc (Vega) > 20.2. The calibration was performed using nearby stars in the USNO B1 catalog.


GRB_name: GRB180512A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22713
SUBJECT: GRB 180512A: NOT upper limits
DATE:    18/05/13 00:15:15 GMT
FROM:    Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI  <keh14@hi.is>

Kasper Elm Heintz (Univ. Iceland and DAWN/NBI), Daniele Malesani (DAWN/NBI and DARK/NBI), Lauri Siltala (NOT), and Pilar Montanes Rodriguez (IAC), report on behalf of a larger collaboration:

We observed the field around GRB 180512A (Deich et al., GCN 22710) with the 2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC.

Observations of 3x100 s were carried out in each of the SDSS r, i, and z filters and started at 22:48:54 UT on May 12, 47 min after trigger. We do not detect the optical counterpart within the Swift-XRT error circle and calibrated against Pan-STARRS local photometry we measure upper limits (at 3-sigma) of:

m(r) > 23.3, m(i) > 23.0, and m(z) > 22.1 AB mag.

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

[GCN OPS NOTE(12may18): Per author's request, a typo in the author name Rodriguez was corrected.]


GRB_name: GRB180512A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22714
SUBJECT: GRB 180512A: GROND upper limits
DATE:    18/05/13 02:42:32 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan@bolmer.de>

J. Bolmer MPE Garching) reports on behalf of the GROND Team:

I observed the field of GRB180512A (Swift trigger 832119; Deich et
al., GCN #22710) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO La Silla
Observatory (Chile).

Observations started at 00:03 UT on 2018-05-13, 2.7 hrs after the GRB
trigger. They were performed at an average seeing of 1.3'' and at an
average airmass of 1.9.

No source is detected within or close to the Swift-XRT error circle.

Based on 40 min of exposure in g'r'i'z' and 41 min in JHK_s, at a mid-time
of 00:44 UT, we derive the following preliminary upper
limits (in AB system):

g' > 25.4 mag,
r' > 24.9 mag,
i' > 24.0 mag,
z' > 23.4 mag,
J > 21.9 mag,
H > 21.2 mag, and
K_s > 20.2 mag.

Given upper limits are calibrated against SDSS field stars in g'r'i'z'
as well as 2MASS field stars in JHK_s. No correction for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.058 mag in
the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.


GRB_name: GRB180512A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22715
SUBJECT: GRB 180512A: Enhanced Swift-XRT position
DATE:    18/05/13 04:49:52 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 1368 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 180512A, 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 = 201.93805, +21.40355 which is equivalent
to:

RA (J2000): 13h 27m 45.13s
Dec (J2000): +21d 24' 12.8"

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: GRB180512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22716
SUBJECT: GRB 180512A: LT prompt observations
DATE:    18/05/13 08:31:12 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

The 2-m Liverpool Telescope automatically began observing Swift GRB 
180512A (Deich et al. GCN 22710) on May 12, 22:07:15 UT (5.5 minutes 
since the GRB) with the RINGO3 polarimeter and the IO:O camera in the 
SDSS-R filter. Within the enhanced XRT error circle (Evans et al. GCN 
22715) we do not detect any optical counterpart down to the following 
magnitude:

Mid time since GRB     Exp        Filter         Magnitude
(hrs)                  (s)
-----------------------------------------------------------
0.64                  6x10       SDSS-R          > 20.8
-----------------------------------------------------------

as calibrated against nearby SDSS objects.


GRB_name: GRB180512A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22717
SUBJECT: GRB 180512A: Swift/UVOT Upper Limits
DATE:    18/05/13 10:53:43 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

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

The Swift/UVOT began settled observations of the field of GRB 180512A
218 s after the BAT trigger (Deich et al., GCN Circ. 22710).  No optical
afterglow consistent with the XRT position (Evans et al. GCN Circ. 22715)
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           218          368          147         >21.1
white              218         4358          344         >21.2
v                 5986         6120          132         >19.0
b                 3953         4153          197         >20.7
u                 3748        16254          422         >20.7
w1                3543        16019         1107         >20.3
m2                9380        10280          886         >20.9
w2                5781         5981          197         >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180512A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22718
SUBJECT: GRB 180512A: LBT optical detection
DATE:    18/05/13 13:13:01 GMT
FROM:    Andrea Rossi at INAF  <a.rossi@iasfbo.inaf.it>

A. Rossi and E. Palazzi (INAF-OAS) report on behalf of the CIBO 
colaboration:

We  observed the field of GRB180512A (Swift trigger 832119; Deich et 
al., GCN #22710) simultaneously in r' and z' bands with the LBC imager 
mounted on LBT (Mt Graham, AZ, USA). Observations started at 04:05 UT on 
2018-05-13, 6 hrs after the GRB trigger and finished at 04:27 UT and 
allowed us to obtain 20min of exposure in each band.

Image inspection reveals a faint source within the Swift/XRT enhanced 
error circle (Evans et al., GCN 22715) with coordinates:
RA(J2000) = 13:27:45.130
Dec(J2000)= +21:24:13.39
with an uncertainty of 0.2" in each coordinate.

The source is detected only r'-band and has magnitude r' = 25.0 mag 
+-0.3 (AB), calibrated against r'-band SDSS field stars. No statement 
about the variability can be made at this point. Further observations 
are planned.

No correction for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V)=0.02 mag in the direction of the 
burst (Schlafly & Finkbeiner 2011) has been applied.

We acknowledge the excellent support from the LBT-INAF staff, 
particularly F. Cusano and A. Gargiulo in obtaining these observations.


GRB_name: GRB180512A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22719
SUBJECT: GRB 180512A: RATIR Optical Observations 
DATE:    18/05/13 16:00:35 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 (U. Wash.), and Vicki
Toy (UMD) report:

We observed the field of GRB 180512A (Deich et al., GCN Circ. 22710)
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 2018/05 13.16 to
2018/05 13.44 UTC (5.75 to 12.58 hours after the BAT trigger), obtaining
a total of 5.22 hours exposure in the r and i bands.

For a source within the enhanced Swift-XRT error circle (Evans et al.,
GCN Circ. 22715), in comparison with the SDSS DR9 and 2MASS catalogs, we
obtain the following 3-sigma upper limits:

 r > 24.30
 i > 24.23

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: GRB180512A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22720
SUBJECT: GRB 180512A: Swift-BAT refined analysis
DATE:    18/05/13 16:56:18 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
A. Deich (PSU), 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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180512A (trigger #832119)
(Deich et al., GCN Circ. 22710).  The BAT ground-calculated position is
RA, Dec = 201.940, 21.404 deg which is
  RA(J2000)  =  13h 27m 45.5s
  Dec(J2000) = +21d 24' 15.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.

The mask-weighted light curve shows a weak pulse that starts at ~T+30 s,
peaks at ~T+40 s, and ends at ~T+55 s. The short spike at T+54.4 s is due
to detector noise. T90 (15-350 keV) is 24.0 +- 7.1 sec (estimated error including systematics).
Note that the burst went out of the BAT FOV at T+469 s. The large pulse
seen in the BAT raw light curve from ~T+400 s to ~T+550 s was from a bright
background source that came in and out of the BAT FOV during this time interval.

The time-averaged spectrum from T+29.00 to T+55.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.10 +- 0.27.  The fluence in the 15-150 keV band is 4.2 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+39.00 sec in the 15-150 keV band
is 0.6 +- 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/832119/BA/


GRB_name: GRB180512A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22721
SUBJECT: GRB 180512A: Swift-XRT refined Analysis
DATE:    18/05/13 22:27:02 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), A. Tohuvavohu (PSU), S.L. Gibson (U. Leicester), Z.
Liu (NAOC / U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo
(INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte
(PSU) and A. Deich report on behalf of the Swift-XRT team:

We have analysed 4.2 ks of XRT data for GRB 180512A (Deich et al. GCN
Circ. 22710), from 230 s to 72.7 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 22715).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.87 (+0.12, -0.11).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.5 (+0.9, -0.8). The
best-fitting absorption column is  2.3 (+1.5, -1.1) x 10^22 cm^-2, in
excess of the Galactic value of 1.7 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 5.2 x 10^-11 (1.9 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.3 (+1.5, -1.1) x 10^22 cm^-2
Galactic foreground: 1.7 x 10^20 cm^-2
Excess significance: 3.6 sigma
Photon index:      2.5 (+0.9, -0.8)

If the light curve continues to decay with a power-law decay index of
0.87, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-13 (4.0 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/00832119.

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


GRB_name: GRB180510A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22722
SUBJECT: Konus-Wind observation of GRB 180510A
DATE:    18/05/14 11:16:13 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

The long-duration GRB 180510A
(Swift detection of a burst: Gropp et al., GCN 22695;
Ukwatta et al., GCN 22704)
triggered Konus-Wind at T0=69881.488 s UT (19:24:41.488).

The burst light curve shows a single pulse
which starts at ~T0-6.4 s and has a total duration of ~23.5 s.
The emission is seen up to ~1 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.07(-0.14,+0.21)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0-0.064 s,
of 3.53(-1.13,+1.18)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+16.640 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.14(-0.31,+0.38),
and Ep = 237(-56,+126) keV (chi2 = 93/60 dof).
Fitting by the GRB (Band) model yields
alpha = -0.62(-0.66,+1.24),
Ep = 150(-54,+131) keV,
and an upper limit on the high energy photon index:
beta < -1.90 (chi2 = 91/59 dof).

The spectrum near the peak count rate
(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
with  alpha = -0.97(-0.30,+0.35),
and Ep = 202(-34,+54) keV (chi2 = 75/50 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.37 (chi2 = 75/49 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180510_T69881/

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


GRB_name: GRB180514A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22723
SUBJECT: GRB 180514A: Swift detection of a burst
DATE:    18/05/14 13:48:36 GMT
FROM:    Boris Sbarufatti at PSU  <bxs60@psu.edu>

S. J. LaPorte (PSU), A. P. Beardmore (U Leicester),
A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), A. Deich (PSU),
S. W. K Emery (UCL-MSSL), J.D. Gropp (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 13:25:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180514A (trigger=832368).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 197.401, +36.969 which is 
   RA(J2000) = 13h 09m 36s
   Dec(J2000) = +36d 58' 10"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 40 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 13:26:51.3 UT, 77.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 197.3713,
36.9720 which is equivalent to:
   RA(J2000)  = 13h 09m 29.12s
   Dec(J2000) = +36d 58' 19.3"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 86 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 1.18
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 1.69e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 86 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
0.01. 

The first BAT Position notice identified this trigger as a transient
from a known source because of proximity with the spiral galaxy NGC
5005. However, given the separation between the XRT position and NGC
5005 (~18 arcmin) and the look of the promptly downlinked BAT and XRT
data we believe this is a GRB not associated with the foreground
galaxy. 

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: GRB180512A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22724
SUBJECT: GRB 180512A: VLT/HAWK-I NIR Observations
DATE:    18/05/14 15:28:16 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

A. Rossi (INAF-OAS), J. Palmerio (IAP, Paris), J. Japelj (API, U. 
Amsterdam), D. Malesani (DAWN/NBI and DARK/NBI), N. R. Tanvir (Univ. 
Leicester), D. A. Kann (HETH/IAA-CSIC), J. P. U. Fynbo (DAWN/NBI), G. 
Pugliese (API, U. Amsterdam),  A. de Ugarte Postigo (HETH/IAA-CSIC and 
DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), and S. D. Vergani 
(GEPI/Obs. Paris) report on behalf of the Stargate Consortium:

We observed the Swift/XRT afterglow localization of GRB 180512A (Swift 
trigger 832119; Deich et al., GCN #22710) with the ESO VLT UT4 equipped 
with the HAWK-I near-infrared imager. Observations started on 2018 May 
13 at 04:27 UT and ended at 05:28 UT, for a total of 36 min on source 
and corresponding to a midtime of ~7 hours after the GRB trigger. We do 
not detect the optical source observed by Rossi et al. (GCN #22718), nor 
any other object within the XRT error circle, down to H > 22.8 (Vega), 
calibrated against 2MASS field stars.

Moreover, we note that after comparing the early GROND upper limit (r' > 
24.9; Bolmer, GCN #22714) with the Swift/XRT observations, we obtain an 
optical to X-ray spectral slope beta_OX < ~0.1 (using the convention 
F_nu ~ nu^-beta). This value is lower than the minimum expected 
following standard afterglow modelling (beta_OX >= 0.5) and, together 
with the r-band detection with LBT as well as the high X-ray column 
density (Burrows et al., GCN #22721), suggests that a combination of 
moderate redshift, intrinsic faintness and dust extinction is 
responsible for the faint optical afterglow.

We acknowledge the excellent support from the ESO staff, particularly 
Cyrielle Opitom, Fuyan Bian, and Steffen Mieske in obtaining these 
observations.


GRB_name: GRB180514A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22725
SUBJECT: GRB 180514A: Enhanced Swift-XRT position
DATE:    18/05/14 18:22:11 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 1002 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 180514A, 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 = 197.37112, +36.97231 which is equivalent
to:

RA (J2000): 13h 09m 29.07s
Dec (J2000): +36d 58' 20.3"

with an uncertainty of 2.4 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: GRB180514A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22726
SUBJECT: GRB 180514A: Swift-XRT refined Analysis
DATE:    18/05/14 21:07:55 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Tohuvavohu (PSU), Z. Liu (NAOC / U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), V. D'Elia (ASDC), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea
(PSU) and S.J. LaPorte report on behalf of the Swift-XRT team:

We have analysed 7.0 ks of XRT data for GRB 180514A (LaPorte et al. GCN
Circ. 22723), from 84 s to 18.0 ks after the  BAT trigger. The data
comprise 88 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Goad et al. (GCN Circ. 22725).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=2.4 (+0.5, -0.8). At T+135 s  the decay
steepens to an alpha of 4.9 (+1.0, -0.4) before breaking again at T+414
s to a final decay with index alpha=0.38 (+0.15, -0.17).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 3.7 (+0.4, -0.3). The
best-fitting absorption column is  2.9 (+0.7, -0.6) x 10^21 cm^-2, in
excess of the Galactic value of 1.2 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 2.1 x 10^-11 (9.6 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      2.9 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^20 cm^-2
Excess significance: 7.0 sigma
Photon index:      3.7 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
0.38, 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 2.3 x
10^-13 (1.1 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/00832368.

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


GRB_name: GRB180514A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22727
SUBJECT: GRB 180514A: Swift-BAT refined analysis
DATE:    18/05/14 21:14:51 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), 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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180514A (trigger #832368)
(LaPorte et al., GCN Circ. 22723).  The BAT ground-calculated position is
RA, Dec = 197.382, 36.970 deg which is
  RA(J2000)  =  13h 09m 31.7s
  Dec(J2000) = +36d 58' 13.0"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 91%.

The mask-weighted light curve shows a weak pulse that starts at ~T-8 s,
peaks at ~T0, and ends at ~T+55 s. T90 (15-350 keV) is 46.9 +- 14.5 sec
(estimated error including systematics).

The time-averaged spectrum from T-8.33 to T+54.71 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.77 +- 0.14.  The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.23 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/832368/BA/


GRB_name: GRB180514A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22728
SUBJECT: GRB 180514A: GOTO Optical Observations
DATE:    18/05/14 21:46:20 GMT
FROM:    Ben Gompertz at U of Warwick  <b.gompertz@warwick.ac.uk>

B.Gompertz (U. Warwick), K.Ulaczyk (U. Warwick), M.Dyer (U. Sheffield), 
E.Rol (Monash U.), K. Ackley (Monash U.), D.Steeghs (U. Warwick), 
D.Galloway (Monash U.), G.Ramsay (Armagh O.), V.Dhillon (U. Sheffield), 
P.O'Brien (U. Leicester), S.Poshyachinda (NARIT), D.Pollacco (U. 
Warwick), E.Thrane (Monash U.)

report on behalf of the GOTO collaboration:


The Gravitational-wave Optical Transient Observer observed the field of 
GRB 180514A (trigger=832368, LaPorte et al. GCN Circ. 22723) from Roque 
de los Muchachos Observatory beginning at 2018-05-14T21:09:12 UT, 7.73 
hours since burst, in several wide-band filters.

In a combined L-band image (400-700nm passband), with a total exposure 
time of 360s, we do not detect any optical source within the enhanced 
XRT error circle (Goad et al., GCN Circ. 22725) down to a 5-sigma 
limiting magnitude of V > 20.7 based on a comparison to APASS V-band 
calibrators.

Further observations are planned.

GOTO is operated at the La Palma observing facilities of the University 
of Warwick on behalf of a consortium including the University of 
Warwick, Monash University, Armagh Observatory, the University of 
Leicester, the University of Sheffield, the National Astronomical 
Research Institute of Thailand (NARIT) and the Instituto de Astrofisica 
de Canarias (IAC)
https://goto-observatory.org/


GRB_name: GRB180514A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22729
SUBJECT: GRB 180514A: 1.5m OSN optical observations
DATE:    18/05/14 22:10:10 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, L. Izzo, C. C. Thoene (all HETH/IAA-CSIC), and A. Sota (IAA-CSIC) report:

We have observed the field of GRB 180514A (LaPorte et al. GCN 22723) with the 1.5m  telescope at the Sierra Nevada Observatory (Granada, Spain). Observations started at 20:50 UT (7.41 hr after the burst) and consisted of multiple 300 s exposures in the Ic-band.

No object is detected within the XRT error circle in the first combined 10 x 300 s exposure, which has been obtained at average time of 7.87 hr after the burst, down to a 3-sigma limit of Ic (AB) > 21.5 mag, as compared with SDSS DR14 field stars.


GRB_name: GRB180510A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22730
SUBJECT: GRB 180510A: MITSuME Ishigakijima optical upper limits
DATE:    18/05/15 01:02:37 GMT
FROM:    Ryosuke Itoh at Tokyo Institute of Tech.  <itoh@hp.phys.titech.ac.jp>

T. Horiuchi,  H. Hanayama, M. Honma (IAO, NAOJ),
R. Itoh, K. L. Murata and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME and OISTER collaboration:

We observed the field of GRB 180510A (Gropp et al.,GCN 22695)
with the optical three color (g', Rc and Ic) CCD camera attached
to the Murikabushi 1m telescope of Ishigakijima Astronomical
Observatory.

The observation started on 2018-05-10 19:29:21 UT, (287 seconds after
the burst).
No new or fading source is detected within the Swift-XRT error circle.

We note that there is faint (~20mag) source detected in DSS images within
XRT error circle (at 18:25:19.2, -31:54:22.7) but the source did not
shows temporal variability during observation (~45 min).

we derive the following upper limits using
UCAC-4 catalog for flux calibration.

#T0+[sec]  MID-UT    T-EXP[sec] g'   Rc   Ic
-------------------------------------------------------------------
287 19:55:17 2700.0 >19.4 >20.4 >20.2
-------------------------------------------------------------------
T0+ : Elapsed time after the burst [hour]
T-EXP: Total Exposure time [sec]


GRB_name: GRB180514A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22731
SUBJECT: GRB 180514A: Detection limits from 2.5m NOT
DATE:    18/05/15 01:04:01 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. Malesani (DAWN/NBI and DARK/NBI), P. Montanes-Rodriguez (IAC), and P. Sorensen (NOT) report:

We observed the field of GRB 180514A (LaPorte et al. GCN 22723) with the 2.5 m Nordic Optical Telescope (NOT) equipped with AlFOSC. The observation consisted of 3x300s exposures in r-band and 5x200s in z-band. The integrations started at 23:22 UT, 9.95 hr after the burst.

No credible counterpart is detected in any of the two bands within the XRT error box. For the r-band image we derive a 3-sigma limit of r > 23.8 mag, calibrated with respect to SDSS field stars.


GRB_name: GRB180514A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22732
SUBJECT: GRB 180514A: MITSuME Akeno optical upper limits
DATE:    18/05/15 01:05:34 GMT
FROM:    Ryosuke Itoh at Tokyo Institute of Tech.  <itoh@hp.phys.titech.ac.jp>

R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, T. Ozawa, H. Mamiya,
K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 180514A
(LaPorte et al., GCN Circular #22723)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan.

The observation started on 2018-05-14 13:39:12 UT.
We did not find any point source at the position of the XRT error
circle in all three bands. We obtained following limits for the magnitudes.

T0+[min]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~13.6      14:18:59  4,200   >18.7   >19.2   >18.1
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.


GRB_name: GRB180514A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22733
SUBJECT: GRB 180514A: Swift/UVOT Upper Limits
DATE:    18/05/15 06:58:41 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (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 180514A 87 
s after the BAT trigger (LaPorte et al., GCN Circ. 22723).
No optical afterglow consistent with the enhanced XRT position (Goad et 
al. GCN Circ. 22725) 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         >20.8
u_FC               300          549          246         >20.2
white               87         7353          688         >22.8
v                 6129         6329          197         >20.1
b                 5513         7148          393         >20.7
u                  300         6943          639         >21.6
w1                5104         6739          393         >20.8
m2                6334         6533          197         >20.1
w2                5924         7540          374         >20.3

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.01 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB180505A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22734
SUBJECT: GRB 180505A: AstroSat CZTI detection
DATE:    18/05/16 12:23:40 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long GRB 180505A, which was also detected by Fermi-GBM (Malacaria E. et al, GCN # 22689).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 12:57:30.50 UT, ~11 s after GBM trigger. The measured peak count rate is 772.4 cts/s above the background in combined data of four quadrants, with a total of 3643 cts. The local mean background count rate was 697.6 cts/s. Using cumulative rates, we measure a T90 of 22.8 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180514A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22735
SUBJECT: GRB 180514A: CrAO/ZTSH optical observations and afterglow candidate
DATE:    18/05/16 17:41:55 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of the GRB 180514A (LaPorte et al., GCN 22723)
with ZTSH 2.6m telescope of CrAO observatory starting on May 14 (UT) 
18:16:14. We took several images in filter R with exposures of 120 s. We 
  detect one object within enhanced XRT  (Goad et al., GCN 22725). The 
coordinates of the object are (J2000) 13 09 29.01 +36 58 19.5 with 
uncertainty of 0.3 arcsec in each coordinate.
Preliminary photometry of the object in a combined image is following

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


2018-05-14 19:07:44   0.23321 R       36*120   22.90   0.07   23.9


The photometry is based on nearby SDSS stars:

SDSS-DR9_id             R(Lupton)
J130934.98+365851.3 18.625 0.020
J130931.60+365838.3 18.933 0.023
J130931.36+365901.6 19.497 0.048

Based only on our observation we can not say about variability the 
object. However taking into account deep upper limit of NOT observation 
at 9.95 hrs (A. de Ugarte Postigo et al., GCN 22731) we can suggest that 
the object is the afterglow of GRB 180514A.

The finding chat can be found in
http://grb.rssi.ru/GRB180514A/GRB180514A_ZTSh_fc.png


GRB_name: GRB180514A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22736
SUBJECT: GRB 180514A: MITSuME Ishigakijima optical upper limits
DATE:    18/05/17 01:11:15 GMT
FROM:    Ryosuke Itoh at Tokyo Institute of Tech.  <itoh@hp.phys.titech.ac.jp>

T. Horiuchi,  H. Hanayama, M. Honma (IAO, NAOJ),
R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita, T. Ozawa, H. Mamiya,
K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 180514A
(LaPorte et al., GCN Circular #22723, Volnova et al., GCN Circular #22735)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.


The observation started on 2018-05-14 13:46:55 UT.
We did not find any point source at the position of the XRT error
circle in all three bands. We obtained following limits for the magnitudes.

T0+[min]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~21.4      14:18:37  3,300   >19.6   >19.2   >17.2
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.


GRB_name: GRB180523A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22738
SUBJECT: GRB 180523A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/05/25 03:50:00 GMT
FROM:    Valentin Pal'shin at AGU  <val.palshin@gmail.com>

A. Tezuka, A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo,
S. Matsukawa, H. Onozawa (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, bright GRB 180523A (INTEGRAL SPI-ACS trigger #8063)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 18:20:26.844 UTC
on 23 May 2018. The burst signal was seen by all CGBM detectors.

The burst light curve shows a bright, multi-peaked pulse which
starts at T+1.3 sec, peaks at T+18.5 sec and ends at ~T+37.3 sec,
followed by a very weak pulse seen from ~T+88 sec to ~T+109 sec.
The T90 and the T50 durations measured by the SGM data are
50.0 +- 35.6 sec and 9.9 +- 0.8 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1211134810/

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


GRB_name: GRB180523B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22739
SUBJECT: GRB180523B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 548793993)
DATE:    18/05/25 05:02:48 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

Michael. W. Coughlin (Caltech), Leo P. Singer (NASA GSFC), S. Bradley Cenko (NASA GSFC), Mansi M. Kasliwal (Caltech), Daniel A. Perley (LJMU), Eric Burns (NASA GSFC), and V. Zach Golkhou (U. Wash.) report on behalf of the ZTF project and the GROWTH collaboration:

We observed the localization region of the short GRB 180523B (trigger 548793993) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi satellite with the Palomar 48 inch telescope equipped with the 47 square degree Zwicky Transient Facility camera.  We obtained a series of r- and g-band images covering 2900 square degrees beginning at 3:51 UT on 2018 May 24 (9.1 hours after the burst trigger time), corresponding to ~ 70% of the probability enclosed in the localization region.  

The images were processed though the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts.  121 high-significance transient and variable candidates were identified by our pipeline in this area, all of which had previous detections with ZTF in the days and weeks prior to the GRB trigger time (e.g., supernovae, active galactic nuclei).  No viable optical counterparts were thus identified.  The median 5 sigma upper limit for an isolated point source in our images was r > 20.3 and g > 20.6 mag.

Further observations of the field are planned.

ZTF (http://ztf.caltech.edu) acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. All alerts were filtered, vetted and follow-up co-ordinated by the GROWTH (http://growth.caltech.edu) project marshal system with generous support of the NSF under PIRE Grant No 1545949.


GRB_name: GRB180523A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22740
SUBJECT: IPN Triangulation of GRB 180523A
DATE:    18/05/28 05:37:28 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,

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:

The long-duration GRB 180523A (CGBM detection: Tezuka et al., GCN Circ. 
22738)
was detected by Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), 
CALET (CGBM),
and Swift(BAT) at about 66029 s UT (18:20:29).
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:
    96.875 (06h 27m 30s) +45.896 (+45d 53' 45")
  Corners:
    94.906 (06h 19m 37s) +45.533 (+45d 31' 58")
    97.577 (06h 30m 18s) +47.934 (+47d 56' 02")
    98.890 (06h 35m 34s) +46.191 (+46d 11' 26")
    96.260 (06h 25m 02s) +43.715 (+43d 42' 53")
  ---------------------------------------------
The error box area is 5.54 sq. deg, and its maximum
dimension is 4.3 deg (the minimum one is 1.8 deg).
The Sun distance was 37 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180523_T66028/IPN/

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


GRB_name: GRB180529A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22741
SUBJECT: AGILE/MCAL detection of GRB 180529 and a possible precursor
DATE:    18/05/29 11:19:15 GMT
FROM:    Andrea Giuliani at IASF/INAF  <giuliani@iasf-milano.inaf.it>

A.Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A.
Giuliani (INAF/IASF-Mi), F. Verrecchia, F. Lucarelli (SSDC and INAF/OAR),
N. Parmiggiani, A. Bulgarelli (INAF/IASF-Bo), A. Trois (INAF/OA-Cagliari),
C. Pittori (SSDC and INAF/OAR),  M. Marisaldi (INAF/IASF-Bo and Bergen
University), F. Longo (Univ. Trieste and INFN Trieste), M. Pilia
(INAF/OA-Cagliari), M. Cardillo, G. Piano (INAF/IAPS), I. Donnarumma (ASI),
G. Minervini, A. Argan, Y. Evangelista (INAF/IAPS), V. Fioretti, F.
Fuschino (INAF/IASF-Bo), report on behalf of the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a burst at T0 = 2018-05-29
08:29:14.72 +/- 0.01 s (UTC), lasting about ~ 1.9 s. The burst was detected
following a possible associated single-peak brief precursor, occurring
about 2 s before, at T0 = 2018-05-29 08:29:12.58 +/- 0.01 s (UTC) and
lasting ~ 4 ms. The light curve of the main burst is composed of several
peaks and released a total of ~2200 counts at E> 400 keV in the detector,
above an average background rate of 23 counts / 32 ms.

Further analysis is still in progress.

The AGILE-MCAL detector has a full solid angle acceptance, and is
operational in the range 0.4 - 100 MeV.


GRB_name: GRB180526A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22742
SUBJECT: GRB 180526A: AstroSat CZTI detection
DATE:    18/05/29 13:32:21 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

Analysis of Astrosat CZTI data showed the detection of a long GRB 180526A at 11:04:09 UT.

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 11:04:20.50 UT. The measured peak count rate is 660.8 cts/s above the background in combined data of four quadrants, with a total of 4580 cts. The local mean background count rate was 510.1 cts/s. Using cumulative rates, we measure a T90 of 23.8 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180523A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22743
SUBJECT: Konus-Wind observation of GRB 180523A
DATE:    18/05/29 14:07:26 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration GRB 180523A
(IPN Triangulation: Hurley et al., GCN Circ. 22740)
triggered Konus-Wind at T0=66028.802 s UT (18:20:28.802).

The burst light curve shows a bright main pulse lasting about 35 s,
which is followed by a fainter second episode which
started at ~T0+87.4 s and lasted up to ~T0+87.9 s.
The emission in the main pulse is seen up to ~2 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.06(-0.08,+0.08)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+12.368 s,
of 1.11(-0.22,+0.22)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the main episode
(measured from T0 to T0+36.608 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.69(-0.06,+0.07),
the high energy photon index beta = -2.68(-0.30,+0.19),
the peak energy Ep = 307(-17,+18) keV
(chi2 = 49/61 dof).

The spectrum near the maximum count rate
(measured from T0+12.288 to T0+14.080 s)
is best fit in the 20 keV - 2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.51(-0.14,+0.16),
the high energy photon index beta = -2.66(-0.89,+0.29),
the peak energy Ep = 325(-39,+49) keV
(chi2 = 53/55 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180523_T66028/

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


GRB_name: GRB180526A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22744
SUBJECT: GRB 180526A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/05/29 14:16:13 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

S. Matsukawa, A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo,
A. Tezuka, H. Onozawa (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, bright GRB 180526A (INTEGRAL SPI-ACS trigger #8067,
Konus-Wind trigger time on 11:03:36.006, AstroSat CZTI detection:
Sharma et al., GCN circ. 22742) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 11:03:36.200 UTC on 26 May 2018.
No real-time CGBM GCN notice was distributed about this
trigger because the real-time communication from the ISS was off
(loss of signal). The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure which starts
at T-2.2 sec, peaks at T+44.4 sec and ends at T+79.2 sec.
The T90 and the T50 durations measured by the SGM data are
56.9 +- 2.8 sec and 16.3 +- 1.3 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1211367794/

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


GRB_name: GRB180526A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22745
SUBJECT: IPN Triangulation of GRB 180526A (long)
DATE:    18/05/29 14:28:44 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,

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 180526A (Sharma et al., GCN Circ. 22742)
was detected by Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND),
and AstroSat (CZTI) at about 39814 s UT (11:03:34).

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   108.576 (07h 14m 18s)  +3.677 ( +3d 40' 36")
  Corners:
   109.188 (07h 16m 45s)  +3.834 ( +3d 50' 02")
   108.877 (07h 15m 31s)  +2.756 ( +2d 45' 23")
   107.965 (07h 11m 52s)  +3.525 ( +3d 31' 31")
   108.274 (07h 13m 06s)  +4.632 ( +4d 37' 57")
  ---------------------------------------------
The error box area is 1.2 sq. deg, and its maximum
dimension is 1.97 deg (the minimum one is 1 deg).
The Sun distance was 47 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180526_T39816/IPN/

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


GRB_name: GRB180526A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22746
SUBJECT: Konus-Wind observation of GRB 180526A
DATE:    18/05/29 15:06:21 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration GRB 180526A
(AstroSat CZTI detection: Sharma et al., GCN 22742;
CGBM detection: Matsukawa et al., GCN 22744;
IPN Triangulation: Hurley et al., GCN 22745)
triggered Konus-Wind at T0=39816.006 s UT (11:03:36.006).

The burst light curve shows a multipeaked structure
started at ~T0-9 s with a total duration of ~87 s.
The emission is seen up to ~4 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.12(-0.13,+0.13)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+42.048 s,
of 1.61(-0.28,+0.29)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+76.032 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.11(-0.13,+0.15),
the high energy photon index beta = -2.23(-0.24,+0.14),
the peak energy Ep = 207(-31,+38) keV
(chi2 = 76/69 dof).

The spectrum near the maximum count rate
(measured from T0+41.216 to T0+43.264 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.52(-0.17,+0.19),
the high energy photon index beta = -2.49(-0.31,+0.20),
the peak energy Ep = 224(-25,+27) keV
(chi2 = 56/58 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180526_T39816/

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


GRB_name: GRB180529A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22748
SUBJECT: IPN Triangulation of GRB 180529A (short/hard)
DATE:    18/05/31 10:19:17 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,

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

A. Ursi, N. Parmiggiani, F. Verrecchia, A. Bulgarelli,
A. Trois, M. Marisaldi, C. Pittori, M. Tavani, Y. Evangelista,
I. Donnarumma, M. Cardillo, G. Piano, G. Minervini, A. Argan,
F. Lucarelli, A. Zoli, V. Fioretti, F. Fuschino, M. Pilia,
F. Longo, A. Giuliani on behalf of the AGILE 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 180529A (Ursi et al., GCN Circ. 22741)
was detected by AGILE (MCAL), Konus-Wind, Mars-Odyssey (HEND),
INTEGRAL (SPI-ACS), CALET (CGBM), and Swift (BAT)
at about 30554 s UT (08:29:14).
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:
    97.947 (06h 31m 47s) -54.908 (-54d 54' 28")
  Corners:
    96.714 (06h 26m 51s) -54.840 (-54d 50' 23")
    98.264 (06h 33m 03s) -55.310 (-55d 18' 34")
    99.183 (06h 36m 44s) -54.962 (-54d 57' 43")
    97.637 (06h 30m 33s) -54.505 (-54d 30' 19")
  ---------------------------------------------
The error box area is 1976 sq. arcmin, and its maximum
dimension is 1.42 deg (the minimum one is 32.9 arcmin).
The Sun distance was 80 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180529_T30554/IPN

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


GRB_name: GRB180529A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22749
SUBJECT: GRB 180529A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/05/31 12:56:50 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

H. Onozawa, A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo,
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 GRB 180529A (AGILE-MCAL detection: Ursi et al.,
GCN Circ. 22741; IPN triangulation: Hurley et al., GCN Circ. 22748)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at
08:29:14.435 UTC on 29 May 2018.  The burst signal was seen
by all CGBM detectors.

The burst light curve shows a single multi-peaked pulse which starts
at T+0.06 sec, peaks at T+1.15 sec and ends at T+3.14 sec.
The T90 and the T50 durations measured by the SGM data are
2.18 +- 0.69 sec and 0.83 +- 0.18 sec (40-1000 keV), respectively.
There is no any sign of the possible short precursor reported
by Ursi et a. (GCN Circ. 22741) in the CGBM event data which
comprise the time interval from ~T-165 sec to T+507 sec.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1211617728/

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


GRB_name: GRB180529A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22750
SUBJECT: Konus-Wind observation of GRB 180529A
DATE:    18/05/31 14:18:43 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The short-duration, bright GRB 180529A
(AGILE-MCAL detection: Ursi et al., GCN Circ. 22741;
IPN triangulation: Hurley et al., GCN Circ. 22748;
CALET-CGBM detection: Onozawa et al., GCN Circ. 22749)
triggered Konus-Wind at T0=30554.458 s UT (08:29:14.458).

The burst light curve shows a multi-peaked structure
which starts at ~T0-0.5 s and has a total duration of ~1.7 s.
The emission is seen up to ~6 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180529_T30554/

As observed by Konus-Wind, the burst
had a fluence of 1.08(-0.22,+0.30)x10^-5 erg/cm2,
and a 16-ms peak flux, measured from T0+0.446 s,
of 1.65(-0.61,+0.71)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 = -0.71(-0.21,+0.26)
and Ep = 1046(-295,+502) keV (chi2 = 99/84 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 = 99/83 dof).

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


GRB_name: GRB180602A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22752
SUBJECT: GRB 180602A: Swift detection of a burst
DATE:    18/06/02 08:35:07 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. B. Cenko (GSFC), J.D. Gropp (PSU), A. Y. Lien (GSFC/UMBC),
A. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL)
and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 08:14:50 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180602A (trigger=835200).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 142.339, +32.093 which is 
   RA(J2000) = 09h 29m 21s
   Dec(J2000) = +32d 05' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The burst appears to have been in progress
as Swift was slewing to the pre-planned pointing target before the
nominal trigger time.  The BAT light curve showed a single peak
structure with a duration of about 50 seconds, however the start
of the peak may be due to the GRB entering the FOV during the slew. 
The peak count rate was ~1300 counts/sec (15-350 keV), at ~20 sec 
before the trigger. 

The XRT began observing the field at 08:16:55.2 UT, 124.3 seconds after
the BAT trigger. The position determined from promptly downlinked data
differs significantly from the on-board position, suggesting that the
XRT may have centroided on a cosmic ray; the initial XRT position
notice should be treated with caution. Using promptly downlinked data
we find an uncatalogued X-ray source with an enhanced position: RA, Dec
142.3319, 32.0661 which is equivalent to:
   RA(J2000)  = 09h 29m 19.65s
   Dec(J2000) = +32d 03' 58.1"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 99 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 (1.56 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.1
(+2.76/-2.42) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 133 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
0.02. 

Burst Advocate for this burst is S. B. Cenko (brad.cenko 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: GRB180602A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22753
SUBJECT: GRB 180602A: Enhanced Swift-XRT position
DATE:    18/06/02 10:38:54 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 2068 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180602A, 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 = 142.33181, +32.06710 which is equivalent
to:

RA (J2000): 09h 29m 19.63s
Dec (J2000): +32d 04' 01.6"

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: GRB180602A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22754
SUBJECT: GRB 180602A: MITSuME Okayama optical upper limits
DATE:    18/06/02 12:30:27 GMT
FROM:    Yutaro Tachibana at Tokyo Tech  <tachibana@hp.phys.titech.ac.jp>

Y. Tachibana, R. Itoh, K. L. Murata, S. Harita, K. Morita,
T. Ozawa, H. Mamita, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration: 

We observed the field of GRB 180602A (Cenko et al., GCN Circular #22752)
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 2018-06-02 11:14:03.47 UT (~3 hours after
the burst). We did not find any new point source within the
enhanced XRT error circle (Osborne et al., GCN Circular #22753) in all
the three bands.

We obtained following limits for the magnitudes.

T0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~3.07      ~11:18:47   420   >17.8   >17.7   >17.1
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB180602A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22755
SUBJECT: GRB 180602A: Swift-BAT refined analysis
DATE:    18/06/02 17:18:13 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
S. B. Cenko (GSFC), J. R. Cummings (CPI),
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 180602A (trigger #835200)
(Cenko et al., GCN Circ. 22752).  The BAT ground-calculated position is
RA, Dec = 142.343, 32.080 deg which is 
  RA(J2000)  =  09h 29m 22.4s 
  Dec(J2000) = +32d 04' 48.1" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows a single-peaked structure that starts 
at ~T-30 s, peaks at ~T-20 s, and ends at ~T+25 s. We note that the burst
emission indeed started and peaked during a pre-planned spacecraft slew,
and the trigger occurred near the end of the pulse when the slew settled. 
T90 (15-350 keV) is 45.4 +- 7.1 sec (estimated error including systematics).

The time-averaged spectrum from T-29.32 to T+25.73 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.72 +- 0.11.  The fluence in the 15-150 keV band is 1.6 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-20.12 sec in the 15-150 keV band
is 0.9 +- 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/835200/BA/


GRB_name: GRB180602A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22756
SUBJECT: GRB 180602A: Swift-XRT refined Analysis
DATE:    18/06/03 02:52:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B.
Sbarufatti (INAF-OAB/PSU) and S.B. Cenko report on behalf of the
Swift-XRT team:

We have analysed 8.4 ks of XRT data for GRB 180602A (Cenko et al. GCN
Circ. 22752), from 130 s to 59.7 ks after the  BAT trigger. The data
comprise 85 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Osborne et al. (GCN Circ. 22753).

The late-time light curve (from T0+5.6 ks) can be modelled with a
power-law decay with a decay index of alpha=1.38 (+0.16, -0.13).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.36 (+0.28, -0.25). The
best-fitting absorption column is  4.0 (+1.3, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.04 (+0.16, -0.15)
and a best-fitting absorption column of 4.2 (+0.8, -0.7) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.8 x 10^-11 (6.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.2 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 9.1 sigma
Photon index:      2.04 (+0.16, -0.15)

If the light curve continues to decay with a power-law decay index of
1.38, the count rate at T+24 hours will be 7.3 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.8 x
10^-13 (4.5 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/00835200.

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


GRB_name: GRB180602A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22757
SUBJECT: GRB 180602A: MITSuME Akeno optical upper limits
DATE:    18/06/03 09:29:22 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

K. L. Murata, Y. Tachibana, R. Itoh, T. Yoshii, S. Harita, K. Morita, T.
Ozawa, H. Mamiya, K. Shiraishi, K. Iida, M. Oeda, R. Adachi, S. Niwano, Y.
Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the field of GRB 180602A (Cenko et al., GCN Circular
#22752) with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.

The observation started on 2018-06-02 11:12:09 UT (~3 hours after the
burst). We did not find any new point source within the enhanced XRT error
circle (Osborne et al., GCN Circular #22753) in all the three bands.


T0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic
------------------------------------------------------------
-------------------------------------------
~3.1        ~12:24       1200     >18.9     >18.3     >18.0
------------------------------------------------------------
-------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.


GRB_name: GRB180602A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22758
SUBJECT: GRB 180602A: Swift/UVOT Upper Limits
DATE:    18/06/03 17:11:58 GMT
FROM:    Jeffrey Gropp at PSU  <jdg44@psu.edu>

J. Gropp (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180602A
133 s after the BAT trigger (Cenko et al., GCN Circ. 22752).
No optical afterglow consistent with the enhanced XRT position
(Osborne et al. GCN Circ. 22753)
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           133          283          147         >19.9
u_FC               291          541          246         >19.8
white              133         1715          411         >20.8
v                  621         2283          194         >19.0
b                  547         2208          175         >20.0
u                  291         2183          401         >20.3
w1                 670         2159          175         >20.0
m2                 645          665           19         >18.7
w2                 597         2086          136         >20.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180602B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22759
SUBJECT: GRB 180602B: Fermi GBM detection
DATE:    18/06/04 01:18:55 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 22:31:05.34 UT on 02 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180602B (trigger 549671470/ 180602938).

The on-ground calculated location, using the GBM trigger
data, is RA = 86.05, DEC = -62.78, with an uncertainty
of 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 9 degrees.

The GBM light curve consists of a single bright peak
with a duration (T90) of about 0.01 s (50-300 keV).
The time-averaged spectrum from T0-0.06 s to T0+0.06 s is
best fit by a power-law function with an exponential
high-energy cutoff. The power law index is -0.68 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 395 +/- 105 keV.

The event fluence (10-1000 keV) in this time interval is
(3.0 +/- 0.4)E-07 erg/cm^2. The 64 ms peak photon flux measured
starting from T0-0.06 s in the 10-1000 keV band
is 14 +/- 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: GRB180602A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22760
SUBJECT: GRB 180602A: MITSuME Ishigakijima optical upper limits
DATE:    18/06/04 16:41:32 GMT
FROM:    Yutaro Tachibana at Tokyo Tech  <tachibana@hp.phys.titech.ac.jp>

T. Horiuchi,  H. Hanayama, M. Honma (IAO, NAOJ),
Y. Tachibana, R. Itoh, K. L. Murata, S. Harita, K. Morita, T. Ozawa, H. Mamiya,
K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 180602A
(Cenko et al., GCN Circular #22752, Osborne et al., GCN Circular #22753, Gropp and Cenko, GCN Circular #22758)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.

The observation started on 2018-06-02 12:38:23 UT.
We did not find any point source at the position of the XRT error
circle in all three bands. We obtained following 3-sigma upper limits: 

T0+[hour]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
~4.5      12:51:13.3  1,560   >19.4   >19.1   >18.7
-------------------------------------------------------------------------------------------------------

T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used UCAC-4 catalog for flux calibration.


GRB_name: GRB180603A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22762
SUBJECT: GRB 180603A: AstroSat CZTI detection
DATE:    18/06/05 08:56:37 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

Analysis of Astrosat CZTI data showed the detection of a long GRB 180603A at 16:23:00.0 UT.

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 16:23:15.5 UT. The measured peak count rate is 609.2 cts/s above the background in combined data of four quadrants, with a total of 7198 cts. The local mean background count rate was 505.8 cts/s. Using cumulative rates, we measure a T90 of 31.1 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB170817A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22763
SUBJECT: GW170817/GRB170817A: LBT optical detection
DATE:    18/06/05 14:03:37 GMT
FROM:    Andrea Rossi at INAF  <a.rossi@iasfbo.inaf.it>

A. Rossi (INAF-OAS),  M. Cantiello (INAF-OA Abruzzo) V. Testa, D. Paris 
(INAF-OAR), A. Melandri, S. Covino,  O. S. Salafia, P. D'Avanzo, S. 
Campana (INAF-OAB), L. Nicastro, E. Palazzi, F. Cusano (INAF-OAS), G. 
Stratta (Urbino University/INFN Firenze), R. Carini, S. Piranomonte, E. 
Brocato (INAF-OAR), V. D'Elia (ASDC), and M. Branchesi (GSSI) report on 
behalf of the GRAWITA collaboration and its partners:

We observed the optical counterpart of GRB 170817A (Kienlin et al., GCN 
21520) associated to GW 170817 (LVC GCN Circ. 21509, 21513) with the LBC 
imager mounted on the Large Binocular Telescope (Mt Graham, AZ, USA). 
Observations were performed in the r-sloan filter on 2018-01-23, i.e., 
~160 days after the GW/GRB trigger.

At the location of the optical transient (e.g., Coulter et al., GCN 
21529; Adams et al., 21816) we detect the optical afterglow of GRB 
170817A with magnitude r-sloan=26.2+-0.4, calibrated against Pan-STARRS 
field stars. Image analysis was performed after preliminary removal of 
an elliptical model of the underlying host galaxy from each single 
frame. However, some residual emission is left which contributes for 
~0.2 mags to the uncertainty of the photometry.

Our detection is the first one from a ground-based optical telescope. It 
is in agreement with a turnover/flattening in the optical light curve of 
GW 170817/GRB 170817A as inferred by Alexander at al. 2018 
(arXiv:1805.02870) and with the overall flattening/declining temporal 
evolution observed in the X-ray and radio bands (D'Avanzo et al. 2018, 
A&A, 613 L1; Hajela et al. GCN Circ. 22692; Troja et al. GCN Circ. 
22693; Dobie et al. arXiv:1803.06853; Alexander at al. 2018; 
arXiv:1805.02870).

We acknowledge the excellent support from the LBT staff in obtaining 
these observations.


GRB_name: GRB180605A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22764
SUBJECT: IPN Triangulation of GRB 180605A (long)
DATE:    18/06/06 21:09:14 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,

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 180605A was detected by
Fermi (GBM; trigger 549889170), INTEGRAL (SPI-ACS), Konus-Wind,
and Mars-Odyssey (HEND), at about 39565 s UT (10:59:25).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    47.510 (03h 10m 02s) -48.025 (-48d 01' 30")
  Corners:
    47.466 (03h 09m 52s) -48.645 (-48d 38' 43")
    48.461 (03h 13m 51s) -48.996 (-48d 59' 45")
    47.551 (03h 10m 12s) -47.403 (-47d 24' 11")
    46.582 (03h 06m 20s) -47.035 (-47d 02' 07")
  ---------------------------------------------
The error box area is 3009 sq. arcmin, and its maximum
dimension is 2.33 deg (the minimum one is 29.28 arcmin).
The Sun distance was 73 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180605_T39565/IPN

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


GRB_name: GRB180605A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22765
SUBJECT: GRB 180605A: AstroSat CZTI detection
DATE:    18/06/07 09:43:57 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and A. Vibhute (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long GRB 180605A, which was also detected by IPN Triangulation (Svinkin D. et al., GCN 22764).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 10:59:28.5 UT. The measured peak count rate is 654.6 cts/s above the background in combined data of four quadrants, with a total of 7288 cts. The local mean background count rate was 495.4 cts/s. Using cumulative rates, we measure a T90 of 24.6 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180605A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22766
SUBJECT: GRB 180605A: Fermi GBM observation
DATE:    18/06/07 19:00:04 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 10:59:25.18 UT on 05 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180605A (trigger 549889170 / 180605458)
which was also detected by the AstroSat CZTI (Sharma et al., GCN
22765)  and IPN (Hurley et al., GCN 22764). The GBM on-ground location
is consistent with the IPN position.

The angle from the Fermi LAT boresight at the GBM trigger time is 61 degrees.

The GBM light curve shows multiple overlapping peaks with a duration
(T90) of about 24 s (50-300 keV). The time-averaged spectrum from T0s
to T0+29.1 s is best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.67 +/- 0.03 and the
cutoff energy, parameterized as Epeak, is 663 +/- 42 keV.

The event fluence (10-1000 keV) in this time interval is (2.36 +/-
0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from
T0+8.3 s in the 10-1000 keV band is 7.2 +/- 0.2 ph/s/cm^2.

A Band function fits the spectrum equally well with Epeak= 632 +/- 48
keV, alpha = -0.66 +/- 0.04 and beta = -2.65 +/- 0.38.

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

[GCN OPS NOTE(07jun18):  Per author's request, the "150605A" in the 
Subject line was changed to "180605A".]


GRB_name: GRB180611A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22767
SUBJECT: IPN Triangulation of GRB 180611A (long)
DATE:    18/06/12 11:23:55 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,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge,
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 180611A was detected by
Fermi (GBM; trigger 550380546), INTEGRAL (SPI-ACS), Konus-Wind,
and Mars-Odyssey (HEND), at about 12541 s UT (03:29:01).

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
   46.471 (03h 05m 53s) -48.835 (-48d 50' 05")
 Corners:
   47.883 (03h 11m 32s) -52.743 (-52d 44' 36")
   50.103 (03h 20m 25s) -53.759 (-53d 45' 33")
   45.101 (03h 00m 24s) -44.765 (-44d 45' 54")
   43.190 (02h 52m 46s) -43.503 (-43d 30' 10")
 ---------------------------------------------
The error box area is 8.7 sq. deg, and its maximum
dimension is 11.2 deg (the minimum one is 53.9 arcmin).
The Sun distance was 75 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180611_T12541/IPN/

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


GRB_name: GRB180611A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22768
SUBJECT: GRB 180611A: Fermi GBM observation
DATE:    18/06/12 19:40:00 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

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


"At 03:29:01.46 UT on 11 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180611A (trigger 550380546 / 180611145),
which was also reported by Hurley et al. 2018 (GCN 22767).
The GBM location is consistent with the IPN triangulated box.

The angle from the Fermi LAT boresight at the GBM trigger time is 62 degrees.

The GBM light curve shows a multipeaked emission episode
with a duration (T90) of about 9 s (50-300 keV).
The time-averaged spectrum from T0-1 s to T0+10 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.95 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 253 +/- 22 keV.

The event fluence (10-1000 keV) in this time interval is
(5.4 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0 in the 10-1000 keV band
is 8.4 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak = 219 +/- 30 keV, alpha = -0.9 +/- 0.1 and
beta = -2.4 +/- 0.3.


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


GRB_name: GRB180613A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22769
SUBJECT: GRB 180613A: Swift detection of a burst
DATE:    18/06/13 15:53:16 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

A. Tohuvavohu (PSU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and
T. N. Ukwatta (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 15:36:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180613A (trigger=840853).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 211.562, -43.076 which is 
   RA(J2000) = 14h 06m 15s
   Dec(J2000) = -43d 04' 31"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual with an image trigger, the available
BAT light curve shows no significant structure. 

The XRT began observing the field at 15:38:47.7 UT, 148.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 211.52004,
-43.07158 which is equivalent to:
   RA(J2000)  = 14h 06m 04.81s
   Dec(J2000) = -43d 04' 17.7"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 111 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 (6.50 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.5
(+3.67/-3.01) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 5.63e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
154 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 19.2 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 18.0 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.09. 

Burst Advocate for this burst is A. Tohuvavohu (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: GRB180611A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22770
SUBJECT: Konus-Wind observation of GRB 180611A
DATE:    18/06/13 16:09:51 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova@mail.ioffe.ru>

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

The long-duration GRB 180611A
(IPN Triangulation: Hurley et al., GCN 22767;
Fermi GBM observation: Bissaldi &  Meegan, GCN 22768)
triggered Konus-Wind at T0=12541.046 s UT (03:29:01.046).

The burst light curve shows several peaks with a total duration of ~7 s.
The emission is seen up to ~1.5 MeV.

As observed by Konus-Wind, the burst
had a fluence of 4.61(-0.56,+0.72)x10^-6 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.148 s,
of 5.04(-2.18,+3.14)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+8.448 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.80(-0.26,+0.30),
and Ep = 250(-47,+77) keV (chi2 = 52/60 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.25 (chi2 = 52/59 dof).

The spectrum near the peak count rate
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 20 MeV range
by the power law with exponential cutoff model
with  alpha = -1.05(-0.29,+0.38),
and Ep = 668(-304,+856) keV (chi2 = 23/19 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -1.80 (chi2 = 23/18 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180611_T12541/

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


GRB_name: GRB180613A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22771
SUBJECT: GRB 180613A: Prompt enhanced Swift-XRT position
DATE:    18/06/13 16:16:56 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 180613A, we find an
enhanced XRT position of the afterglow: RA, Dec: 211.5204, -43.0722
which is equivalent to:
   RA (J2000)  = 14 06 04.89
   Dec (J2000) = -43 04 19.9
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/840853.

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: GRB180613A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22772
SUBJECT: GRB 180613A: Possible host galaxy at XRT position, or star
DATE:    18/06/13 16:20:33 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann and L. Izzo (HETH/IAA-CSIC) report:

Inspection of archival DSS images of the enhanced XRT position (error 
radius 2.0", Evans, GCN #22771) of GRB 180613A (Tohuvavohu et al., GCN 
#22769) reveals a known source within the XRT error circle. This source 
is known in the USNO B1.0 catalog, and is also part of Gaia DR1/2 
(source ID 6109389046377848320, with possible parallax of 0.98 +/- 0.62 
mas, Gmag = 19.748). PS1 and SDSS do not cover this location.

It is not possible to determine from the DSS2 image if this source is 
stellar or slightly extended. We suggest this source may be the host 
galaxy of this GRB, but it could also be a foreground star, as the 
stellar density of this field is quite high.

[GCN OPS NOTE(13jun18): Per author's request, "Ecans" was changed to "Evans"
in the second line.]


GRB_name: GRB180613A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22773
SUBJECT: GRB 180613A: Enhanced Swift-XRT position
DATE:    18/06/13 21:08:20 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 615 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180613A, 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 = 211.52057, -43.07237 which is equivalent
to:

RA (J2000): 14h 06m 4.94s
Dec (J2000): -43d 04' 20.5"

with an uncertainty of 4.9 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: GRB180613A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22774
SUBJECT: GRB 180613A: Swift-XRT refined Analysis
DATE:    18/06/14 00:02:55 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 8.3 ks of XRT data for GRB 180613A (Tohuvavohu et al.
GCN Circ. 22769), from 155 s to 19.0 ks after the  BAT trigger. The
data comprise 95 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 22771).

The light curve can be modelled with a power-law decay with a decay
index of alpha=2.05 (+0.07, -0.06).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.04 (+0.17, -0.16). The
best-fitting absorption column is  1.5 (+1.1, -0.9) x 10^21 cm^-2,
consistent with the Galactic value of 6.5 x 10^20 cm^-2 (Willingale et
al. 2013). The PC mode spectrum has a photon index of 1.45 (+0.20,
-0.19) and a best-fitting absorption column of 2.0 (+1.1, -0.9) x 10^21
cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.0 x 10^-11 (5.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.0 (+1.1, -0.9) x 10^21 cm^-2
Galactic foreground: 6.5 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index:      1.45 (+0.20, -0.19)

If the light curve continues to decay with a power-law decay index of
2.05, the count rate at T+24 hours will be 2.9 x 10^-5 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x
10^-15 (1.6 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/00840853.

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


GRB_name: GRB180613A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22775
SUBJECT: GRB 180613A: Possible IR afterglow
DATE:    18/06/14 01:45:46 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

C. C. Thoene (HETH/IAA-CSIC), N. Tanvir (Univ. of Leicester), A. de Ugarte
Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, L. Izzo (both
HETH/IAA-CSIC), G. Pugliese (API/U. Amsterdam), P. Schady (MPE) and D. Xu
(NAO/CAS) report on behalf of the Stargate consortium:


We observed the field of GRB 180613A (GCN 22769, Tohuvavohu et al.) with
HAWKI at the VLT (ESO, Paranal, Chile) starting on June 13, 2018, at 22:51
UT (7.25 hours after the burst). Imaging observations were obtained in J, H
and Ks filters with exposure times of 11-12 min under thin clouds but
excellent seeing conditions (around 0.4 arcsec) and preliminary reductions
provided by the observatory.

The object reported in GCN 22772 (Kann & Izzo) is clearly detected and
likely a foreground star. Inside the refined XRT error circle (GCN 22771,
Evans) we detect a faint source in all three bands at the coordinates
(errors +/-0.5 arcsec):

RA 14:06:04.89
DEC -43:04:19.6

The source seems to be slightly extended to the NW and a point-like source
at the SW end of it. This could possibly be the underlying host +
afterglow. Further observations are needed to determine a possible fading
of the source. Preliminary photometry gives J = 22.86 +/- 0.25 mag using
aperture photometry centered on the point-like part of the source and
compared to field stars from the 2MASS catalogue.

We acknowledge the excellent support from ESO staff, in particular FrÃ©dÃ©ric
Vogt, Ivan Aranda and Stephane Brillant and enjoyed the great new option to
chat on Skype with the telescope during the observations.

[GCN OPS NOTE(14jun18):  Per author's request, the "days" in the 3rd line
was changed to "hours".]


GRB_name: GRB180613A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22776
SUBJECT: GRB 180613A, Swift-BAT refined analysis
DATE:    18/06/14 03:12:15 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), 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-239 to T+625 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180613A (trigger #840853)
(Tohuvavohu et al., GCN Circ. 22769).  The BAT ground-calculated position is
RA, Dec = 211.545, -43.082 deg which is
  RA(J2000)  =  14h 06m 10.9s
  Dec(J2000) = -43d 04' 56.5"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.

The mask-weighted light curve shows some weak emission that starts
at ~T+25 s and ends at ~T+80 s. T90 (15-350 keV) is 50.8 +- 8.4 sec
(estimated error including systematics).

Because this trigger occurred when BAT was in the process of resuming to
normal operation from the recent reboot. The entire detector array had the
lower level discriminators set to a value higher than the level of normal operations.
Therefore, the standard spectral analyses are unavailable.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/840853/BA/


GRB_name: GRB180613A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22777
SUBJECT: GRB 180613A GROND observations
DATE:    18/06/14 11:42:07 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady, T. Schweyer, T.-W. Chen (all MPE Garching) and J. Bolmer (ESO
Santiago) report:

We observed the field of GRB 180613A (Swift trigger 840853; Tohuvavohu et
al., GCN #22769) 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 23:30 UT on 2018-06-13, 7.9 hrs after the GRB
trigger. They were performed at an average seeing of 1.5" and at an
average airmass of 1.1.

We do not detect the HAWKI source reported by Thoene et al. (GCN #2275).
However, we note that the larger 4.9 arcsec uncertainty on the enhanced
XRT position (Beardmore et al., GCN #22773) now includes two, brighter
sources that are below the sensitivity of the DSS images.

Source #1 lies at the SW edge of the enhanced XRT 90% error circle, at

RA = 14:06:05.24
Dec = -43:04:21.6

with a preliminary magnitude r' = 23.1 +/- 0.1 mag.

Source #2 lies at the NW edge of the enhanced XRT error circle, at

RA = 14:06:05.24
Dec = -43:04:21.6

with r' = 22.9 +/- 0.1 mag. The above positions have an accuracy of 0.1"
in both directions.

Our g' band photometry is strongly affected by a nearby 5.6 mag star
located SW of the GRB position, but source #1 is detected in all other
GROND bands. Source #2 is detected in r', i' and z'. Our observations at
the position of the XRT afterglow have preliminary 3 sigma upper limits of

r' > 23.7 mag
i' > 22.8 mag
z' > 22.7 mag
J > 21.5 mag
H > 21.0 mag
K > 20.4 mag

All quoted magnitudes are in the AB system and are calibrated against
GROND zeropoints and 2MASS field stars. They are not corrected for the
Galactic foreground extinction corresponding to a reddening of E_(B-V)=
0.08 in the direction of the burst (Schlafly & Finkbeiner 2011).


GRB_name: GRB180613A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22778
SUBJECT: GRB 180613A GROND observations: correction
DATE:    18/06/14 13:13:55 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

P. Schady (MPE, Garching) reports:

We note a mistake in the position reported for source #2 in Schady et al.
(GCN #22777), which should have been

RA = 14:06:04.69
Dec = -43:04:17.7

There was also a mistake in our reference to Thoene et al. which should be
GCN#22775, rather than GCN #2275.

We apologise for any confusion that this error may have caused.


GRB_name: GRB180613A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22779
SUBJECT: GRB 180613A: Swift/UVOT Upper Limits
DATE:    18/06/14 19:10:11 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

S. Sebzda (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180613A
156 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 22769).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 22773)
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               156          405          246         >20.4
v                  461        24234         1434         >20.9
b                  411        13230         1022         >99.0
u                  156        18973         2109         >21.8
w1                 510        18472         2212         >21.2
m2                 486        24474         1627         >21.0
w2                1036        23321         1318         >20.1

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: GRB180614A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22780
SUBJECT: GRB 180614A: Swift detection of a burst
DATE:    18/06/14 19:28:07 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

J.D. Gropp (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU),
A. Tohuvavohu (PSU) and T. N. Ukwatta (LANL) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 19:16:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180614A (trigger=841548).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 3.157, +46.943, which is 
   RA(J2000)  =  00h 12m 38s
   Dec(J2000) = +46d 56' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a couple peaks
with a duration of about 25 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 19:17:19.1 UT, 65.6 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 3.07620, 46.95342 which is equivalent
to:
   RA(J2000)  = 00h 12m 18.29s
   Dec(J2000) = +46d 57' 12.3"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 202 arcseconds from the BAT onboard position. 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. This position is more than
2-sigma away from the BAT position, and so possibly unrelated to the
trigger. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.14
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 68 seconds after the BAT trigger. No credible
afterglow candidate has  been found in the initial data products. The
2.7'x2.7' image covers none of the XRT  error circle. Data from the list of
sources generated  on-board are not available at this time. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT 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: GRB180614A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22781
SUBJECT: GRB 180614A: Enhanced Swift-XRT position
DATE:    18/06/15 03:10:39 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 1822 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 180614A, 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 = 3.07846, +46.95299 which is equivalent
to:

RA (J2000): 00h 12m 18.83s
Dec (J2000): +46d 57' 10.8"

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: GRB180614A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22782
SUBJECT: GRB 180614A: Swift-XRT refined Analysis
DATE:    18/06/15 04:15:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.9 ks of XRT data for GRB 180614A (Gropp et al. GCN
Circ. 22780), from 77 s to 24.9 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Evans et al. (GCN Circ. 22781).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.70 (+/-0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.8 (+/-0.4). The
best-fitting absorption column is  1.7 (+0.5, -0.4) x 10^22 cm^-2, in
excess of the Galactic value of 1.1 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 4.0 x 10^-11 (2.0 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.7 (+0.5, -0.4) x 10^22 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 6.8 sigma
Photon index:      2.8 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
0.70, the count rate at T+24 hours will be 4.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x
10^-13 (9.2 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/00841548.

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


GRB_name: GRB180614A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22783
SUBJECT: GRB 180614A: MASTER observation 
DATE:    18/06/15 11:28:04 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, A.Kuznetsov,
I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

R. Podesta, F. Podesta, C. Lopez, C.Francile
Observatorio Astronomico Felix Aguilar (OAFA)

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

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

D. Buckley
South African Astronomical Observatory

O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University

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

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

MASTER-Kislovodsk  robotic telescope (MASTER-Net: http://observ.pereplet.ru  Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) ,
located in Kislovodsk Solar Station of Pulkovo observatory,
was pointed to the Swift GRB180614A (Gropp et al. GCN #22780)
11 sec after notice time and 26 sec after trigger time at 2018-06-14 19:16:40 UT.

On our images we  didn't find optical transient  up to 20 mag, within SWIFT error-box
RA,Dec=00h 12m 18.83s +46d 57' 10.8"  ( Evans et al. GCN22781, Beardmore et al. GCN22782).

We have a number of  images  with the following unfiltered upper limits:

Time_start,UT              Exp,s  m_lim

2018-06-14 19:16:40 10 16.6
2018-06-14 19:17:00 10 16.5
2018-06-14 19:17:20 10 16.7
2018-06-14 19:17:41 20 17.1
2018-06-14 19:18:11 20 17.2
2018-06-14 19:18:41 30 17.3
2018-06-14 19:19:21 40 17.6
2018-06-14 19:20:11 50 17.8
2018-06-14 19:21:12 60 18.0
2018-06-14 19:22:22 70 18.0
2018-06-14 19:25:23 110 18.4
2018-06-14 19:27:23 130 18.4
2018-06-14 19:33:27 180 18.3
2018-06-14 19:33:27    3600     20.0 [20 images x 180 seconds]
2018-06-14 19:36:52 180 18.3
2018-06-14 19:40:16 180 18.3
2018-06-14 19:43:41 180 18.3
2018-06-14 19:47:05 180 18.4
2018-06-14 19:50:29 180 18.6
2018-06-14 19:53:54 180 18.5
2018-06-14 19:57:18 180 18.6
2018-06-14 20:00:43 180 18.6
2018-06-14 20:04:07 180 18.6
2018-06-14 20:07:31 180 18.6
2018-06-14 20:10:55 180 18.6
2018-06-14 20:14:20 180 18.6
2018-06-14 20:17:45 180 18.6
2018-06-14 20:21:09 180 18.8
2018-06-14 20:24:34 180 18.6
2018-06-14 20:27:59 180 18.6
2018-06-14 20:31:23 180 18.9
2018-06-14 20:34:48 180 18.8
2018-06-14 20:38:12 180 18.8
====================================================================
The observations started on zenit distance = 78 degrees, galaxy latitude b = -15 degree.
The moon ( 2 % bright part) below the horizon (The altitude of the Moon is  -15 degree ).
The sun  altitude  is -18.8 degree.
The object could be observed up to sunrise at 2018-06-15 01:26:34


GRB_name: GRB180614A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22784
SUBJECT: GRB 180614A: NOT optical upper limits 
DATE:    18/06/15 12:42:31 GMT
FROM:    Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI  <keh14@hi.is>

Kasper E. Heintz (Univ. of Iceland and DAWN/NBI), Johan P. U. Fynbo (DAWN/NBI), Daniele B. Malesani (DAWN/NBI and DARK/NBI), Jyri J. Lehtinen (MPS), Teemu Willamo (Univ. of Helsinki), and Paco Galindo (NOT), report on behalf of a larger collaboration:

We observed the field around GRB 180614A (Gropp et al., GCN 22780) with the 2.5-m Nordic Optical Telescope (NOT) equipped with StanCam.

Observations of 3x100 s were carried out in the R filter and started at 04:12:59 UT on June 15, 8.93 hr after trigger. We do not detect the optical counterpart within the enhanced Swift-XRT error circle and calibrated against local photometry from the USNO-B1 catalog we measure an upper limit (at 3-sigma) of m(R) > 22.9 AB mag.

This upper limit is not corrected for the Galactic extinction of A_V = 0.36 mag (Schlafly & Finkbeiner, 2011, ApJ, 737, 103) in the direction of the GRB.


GRB_name: GRB180529A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22785
SUBJECT: GRB 180529A: AstroSat CZTI detection
DATE:    18/06/15 15:14:41 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

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

Analysis of Astrosat CZTI data showed the detection of a short GRB 180529A, which was also detected by IPN Triangulation (Hurley K. et al., GCN 22748), CALET (Onozawa H., GCN 22749) and Konus-Wind (Svinkin D. et al., GCN 22750).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 08:29:15.5 UT. The measured peak count rate is 346.4 cts/s above the background in combined data of four quadrants, with a total of 508 cts. The local mean background count rate was 496.5 cts/s. Using cumulative rates, we measure a T90 of 2.9 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180614A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22786
SUBJECT: GRB 180614A: Swift-BAT refined analysis
DATE:    18/06/15 16:03:33 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), J. D. Gropp (PSU),
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):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180614A (trigger #841548)
(Gropp et al., GCN Circ. 22780).  The BAT ground-calculated position is
RA, Dec = 3.073, 46.969 deg which is
  RA(J2000)  =  00h 12m 17.6s
  Dec(J2000) = +46d 58' 07.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-4 s and ends at ~T+3 s. The main peak occurs at ~T+2 s.
T90 (15-350 keV) is 7.04 +- 0.92 sec (estimated error including systematics).

The time-averaged spectrum from T-4.35 to T+3.45 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.53 +- 0.26.  The fluence in the 15-150 keV band is 2.1 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.56 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/841548/BA/


GRB_name: GRB180614A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22787
SUBJECT: GRB 180614A: Swift/UVOT Upper Limits
DATE:    18/06/15 17:20:41 GMT
FROM:    Jeffrey Gropp at PSU  <jdg44@psu.edu>

J. D. Gropp (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180614A
65s after the BAT trigger (Gropp et al., GCN Circ. 22780).
No optical afterglow consistent with the enhanced XRT position
(Gropp et al. GCN Circ. 22780)
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

b              556     1872    136    >19.63
uvm2       654     1797    136    >18.91
u              300     1847    362    >20.06
v              630     1773    136    >18.75
uvw1        679     1823    136    >19.03
uvw2        605     1922    155    >19.20
white          87     1897    430    >21.15
white_FC    87      237    147    >20.75

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180614A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22788
SUBJECT: GRB 180614A: 1.5m OSN I-band observation
DATE:    18/06/15 21:46:08 GMT
FROM:    Youdong HU at IAA-CSIC, UGR  <youdong@iaa.es>

Y.-D. Hu, F. Aceituno and A.J. Castro-Tirado (IAA-CSIC Granada), on 
behalf of a larger collaboration, report:

Following the detection of GRB 180614A by Swift (Gropp et al. GCNC 
22780), optical images in the I-band were obtained at the 1.5m OSN 
telescope in Granada (Spain) starting at 01:57 (Jun 15), i.e. 6.67 h 
postburst. No optical afterglow is detected in the co-added image (9 x 
600s, mid time 02:43 UT, 7.4 h after the trigger) within the enhanced 
Swift/XRT error box (Beardmore et al. GCNC 22782) down to I=21.0.


GRB_name: GRB180614A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22789
SUBJECT: GRB 180614A: AbAO optical observations
DATE:    18/06/16 15:19:10 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI),  A. Pozanenko (IKI),   R. Inasaridze (AbAO),  V. 
Ayvazian  (AbAO),  O. Kvaratskhelia (AbAO), G. Kapanadze (AbAO),  A. 
Volnova  (IKI), I. Molotov (KIAM), report on behalf of larger GRB 
follow-up collaboration:

We observed the field of GRB 180614A  (Gropp et al., GCN 22780) with 
AS-32 (0.7m) telescope of Abastumani Observatory starting on June 14 
(UT) 21:33:14.   We do not detect any object within enhanced XRT 
position (Evans et al., GCN 22781). Preliminary photometry of the field 
is following.

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

2018-06-14  21:33:14   0.12582   CR     51*60  n/d   n/d  21.5

The photometry is based on nearby USNO-B1.0 stars (R2 magnitude)
USNO-B.1_id R2
1369-0005473 17.71
1369-0005482 16.67
1369-0005487 16.97
1369-0005592 16.51


GRB_name: GRB180618A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22790
SUBJECT: GRB 180618A: Swift detection of a burst with an optical counterpart
DATE:    18/06/18 00:53:53 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. J. LaPorte (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 00:43:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180618A (trigger=842475).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 169.937, +73.848 which is 
   RA(J2000) = 11h 19m 45s
   Dec(J2000) = +73d 50' 52"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single FRED
structure with a duration of about 20 sec.  The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 00:44:30.5 UT, 77.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 169.9415, 73.8358 which is equivalent to:
   RA(J2000)  = +11h 19m 45.96s
   Dec(J2000) = +73d 50' 08.9"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 44 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. 

The initial flux in the 2.5 s image was 1.27e-09 erg cm^-2 s^-1 (0.2-10
keV). 

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)  = 11:19:45.78 = 169.94074
  DEC(J2000) = +73:50:13.3  =  73.83704
with a 90%-confidence error radius of about 1.10 arc sec. This position is 4.5
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.81. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.07. 

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: GRB180618A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22791
SUBJECT: GRB 180618A: Enhanced Swift-XRT position
DATE:    18/06/18 03:26:07 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 1241 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180618A, 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 = 169.94141, +73.83731 which is equivalent
to:

RA (J2000): 11h 19m 45.94s
Dec (J2000): +73d 50' 14.3"

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: GRB180618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22792
SUBJECT: GRB 180618A: LT prompt observations
DATE:    18/06/18 08:18:45 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

The 2-m Liverpool Telescope automatically began observing Swift GRB 
180618A (LaPorte et al. GCN 22790) on June 18, 00:46:30 UT (197 s since 
the GRB trigger time) with the RINGO3 polarimeter and the IO:O camera in 
the SDSS-R filter. The optical counterpart identified by Swift-UVOT is 
clearly detected with r'=19.36 +- 0.05 mag in a 6x10s exposure at a mid 
time of 36.3 minutes post GRB, as calibrated against nearby SDSS objects.


GRB_name: GRB180618A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22793
SUBJECT: GRB 180618A: Swift-XRT refined Analysis
DATE:    18/06/18 10:23:59 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), D.N.
Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), P.A. Evans (U.
Leicester), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester)
and S.J. LaPorte report on behalf of the Swift-XRT team:

We have analysed 7.8 ks of XRT data for GRB 180618A (LaPorte et al. GCN
Circ. 22790), from 83 s to 24.6 ks after the  BAT trigger. The data
comprise 293 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Goad et al. (GCN Circ. 22791).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.66 (+0.19, -0.31), followed by a break at T+158 s to
an alpha of 1.80 (+/-0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.91 (+/-0.09). The
best-fitting absorption column is  2.0 (+0.4, -0.3) x 10^21 cm^-2, in
excess of the Galactic value of 4.4 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.23 (+0.22, -0.21)
and a best-fitting absorption column of 2.9 (+0.8, -0.7) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.3 x 10^-11 (5.4 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.9 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: 5.3 sigma
Photon index:      2.23 (+0.22, -0.21)

If the light curve continues to decay with a power-law decay index of
1.80, the count rate at T+24 hours will be 1.9 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.4 x
10^-15 (1.1 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/00842475.

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


GRB_name: GRB180618A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22794
SUBJECT: GRB 180618A: Fermi GBM detection
DATE:    18/06/18 15:47:53 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

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

"At 00:43:13.11 UT on 18 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180618A (trigger 550975398 / 180618030),
which was also detected by the Swift/BAT (LaPorte et al. 2018, GCN 22790).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 103
degrees.

The GBM light curve shows one main peak
with a duration (T90) of about 3.7 s (50-300 keV).
LaPorte et al. 2018 report a longer duration of
~20 s in the Swift/BAT. Given the soft tail following
the initial hard spike, we suggest the discrepancy
may be due to extended emission of this short GRB.

The time-averaged spectrum from T0 to T0+1.8 s
is adequately fit a power law function with an exponential
high-energy cutoff. The power law index is 1.08 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 2.8 +/- 0.8 MeV.

The event fluence (10-1000 keV) in this time interval is
(2.12 +/- 0.12)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 in the 10-1000 keV band is 14.6 +/- 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: GRB180611A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22795
SUBJECT: GRB 180611A: AstroSat CZTI detection
DATE:    18/06/18 16:37:30 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

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

Analysis of Astrosat CZTI data showed the detection of a long GRB 180611A, which was also detected by IPN Triangulation (Hurley K. et al., GCN 22767), Fermi-GBM (Bissaldi E. et al., GCN 22768), Konus-Wind (Tsvetkova A. et al., GCN 22770).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 03:29:02.5 UT. The measured peak count rate is 265.9 cts/s above the background in combined data of four quadrants, with a total of 1173 cts. The local mean background count rate was 478.1 cts/s. Using cumulative rates, we measure a T90 of 11.5 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 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: GRB180618A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22796
SUBJECT: GRB 180618A: Swift-BAT refined analysis (a short GRB with extended emission)
DATE:    18/06/18 18:27:23 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), J. P. Norris (BSU),
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 180618A (trigger #842475)
(LaPorte et al., GCN Circ. 22790).  The BAT ground-calculated position is
RA, Dec = 169.948, 73.825 deg which is
  RA(J2000)  =  11h 19m 47.6s
  Dec(J2000) = +73d 49' 29.3"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 70%.

The mask-weighted light curve shows a short multi-peaked structure from ~ T0
to ~T+0.3, followed by some extended emission that lasts till ~T+50 s.
T90 (15-350 keV) is 47.4 +- 11.1 sec (estimated error including systematics).

The time-averaged spectrum from T-0.06 to T+56.33 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.39 +- 0.27.  The fluence in the 15-150 keV band is 6.7 +- 1.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.08 sec in the 15-150 keV band
is 2.2 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The structure of the burst shows similarity to those of short GRBs with
extended emission, as mentioned in Hamburg et al., GCN Circ. 22794.
We thus perform further analysis on the short spike and the extended emission.

The spectrum of the short multi-peaked structure from T-0.056 to T+0.264 sec
is best fit by a simple power-law model, with power-law index of 0.60 +- 0.24
and fluence (15-150 keV) of 1.3 +- 0.2 x 10^-7 erg/cm2. The spectrum of the
extended emission from T+0.264 to T+56.328 sec is best fit by a simple power-law
model, with power-law index of 1.53 +- 0.31 and fluence (15-150 keV) of
5.5 +- 1.0 x 10^-7 erg/cm2. These values are consistent with those of short GRBs
with extended emission (Lien & Sakamoto et al. 2016).

Using a 4-ms binned light curve, the lag analysis of the first two tallest pulses
(from ~T0 to ~T+0.1 s) finds a lag of 0.7 +/- 0.9 ms for the 100-350 keV to 25-50 keV
band, and 1.5 (+1.8, -1.2) ms for the 50-100 keV to 15-25 keV band. Therefore, the
lag values of these short pulses are consistent with those of short GRBs.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/842475/BA/


GRB_name: GRB180618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22797
SUBJECT: GRB 180618A: MASTER OT observation (a short GRB with extended emission)
DATE:    18/06/19 12:00:58 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov,  A.Kuznetsov,
I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

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

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

R. Podesta, F. Podesta, C. Lopez, C.Francile
Observatorio Astronomico Felix Aguilar (OAFA)

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

D. Buckley
South African Astronomical Observatory

O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University

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

MASTER-Kislovodsk  robotic telescope (MASTER-Net: http://observ.pereplet.ru 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) ,
located in Kislovodsk Solar Station of Pulkovo observatory,
was pointed to the Swift GRB180618A (LaPorte et al. GCN #22790; Sakamoto 
et al., GCN #22796)
25 sec after notice time and 41 sec after trigger time at 2018-06-18 
00:43:53 UT.
On our first (10s exposure)  polarization set we haven't found optical 
transient  within SWIFT error-box (ra=169.933 dec=73.8478 r=0.05).
The 5-sigma upper limit has been about 15.2 mag

The observations made on zenit distance = 61 degrees, galaxy latitude b = 
42 degree.
The moon (24 % bright part) below the horizon (The altitude of the Moon is 
-31 degree ).
Observations started at twilight and bad transparency.  The sun  altitude 
is -6.8 degree.

  MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in IAC was pointed to the  GRB180618A 1734  sec after trigger time 
at 2018-06-18 01:12:07 UT.
On our first (180s exposure)  set we found  ~19 mag optical transient 
within SWIFT UVOT error-box (LaPorte et al. GCN #22790; Guidorzi et al., 
GCN #22792;).
  The 5-sigma upper limit has been about 19.0 mag on single (180 s) and 
20.5 on coadd (1800 s) exposures.

====================================================================
  The observations made on zenit distance = 64 degrees, galaxy latitude b = 
42 degree. 
The moon (24 % bright part) below the horizon (The altitude of the Moon is 
-15 degree ). 
The sun  altitude  is -38.3 degree. 
The object can be observed till sunrise at 2018-06-18 06:08:21 
The message may be cited.


GRB_name: GRB180620A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22798
SUBJECT: GRB 180620A: Swift detection of a burst with an optical counterpart
DATE:    18/06/20 08:50:56 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

P. A. Evans (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL),
S. W. K Emery (UCL-MSSL), A. Y. Lien (GSFC/UMBC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
R. L. C. Starling (U Leicester) and A. Tohuvavohu (PSU) report on
behalf of the Neil Gehrels Swift Observatory Team:

At 08:34:58 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180620A (trigger=843122).  Swift slewed to the burst with a 3 min delay. 
The BAT on-board calculated location is 
RA, Dec 279.883, +23.265, which is 
   RA(J2000)  =  18h 39m 32s
   Dec(J2000) = +23d 15' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several overlapping peaks
with a total duration of about 25 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~12 sec after the trigger. 

The XRT began observing the field at 08:39:25.1 UT, 267.1 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 279.89575, 23.24373 which is equivalent
to:
   RA(J2000)  = 18h 39m 34.98s
   Dec(J2000) = +23d 14' 37.4"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 87 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 1.60
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of nominal 150.000 seconds with the White
filter starting 270 seconds after the BAT trigger. There is a candidate
afterglow in the list of sources generated on-board at
  RA(J2000)  = 18:39:35.08 = 279.89618
  DEC(J2000) = +23:14:39.7  =  23.24437
with a 90%-confidence error radius of about 1.10 arc sec. This position is 1.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.24. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.13. 

Burst Advocate for this burst is P. A. Evans (pae9 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: GRB180620A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22799
SUBJECT: GRB 180620A: RATIR Optical Afterglow Detection
DATE:    18/06/20 09:16:28 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 (U. Wash.), and
Vicki Toy (UMD) report:

We observed the field of GRB 180620A (Evans, et al., GCN 22798) 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 2018/06 20.36 to 2018/06 20.38 UTC (0.03
to 0.47 hours after the BAT trigger), obtaining a total of 0.36 hours
exposure in the r and i bands.

For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 and 2MASS catalogs, we
obtain the following detections:

  r = 18.01 +/- 0.01
  i = 17.71 +/- 0.01

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  We observe the rise and
initial decline of the afterglow.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro
MÃ¡rtir.  Further observations are planned.


GRB_name: GRB180620A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22800
SUBJECT: GRB 180620A:  ISON-MN  afterglow confirmation
DATE:    18/06/20 09:21:07 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

L. Elenin (KIAM),  A. Pozanenko (IKI),  A. Volnova (IKI), E. Mazaeva, I. 
Molotov (KIAM) report on behalf of larger GRB  follow-up collaboration:

We observed the field of  the Swift GRB 180620A  (Evans et al., GCN  22798) 
with ISON-NM observatory. Observation started 84 s after burst trigger. We 
find  fading object in coordinates (J2000) 18:39:35.09 +23:14:39.0 which 
correspond to the OT candidate (Evans et al., GCN  22798). Preliminary 
photometry of the OT in the first image started   on 2018-06-20T08:36:21.666 
is 17.1m in clear filter. Observation is ongoing.

 


GRB_name: GRB180620A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22801
SUBJECT: GRB 180620A: MASTER OT observation 
DATE:    18/06/20 09:27:40 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov,  A.Kuznetsov,
I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

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

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

R. Podesta, F. Podesta, C. Lopez, C.Francile
Observatorio Astronomico Felix Aguilar (OAFA)

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

D. Buckley
South African Astronomical Observatory

O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University

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

MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) ,
located in Argentina (OAFA observatory of San Juan National University),
was pointed to the Swift GRB180620A ( Evans et al. GCN #22798)
20 sec after Notice and  41 sec after trigger time at 2018-06-20 08:35:39 
UT.

We see OT at Swift UVOT coordinates ~17 mag  (Evans et al. GCN #22798).

====================================================================



The observations made on zenit distance = 72 degrees, galaxy latitude b = 
12 degree.
The moon (49 % bright part) below the horizon (The altitude of the Moon is 
-50 degree ).
The sun  altitude  is -37.3 degree.
The object can be observed till 2018-06-20 10:23:39.


GRB_name: GRB180620A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22802
SUBJECT: GRB 180620A: Enhanced Swift-XRT position
DATE:    18/06/20 10:42:13 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 1128 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180620A, 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 = 279.89648, +23.24418 which is equivalent
to:

RA (J2000): 18h 39m 35.15s
Dec (J2000): +23d 14' 39.0"

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: GRB180620A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22803
SUBJECT: GRB 180620A: LCO McDonald observations
DATE:    18/06/20 12:01:56 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

The LCO 1-m unit at McDonald Observatory began observing Swift GRB 
180620A (Evans et al. GCN 22798) on June 20, 08:55 UT (20 min since the 
GRB trigger time) with the SDSS griz filters. The optical counterpart 
(Evans et al.; Butler et al. GCN 22799; Elenin et al. GCN 22800; Tyurina 
et al. GCN 22801) is clearly detected in each individual frame with the 
following magnitudes:

Mid Time since GRB Exposure Filter Magnitude
(hrs) (s)
------------------------------------------------------------------
0.349 1x120 SDSS-R 18.63 +- 0.04
0.583 1x120 SDSS-I 18.27 +- 0.04
------------------------------------------------------------------

as calibrated against nearby PanSTARRS objects.


GRB_name: GRB180618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22804
SUBJECT: GRB 180618A: Xinglong-2.16m optical upper limit
DATE:    18/06/20 13:02:02 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu, D. Xu, J.B. Zhang (NAOC), X. Zhang, J.H. Liu (XAO), Z.B. Dai 
(YNAO) report:

We observed the field of GRB 180618A (LaPorte et al., GCN 22790) using 
the 2.16-m telescope located at Xinglong, Hebei, China, equipped with 
the BFOSC camera. We obtained 6x600s R-band frames, starting at 12:43:22 
UT on 2018-06-19, i.e., 1.50 days after the BAT trigger.

The previously detected optical afterglow of the GRB (e.g., LaPorte et 
al., GCN 22790; Guidorzi et al., GCN 22792; Tyurina et al., GCN 22797) 
was not present in our stacked image, down to a limiting magnitude of 
R~21.4 mag, calibrated with the SDSS field.


GRB_name: GRB180620A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22805
SUBJECT: GRB 180620A: Swift/UVOT Detection
DATE:    18/06/20 14:19:58 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

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

The Swift/UVOT began settled observations of the field of GRB 180620A 
270 s after the BAT trigger (Evans et al., GCN Circ. 22798).
A fading source consistent with the XRT position (Osborne et al. GCN 
Circ. 22802), and also detected by Butler et al. (GCN Circ. 22799), 
Elenin et al. (GCN Circ. 22800), Tyurina et al. (GCN Circ. 22801) and 
Guidorzi et al. (GCN Circ. 22803), is detected in the initial UVOT 
exposures. The detection in the UVOT uvw2 filter implies a redshift 
limit of 1.2.

The preliminary UVOT position is:
     RA  (J2000) =  18:39:35.09 = 279.89619 (deg.)
     Dec (J2000) = +23:14:39.1  =  23.24419 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).

Preliminary detections 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              270          420          147         17.68 Â± 0.04
v                  427         1420          117         18.43 Â± 0.19
b                  525          717           39         18.77 Â± 0.20
u                  500          692           39         17.92 Â± 0.17
w1                 476         2158          194         18.86 Â± 0.20
m2                 623         7111          391         19.65 Â± 0.27
w2                 574         8136          588         20.00 Â± 0.23

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: GRB180620A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22806
SUBJECT: GRB 180620A: COATLI Detection and Light Curve 
DATE:    18/06/20 15:16:55 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC) report:

We observed the field of GRB 180620A (Evans et al., GCN 22798) with the
COATLI 50-cm telescope and interim imager at the Observatorio
AstronÃ³mico Nacional on the Sierra de San Pedro MÃ¡rtir
(http://coatli.astroscu.unam.mx) from 2018-06-20 08:35:37 to 11:17:31
(from 39.2 seconds after the trigger or 21.1 seconds after the alert to
2.7 hours after the trigger), obtaining a total of 6250 seconds of
exposure in the w filter.

We detect the source reported by Butler et al. (GCN Circ. 22799) with

w = 18.00 +/- 0.02

This magnitude is in the USNO system and is not corrected for Galactic
extinction in the direction of the GRB.

Our light curve shows a sharp initial fall from 16.5 mag to 17.3 mag,
followed by a slower rise to 16.7 mag (also seen by Butler et al.),
followed by a monotonic fall to 19.0 mag.

We thank the COATLI technical team (Fernando Ãngeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, RosalÃ­a Langarica,
Fernando QuirÃ³s, and Carlos Tejada) and the staff of the Observatorio
AstronÃ³mico Nacional.


GRB_name: GRB180620B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22807
SUBJECT: GRB 180620B: Swift detection of a burst with an optical counterpart
DATE:    18/06/20 16:05:27 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

P. A. Evans (U Leicester), A. A. Breeveld (UCL-MSSL), A. Deich (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), M. H. Siegel (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 15:50:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180620B (trigger=843211).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 357.517, -57.957 which is 
   RA(J2000) = 23h 50m 04s
   Dec(J2000) = -57d 57' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 15:52:00.3 UT, 83.2 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 357.52114, -57.96306 which
is equivalent to:
   RA(J2000)  = 23h 50m 05.07s
   Dec(J2000) = -57d 57' 47.0"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 23 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 1.39
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 7.04e-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)  = 23:50:05.10 = 357.52126
  DEC(J2000) = -57:57:44.1  = -57.96224
with a 90%-confidence error radius of about 0.75 arc sec. This position is 1.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.98 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01. 

Burst Advocate for this burst is P. A. Evans (pae9 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: GRB180620A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22808
SUBJECT: GRB 180620A: Swift-XRT refined Analysis
DATE:    18/06/20 17:03:02 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), A. Tohuvavohu (PSU), S.
J. LaPorte (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester), Z. Liu
(NAOC / U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo
(INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 9.6 ks of XRT data for GRB 180620A (Evans et al. GCN
Circ. 22798), from 274 s to 23.4 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Osborne et al. (GCN Circ. 22802).

The late-time light curve (from T0+6.1 ks) can be modelled with a
power-law decay with a decay index of alpha=2.16 (+/-0.13).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.46 (+0.10, -0.08). The
best-fitting absorption column is  1.76 (+0.43, -0.16) x 10^21 cm^-2,
consistent with the Galactic value of 1.6 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 4.9 x 10^-11 (5.6 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.76 (+0.43, -0.16) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.46 (+0.10, -0.08)

If the light curve continues to decay with a power-law decay index of
2.16, the count rate at T+24 hours will be 2.3 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-13 (1.3 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/00843122.

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


GRB_name: GRB180618A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22809
SUBJECT: GRB 180618A: TSHAO optical upper limit
DATE:    18/06/20 17:57:39 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Kusakin (FAPHI), A. Pozanenko (IKI), I. Reva 
(FAPHI),    A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of GRB GRB 180618A (LaPorte et al., GCN 22790) 
with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory 
starting on June 18 (UT) 15:39:19. We obtained several images in 
R-filter.  The optical afterglow (LaPorte et al., GCN 22790; Guidorzi et 
al., GCN 22792; Tyurina et al., GCN 22797)  is not detected in a stacked 
image. Preliminary photometry of the field is following.

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

2018-06-18  15:39:19 0.65209  R      36*120  n/d  n/d    22.2

The photometry is based on several nearby SDSS-DR10 stars.

Ref.stars
SDSS_id             R(Lupton)
J112037.79+735136.8 17.37
J111905.28+734733.2 17.54
J111907.19+734657.8 17.04


GRB_name: GRB180618A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22810
SUBJECT: GRB 180618A: Swift/UVOT Detection
DATE:    18/06/20 18:15:17 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and S. J. LaPorte (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180618A
86 s after the BAT trigger (LaPorte et al., GCN Circ. 22790). We confirm
the previously reported fading optical afterglow, also detected by LT (Guidorzi 
et al., GCN Circ. 22792) and MASTER (Tyurina et al., GCN Circ. 22797). We find
that the source had faded away completely by the second orbit. The detection of the
afterglow in six of UVOT's filters places an upper limit on the redshift of z < 1.2.

The preliminary UVOT position is:
    RA  (J2000) =  11:19:45.84 = 169.94102 (deg.)
    Dec (J2000) = +73:50:13.5  =  73.83707 (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 (fc)          86          236          147         17.46 +/- 0.04
white               86         1544          390         17.95 +/- 0.03
white             5680         7315          393        >21.09
v                  628         1596          117         18.71 +/- 0.22
v                 6090         6290          196        >19.25
b                  553         1175           58         18.84 +/- 0.16
b                 5475         7110          393        >20.39
u (fc)             298          548          246         17.50 +/- 0.06
u                  298         1497          313         17.62 +/- 0.06
u                 5270         6905          393        >19.94
w1                 676         1472           97         18.59 +/- 0.24
w1                5065         6700          393        >19.63
m2                1254         1621           58        >17.6
w2                 604         1398           97         18.85 +/- 0.28

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180620A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22811
SUBJECT: GRB 180620A: Xinglong-2.16m optical observations
DATE:    18/06/20 19:20:31 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu, D. Xu, J.B. Zhang (NAOC), X. Zhang, J.H. Liu (XAO) report

We observed the field of GRB 180620A (Evans et al., GCN 22790) using the 
2.16-m telescope located at Xinglong, Hebei, China, equipped with the 
BFOSC camera. We obtained 3x600s R-band frames, starting at 12:39:01 UT 
on 2018-06-20, i.e., 4.068 hrs after the BAT trigger.

The GRB's optical afterglow (Evans et al., GCN 22790; Butler et al., GCN 
22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801; Guidorzi et 
al., GCN 22803) is clearly detected in each frame. Preliminary 
photometry shows the afterglow has decayed to m(R)~20.0, calibrated with 
nearby USNO B1 stars.

We acknowledge the excellent support from the Xinglong staff, 
particularly Xiao Feng and Huijuan Wang, in obtaining these observations.


GRB_name: GRB180620A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22812
SUBJECT: GRB 180620A: KAIT Optical Observations
DATE:    18/06/20 20:13:48 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang@berkeley.edu>

WeiKang Zheng and Alex Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT) at
Lick Observatory responded to Swift GRB 180620A (Evans et al.,
GCN 22798) starting at 08:37:19 UT, 141s after the burst.
Observations were performed with an automatic sequence in the
V, I, and clear (roughly R) filters, and the exposure time was
20 s per image, observations lasted about 3 hours.
The optical afterglow (Evans et al., GCN 22790; Butler et al.,
GCN 22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801;
Guidorzi et al., GCN 22803; Breeveld et al., GCN 22805;
Watson et al., GCN 22806; Zhu et al., GCN 22811) was well
detected in our V, I and clear filter images. A preliminary
analysis shows that the afterglow rises at early time and peaked
around 300s (also seen by Butler et al. GCN 22799; Watson et al.,
GCN 22806). After that the light curve shows monotonic decay,
followed by a flat phase between ~1ks to ~3ks.
A preliminary light curve is posted at:
http://astro.berkeley.edu/~zwk/grb/GRB180620A/GRB180620A_kait.png


GRB_name: GRB180620B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22813
SUBJECT: GRB 180620B: Fermi GBM detection
DATE:    18/06/20 22:18:37 GMT
FROM:    Bagrat Mailyan at UAH  <bm0054@uah.edu>

B. Mailyan (UAH) reports on behalf of the Fermi GBM Team:

"At 15:50:36.05 UT on 20 June 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180620B (trigger 551202641 / 180620660),
which was also detected by the Swift/BAT and XRT (Evans et al. 2018, GCN
22807).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 137
degrees.

The GBM light curve shows multi-peaked structure
with a duration (T90) of about 46.7 s (50-300 keV).
Evans et al. 2018 report a shorter duration of
~30 s in the Swift/BAT. We suggest the discrepancy
may be due to extended hard emission of this GRB.

The time-averaged spectrum from T0 to T0+46 s
is adequately fit a power law function with an exponential
high-energy cutoff. The power law index is 0.85 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 149 +/- 11 KeV.
A Band function fits the spectrum equally well
with Epeak= 106 +/- 15 keV, alpha = -0.5 +/- 0.2 and
beta = -2.2 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(7.7 +/- 0.04)E-06 erg/cm^2. The 1-s peak photon flux measured
starting from T0 in the 10-1000 keV band is 6.8 +/- 0.5 ph/s/cm^2.

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


GRB_name: GRB180620B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22814
SUBJECT: GRB 180620B: Enhanced Swift-XRT position
DATE:    18/06/21 01:15:28 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 3193 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 180620B, 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 = 357.52122, -57.96243 which is equivalent
to:

RA (J2000): 23h 50m 5.09s
Dec (J2000): -57d 57' 44.8"

with an uncertainty of 1.4 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: GRB180620A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22815
SUBJECT: GRB 180620A: Swift-BAT refined analysis
DATE:    18/06/21 02:37:49 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), 
J. R. Cummings (CPI), P. A. Evans (U Leicester),
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-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180620A (trigger #843122)
(Evans et al., GCN Circ. 22798).  The BAT ground-calculated position is
RA, Dec = 279.890, 23.239 deg which is 
  RA(J2000)  =  18h 39m 33.5s 
  Dec(J2000) = +23d 14' 18.6" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 42%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-7 s and ends at ~T+37 s. The two main peaks occur at ~T+5 s and ~T+12 s,
respectively. T90 (15-350 keV) is 23.16 +- 4.82 sec (estimated error including 
systematics).

The time-averaged spectrum from T-6.92 to T+37.07 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.72 +- 0.05.  The fluence in the 15-150 keV band is 5.8 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+4.47 sec in the 15-150 keV band
is 7.7 +- 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/843122/BA/


GRB_name: GRB180618B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22816
SUBJECT: GRB 180618B: CALET Gamma-Ray Burst Monitor detection
DATE:    18/06/21 06:58:09 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

K. Yamaoka (Nagoya U), A. Yoshida, T. Sakamoto, V. Pal'shin,
Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito,
H. Morita, Y. Sone (AGU), 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 GRB 180618B (INTEGRAL SPI-ACS trigger #8079;
Konus-Wind trigger time on 22:40:26.066)
triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 22:40:18.199 UTC on 18 June 2018.  The burst signal
was clearly seen by the SGM instrument.  There is a hint
of the emission seen by the HXM instrument.

The burst light curve shows a single FRED-like pulse which starts
at T-3.8 sec, peaks at T-1.5 sec and ends at T+15.4 sec.
The T90 and the T50 durations measured by the SGM data are
17 +- 4 sec and 5.3 +- 0.5 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1213396756

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


GRB_name: GRB180620B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22817
SUBJECT: GRB 180620B: Swift-XRT refined Analysis
DATE:    18/06/21 10:04:12 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.6 ks of XRT data for GRB 180620B (Evans et al. GCN
Circ. 22807), from 89 s to 56.0 ks after the  BAT trigger. The data
comprise 237 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 22814).

The late-time light curve (from T0+4.3 ks) can be modelled with a
power-law decay with a decay index of alpha=0.61 (+/-0.08).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.34 (+/-0.05). The
best-fitting absorption column is  2.30 (+/-0.15) x 10^21 cm^-2, in
excess of the Galactic value of 1.4 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.99 (+0.11, -0.10)
and a best-fitting absorption column of 1.6 (+/-0.3) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.6 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 1.4 x 10^20 cm^-2
Excess significance: 7.9 sigma
Photon index:      1.99 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
0.61, the count rate at T+24 hours will be 0.12 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.1 x
10^-12 (5.5 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/00843211.

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


GRB_name: GRB180620A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22818
SUBJECT: GROND observations of GRB 180620A
DATE:    18/06/21 11:16:12 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

Tassilo Schweyer and Patricia Schady (MPE Garching) report:

We observed the field of GRB 180620A (Swift trigger 843211; Evans et al.,
GCN #22807) 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 04:35 UT on 2018-06-21, 20 hours after the GRB
trigger. They were performed at an average seeing of 1.4" and at an
average airmass of 1.7.

We detect a faint point source consistent with the position of the
reported X-ray and optical afterglow (Elenin et al., GCN #22800; Osborne
et al., GCN #22802; Breeveld et al., GCN #22805). Based on a total
exposures time of around 30mins we estimate the following AB magnitudes:

g' = 23.9 +/- 0.1 mag
r' = 23.4 +/- 0.1 mag
i' = 23.1 +/- 0.1 mag
z' > 23.2 mag
J > 21.2 mag
H > 20.5 mag
K > 19.3 mag

Given magnitudes are calibrated against PanSTARRS and 2MASS field stars
and are not corrected for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V)=0.11 in the direction of the burst
(Schlafly & Finkbeiner 2011).

We thank Markus Rabus for the excellent support from La Silla.


GRB_name: GRB180620B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22819
SUBJECT: GROND observations of GRB 180620B
DATE:    18/06/21 11:18:56 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady@mpe.mpg.de>

Tassilo Schweyer and Patricia Schady (MPE Garching) report:

We observed the field of GRB 180620B (Swift trigger 843211; Evans et al.,
GCN #22807) 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 05:06 UT on 2018-06-21, 13.3 hours after the GRB
trigger. They were performed at an average seeing of 1.6" and at an
average airmass of 1.5.

We found a single, bright point source within the 1.4" Swift-XRT enhanced
error circle reported by Beardmore et al. (GCN #22814) at

RA (J2000) = 23:50:05.088
Dec (J2000) = -57:57:43.88

with an uncertainty of 0.14" in each coordinate.

Based on a total exposure time of around 30mins we estimate the following
AB magnitudes:

g' = 21.3 +/- 0.1 mag
r' = 20.8 +/- 0.1 mag
i' = 20.4 +/- 0.1 mag
z' = 20.3 +/- 0.1 mag
J = 19.7 +/- 0.1 mag
H = 19.6 +/- 0.2 mag
K = 19.1 +/- 0.4 mag

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.01 in the direction
of the burst (Schlafly & Finkbeiner 2011).

We thank Markus Rabus for the excellent support from La Silla.


GRB_name: GRB180613A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22820
SUBJECT: GRB 180613A: Afterglow confirmation and added photometry
DATE:    18/06/21 14:47:01 GMT
FROM:    Christina Thoene at IAA-CSIC  <christina.thoene@gmail.com>

C.C. Thoene (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), N.R. Tanvir (Univ. of Leicester),  D.A. Kann, L. Izzo (both
HETH/IAA-CSIC), J.P.U. Fynbo (DAWN/NBI) and D.B. Malesani (DAWN/NBI,
DARK/NBI) report on behalf of the Stargate consortium:

We re-observed the field of GRB 180613A (Tohuvavohu et al., GCN 22769) with
HAWK-I/VLT on 14 June 2018 at 23:37 UT (32.02 hr after the burst). The
observation consisted of a combined exposure of 36 min in the J-band. The
seeing of this observation was worse than during the first epoch (Thoene et
al., GCN 22775) with an average value of 0.8", but the exposure time was
significantly longer, allowing us to reach a deeper limit. In this second
epoch we do not detect any more the source found by Thoene et al. (GCN
22775) down to a 3-sigma limit of J(Vega) > 24.2 mag. This implies that the
source has faded, confirming that this source was indeed the afterglow of
GRB 180613A.

We also revise and provide the full photometry of our first HAWK-I epoch
(GCN 22775, Thoene et al.) and obtain the following values:
J(Vega)=23.24+/-0.26 or J(AB)=24.15+/-0.26
H(Vega)=22.23+/-0.22 or H(AB)=23.62+/-0.22
Ks(Vega)=21.04+/-0.27 or Ks(AB)=22.89+/-0.27

These values result in an IR spectral slope of 2.02 +/- 0.64, which would
indicate a significant amount of extinction, explaining the faintness of
the afterglow. Due to the lack of further data, we are not able to draw any
definite conclusions in this matter.

We acknowledge the continued excellent support from the ESO staff, in
particular Frederic Vogt, Ivan Aranda and Eleonora Sani.


GRB_name: GRB180620B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22821
SUBJECT: GRB 180620B: Swift-BAT refined analysis
DATE:    18/06/22 00:45:20 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), P. A. Evans (U Leicester),
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-179 to T+843 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180620B (trigger #843211)
(Evans et al., GCN Circ. 22807).  The BAT ground-calculated position is
RA, Dec = 357.514, -57.954 deg which is
  RA(J2000)  =  23h 50m 03.3s
  Dec(J2000) = -57d 57' 13.5"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-160 s and ends at ~T+160 s. The three main peaks occur at ~T0, ~T+40 s,
and ~T+100 s, respectively. Note that because the event data are only available
from ~T-180 s, there might be additional burst emission before the available
event data range. T90 (15-350 keV) is 198.8 +- 27.4 sec (estimated
error including systematics).

The time-averaged spectrum from T-159.376 to T+162.428 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.30 +- 0.20,
and Epeak of 123.9 +- 68.3 keV (chi squared 58.09 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.0 +- 0.03 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T-0.33 sec in the 15-150 keV band is
3.6 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.60 +- 0.05 (chi squared 65.76 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/843211/BA/


GRB_name: GRB180618A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22822
SUBJECT: Konus-Wind observation of GRB 180618A (a short GRB with extended emission)
DATE:    18/06/22 10:32:51 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The bright, short-duration, hard GRB 180618A
(Swift-BAT detection: LaPorte et al., GCN Circ 22790;
Fermi-GBM detection: Hamburg et al., GCN Circ 22794)
triggered Konus-Wind at T0=2591.201 s UT (00:43:11.201).

The burst light curve shows a bright multi-peaked initial pulse
with a total duration of ~0.250 s, followed by
an extended emission seen up to ~T0+10 s.
The emission of the initial pulse is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180618_T02591/

As observed by Konus-Wind, the burst
had a fluence of 6.24(-1.13,+1.20)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.010 s,
of 5.60(-1.83,+1.88)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the initial pulse
(measured from T0 to T0+0.192 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 = -0.36(-0.24,+0.30)
and Ep = 2461(-565,+788) keV (chi2 = 47/38 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.4
(chi2 = 47/37 dof).

The time-averaged spectrum of the extended emission
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by the CPL model with alpha = -0.68(-0.79,+1.59),
Ep = 170(-66,+203) keV (chi2 = 102/98 dof).

Among ~300 bursts from the Konus catalog of short GRBs
(Svinkin et al., 2016, ApJS 224, 10), GRB 180618A is within top 1%
in the terms of 16-ms peak energy flux and within top 15% in the terms
of the total energy fluence, both in the 20 keV - 10 MeV range.
In the terms of Epeak, the burst is within 1% hardest
GRBs in the sample.

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


GRB_name: GRB180620B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22823
SUBJECT: GRB 180620B: VLT/X-shooter redshift
DATE:    18/06/22 13:02:56 GMT
FROM:    Maryam Arabsalmani at CEA Paris-Saclay  <maryam.arabsalmani@cea.fr>

L. Izzo (HETH/IAA-CSIC), M. Arabsalmani (CEA Saclay), D. B. Malesani (DAWN/NBI and DARK/NBI), K. Wiersema (Warwick), G. Pugliese (API/U. Amsterdam), S. D. Vergani (GEPI/Obs. Paris), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), D.A. Kann (HETH/IAA-CSIC), P. Schady (MPE), N.R. Tanvir (Leicester), J.P.U. Fynbo (DAWN/NBI), C. C. Thoene (HETH/IAA-CSIC), J. Bolmer (MPE Garching), report on behalf of the Stargate Consortium:

We observed the optical afterglow of GRB 180620B (Evans et al. GCN 22807; Schweyer & Schady GCN 22819) using the ESO Very Large Telescope (VLT) UT2 equipped with the X-shooter spectrograph. Spectroscopic observations started on 09:27 UT on 21 June 2018, i.e. 0.73 days after burst. In the resulting spectrum, we find a series of strong absorption lines that we identify as Fe II, Mg II, Mg I, Zn II, Cr II, Al II and Al III at a common redshift of 1.1175. At this redshift, we also detect emission lines of [O II], [Ne III] and Balmer lines. Both absorption and emission lines show velocity structure. The absorption profiles are broad and spread over more than 800 km/s in velocity space.

We are grateful to the visiting observers, Jean-Christophe Loison and Pedro Machado, for giving up some of their observing time. We thank the ESO staff, Marcela Espinoza and Alain Smette, for excellent support.


GRB_name: GRB180620A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22824
SUBJECT: Konus-Wind observation of GRB 180620A
DATE:    18/06/22 15:25:50 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 180620A
(Swift-BAT detection: Evans et al., GCN Cric. 22798)
triggered Konus-Wind at T0=30906.173 s UT (08:35:06.173).

The burst light curve shows a multi-peaked structure
which starts at ~T0-6.6 s and has a total duration of ~16 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180620_T30906/

As observed by Konus-Wind, the burst
had a fluence of 9.80(-1.02,+1.74)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+7.504 s,
of 2.69(-0.82,+0.94)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 - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.19(-0.14,+0.16),
the high energy photon index beta = -3.09(-6.91,+0.63),
the peak energy Ep = 164(-24,+29) keV
(chi2 = 70/75 dof).

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


GRB_name: GRB180620B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22825
SUBJECT: Konus-Wind observation of GRB 180620B
DATE:    18/06/22 15:28:00 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 180620B
(Swift-BAT detection: Evans et al., GCN Circ. 22807;
Fermi-GBM detection: Mailyan, GCN Circ. 22813)
triggered Konus-Wind at T0=57039.332 s UT (15:50:39.332).

The burst light curve shows a multi-peaked structure
which starts at ~T0-156 s and has a total duration of ~260 s.
The emission is seen up to 0.8 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180620_T57039/

As observed by Konus-Wind, the burst
had a fluence of 1.19(-0.12,+0.14)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0-0.056 s,
of 1.52(-0.61,+0.72)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum integrated over the most intense
part of the burst (measured from T0 to T0+49.408 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 = -1.04(-0.31,+0.36)
and Ep = 118(-16,+23) keV (chi2 = 44/57 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 = 44/56 dof).

The spectrum near the maximum count rate
(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:
with  alpha = -0.74(-0.33,+0.37)
and Ep = 129(-15,+21) keV (chi2 = 66/57 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 = 66/56 dof).

Assuming the redshift z=1.1175 (Izzo et al., GCN Circ. 22823)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.27, and Omega_Lambda = 0.73,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~3.9x10^52 erg,
the peak luminosity L_iso is ~1.0x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~273 keV.

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


GRB_name: GRB180620A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22826
SUBJECT: GRB 180620A iTelescope observation
DATE:    18/06/23 09:36:13 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. Nakamura, T. Sakamoto (AGU)

We observed the field of GRB 180620A detected by Swift
(Evans et al., GCN Circ. 22798) with the iTelescope.Net
(http://www.itelescope.net) T11 (Planewave 20") telescope
located at the New Mexico Skies Observatory (NM, USA).
20 images of 60 sec exposures were taken in the R filter
starting from June 20 on 10:11:01 (UT) about 1.6 hours after
the trigger and stopped on 10:44:55 (UT).  Due to the tracking
issue of the telescope, we only obtained nine good quality images.

We do not detect the optical afterglow both in the individual
images and the stacked image at the UVOT position
(Evans et al., GCN Circ. 22798).  The estimated five sigma
upper limit of the combined image (total exposure of 540 sec)
is ~18.1 using the USNO-B1 catalog.


GRB_name: GRB180620B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22827
SUBJECT: GRB 180620B: Swift/UVOT Detection
DATE:    18/06/23 11:44:09 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL), P. A. Evans (U. Leicester) and M. De Pasquale 
(U. Instanbul) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180620B 92 
s after the BAT trigger (Evans et al., GCN Circ. 22807).
A source consistent with the enhanced XRT position (Beardmore et al., 
GCN Circ. 22814) and the Grond position (Schweyer and Schady, GCN Circ. 
22819), and also detected by Izzo et al. (GCN Circ. 22823) is detected 
in the initial UVOT exposures in all filters except uvw2. The 
non-detection in the uvw2 filter is consistent with the redshift of 1.12 
(Izzo et al. GCN Circ. 22823).

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               92          242          147         18.06 Â± 0.08
v                  634          826           39         17.41 Â± 0.22
b                  559          579           20         17.56 Â± 0.18
u                  304          554          246         17.40 Â± 0.09
uvw1              9950        18219         1394         20.17 Â± 0.2
uvm2              6563        16382          804         20.6 Â± 0.3
uvw2              4256         4443          183         > 19.7

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.01 in the direction of the 
burst (Schlegel et al. 1998).


GRB_name: GRB180623A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22828
SUBJECT: GRB 180623A: Swift detection of a burst
DATE:    18/06/23 17:00:40 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

K. L. Page (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
A. Deich (PSU), S. W. K Emery (UCL-MSSL), J.D. Gropp (PSU),
F. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 16:41:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180623A (trigger=844015).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 214.511, -60.294, which is 
   RA(J2000)  =  14h 18m 03s
   Dec(J2000) = -60d 17' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows 4 large peaks and many
little peaks with a total duration of about 90 sec.  The peak count rate
was ~6500 counts/sec (15-350 keV), at ~61 sec after the trigger. 

The XRT began observing the field at 16:43:13.3 UT, 76.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 214.5295,
-60.2539 which is equivalent to:
   RA(J2000)  = 14h 18m 07.08s
   Dec(J2000) = -60d 15' 13.9"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 148 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 1.31e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of nominal 150.000 seconds with the
White  filter starting 85 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 8'x8'
region for the list of  sources generated on-board covers 100% of the
XRT error circle. The typical 3-sigma upper limit has been about 19.6
mag. The list of  sources is typically complete to about 18 mag. No
correction has been made for  the large, but uncertain, extinction
expected. 

Although this source is close to the Galactic plane (lat = 0.83 degrees), 
its distance from the Galactic center (46 degrees), the presence 
of significant flux above 100 keV, and the complexity and overall
shape of the lightcurve are consistent with a GRB that is aligned
with the plane due to random coincidence. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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: GRB180623A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22829
SUBJECT: GRB 180623A: Enhanced Swift-XRT position
DATE:    18/06/23 21:24:42 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 3088 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 180623A, 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 = 214.52879, -60.25352 which is equivalent
to:

RA (J2000): 14h 18m 6.91s
Dec (J2000): -60d 15' 12.7"

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: GRB180623A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22830
SUBJECT: GRB 180623A: Swift-XRT refined Analysis
DATE:    18/06/23 23:56:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 7.7 ks of XRT data for GRB 180623A (Page et al. GCN
Circ. 22828), from 83 s to 18.2 ks after the  BAT trigger. The data
comprise 90 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Evans et al. (GCN Circ. 22829).

The late-time light curve (from T0+4.5 ks) can be modelled with a
power-law decay with a decay index of alpha=1.72 (+/-0.14).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.73 (+0.20, -0.19). The
best-fitting absorption column is  6.4 (+/-0.7) x 10^22 cm^-2, in
excess of the Galactic value of 1.5 x 10^22 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.04 (+0.27, -0.25)
and a best-fitting absorption column of 6.6 (+/-0.9) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 9.0 x 10^-11 (2.9 x 10^-10) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.6 (+/-0.9) x 10^22 cm^-2
Galactic foreground: 1.5 x 10^22 cm^-2
Excess significance: 9.9 sigma
Photon index:      2.04 (+0.27, -0.25)

If the light curve continues to decay with a power-law decay index of
1.72, the count rate at T+24 hours will be 2.3 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x
10^-13 (6.5 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/00844015.

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


GRB_name: GRB180623A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22831
SUBJECT: GRB 180623A: Swift/UVOT Detection
DATE:    18/06/24 13:58:14 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180623A
86 s after the BAT trigger (Page et al., GCN Circ. 22828).
A source consistent with the XRT position (Evans et al. GCN Circ. 22829)
is detected in the initial UVOT exposures.

The UVOT refined position is ra, deg = 214.5288,-60.2541 deg which is
RA = 14:18:06.9
Dec = -60:15:14.8
with an estimated uncertainty of 1".

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               86          236          150        >20.68
white              878          997          119         20.04 +/- 0.24
v                  629         6296          432        >19.2
b                18042        18207          162         19.86 +/- 0.28
u                  299        17732         2252        >21.6
w1                 678        16819         1318        >20.8
m2                 653         6501          432        >20.0
w2                 604         6092          432        >20.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 7.04 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180624A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22832
SUBJECT: GRB 180624A: Swift detection of a burst
DATE:    18/06/24 14:02:45 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

S. L. Gibson (U Leicester), S. D. Barthelmy (GSFC), A. Deich (PSU),
S. W. K Emery (UCL-MSSL), J.D. Gropp (PSU), K. L. Page (U Leicester),
T. Sakamoto (AGU) and M. H. Siegel (PSU) report on behalf of the Neil
Gehrels Swift Observatory Team:

At 13:49:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180624A (trigger=844192).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 318.071, -2.332, which is 
   RA(J2000)  =  21h 12m 17s
   Dec(J2000) = -02d 19' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Due to missing downlinked realtime data
in the light curve, we cannot give the BAT light curve description. 

The XRT began observing the field at 13:51:32.6 UT, 112.2 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 318.0951, -2.3397 which is equivalent to:
   RA(J2000)  = +21h 12m 22.82s
   Dec(J2000) = -02d 20' 22.9"
with an uncertainty of 5.2 arcseconds (radius, 90% containment). This
location is 91 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. 

The initial flux in the 2.5 s image was 1.93e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 118 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 S. L. Gibson (slg44 AT 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: GRB180623A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22833
SUBJECT: GRB 180623A: Swift-BAT refined analysis
DATE:    18/06/24 15:48:24 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), K. L. Page (U Leicester),
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+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180623A (trigger #844015)
(Page et al., GCN Circ. 22828).  The BAT ground-calculated position is
RA, Dec = 214.528, -60.268 deg which is
  RA(J2000)  =  14h 18m 06.8s
  Dec(J2000) = -60d 16' 05.6"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 63%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-60 s and ends at ~T+115 s. The three main peaks occur at ~T0, ~T+25 s,
and ~T+60 s, respectively. T90 (15-350 keV) is 114.9 +- 6.8 sec (estimated
error including systematics). Note that the burst entered the BAT FOV around
~ T-90 s. Therefore, there might be additional burst emission beforehand.

The time-averaged spectrum from T-61.8 to T+114.1 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.45 +- 0.04.  The fluence in the 15-150 keV band is 1.2 +- 0.02 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+59.11 sec in the 15-150 keV band
is 5.6 +- 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/844015/BA/


GRB_name: GRB180623A
Detection_method: retraction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22834
SUBJECT: GRB 180623A: retraction of the Swift/UVOT Detection
DATE:    18/06/24 18:46:53 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Source reported in our previous GCN Circ. No 22831 is
in fact a source present in the DSS survey. The extinction
of this bursts is very high, so there is no afterglow seen.
Our apologies for this error.


GRB_name: GRB180624A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22835
SUBJECT: GRB 180624A: Enhanced Swift-XRT position
DATE:    18/06/24 21:20:42 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 2472 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 180624A, 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 = 318.09749, -2.33826 which is equivalent
to:

RA (J2000): 21h 12m 23.40s
Dec (J2000): -02d 20' 17.7"

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: GRB180624A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22836
SUBJECT: GRB 180624A: Swift/UVOT Upper Limits
DATE:    18/06/24 22:33:42 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and S. L. Gibson (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180624A
118 s after the BAT trigger (Gibson et al., GCN Circ. 22832). No optical
afterglow consistent with the XRT position (Gibson et al. GCN Circ.
22832) 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           118          268          147         >20.7
u_FC               276          526          246         >19.4
white              118         6151          541         >21.3
v                 4927         6395          229         >20.0
b                 4312         5947          393         >21.2
u                  276         5742          639         >20.6
w1                3902         5537          393         >20.2
m2                5132         5332          197         >19.7
w2                4723         6357          393         >20.8

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: GRB180624A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  22837
SUBJECT: GRB 180624A: Swift-XRT refined Analysis
DATE:    18/06/25 00:10:26 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 10 ks of XRT data for GRB 180624A (Gibson et al. GCN
Circ. 22832), from 118 s to 23.6 ks after the  BAT trigger. The data
comprise 538 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Goad et al. (GCN Circ. 22835).

The late-time light curve (from T0+3.9 ks) can be modelled with a
power-law decay with a decay index of alpha=0.84 (+0.12, -0.11).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.472 (+/-0.025). The
best-fitting absorption column is  1.53 (+/-0.11) x 10^21 cm^-2, in
excess of the Galactic value of 4.6 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.08 (+0.19, -0.18)
and a best-fitting absorption column of 1.3 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.2 x 10^-11 (4.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.3 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 4.6 x 10^20 cm^-2
Excess significance: 3.0 sigma
Photon index:      2.08 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
0.84, the count rate at T+24 hours will be 0.013 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x
10^-13 (5.5 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/00844192.

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


