# GCN_circulars

GRB_name: GRB180724A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23100
SUBJECT: GRB 180724A: AstroSat CZTI detection
DATE:    18/08/08 08:29:11 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 180724A, which was also detected by Insight-HXMT/HE (Nang Y. et al., GCN 23038).

The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission with peak at 19:22:37.5 UT. The measured peak count rate is 585 cts/s above the background in combined data of four quadrants, with a total of 8613 cts. The local mean background count rate was 673.9 cts/s. Using cumulative rates, we measure a T90 of 30.3 s. In preliminary analysis, we find that 786 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: GRB180806A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23101
SUBJECT: GRB180806A: correction to Circular 23097
DATE:    18/08/08 21:30:10 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>

A. D'Ai (INAF/Iasf-PA) reports on behalf of the Swift/XRT Team:

this is a correction to the recent GCN Circ 23097 (S.L. Gibson et al).  
The angular distance between the  â€œSource 1" position and the 
Fermi/GBM final position was incorrectly reported.
The distance is 4.3 deg, not 1.3 arcsec.

We thank Alan Watson for spotting the error and we apologize for any inconvenience.


GRB_name: GRB180728A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23102
SUBJECT: GRB 180728A: AstroSat CZTI detection
DATE:    18/08/09 11:23:16 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 180728A, which was also detected by Swift (Starling R. L. C. et al., GCN 23046), Fermi-GBM (Veres P. et al., GCN 23053) and Konus-Wind (Frederiks D. et al., GCN 23061).

The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission with peak at 17:29:13.50 UT. The measured peak count rate is 1849.2 cts/s above the background in combined data of four quadrants, with a total of 6236 cts. The local mean background count rate was 650.8 cts/s. Using cumulative rates, we measure a T90 of 13.4 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: GRB180809A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23103
SUBJECT: GRB 180809A: MAXI/GSC detection
DATE:    18/08/09 12:32:01 GMT
FROM:    Satoshi Nakahira at RIKEN  <nakahira@crab.riken.jp>

F. Yatabe, S. Nakahira, T. Mihara, Y. Takao, M. Matsuoka (RIKEN),
M. Serino, T. Sakamoto,  S. Sugita, Y. Kawakubo, T. Hashimoto, A. Yoshida (AGU),
H. Negoro, M. Nakajima, A. Sakamaki, W. Maruyama (Nihon U.),
N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita (Tokyo Tech),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA),
Y. Ueda, A. Tanimoto, T. Morita, S. Yamada (Kyoto U.),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
H. Tsunemi, T. Yoneyama (Osaka U.),
M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.),
M. Shidatsu (Ehime U.)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient
source at  11:38:25 UT on 9 August 2018.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (297.793 deg, -34.663 deg) = (19 51 10, -34 39 46) (J2000)
with a 90% C.L. statistical error of 0.09 deg and an additional systematic
uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 890 +- 57 mCrab
(4.0-10.0keV, 1 sigma error).
Without assumptions on the source constancy,we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (297.202, -33.964) deg = (19 48 48, -33 57 49) (J2000)
(R.A., Dec) = (297.086, -34.046) deg = (19 48 20, -34 02 46) (J2000)
(R.A., Dec) = (298.358, -35.535) deg = (19 53 25, -35 32 04) (J2000)
(R.A., Dec) = (298.475, -35.451) deg = (19 53 54, -35 27 03) (J2000)
There was no significant excess flux in the previous transit at UT 10:05
with an upper limit of 20 mCrab.


GRB_name: GRB180809A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23104
SUBJECT: GRB 180809A: Tiled Swift observations
DATE:    18/08/09 15:34:24 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
MAXI GRB 180809A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00072

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 MAXI 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: GRB180809B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23105
SUBJECT: GRB 180809B: Swift detection of a burst with an optical afterglow
DATE:    18/08/09 20:40:30 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

M. J. Moss (George Washington University), S. D. Barthelmy (GSFC),
V. D'Elia (ASDC), C. Gronwall (PSU), J.D. Gropp (PSU),
J. A. Kennea (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 20:28:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180809B (trigger=852553).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 299.712, -15.302, which is 
   RA(J2000)  =  19h 58m 51s
   Dec(J2000) = -15d 18' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple bright peaks
structure with a total duration of about 80 sec.  The peak count rate
was ~35,000 counts/sec (15-350 keV), at ~35 sec after the trigger. 

XRT found a bright, uncatalogued X-ray source located at RA, Dec
299.6998, -15.2988 which is equivalent to:
   RA(J2000)  = +19h 58m 47.95s
   Dec(J2000) = -15d 17' 55.7"
with an uncertainty of 6.1 arcseconds (radius, 90% containment). No
event data are yet available to determine the column density using
X-ray spectroscopy. 

The initial flux in the 0.1 s image was 1.51e-08 erg cm^-2 s^-1 (0.2-10
keV). 

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)  = 19:58:47.96 = 299.69983
  DEC(J2000) = -15:17:56.9  = -15.29915
with a 90%-confidence error radius of about 0.64 arc sec. This position is 1.3
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.91 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.16. 

Burst Advocate for this burst is M. J. Moss (mikejmoss3 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: GRB180809A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23106
SUBJECT: GRB 180809A: Swift-XRT afterglow detection
DATE:    18/08/09 20:48:31 GMT
FROM:    Valerio D'Elia at ASDC  <valerio.delia@ssdc.asi.it>

V. D'Elia (SSDC), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U.
Leicester), A. D'Ai (INAF-IASFPA), 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) and P.A. Evans (U. Leicester) report
on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 180809A (Yatabe et al. GCN Circ. 23103) in a series of
observations tiled on the sky. The total exposure time is 777 s,
distributed over 6 tiles; the maximum exposure at a single sky location
was 898 s. The data were collected between T0+13.7 ks and T0+22.0 ks,
and are entirely in Photon Counting (PC) mode. 

An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow. Using 731 s of PC mode data
and 3 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 = 297.90271, -34.78546 which is equivalent to:

RA (J2000): 19h 51m 36.65s
Dec(J2000): -34d 47' 07.6"

with an uncertainty of 2.3 arcsec (radius, 90% confidence). This
position is 9.1 arcmin from the MAXI position. The light curve is
currently consistent with a constant source of mean count rate 2.2e-01
ct/sec. A power-law fit gives an index of 0.3 (+/-0.9). More data are
necessary to determine potential fading.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.4 (+0.7, -0.6). The
best-fitting absorption column is  8.4 (+5.4, -3.8) x 10^21 cm^-2, in
excess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.2 x 10^-11 (8.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.4 (+5.4, -3.8) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^21 cm^-2
Excess significance: 3.1 sigma
Photon index:      2.4 (+0.7, -0.6)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020814.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00072.

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


GRB_name: GRB180809A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23107
SUBJECT: GRB 180809A: iTelescope optical limit
DATE:    18/08/09 21:38:39 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

A.K.H. Kong (NTHU, Taiwan) reports

We observed the field of GRB 180809A (Yatabe et al. GCN 23103) with
the T30 0.51m telescope of iTelescope.Net in Siding Spring, Australia.
The observation was done with a luminance filter (400-700 nm)
beginning at 2018-08-09 12:51:14 UT (73 min after the trigger) for 300
sec. At the position of the proposed X-ray afterglow (D'Elia et al.
GCN 23106), we do not detect any optical emission with a detection
limit of about 20 mag by comparing with the Gaia DR2 catalogue.


GRB_name: GRB180805B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23108
SUBJECT: GRB 180805B: Teide LCO optical observations
DATE:    18/08/09 22:48:10 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele B. Malesani (DAWN/NBI and DARK/NBI) and Nicolas Crouzet (IAC) 
report:

We observed the field of the short GRB 180805B (D'Avanzo et al., GCN 
23076; Sakamoto et al., GCN 23082) using one of the 40-cm telescopes 
located in the Teide observatory (Canary Islands), part of the Las 
Cumbres Observatory network.

Observations consisted of 9x300 s exposures in the SDSS r filter, 
centered around the mean epoch Aug 6.19 UT (15.49 hr after the GRB). The 
PSF delivered to the image is around 3".

No object is detected within or close to the X-ray afterglow error 
circle (Evans et al., GCN 23077), down to a 3-sigma limiting magnitude 
of r = 20 AB, calibrated using nearby stars from the Pan-STARRS catalog.


GRB_name: GRB180809B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23109
SUBJECT: GRB180809B: MASTER OT observation
DATE:    18/08/10 00:26:43 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, N.Tiurina, E. Gorbovskoy,
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, D. Vlasenko
Lomonosov Moscow State University,SAI

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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,
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

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

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


MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
South Africa (South African Astronomical Observatory)
was pointed to the   GRB180809B(Moss et al. GCN 23105) 16 sec after notice 
time and 42 sec after trigger time at 2018-08-09 20:30:40 UT.
On our 3-th (20s exposure)  set , obtained 101 sec after tigger time at 2018-08-09 20:31:39 UT,
we  found 1 optical transient  within SWIFT error-box


  T-Tmid      Date      Time       Expt.        Ra                Dec           mag
---------|---------------------|-------|-----------------|-----------------|-------
      111   2018-08-09 20:31:39      20    (19h 58m 48.0s , -15d 17m 57.1s)     16.87

also detected by Swift UVOT (Moss et al. GCN 23105)

The 5-sigma upper limit has been about 17.4mag
The message may be cited.


GRB_name: GRB180809B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23110
SUBJECT: GRB 180809B: RATIR Optical Observations and Confirmation of Rapid Fading 
DATE:    18/08/10 07:17:19 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Eleonora Troja (GSFC), 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), 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 180809B (Moss et al., GCN Circ. 23105) 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 2018/08 10.19 to 2018/08 10.29
UTC (8.2 to 10.6 hours after the BAT trigger), obtaining a total of 1.42
hours exposure in the r and i bands.

We do not detect the UVOT and MASTER optical counterpart (Moss et al.,
GCN Circ. 23105; Lipunov et al., GCN Circ. 23109) to the following
3-sigma limits:

r > 23.6
i > 23.5

These magnitudes are in comparison with the USNO-B1, are in the AB
system and are not corrected for Galactic extinction in the direction of
the GRB.

The optical counterpart has faded by more than 6 magnitudes between the
MASTER and RATIR observations.

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


GRB_name: GRB180809B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23111
SUBJECT: GRB 180809B: GROND Detection of the NIR Afterglow 
DATE:    18/08/10 07:19:10 GMT
FROM:    Patricia Schady at Swift  <p.schady@bath.ac.uk>

Tassilo Schweyer (MPE Garching) and Patricia Schady (University of Bath) report:

We observed the field of GRB 180809B (Swift trigger 852553; Moss et al., GCN #23105) 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  23:00UT on 2018-08-09, 2.5 hrs after the GRB trigger. They were performed at an average seeing of 1.3" and at an average airmass of 2.

We detect a source in the JHK bands consistent with the position of the X-ray and optical afterglow (Mass et al., GCN #23105; Lipunov et al., GCN #23109). Based on a total exposure of time of 19 minutes in g'r'i'z' and 29 minutes in JHK we estimate the following AB magnitudes and upper limits at the position of the UVOT detection:

g' > 23.9 mag
r' > 23.9 mag
i' > 22.9 mag
z' > 22.4 mag
J = 21.0 +/- 0.3 mag
H = 19.9 +/- 0.2 mag
K = 18.7 +/- 0.1 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)=0.14 in the direction of the burst (Schlafly & Finkbeiner 2011).

We thank Markus Rabus for the excellent support from La Silla.


GRB_name: GRB180809B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23112
SUBJECT: GRB 180809B: LCO Sutherland observations
DATE:    18/08/10 08:59:56 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), A. Cucchiara, 
D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:

We observed Swift GRB 180809B (Moss et al. GCN 23105) with the LCO 1-m 
units at Sutherland Observatory (South Africa) on August 09, from 20:58 
to 22:29 UT (corresponding to 0.5 to 2.0 hours from the GRB trigger 
time) with the SDSS r' and i' filters. We clearly detect the optical 
afterglow (Moss et al; Lipunov et al. GCN 23109; Watson et al. GCN 
23110; Schweyer et al. GCN 23111) in both filters with the following 
magnitudes:

Mid time from GRB      Exposure         Filter Magnitude
trigger time (hrs)     (s)
---------------------------------------------------------------------
0.55                   5x60             SDSS r'         19.54 +- 0.08
0.70                   5x60             SDSS i'         19.24 +- 0.07
---------------------------------------------------------------------

as calibrated against nearby Pan-STARRS objects.


GRB_name: GRB180809B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23113
SUBJECT: GRB180809B: MASTER  Triple Independent Automatic OT Detection
DATE:    18/08/10 09:07:16 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

N.Tiurina, V. Lipunov, E. Gorbovskoy,
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, D. Vlasenko
Lomonosov Moscow State University,SAI

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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,
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

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

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


We have already reported the observation of the optical transient GRB 
180809B (Moss et al., GCN # 23105) by one of the telescopes of the MASTER 
Global Network (Lipunov et al., GCN 23109).

Here we report on the triple independent, automatic detection of the 
optical transient (also found by Swift UVOT (Moss et al., GCN 23105)). The 
relatively later guidance of the three MASTER robotic telescopes is due to 
the fact that the first socket message did not indicate the time of the 
trigger. As a result, everyone went to the CALET Alert (trig 
number 1217881726) with poor defined coordinates. 
Nevertheless, we were able to obtain detailed light curves 
with a maximum in 4 polarizations.


MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
South Africa (South African Astronomical Observatory) was pointed to the 
GRB180809.85 16 sec after notice time and 111 sec after trigger time at 
2018-08-09 20:30:39 UT. On our 1-th (10s exposure)  set in two 
polarizations (/\), obtained 111 
sec after tigger time at 2018-08-09 20:30:39 UT, we  found 1 optical transient 
within SWIFT error-box (ra=299.7 dec=-15.2989 r=0.05) brighter then 17.4.


  T-Tmid      Date   Time       Expt.        Ra                Dec        Mag
    s                 UT         s
-------|--------------------|-------|-----------------|---------------|-------
   116    2018-08-09 20:30:39    10    (19h 58m 48.0s , -15d 17m 57.1s)   16.5

The 5-sigma upper limit has been about 17.9 mag


The observations started on zenit distance = 21 deg., galactic latitude b 
= -22 deg. The moon ( 4 % bright part) was below the horizon (The altitude 
of the  Moon = -75 deg ). The sun  altitude  = -56.3 degree. The object 
can be observed till 2018-08-10 04:03:58 UT.


MASTER-Tavrida robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the 
GRB180809.85 35 sec after notice time and 133 sec after trigger time at 
2018-08-09 20:31:01 UT. On our first (10s 
exposure)  set we  found 1 optical transient within SWIFT error-box
(ra=299.7 dec=-15.2989 r=0.05) brighter then 17.9:


T-Tmid   Date      Time       Expt.        Ra                Dec           Mag
   s                UT         s
------|--------------------|-------|-----------------|-----------------|-------
  138    2018-08-09 20:31:01    10    ( 19h 58m 48.0s , -15d 17m 56.5s)    16.8

The 5-sigma upper limit has been about 17.9 mag


The observations made on zenit distance = 60 degrees, galaxy latitude b = -22 degree.
The moon ( 4 % bright part) below the horizon (The altitude of the Moon is 
-25 degree ). The sun  altitude  is -27.0 degree.
The object can be observed till 2018-08-10 01:29:20.


MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Spain (IAC Teide Observatory) was pointed to the  GRB180809.85 120 sec 
after notice time and 147 sec after trigger time at 2018-08-09 20:31:15 
UT in two polarizations (|-). 
On our first  set, obtained   we  found 1 optical transient within SWIFT 
error-box (ra=299.7 dec=-15.2989 r=0.05):


  T-Tmid      Date      Time       Expt.        Ra                Dec           Mag
---------|---------------------|-------|-----------------|-----------------|-------
   152      2018-08-10 20 31 15     20   ( 19h 58m 43.3s , -15d 20m 37.9s)     15.5

The 5-sigma upper limit has been about 16.0 magThe message may be cited.

The observations made on zenit distance = 44 degrees, galaxy latitude b = 
-22 degree. The moon ( 3 % bright part) below the horizon (The altitude of 
the Moon is  -41 degree ). The sun  altitude  is  -9.1 deg.
The object can be observed till 2018-08-10 05:19:05 UT.


The message may be cited.


GRB_name: GRB180809B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23114
SUBJECT: GRB 180809B: VLT optical upper limits
DATE:    18/08/10 10:18:56 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

J. Japelj (U. Amsterdam), D. B. Malesani (DAWN/NBI and DARK/NBI), J. 
Selsing (DAWN/NBI), N. R. Tanvir (U. Leicester), D. A. Kann 
(HETH/IAA-CSIC), V. D'Elia (ASI-SSDC), G. Pugliese (U. Amsterdam), K. E. 
Heintz (Univ. Iceland and DAWN/NBI), J. P. U. Fynbo (DAWN/NBI), A. J. 
Levan (Univ. Warwick), P. Schady (University of Bath), report on behalf 
of the Stargate collaboration:

We observed the field of GRB 180809B with the ESO VLT UT2 (Kueyen), 
using the X-shooter acquisition camera. In a single 120-s r-band 
exposure, with a mean epoch Aug 10.055 UT (4.84 hr after the GRB), we 
detect no object at the position of the optical afterglow (e.g., Moss et 
al., GCN 23105; Lipunov et al., GCN 23109; Schweyer et al. GCN 23111; 
Guidorzi et al., GCN 23112, Tiurina et al., GCN 23113), down to a 
limiting magnitude r > 24.7 AB (calibrated against nearby Pan-STARRS 
sources).

Compared to the r-band measurement by Guidorzi et al. (GCN 23112), and 
assuming an unbroken power-law decay F(t) propto t^-alpha, the 
corresponding decay index is alpha > 2.2 between 0.55 and 4.84 hr after 
the GRB.

We acknowledge excellent support from the observing team in Paranal, 
including Steffen Mieske and Boris Haeussler.


GRB_name: GRB180809B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23116
SUBJECT: GRB 180809B: CALET Gamma-Ray Burst Monitor detection
DATE:    18/08/10 12:21:10 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, V. Pal'shin,
S. Sugita, Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa,
T. Ito, H. Morita, Y. Sone (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),
S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long, bright GRB 180809B (Swift-BAT trigger #852553: Moss et al.,
GCN Circ. 23105) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 20:28:41.478 UTC on 9 August 2018 while exiting the radiation belts.
The burst signal was seen by all CGBM detectors.

The burst light curve shows the main multi-peaked emission episode which
starts at T-5 sec, peaks at T+41.4 sec, and ends at T+79.9 sec, followed by
a weaker pulse which starts at T+210.0 sec and ends at T+254.6 sec.
The T90 and the T50 durations measured by the SGM data are
227.6 +- 5.4 sec and 28.3 +- 5.7 sec (40-1000 keV), respectively.
Since the CGBM HV was set to its nominal value at T-21 sec for
the HXM1 and HXM2 detectors and at T-5 sec for the SGM detector,
CGBM was blind to a possible earlier emission.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1217881726/

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


GRB_name: GRB180809A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23117
SUBJECT: GRB 180809A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/08/10 12:55:19 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, V. Pal'shin,
S. Sugita, Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa,
T. Ito, H. Morita, Y. Sone (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),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The GRB 180809A (MAXI/GSC detection: Yatabe et al., GCN Circ. 23103;
Fermi-GBM trigger #555507497) was detected in ground analysis
of the CALET Gamma-ray Burst Monitor (CGBM) data near the MAXI trigger
time at T0=11:38:25 UT on 9 August 2018.
The burst signal was seen by all CGBM detectors.

The burst light curve shows a weak pulse which starts
at T-15.1 sec and ends at T-4.2 sec.
The T90 and the T50 durations measured by the SGM data are
10.0 +- 1.6 sec and 5.0 +- 1.6 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1217849910/

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


GRB_name: GRB180809A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23118
SUBJECT: GRB 180809A: Fermi GBM observation
DATE:    18/08/10 13:00:48 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 11:38:12.08 UT on 9 August 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180809A (trigger 555507497 / 180809485),
which was also detected by MAXI/GSC (Yatabe et al. 2018, GCN 23103) and
Swift/XRT (D'Elia et al. 2018, GCN 23106).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 60 degrees.

The GBM light curve consists of multiple emission episodes
with a duration (T90) of about 220 s (50-300 keV).
The time-averaged spectrum of the main emission episode
from T0-5 s to T0+15 s is adequately fit by a power law
function with an exponential high-energy cutoff.
The power law index is -1.37 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 620 +/- 230 keV.

The event fluence (10-1000 keV) in this time interval is
(6.8 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+3.2 s in the 10-1000 keV band is 4.0 +/- 0.3 ph/s/cm^2.


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


GRB_name: GRB180806A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23119
SUBJECT: Konus-Wind observation of GRB 180806A
DATE:    18/08/10 15:33:07 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 180806A
(Fermi GBM detection: Malacaria et al., GCN 23095)
triggered Konus-Wind at T0=81544.19 s UT (22:39:04.190).

The burst light curve shows a single pulse with a total duration of ~20 s.
The emission is seen up to ~1.2 MeV.

As observed by Konus-Wind, the burst
had a fluence of 2.92(-0.36,+0.41)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+5.712 s,
of 5.52(-1.59,+1.66)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+7.424 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.76(-0.14,+0.16),
the high energy photon index beta = -2.56(-0.79,+0.32),
the peak energy Ep = 352(-53,+59) keV,
chi2 = 90/94 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180806_T81544/

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


GRB_name: GRB180809B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23120
SUBJECT: GRB 180809B: Swift/UVOT Detection
DATE:    18/08/10 16:29:24 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 180809B: Swift/UVOT Detection

S. Sebzda (PSU) and M. Moss (George Washington University)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180809B
82 s after the BAT trigger (Moss et al., GCN Circ. 23105).
A fading source consistent with the XRT position
(Moss et al. GCN Circ. 23105)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  19:58:47.96 = 299.69984 (deg.)
    Dec (J2000) = -15:17:57.1  = -15.29920 (deg.)
with an estimated uncertainty of 0.48 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               81          231          293         18.99+-0.07
white              573         6926          441        >21.55
v                  623         7289          444        >19.8
b                  549         6721          294        >20.9
u                  294         6516          520        >21.0
w1                 672        13027          915        >20.7
m2                 648        11053          906        >20.9
w2                 599        16967         1262        >21.3

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


GRB_name: GRB180806A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23122
SUBJECT: GRB 180806A: AstroSat CZTI detection
DATE:    18/08/10 17:58:28 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 180806A, which was also detected by Fermi-GBM (Malacaria C. et al., GCN 23095) and Konus-Wind (Tsvetkova A. et al., GCN 23119).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 22:39:04.500 UT. The measured peak count rate is 994 cts/s above the background in combined data of four quadrants, with a total of 9327 cts. The local mean background count rate was 498 cts/s. Using cumulative rates, we measure a T90 of 25.8 s. In preliminary analysis, we find that 623 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: GRB180809B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23123
SUBJECT: GRB 180809B, Swift-BAT refined analysis
DATE:    18/08/10 18:20:37 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),
M. J. Moss (GWU), D. M. Palmer (LANL),
T. Sakamoto (AGU), 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 180809B (trigger #852553)
(Moss et al., GCN Circ. 23105).  The BAT ground-calculated position is
RA, Dec = 299.712, -15.293 deg which is
  RA(J2000)  =  19h 58m 50.8s
  Dec(J2000) = -15d 17' 34.0"
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-36 s and ends at ~T+80 s, followed by another pulse that starts
at ~T+200 s and ends at ~T+250 s. The total burst emission ends at ~T+300 s.
T90 (15-350 keV) is 233.2 +- 1.1 sec (estimated error including systematics).

We note that the later pulse overlaps with the XRT flare and some ground-based
optical observations (e.g. Tiurina et al.; GCN #23113), which indicates an increase
 in the optical magnitude from Mag 16.5 to 15.5 at the pulse time.

The time-averaged spectrum from T-36.1 to T+302.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.26 +- 0.02.  The fluence in the 15-150 keV band is 7.3 +- 0.1 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+35.10 sec in the 15-150 keV band
is 26.3 +- 0.6 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/852553/BA/


GRB_name: GRB180809B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23124
SUBJECT: GRB 180809B: CrAO optical observations
DATE:    18/08/10 19:50:36 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of the GRB 180809B (Moss  et al., GCN 23105)
with ZTSH 2.6m telescope of CrAO observatory starting on Aug. 9 (UT) 
21:14:58. We took several images in BVRI filters  with exposures of 120 
s. We  detect  the afterglow (e.g., Moss et al., GCN 23105; Lipunov et 
al., GCN 23109; Schweyer et al. GCN 23111; Guidorzi et al., GCN 23112, 
Tiurina et al., GCN 23113).
Preliminary photometry of the afterglow in R- filter is following

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

21:14:58.579          0.03276 R       1*120    19.80 0.05
21:17:05.489          0.03423 R       1*120    19.86 0.04
21:19:12.801          0.03570 R       1*120    19.93 0.05
21:25:54.597          0.04035 R       1*120    20.35 0.05
21:34:27.347          0.04629 R       1*120    20.86 0.08
21:43:00.178          0.05519 R       2*120    21.51 0.11

The photometry is based on nearby  USNO-B1.0 stars:

Ref.stars 
USNO-B1.0_id R2
0747-0765959 19.65
0746-0776364 18.76
0746-0776499 19.18


GRB_name: GRB180809B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23125
SUBJECT: GRB 180809B: Swift-XRT refined Analysis
DATE:    18/08/10 20:40:03 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), V. D'Elia (ASDC), A. Tohuvavohu (PSU), S. J. LaPorte (PSU),
J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and M.J. Moss report on behalf of the Swift-XRT team:

We have analysed 3.9 ks of XRT data for GRB 180809B (Moss et al. GCN
Circ. 23105), from 74 s to 12.6 ks after the  BAT trigger. The data
comprise 1.7 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. Using 1724 s of PC mode data and 4 UVOT
images, we find an enhanced XRT position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
299.69997, -15.29893 which is equivalent to:

RA (J2000): 19h 58m 47.99s
Dec(J2000): -15d 17' 56.1"

with an uncertainty of 1.4 arcsec (radius, 90% confidence).

The late-time light curve (from T0+4.7 ks) can be modelled with a
power-law decay with a decay index of alpha=1.37 (+/-0.12).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.609 (+/-0.017). The
best-fitting absorption column is  2.29 (+0.09, -0.08) x 10^21 cm^-2,
in excess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.63 (+/-0.11) and a
best-fitting absorption column of 2.4 (+/-0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.6 x 10^-11 (5.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.4 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^21 cm^-2
Excess significance: 4.0 sigma
Photon index:      1.63 (+/-0.11)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00852553.

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


GRB_name: GRB180809B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23127
SUBJECT: GRB180809B TUG T60 observations
DATE:    18/08/11 11:25:53 GMT
FROM:    Yucel Kilic at TUBITAK,TUG  <yucel.kilic@tubitak.gov.tr>

Y. Kilic, M. Dindar, T. Ozisik, M. T. Ozkan, S. Ozdemir
TUBITAK National Observatory (TUG)

TUG T60 robotic telescope (http://tug.tubitak.gov.tr/en/teleskoplar/t60-0,
Dindar, M. et al. Exp Astron (2015)) located in TUBITAK National Observatory
in Antalya was pointed to GRB180809B (Moss et al. GCN 23105) field 54 seconds
after receiving the alert and began to take the exposure. In total, 8 R filter
images and 4 B filter images were taken with the FLI PL 3041 CCD camera.
No source could be detected on B filter. The GRB180809B is detected in the all
the images observed in the R filter within the SWIFT error-box. Astrometry was
made with the astrometry.net and magnitudes were estimated using the NOMAD catalog.


T-Tmid      Date      Time       Expt.        Ra                Dec        Mag.
   s                   UT         s                                         R
---------|---------------------|-------|-----------------|---------------|----
      64   2018-08-09 20:31:13    20     19h 58m 48.0s   -15d 17m 56.7s   16.07
      91   2018-08-09 20:31:39    20     19h 58m 48.0s   -15d 17m 56.7s   16.24
     117   2018-08-09 20:32:05    20     19h 58m 48.0s   -15d 17m 56.7s   16.52
     183   2018-08-09 20:33:12    60     19h 58m 48.0s   -15d 17m 56.7s   16.29
     249   2018-08-09 20:34:18    60     19h 58m 48.0s   -15d 17m 56.7s   16.59
     316   2018-08-09 20:35:25    60     19h 58m 48.0s   -15d 17m 56.7s   16.90
     382   2018-08-09 20:36:31    60     19h 58m 48.0s   -15d 17m 56.7s   17.20
     449   2018-08-09 20:37:38    60     19h 58m 48.0s   -15d 17m 56.7s   17.37


GRB_name: GRB180809B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23128
SUBJECT: Konus-Wind observation of GRB 180809B
DATE:    18/08/11 16:06:36 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 180809B
(Swift-BAT detection: Moss et al., GCN Circ. 23105;
CALET-GBM detection: Cherry, et al., GCN Circ. 23116)
triggered Konus-Wind at T0=73730.033 s UT (20:28:50.033).

The burst light curve shows a bright multi-peaked emission episode
which starts at ~T0-4 s and has a duration of ~80 s, followed by a 
weaker episode at ~T0-205 s. The total burst duration is ~300 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/GRB180809_T73730/

As observed by Konus-Wind, the burst
had a fluence of 3.07(-0.30,+0.36)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+37.952 s,
of 2.66(-0.41,+0.42)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+252.672 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.87(-0.10,+0.12),
the high energy photon index beta = -2.44(-0.24,+0.19),
the peak energy Ep = 275(-30,+25) keV
(chi2 = 123/97 dof).

The spectrum near the maximum count rate
(measured from T0+36.608 to T0+38.144 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.77(-0.12,+0.15),
the high energy photon index beta = -2.20(-0.21,+0.15),
the peak energy Ep = 525(-95,+103) keV
(chi2 = 66/68 dof).

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


GRB_name: GRB180812A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23129
SUBJECT: GRB 180812A: Swift detection of a burst
DATE:    18/08/12 08:37:38 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA),
V. D'Elia (ASDC), C. Gronwall (PSU), K. L. Page (U Leicester) and
E. Troja (NASA/GSFC/UMCP) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 08:22:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180812A (trigger=852903).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 245.886, +74.670, which is 
   RA(J2000)  =  16h 23m 33s
   Dec(J2000) = +74d 40' 11"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several peaks
with a total duration of about 25 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 08:24:17.6 UT, 107.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 245.8360, 74.6647 which
is equivalent to:
   RA(J2000)  = 16h 23m 20.64s
   Dec(J2000) = +74d 39' 53.0"
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This
location is 51 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 in excess of the Galactic value (4.37 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.8
(+4.29/-3.49) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 112 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: GRB180812A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23130
SUBJECT: GRB 180812A: BOOTES-5/JGT optical afterglow detection
DATE:    18/08/12 09:52:43 GMT
FROM:    Irene Carrasco at Inst.De Astrofisica de Andalucia  <irene@iaa.es>

I. Carrasco (Univ. de Malaga), Y. Hu, E. Fernandez-Garcia, J. C. Tello 
and A. J. Castro-Tirado (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), S. 
Jeong and I. H. Park (SKKU), M. D.
Caballero-Garcia (ASU-CAS, CZ) and R. Cunniffe (Inst. of Physics, CZ) on 
behalf of a larger collaboration, report:

The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico 
Nacional in San Pedro Martir (Mexico) automatically responded in 22s 
(and 52s after the GRB onset) to the
Swift trigger of GRB 180812A (Lien et al., GCNC 23129). The first image 
(10s exposure, r-band) was obtained at 08:23:25 UT. At the position of 
the Swift X-ray afterglow, a variable optical source with r about 17 mag 
is detected, which is fading in brightness in the late images. Therefore 
we propose this source to be the optical afterglow to GRB 180812A. 
Spectroscopic observations are encouraged.

We thank the staff at Observatorio Astronomico Nacional in San Pedro 
Martir for its excellent support.


GRB_name: GRB180812A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23131
SUBJECT: GRB 180812A: Enhanced Swift-XRT position
DATE:    18/08/12 12:30:57 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 2046 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 180812A, 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 = 245.83465, +74.66472 which is equivalent
to:

RA (J2000): 16h 23m 20.32s
Dec (J2000): +74d 39' 53.0"

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

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

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


GRB_name: GRB180812A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23132
SUBJECT: GRB 180812A: COATLI Detection and Light Curve 
DATE:    18/08/12 12:52:06 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

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

We observed the field of GRB 180812A (Lien et al., GCN 23129) 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 2018-08-12 08:13.5 to 11:53:16.7
(from 11.6 seconds after the alert or 43.1 seconds after the trigger to
3.5 hours after the trigger), obtaining a total of 2.46 hours of
exposure in the w filter.

We detect the optical counterpart reported by Carrasco et al. (GCN Circ.
23130). We see it rise from w = 17.4 to w = 17.2 at 160 seconds after
burst, and then fade rapidly.

We note that simultaneous observations with UVOT in the white filter do
not detect anything to a limit of about 19.8 (Lien et al., GCN 23129).
Our w filter is much redder than the UVOT white filter, which suggests
that this might be an intrinsically red afterglow or be attenuated by
intergalactic absorption in the blue.

These magnitudes are calibrated against the USNO-B1 catalog (adjusted to
an approximate AB system) and are 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.

[GCN OPS NOTE(12aug18): The GRB name in the Subject-line and the first pagragraph
has been changed from "180612A" to "180812A".]


GRB_name: GRB180809B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23133
SUBJECT: GRB 180809B: ePESSTO NTT NIR observations
DATE:    18/08/12 14:02:05 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

Z. Kostrzewa-Rutkowska (SRON/RU), E. Callis (UCD), R. Stein (HU Berlin/DESY), P. D'Avanzo (INAF-OAB), M. Fraser (UCD), J. Lyman (Warwick), D. B. Malesani (DAWN/NBI and DARK/NBI), C. Inserra (Southampton), E. Kankare (QUB), K. Maguire (QUB), S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), I. Manulis (Weizmann) report:

We observed the field of GRB 180809B (Moss et al., GCN Circ. 23105) 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 on 2018-08-12 between 03:38 and 04:27 UT (i.e. about 2.298 and 2.332 days from the burst) with the H filter.

The NIR counterpart (Schweyer et al. GCN Circ. 23111) is clearly detected. From preliminary photometry, we estimate a magnitude of H ~ 20.3 (Vega, calibrated against the 2MASS catalogue). Compared to earlier reports (Schweyer et al. GCN Circ. 23111), our measure indicates significan fading. However, we cannot assess if we already reached the host galaxy level. 


GRB_name: GRB180812A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23134
SUBJECT: GRB 180812A: Swift-XRT refined Analysis
DATE:    18/08/12 17:18:20 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), S. J.
LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester) and A.Y. Lien report on behalf of the Swift-XRT team:

We have analysed 8.2 ks of XRT data for GRB 180812A (Lien et al. GCN
Circ. 23129), from 114 s to 24.0 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. 23131).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.08 (+/-0.05).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.74 (+0.16, -0.14). The
best-fitting absorption column is  6.8 (+4.3, -2.4) x 10^20 cm^-2,
consistent with the Galactic value of 4.4 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 3.8 x 10^-11 (4.2 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.8 (+4.3, -2.4) x 10^20 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.74 (+0.16, -0.14)

If the light curve continues to decay with a power-law decay index of
1.08, 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 (1.1 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/00852903.

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


GRB_name: GRB180812A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23135
SUBJECT: GRB 180812A: Fermi GBM detection
DATE:    18/08/12 20:52:06 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

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


"At 08:22:30.31 UT on 12 August 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180812A (trigger 555754955 / 180812349),
which was also detected by the Swift BAT and XRT instruments (Lien et al.
2008, GCN 23129). The GBM on-ground location is consistent with the Swift
position.

The angle from the Fermi LAT boresight at the GBM trigger time is 46
degrees.

The GBM light curve shows several peaks with a duration (T90) of about 38 s
(50-300 keV). The time-averaged spectrum from T0-2.0 s to T0+34.8 s is
adequately fit by a power law function with an exponential high-energy
cutoff.
The power law index is -0.56 +/- 0.36 and the cutoff energy, parameterized
as Epeak, is 110 +/- 25 keV.

The event fluence (10-1000 keV) in this time interval is
(1.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+15.7 s in the 10-1000 keV band
is 2.5 +/- 0.2 ph/s/cm^2.

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


GRB_name: GRB180812A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23136
SUBJECT: GRB 180812A: Swift-BAT refined analysis
DATE:    18/08/12 21:19:33 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-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180812A (trigger #852903)
(Lien et al., GCN Circ. 23129).  The BAT ground-calculated position is
RA, Dec = 245.839, 74.674 deg which is
  RA(J2000)  =  16h 23m 21.3s
  Dec(J2000) = +74d 40' 27.0"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T0 and ends at ~T+17 s. T90 (15-350 keV) is 16.51 +- 0.92 sec (estimated
error including systematics).

The time-averaged spectrum from T-0.30 to T+16.63 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.22 +- 0.27.  The fluence in the 15-150 keV band is 8.0 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+15.62 sec in the 15-150 keV band
is 1.9 +- 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/852903/BA/


GRB_name: GRB180812A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23138
SUBJECT: GRB 180812A: Swift/UVOT Detection
DATE:    18/08/13 18:24:45 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 180812A: Swift/UVOT Detection

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 180812A
112 s after the BAT trigger (Lien et al., GCN Circ. 23129).
A fading source consistent with the XRT position
(Goad et al. GCN Circ. 23131)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  16:23:20.45 =  245.83522 (deg.)
    Dec (J2000) = 74:39:52.9 =  74.66471 (deg.)
with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence),
consistent with detections reported by BOOTES-5/JGT (Carrasco et al. GCN
Circ. 23130) and COATLI (Watson et al. GCN Circ. 23132).

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              140          289          431         19.81 +/- 0.17
white             1551         2092           77        >20.85
v                  600         6610          372        >18.9
b                  526         5994          352        >20.0
u                  270         5789          598        >19.8
w1                 650         6857          211        >19.5
m2                6616         6815          197        >20.2
w2                6206         6406          197        >20.2

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: GRB180809A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23141
SUBJECT: GRB 180809A: further Swift/XRT observations
DATE:    18/08/15 14:06:39 GMT
FROM:    Valerio D'Elia at ASDC  <valerio.delia@ssdc.asi.it>

V. D'Elia (SSDC) reports on behalf of the Swift/XRT team:

Swift performed a second visit to the field of the  MAXI-detected burst GRB 180809A (Yatabe et al. GCN Circ. 23103). The XRT data comprise 3700 s of exposure time, acquired ~5 days after the GRB trigger and entirely in PC mode. 

No excess is found at the position of the candidate afterglow reported by D'Elia et al. (GCN Circ. 23106), down to a three sigma upper limit of ~4E-3 cts/s, corresponding to a 0.3-10 keV observed flux of ~1E-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). We thus conclude that the source reported by D'Elia et al. (GCN Circ. 23106) was indeed the X-ray counterpart of the MAXI GRB 180809A.

This circular is an official product of the Swift/XRT team


GRB_name: GRB180728A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23142
SUBJECT: GRB 180728A: discovery of the associated supernova
DATE:    18/08/15 15:28:06 GMT
FROM:    Luca Izzo at IAA-CSIC  <Luca.Izzo@ICRA.it>

L. Izzo (HETH/IAA-CSIC), A. Rossi (INAF/OAS), D. B. Malesani (DAWN/NBI and DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), J. Selsing (DAWN/NBI), P. Schady (Univ. Bath), R. L. C. Starling (Univ. Leicester), J. Sollerman (OKC Stockholm), G. Leloudas (DTU space), Z. Cano (BCA), J. P. U. Fynbo (DAWN/NBI), M. Della Valle (INAF-Naples), E. Pian (INAF/OAS), D. A. Kann (HETH/IAA-CSIC), D. A. Perley (LJMU), E. Palazzi (INAF/OAS), S. Klose (TLS Tautenburg), J. Hjorth (DARK/NBI), S. Covino (INAF-OAB), V. Dâ€™Elia (SSDC), N. R. Tanvir (Univ. Leicester), A. J. Levan (Univ. Warwick), D. Hartmann (Clemson U.), C. Kouveliotou (GWU) report:

We report the results of continued photometric and spectroscopic follow-up of GRB 180728A at z = 0.117 (Starling et al., GCN 23046; Lipunov et al., GCN 23048; Rossi et al., GCN 23055; Heintz et al., GCN 23067) obtained with the X-shooter instrument on the ESO/VLT UT2, Chile.

Up to now, we have observed at three epochs, specifically at 6.27, 9.32 and 12.28 days after the GRB trigger. The optical counterpart is visible in all epochs using the X-shooter acquisition camera in the g, r and z filters. We report a rebrightening of 0.5 +- 0.1 mag in the r band between 6.27 and 12.28 days. This is consistent with what is observed in many other low-redshift GRBs, which in those cases is indicative of an emerging type Ic SN.

The spectra cover the wavelength range 3,000 - 21,000 AA. All the spectra have been corrected for the Galactic extinction (A_V = 0.92), while the host extinction is likely to be small, as indicated by our early-time spectra of the afterglow (Rossi et al., GCN 23055; Heintz et al., GCN 23067). The continuum shows a strong peak around 4500 AA (rest frame; 12.28 days after the GRB), but a black body is not a good fit, as the observed peak is too narrow. The peak shifts to longer wavelengths with time. Over the three epochs, significant features develop, including a broad absorption at ~7600 AA and a deep trough around 4900 AA (all rest frame), visible in our latest spectrum. However, over the covered epochs there is not much resemblance with other broad-lined SNe seen in previous low-redshift GRBs.

For the last spectrum, we attempted the identification of a few features. In particular, we identify the broad dip at 7600 AA as due to the blend O I 8446 AA and Ca II 8492 AA, at the expansion velocity of ~30,000 km s^-1. At this velocity, we also identify the Si II 6355 doublet, as well as C II 6580. The width of the lines spans several thousands km s^-1. Independent of the interpretation of the lines, the overall shape of the continuum, together with the presence of several absorption features a few thousands km s^-1 wide, strongly indicate that this is a SN. The lack of identified H and He in the spectra suggests a classification of type Ic.

A plot of the spectrum obtained at Day 12.28 compared with GRB 980425/SN 1998bw and XRF 100316D/SN 2010bh can be found at the following link : 

http://www.astro.ku.dk/~malesani/GRB/180728A/Day12_vs_98bw_2010bh_flux.png

Further observations are planned for this event, which are possible thanks to ESO director's discretionary time allocated to our project (program 2101.D-5044, PI Rossi). Further observations of this GRB/SN, particularly at different wavelengths, are strongly encouraged.

We thank the ESO staff for their kind availability in executing our series of observations, in particular we want to thank Boris Haeussler, Emanuela Pompei, John Pritchard, Luca Sbordone, Marcela Espinoza, Nestor Jimenez, Rodrigo Palomino, Steffen Mieske, Stephane Brillant. We also thank Dilyar Barat (ANU) and Francesco Dâ€™Eugenio (Univ. Ghent) for kindly providing their telescope time to observe the GRB/SN during their visitor run at ESO/VLT.


GRB_name: GRB180728A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23143
SUBJECT: GRB 180728A: MASTER early polarization and 19 days monitoring 
DATE:    18/08/16 20:33:39 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, N.Tiurina, D.Vlasenko, V.Kornilov, A.Kuznetsov,
V.Chazov, I.  Gorbunov, D.Zimnukhov, D.Kuvshinov, 
P.Balanutsa,V.Vladimirov,
Lomonosov Moscow State University,SAI

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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,
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

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

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

MASTER Global Robotic Net ( Lipunov et al., 2010, Advances in Astronomy, 
vol. 2010, 30L) inspected GRB 180728A
(SwiftBAT GRB discovery : Starling et al. GCN 23046;
MASTER optical counterpart discovery: Lipunov et al. GCN 23048;GCN23050;
SwiftXRT: Perri et al. GCN 23049; Redshift, VLT: Rossi et al. GCN 23055;
SN discovery,VLT: Izzo et al. GCN 23142).
every night since the discovery.

There are unfiltered limits at MASTER images and absolute magnitude of 
SN ( Izzo et al. GCN 23142) for
Omega_Vac = 0.7 and H_0 = 70 km/s/Mpc and Galactic extinction 0.1 for our 
red ccd:

Date_Time,UT            |   Exp,s | MASTER-Site |  m_lim| M

2018-07-29 21:18:37.092 |    2340 | MASTER-SAAO |  21.8 | -16.3
2018-07-30 21:07:24.839 |    1440 | MASTER-SAAO |  20.8 | -17.3
2018-07-30 21:07:24.912 |    1440 | MASTER-SAAO |  21.4 | -16.7
2018-08-01 19:11:32.906 |    1620 | MASTER-SAAO |  20.9 | -17.2
2018-08-01 19:15:07.977 |    1620 | MASTER-SAAO |  20.9 | -17.2
2018-08-02 17:03:40.025 |    3780 | MASTER-SAAO |  20.8 | -17.2
2018-08-02 18:12:49.446 |    3960 | MASTER-SAAO |  20.9 | -17.2
2018-08-03 17:53:21.097 |    4140 | MASTER-SAAO |  20.8 | -17.3
2018-08-03 17:53:21.347 |    4140 | MASTER-SAAO |  21.1 | -17.0
2018-08-03 23:21:10.842 |    3420 | MASTER-OAFA |  20.6 | -17.5
2018-08-04 17:05:35.120 |    2700 | MASTER-SAAO |  20.9 | -17.2
2018-08-04 17:12:46.879 |    2880 | MASTER-SAAO |  20.8 | -17.3
2018-08-04 23:07:09.154 |     720 | MASTER-OAFA |  20.5 | -17.6
2018-08-05 22:18:29.225 |    3240 | MASTER-SAAO |  20.8 | -17.3
2018-08-05 22:22:04.704 |    3240 | MASTER-SAAO |  21.1 | -17.0
2018-08-05 23:08:46.934 |    1260 | MASTER-OAFA |  21.5 | -16.5
2018-08-06 18:46:19.565 |    3600 | MASTER-SAAO |  20.8 | -17.3
2018-08-06 18:46:19.605 |    3600 | MASTER-SAAO |  20.8 | -17.3
2018-08-07 00:26:41.653 |     900 | MASTER-OAFA |  20.4 | -17.7
2018-08-07 03:30:36.096 |    2520 | MASTER-OAFA |  20.6 | -17.5
2018-08-07 17:15:34.447 |    3780 | MASTER-SAAO |  20.9 | -17.2
2018-08-07 18:23:07.857 |    3780 | MASTER-SAAO |  21.7 | -16.4
2018-08-08 17:59:05.042 |    4140 | MASTER-SAAO |  20.8 | -17.3
2018-08-08 18:02:42.597 |    4140 | MASTER-SAAO |  20.9 | -17.2
2018-08-08 23:11:34.904 |    3240 | MASTER-OAFA |  21.9 | -16.2
2018-08-09 18:55:17.807 |     540 | MASTER-SAAO |  20.8 | -17.2
2018-08-09 18:58:54.517 |     540 | MASTER-SAAO |  20.8 | -17.2
2018-08-09 23:04:26.723 |    3240 | MASTER-OAFA |  20.5 | -17.5
2018-08-10 17:00:41.943 |    2520 | MASTER-SAAO |  20.9 | -17.1
2018-08-11 00:08:05.570 |    4500 | MASTER-OAFA |  20.7 | -17.3
2018-08-11 18:43:29.720 |    7020 | MASTER-SAAO |  20.9 | -17.1
2018-08-11 23:12:32.140 |    3240 | MASTER-OAFA |  20.6 | -17.4
2018-08-12 19:46:57.192 |    7560 | MASTER-SAAO |  22.1 | -15.9
2018-08-12 19:46:57.246 |    7560 | MASTER-SAAO |  20.9 | -17.1
2018-08-12 23:18:02.053 |    3240 | MASTER-OAFA |  19.8 | -18.2
2018-08-13 07:43:55.504 |    3420 | MASTER-OAFA |  21.2 | -16.8

We have carried out preliminary photometry of MASTER early observations
  (Lipunov et al. GCN 23048; GCN23050;) also we report about 
considerable polarization of optical radiation of gamma burst the first 
minute after its beginning.

This message can be cited.


GRB_name: GRB180809B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23144
SUBJECT: GRB 180809B: AstroSat CZTI detection
DATE:    18/08/17 11:29:28 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 180809B, which was also detected by Swift (Moss M. J. et al., GCN 23105), CALET (Cherry M. L. et al., GCN 23116) and Konus-Wind (Svinkin D. et al., GCN 23128).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 20:29:23.500 UT. The measured peak count rate is 2562 cts/s above the background in combined data of four quadrants, with a total of 38208 cts. The local mean background count rate was 501 cts/s. Using cumulative rates, we measure a T90 of 44.1 s. In preliminary analysis, we find that 3257 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: GRB180818A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23146
SUBJECT: GRB 180818A: Swift detection of a burst
DATE:    18/08/18 03:25:43 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

F. E. Marshall (NASA/GSFC), 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 03:12:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180818A (trigger=853824).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 169.611, -48.344 which is 
   RA(J2000) = 11h 18m 27s
   Dec(J2000) = -48d 20' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 03:13:18.0 UT, 74.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
169.6364, -48.3444 which is equivalent to:
   RA(J2000)  = 11h 18m 32.73s
   Dec(J2000) = -48d 20' 39.7"
with an uncertainty of 2.4 arcseconds (radius, 90% containment). This
location is 60 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 (1.14 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.5
(+7.18/-5.58) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 1.28e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 82 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
0.11. 

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: GRB180818A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23147
SUBJECT: GRB 180818A: Enhanced Swift-XRT position
DATE:    18/08/18 05:32:00 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 1503 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180818A, 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 = 169.63679, -48.34440 which is equivalent
to:

RA (J2000): 11h 18m 32.83s
Dec (J2000): -48d 20' 39.9"

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: GRB180818A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23148
SUBJECT: GRB 180818A: Swift-XRT refined Analysis
DATE:    18/08/18 09:38:04 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.9 ks of XRT data for GRB 180818A (Marshall et al.
GCN Circ. 23146), from 80 s to 17.2 ks after the  BAT trigger. The data
comprise 587 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. 23147).

The light curve can be modelled with an initial power-law decay with an
index of alpha=6.0 (+0.8, -0.6), followed by a break at T+172 s to an
alpha of 0.63 (+/-0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.8 (+0.5, -0.4). The
best-fitting absorption column is  8.9 (+3.1, -2.6) x 10^21 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 3.2 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.9 (+3.1, -2.6) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 4.9 sigma
Photon index:      2.8 (+0.5, -0.4)

If the light curve continues to decay with a power-law decay index of
0.63, 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 1.4 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/00853824.

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


GRB_name: GRB180818B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23149
SUBJECT: GRB 180818B: Swift detection of a burst
DATE:    18/08/18 12:44:59 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

F. E. Marshall (NASA/GSFC), V. D'Elia (ASDC),
S. W. K Emery (UCL-MSSL), J. A. Kennea (PSU),
M. J. Moss (George Washington University), K. L. Page (U Leicester)
and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 12:30:18 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180818B (trigger=853882).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 104.235, +39.329 which is 
   RA(J2000) = 06h 56m 56s
   Dec(J2000) = +39d 19' 43"
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 130 sec, starting ~100 sec before
the trigger time during the previous spacecraft slew.  The peak count 
rate was ~1000 counts/sec (15-350 keV), at ~-90 sec after the trigger. 

The XRT began observing the field at 12:33:42.4 UT, 203.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 104.22468, 39.31662 which
is equivalent to:
   RA(J2000)  = 06h 56m 53.92s
   Dec(J2000) = +39d 18' 59.8"
with an uncertainty of 4.4 arcseconds (radius, 90% containment). This
location is 53 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 1.30e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 212 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
0.09. 

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: GRB180818A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23150
SUBJECT: GRB 180818A: Swift/UVOT Upper Limits
DATE:    18/08/18 14:15:56 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (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 180818A
83 s after the BAT trigger (Marshall et al., GCN Circ. 23146). No
optical afterglow consistent with the XRT position (Osborne et al. GCN
Circ. 23147) 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            83          232          147         >20.7
u_FC               241          490          246         >20.1
white               83         7151          785         >21.9
v                  570        11683         1198         >19.8
b                  496         6946          510         >20.8
u                  241        17153         1326         >20.9
w1                 621        13097          985         >20.1
m2                 596        12588         1199         >20.5
w2                 546         7357          510         >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the
reddening of E(B-V) = 0.11 in the direction of the burst (Schlegel et al.
1998).


GRB_name: GRB180818B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23151
SUBJECT: GRB 180818B: Enhanced Swift-XRT position
DATE:    18/08/18 15:50:51 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 1716 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 180818B, 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 = 104.22470, +39.31571 which is equivalent
to:

RA (J2000): 06h 56m 53.93s
Dec (J2000): +39d 18' 56.6"

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: GRB180818B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23152
SUBJECT: GRB 180818B: Swift/UVOT Upper Limits
DATE:    18/08/18 18:08:33 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (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 180818B
212 s after the BAT trigger (Marshall et al., GCN Circ. 23149).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 23151)
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           212          362          147         >19.9
white              212        11082         1482         >21.1
v                  369        12690         1148         >19.8
b                  467         6919          471         >19.9
u                  442         6714          469         >19.6
w1                 418         6509          468         >19.9
m2                 393         6304          471         >20.5
w2                 517        11988         1160         >20.3

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: GRB180818B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23153
SUBJECT: GRB 180818B: Fermi GBM observations
DATE:    18/08/18 23:14:07 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 12:28:57.24 UT on 18 August 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180818B (trigger 556288142 / 180818520).
which was also detected by the Swift/BAT
(Marshall et al., GCN 23149). The GBM on-ground location is consistent
with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 89 degrees.

The GBM light curve consists of two separate emission episodes
with a duration (T90) of about 169 s (50-300 keV).
The time-averaged spectrum from T0-16 s to T0+125 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is 1.8 +/- 1.32 and
the cutoff energy, parameterized as Epeak, is 78 +/- 9 keV.

The event fluence (10-1000 keV) in this time interval is
(4.7 +/- 0.7)E-7 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-2.4 s in the 10-1000 keV band
is 2.1 +/- 0.2 ph/s/cm^2.

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


GRB_name: GRB180818A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23154
SUBJECT: GRB 180818A: Swift-BAT refined analysis
DATE:    18/08/19 01:00:13 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), F. E. Marshall (NASA/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 180818A (trigger #853824)
(Marshall et al., GCN Circ. 23146).  The BAT ground-calculated position is
RA, Dec = 169.698, -48.344 deg which is
  RA(J2000)  =  11h 18m 47.5s
  Dec(J2000) = -48d 20' 37.9"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows a single-pulsed structure that starts
at ~T-2 s, peaks at ~T+2 s, and ends at ~T+14 s. T90 (15-350 keV) is
13.7 +- 4.1 sec (estimated error including systematics).

The time-averaged spectrum from T-2.14 to T+14.10 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.15 +- 0.36.  The fluence in the 15-150 keV band is 2.6 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.64 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/853824/BA/


GRB_name: GRB180818B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23155
SUBJECT: GRB 180818B: Swift-BAT refined analysis
DATE:    18/08/19 01:00:33 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), F. E. Marshall (NASA/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 180818B (trigger #853882)
(Marshall et al., GCN Circ. 23149).  The BAT ground-calculated position is
RA, Dec = 104.227, 39.310 deg which is
  RA(J2000)  =  06h 56m 54.5s
  Dec(J2000) = +39d 18' 35.1"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 89%.

The mask-weighted light curve shows two pulses. The first pulse starts at
at ~T-100 s, peaks at ~T-80 s, and ends at ~T-50 s. The second pulse starts
at ~T+10 s, peaks at ~T+30 s, and ends at ~T+60 s. T90 (15-350 keV) is
134.4 +- 9.8 sec (estimated error including systematics). However, note that
the burst came into the BAT FOV at ~T-128 s, and thus there might be additional
burst emission beforehand.

The time-averaged spectrum from T-93.58 to T+62.74 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.77 +- 0.12.  The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-82.11 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/853882/BA/


GRB_name: GRB180818B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23156
SUBJECT: GRB 180818B: Swift-XRT refined Analysis
DATE:    18/08/19 05:11:20 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows
(PSU), A. Tohuvavohu (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 F.E. Marshall report on behalf of the Swift-XRT
team:

We have analysed 8.1 ks of XRT data for GRB 180818B (Marshall et al.
GCN Circ. 23149), from 210 s to 52.8 ks after the  BAT trigger. The
data comprise 205 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. 23151).

The late-time light curve (from T0+4.5 ks) can be modelled with a
power-law decay with a decay index of alpha=0.86 (+/-0.07).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 3.47 (+0.12, -0.11). The
best-fitting absorption column is  2.89 (+0.25, -0.23) x 10^21 cm^-2,
in excess of the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.77 (+0.07, -0.06)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.8 x 10^-11 (4.5 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.27 (+0.11, -0.00) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.77 (+0.07, -0.06)

If the light curve continues to decay with a power-law decay index of
0.86, the count rate at T+24 hours will be 0.030 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-12 (1.3 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00853882.

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


GRB_name: GRB180806A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23157
SUBJECT: GRB180806A: confirmation of the X-ray afterglow
DATE:    18/08/19 22:26:22 GMT
FROM:    Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>

A. D'Ai (IASF-PA) reports on behalf of the Swift/XRT team:

Swift has performed further observations of the field of the
Fermi/LAT-detected burst GRB 180806A (Malacaria et al., GCN 23095). 
An additional 4.2 ks of data were collected between 11.4 days 
and 12.0 days after the Fermi trigger.
Source 1, initially reported by Gibson et al. (GCN 23097)
as the likely X-ray counterpart, is no longer detected down to a 3-sigma 
upper limit of 1.0e-2 ct s^-1. Source 1 position was also consistent with an 
optically fading source (GCN 23091, 23092, 23094, 23096, 23098, 23101).
Source1 is therefore confirmed as the X-ray afterglow of GRB 180806A.

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


GRB_name: GRB180821A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23158
SUBJECT: GRB 180821A: Swift detection of a burst
DATE:    18/08/21 16:53:28 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Tohuvavohu (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU),
H. A. Krimm (NSF/USRA), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU),
M. H. Siegel (PSU) and K. K. Simpson (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 16:40:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180821A (trigger=854578).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 7.763, -38.619 which is 
   RA(J2000) = 00h 31m 03s
   Dec(J2000) = -38d 37' 07"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual for an image trigger, the
immediately-available BAT lightcurve shows no obvious variation. 

The XRT began observing the field at 16:44:04.8 UT, 210.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 7.78833, -38.62660
which is equivalent to:
   RA(J2000)  = 00h 31m 09.20s
   Dec(J2000) = -38d 37' 35.8"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 76 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 3.67e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 218 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 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: GRB180821A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23159
SUBJECT: GRB 180821A: BOOTES-3/YA optical observations
DATE:    18/08/21 19:09:08 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct@iaa.es>

E. Fernandez-Garcia, Y.-D. Hu, J. C. Tello, A. Ayala and A. J. 
Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de 
Malaga), M. D.
Caballero-Garcia and M. Jelinek (ASU-CAS, CZ), R. Cunniffe (Inst. of 
Physics, CZ) and R. Querel (NIWA), on behalf of a larger collaboration, 
report:

The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New 
Zealand) automatically responded in 59s (and 193s after the GRB onset) 
to the Swift trigger of GRB 180821A (Tohuvavohu et al., GCNC 23158). The 
first images (clear filter) were obtained starting at 16:43:47 UT. At 
the position of the Swift/XR X-ray position, no optical afterglow is 
detected down to 19 mag on a 100s co-added image at 16:44:45 
(mid-exposure), in agreement with the non-detection by Swift/UVOT. 
Further analysis is ongoing.

We thank the staff at NIWA for its excellent support.


GRB_name: GRB180821A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23160
SUBJECT: GRB 180821A: iTelescope optical afterglow detection
DATE:    18/08/21 19:26:09 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

A.K.H. Kong (NTHU, Taiwan) reports

We observed the field of GRB 180821A (Tohuvavohu et al. GCN 23158)
with the T30 0.51m telescope of iTelescope.Net in Siding Spring,
Australia. The observation was done with a luminance filter (400-700
nm) beginning at 2018-08-21 17:26:22 UT (46 min after the BAT
trigger). At the position of the Swift X-ray afterglow, an optical
source is marginally detected with a magnitude of 20.4 +/- 0.2. We
propose this source is the optical afterglow to GRB 180821A. Follow-up
observations are encouraged.


GRB_name: GRB180818B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23161
SUBJECT: GRB 180818B: 1.5m OSN optical afterglow candidate
DATE:    18/08/21 21:58:52 GMT
FROM:    Youdong HU at IAA-CSIC, UGR  <youdong@iaa.es>

Y.-D. Hu, A. Sota, V. Casanova and A.J. Castro-Tirado (IAA-CSIC 
Granada), on behalf of a larger collaboration, report:

We observed the field of the Swift/Fermi burst GRB 180818B (Marshall et 
al. GCNC 23149, Veres et al. GCNC 23153), with the 150-cm telescope of 
the Observatorio de Sierra Nevada (OSN) near Granada, Spain.

Two I-band observations were taken on Aug 19 and 21 (starting at 03:40 
and 04:19 UT respectively, i.e. ~15.2 h and ~63.8 h after trigger) with 
total exposure times of 2100s and 1200s respectively. Within the 
enhanced Swift/XRT position (Beardmore et al. GCNC 23151), an optical 
source was detected on the first epoch with an I-band magnitude of 21.6, 
which faded by at least 0.5 mag on the 2nd epoch observation. We propose 
this source to be the optical afterglow to GRB 180818B.

The above mentioned magnitude is calibrated against the USNO-B1 catalog 
and is not corrected for Galactic extinction in the direction of the 
GRB. Further observations are encouraged.


GRB_name: GRB180821A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23162
SUBJECT: GRB 180821A: Enhanced Swift-XRT position
DATE:    18/08/21 22:55:23 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 2528 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 180821A, 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 = 7.79011, -38.62713 which is equivalent
to:

RA (J2000): 00h 31m 9.63s
Dec (J2000): -38d 37' 37.7"

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: GRB180821A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23163
SUBJECT: GRB 180821A: LCO Siding Springs observations
DATE:    18/08/22 06:59:47 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), A. Cucchiara, 
D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:

We automatically observed Swift GRB 180821A (Tohuvavohu et al. GCN 
23158) with the LCO 2-m unit at Siding Springs on August 21, from 16:54 
to 17:07 UT (corresponding to 14 to 27 minutes from the GRB trigger 
time) with the SDSS i' filter. Within the enhanced Swift-XRT error 
circle (Evans et al. GCN 23162) we do not detect any source down to 
i'>21.0 mag from a 10x60s exposure at a mid time of 0.33 hours post GRB, 
as calibrated against nearby USNOB1 objects.


GRB_name: GRB180821A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23164
SUBJECT: GRB 180821A: Swift-XRT refined Analysis
DATE:    18/08/22 08:10:45 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

D.N. Burrows (PSU), S. J. LaPorte (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 8.8 ks of XRT data for GRB 180821A (Tohuvavohu et al.
GCN Circ. 23158), from 199 s to 46.5 ks after the  BAT trigger. The
data comprise 171 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 enhanced XRT position for this burst was given by Evans
et al. (GCN Circ. 23162).

The late-time light curve (from T0+3.8 ks) can be modelled with a
power-law decay with a decay index of alpha=0.49 (+0.13, -0.12).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 5.1 (+0.4, -0.3). The
best-fitting absorption column is  6.8 (+/-0.8) x 10^21 cm^-2, in
excess of the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.80 (+0.31, -0.29)
and a best-fitting absorption column of 3.4 (+1.0, -0.8) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 2.6 x 10^-11 (6.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.4 (+1.0, -0.8) x 10^21 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 6.2 sigma
Photon index:      2.80 (+0.31, -0.29)

If the light curve continues to decay with a power-law decay index of
0.49, the count rate at T+24 hours will be 0.014 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 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/00854578.

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


GRB_name: GRB180821A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23165
SUBJECT: GRB 180821A: iTelescope counterpart is not the afterglow
DATE:    18/08/22 10:06:54 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

A. K. H. Kong (NTHU, Taiwan) reports

We reanalyse the image obtained with the T30 telescope of
iTelescope.Net (Kong GCN 23160) together with the enhanced Swift XRT
position (Evans et al. GCN 23162). Within the new error circle, we do
not detect any source with a detection limit of ~20.5 mag. The result
is consistent with Guidorzi et al. (GCN 23163). We conclude that the
previous counterpart candidate (which is outside the enhanced X-ray
error circle) is not the optical afterglow.


GRB_name: GRB180821A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23166
SUBJECT: GRB 180821A: Swift-BAT refined analysis
DATE:    18/08/22 13:15:43 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), 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 180821A (trigger #854578)
(Tohuvavohu, et al., GCN Circ. 23158).  The BAT ground-calculated position is
RA, Dec = 7.739, -38.612 deg which is 
 RA(J2000)  =  00h 30m 57.4s 
 Dec(J2000) = -38d 36' 41.9" 
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 17%.

The mask-weighted light curve showed a broad peak with some structure, 
running from ~T+0 to T+70 sec. T90 (15-350 keV) is 64.00 +- 22.6 sec 
(estimated error including systematics).

The time-averaged spectrum from T+1.00 to T+65.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.79 +- 0.31.  The fluence in the 15-150 keV band is 1.4 +- 0.3 x 10^-6 erg/cm2.
Since the peak was so broad, the automated analysis software was unable to 
derive a significant peak photon flux at the highest point in the light curve, T+56.5 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/854578/BA/


GRB_name: GRB180821A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23167
SUBJECT: GRB 180821A: Swift/UVOT Upper Limits
DATE:    18/08/22 16:24:33 GMT
FROM:    Frank Marshall at Swift/UVOT  <marshall@milkyway.gsfc.nasa.gov>

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

The Swift/UVOT began settled observations of the field of GRB 180821A
219 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 23158).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 23162) 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           219          369          147         >21.0
white              219          495          167         >21.1
v                  526          546           19         >17.7
v                 4604         6039          393         >20.0
b                  451          471           19         >19.3
b                 3988         5624          393         >21.3
u                  426          446           19         >18.6
u                 3783         5418          393         >20.5
w1                 402          421           19         >19.3
w1                5015        15906          241         >20.5
m2                4808        10398          812         >20.5
w2                4399         6034          393         >20.3

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: GRB180821A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23168
SUBJECT: GRB 180821A: VLT observations
DATE:    18/08/23 16:22:15 GMT
FROM:    Paul Vreeswijk at Radboud U/Nijmegen  <p.vreeswijk@astro.ru.nl>

Paul Vreeswijk (Radboud U. Nijmegen), Daniele Malesani, Jonatan
Selsing (DAWN/NBI, DARK/NBI), Nial Tanvir (U. Leicester), Giovanna
Pugliese (API/U. Amsterdam), Andrea Rossi (INAF-OAS) and Andrew Levan
(U. Warwick) report on behalf of the Stargate collaboration:

The Swift XRT error circle (Tohuvavohu et al., GCN 23158; Burrows et 
al., GCN 23164) of GRB 180821A (Krimm et al., GCN 23166) was observed
with the Very Large Telescope on the night of August 21/22, 2018,
using the telescope/instrument combinations Kueyen/X-shooter and
Antu/FORS2.

The FORS2 imaging observations started at 5:58 UT on August 22 (13.3
hours after the GRB trigger) and consisted of 8 exposures of 120
seconds in the z_Gunn filter. No object is detected in the enhanced
XRT error circle (Evans et al., GCN 23162), down to a 3-sigma limiting
magnitude of z(AB)=24.9 (see also Fernandez-Garcia, GCN 23159;
Guidorzi et al., GCN 23163; Kong, GCNs 23160 and 23165; Marshall et
al., GCN 23167). The z-band coverage of this field by the SkyMapper
Southern Sky Survey (see http://skymapper.anu.edu.au) was used in the
determination of the magnitude limit.

The X-shooter spectroscopic observations started at 6:55 UT on August
22 (14.3 hours after the GRB). A sequence of 4 spectra of 10 minutes
each was taken of the object at the Southwestern edge of the
preliminary XRT error circle, at coordinates R.A.: 00:31:09.0, decl.:
-38:37:39.5 (J2000). The reduced spectra show emission lines typical
of a star-forming galaxy, such as [OII] 3727, Hbeta, [OIII] 4959, 5007
and Halpha, at a redshift of z=0.58. Although the location of this
galaxy is consistent with the initial XRT afterglow localization, it
is about 6 arcseconds to the West and well outside of the enhanced XRT
error circle, and is therefore unrelated to the GRB.

We acknowledge the excellent assistance of the staff at Paranal
observatory, and in particular that of S. Brillant, C. Ledoux,
F. Gaete, E. Sedaghati and J. Velasquez.


GRB_name: GRB180823A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23169
SUBJECT: GRB 180823A: Swift detection of a burst
DATE:    18/08/23 19:31:39 GMT
FROM:    Aaron Tohuvavohu at PSU/Swift  <aaronb@swift.psu.edu>

B. Sbarufatti (PSU), H. A. Krimm (NSF/USRA),
F. E. Marshall (NASA/GSFC) and A. Tohuvavohu (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 19:04:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180823A (trigger=855434).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 210.349, +14.884 which is 
   RA(J2000) = 14h 01m 24s
   Dec(J2000) = +14d 53' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve, which is superimposed 
on a declining background, shows a double-peaked structure with a 
duration of about 40 sec.  The peak count rate was ~2000 counts/sec 
(15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 19:06:02.2 UT, 89.2 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 210.35630, 14.89029 which
is equivalent to:
   RA(J2000)  = 14h 01m 25.51s
   Dec(J2000) = +14d 53' 25.0"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 34 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 3.10e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of  37 seconds with the White
filter  starting 379 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 is expected to be  about 18.5 mag. No correction
has been made  for the expected extinction corresponding to E(B-V) of
0.02. 

Burst Advocate for this burst is B. Sbarufatti (bxs60 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: GRB180823A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23170
SUBJECT: GRB 180823A: Enhanced Swift-XRT position
DATE:    18/08/24 00:43:22 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 2364 s of XRT Photon Counting mode data and 7 UVOT
images for GRB 180823A, 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 = 210.35583, +14.89245 which is equivalent
to:

RA (J2000): 14h 01m 25.40s
Dec (J2000): +14d 53' 32.8"

with an uncertainty of 1.6 arcsec (radius, 90% confidence).

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

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


GRB_name: GRB180823A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23171
SUBJECT: GRB 180823A: Swift-XRT refined Analysis
DATE:    18/08/24 13:43:15 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Tohuvavohu (PSU), S. J. LaPorte (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), J.A. Kennea (PSU)
and B. Sbarufatti report on behalf of the Swift-XRT team:

We have analysed 7.7 ks of XRT data for GRB 180823A (Sbarufatti et al.
GCN Circ. 23169), from 331 s to 39.4 ks after the  BAT trigger. The
data comprise 46 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. 23170).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.00 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.99 (+0.19, -0.18). The
best-fitting absorption column is  1.2 (+/-0.5) 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 3.3 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: 1.2 x 10^20 cm^-2
Excess significance: 3.7 sigma
Photon index:      1.99 (+0.19, -0.18)

If the light curve continues to decay with a power-law decay index of
1.00, 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 4.3 x
10^-13 (5.3 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/00855434.

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


GRB_name: GRB180823A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23172
SUBJECT: GRB 180823A: RATIR Optical and NIR Observations
DATE:    18/08/24 14:46:19 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 180823A (Sbarufatti, et al., GCN 23169) 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 2018/08 24.14 to 2018/08 24.19 UTC (8.40 to
9.45 hours after the BAT trigger), obtaining a total of 0.40 hours exposure
in the r and i bands and 0.29 hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (Evans, et al., GCN 23170),
in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following
upper limits (3-sigma):

 r > 22.20
 i > 22.05
 Z > 20.84
 Y > 19.72
 J > 20.45
 H > 19.12

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: GRB180823A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23173
SUBJECT: GRB 180823A: Swift/UVOT Upper Limits
DATE:    18/08/24 16:26:22 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 180823A: Swift/UVOT Upper Limits

S. Sebzda (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180823A
381 s after the BAT trigger (Sbarufatti et al., GCN Circ. 23169).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 23170)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

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

white              381          417           36         >19.1
white              381         4476          380         >20.9
v                 4686        10356          927         >19.2
b                 4071         4271          197         >19.7
u                 3866         4066          197         >19.8
m2               10361        10803          435         >19.8
w2                4482         4681          197         >20.0

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: GRB180824A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23174
SUBJECT: IPN Triangulation of GRB 180824A (short)
DATE:    18/08/25 16:37:39 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

K. Hurley, on behalf of the IPN,

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

and

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

The short-duration GRB 180824A was detected by
Konus-Wind, INTEGRAL (SPI-ACS), and Swift (BAT),
at about 36319 s UT (10:05:19).
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:
   10.060 (00h 40m 14s) +56.619 (+56d 37' 09")
Corners:
  357.831 (23h 51m 19s) +60.118 (+60d 07' 04")
    6.353 (00h 25m 25s) +58.199 (+58d 11' 58")
   18.977 (01h 15m 55s) +52.272 (+52d 16' 18")
   13.317 (00h 53m 16s) +54.952 (+54d 57' 07")
---------------------------------------------
The error box area is 3.30 sq. deg, and its maximum
dimension is 14.0 deg (the minimum one is 20.76 arcmin).
The Sun distance was 105 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180824_T36319/IPN/

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


GRB_name: GRB180823A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23175
SUBJECT: GRB 180823A, Swift-BAT refined analysis 
DATE:    18/08/25 20:56:53 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

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

Using the data set from T-43 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180823A (trigger #855434)
(Sbarufatti, et al., GCN Circ. 23169).  The BAT ground-calculated position is
RA, Dec = 210.358, 14.901 deg which is 
  RA(J2000)  =  14h 01m 25.9s 
  Dec(J2000) = +14d 54' 03.2" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

The available data starts as the burst is rising, but it appears that it includes the
entire burst.   The mask-weighted light curve shows a double-peaked structure, 
starting at ~T-43 seconds, with comparably sized peaks at ~T+5 and ~T+20 sec,
and returning to near background by T+70 seconds, with a fainter tail out past
T+100 seconds.  A spacecraft slew took the burst location out of the BAT field
of view around T+450 seconds. T90 (15-350 keV) is 80.3 +- 6.9 sec (estimated 
error including systematics).

The time-averaged spectrum from T-37.5 to T+72.0 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.58 +- 0.05.  The fluence in the 15-150 keV band is 7.8 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+18.33 sec in the 15-150 keV band
is 2.3 +- 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/855434/BA/


GRB_name: GRB180824A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23176
SUBJECT: GRB 180824A: MASTER inspection IPN short GRB error box
DATE:    18/08/26 07:28:28 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, D. Vlasenko, N.Tiurina,
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI

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

D.Svinkin (Ioffe Institute, Sankt Petersburg)

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

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

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


MASTER-Kislovodsk  robotic telescope (MASTER-Net: 
http://observ.pereplet.ru) 
located in Kislovodsk Solar Station of the Pulkovo Observatory  was 
starting survey on the IPN 
GRB180824A error-box (Svinkin et al., GCN #23174)  274 sec after 
notice time and 35665 sec after trigger time at 2018-08-24 19:59:44 UT.
The 5-sigma upper limit on our first (180s exposure)  set is about 18.9 
mag .

The galacitc latitude b =  0 deg.

The observations made on zenit distance = 36 deg.The moon (97 % bright 
part) is 29 deg. above the horizon. The distance between  moon and  object 
is 87
The sun  altitude  is -32.9 deg.
The object can be observed till sunrise at 2018-08-25 02:23:27

There are several bright galaxy (d < 100 Mpc) in IPN error box:

    Galaxy name         |        center         | b_mag  |  dist
-----------------------+-----------------------+--------+---------
  PGC089890             | (15.7675d , 54.0347d) | 14.178 | 88.7359
  2MASS00061177+5916507 | (1.54907d , 59.2808d) | 14.559 | 81.8258
  2MASS00095357+5859451 | (2.47322d , 58.9959d) | 14.733 | 32.3946
  2MASS00035040+5929552 | (0.96001d , 59.4987d) | 15.373 | 14.6266

The MASTER-Kislovodsk cover map is available at
http://www.pereplet.ru/lipunov/images/master_MAP_GRB180824A.jpg

There is no OT detetcted.

The message may be cited.


GRB_name: GRB180818B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23177
SUBJECT: GRB 180818B: TSHAO optical upper limit
DATE:    18/08/26 16:17:39 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI),  A. Kusakin (FAPHI), I. Reva 
(FAPHI),  A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger 
GRB follow-up collaboration:

We observed the field of GRB 180818B  (Marshall et al., GCN 23149; Veres 
et al., GCN 23153) with Zeiss-1000 1-m telescope of Tien Shan 
Astronomical Observatory starting on August 08 (UT) 22:20:38. We 
obtained several images in R-filter.  Within enhanced XRT Swift-XRT 
position (Beardmore et al., GCN 23151)  we do not detect any object.  In 
  particular we do not detect the afterglow candidate reported in  GCN 
23161 (Hu et al.) Preliminary photometry of the field is following.

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

2018-08-18  22:20:38 0.42710  R      36*60  n/d  n/d    20.4

The photometry is based on several nearby USNO-B1.0 stars.


GRB_name: GRB180824A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23180
SUBJECT: Konus-Wind observation of GRB 180824A
DATE:    18/08/27 14:57:16 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 short-duration GRB 180824A
(IPN triangulation: Svinkin et al., GCN 23174)
triggered Konus-Wind at T0=36319.887 s UT (10:05:19.887).

The burst light curve shows a double-peaked structure
with a total duration of ~2 s.
The emission is seen up to ~1.2 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.02(-0.34,+0.41)x10^-6 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.012 s,
of 7.15(-3.46,+4.02)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the main pulse
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 16 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.04(-0.85,+1.65),
and Ep = 375(-128,+267) keV (chi2 = 16/18 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180824_T36319/

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


GRB_name: GRB180728A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23181
SUBJECT: GRB 180728A: classification of the associated SN 2018fip
DATE:    18/08/27 23:18:21 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

J. Selsing (DAWN/NBI), L. Izzo (HETH/IAA-CSIC), A. Rossi (INAF/OAS),
D. B. Malesani (DAWN/NBI and DARK/NBI), K. E. Heintz (Univ. Iceland and 
DAWN/NBI), A. de Ugarte Postigo (HETH/IAA-CSIC), P. Schady (Univ. Bath),
R. L. C. Starling (Univ. Leicester), J. Sollerman (OKC Stockholm),
G. Leloudas (DTU space), Z. Cano (BCA), J.  P. U. Fynbo (DAWN/NBI),
M. Della Valle (INAF-Naples), E. Pian (INAF/OAS), D. A. Kann (HETH/IAA-CSIC),
D. A. Perley (LJMU), E. Palazzi (INAF/OAS), S. Klose (TLS Tautenburg),
J. Hjorth (DARK/NBI), S. Covino (INAF-OAB), V. D'Elia (SSDC),
N. R. Tanvir (Univ. Leicester), A. J.  Levan (Univ. Warwick),
D. Hartmann (Clemson U.), and C. Kouveliotou (GWU)
report on behalf of a larger collaboration:

We observed again the SN associated with GRB 180728A (Starling et al., 
GCN 23046; Izzo et al., GCN 23142) with the ESO VLT UT2 equipped with 
X-shooter. Observations had a mean epoch of 2018 August 21.078 UT (23.3 
days after the GRB) and spanned the wavelength range 3200-20,900 AA.

The features previously observed in our spectroscopic sequence (Izzo et 
al., GCN 23142) have evolved and become more prominent. Using the 
Superfit tool (Howell et al. 2005, ApJ, 634, 1190; 
http://www.dahowell.com/superfit.html) we find a convincing match with 
the type-Ic SN 2002ap at a phase of 8 days after maximum. The timing is 
consistent with the epoch of our observation (21 days after the GRB 
after correcting for cosmic time dilation). We thus conclusively 
classify the SN as a broad-lined type-Ic SN. We note however that the 
velocity measured at this epoch (~10,000 km/s) is at the low end of what 
measured for GRB-associated SNe (e.g. Modjaz et al. 2016, 832, 108).

The SN associated to GRB 180728A has been dubbed SN 2018fip via the 
Transient Name Server: https://wis-tns.weizmann.ac.il/object/2018fip

[GCN OPS NOTE(28aug18): Per author's request, AdUP was added to the
author list.]


GRB_name: GRB180828A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23182
SUBJECT: GRB 180828A: Swift detection of a GRB or possible Galactic Transient Swift J1754.9-2548
DATE:    18/08/28 19:27:00 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. P. Beardmore (U Leicester), S. W. K Emery (UCL-MSSL),
J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), S. J. LaPorte (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 18:57:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a source which is either GRB 180828A or a previously-unknown 
Galactic transient (trigger=856977).  
Swift slewed immediately to the source location. 
The BAT on-board calculated location is 
RA, Dec 268.700, -25.800 which is 
   RA(J2000) = 17h 54m 48s
   Dec(J2000) = -25d 47' 58"
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 ~20,000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 18:59:30.3 UT, 115.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 268.7184, -25.7991 which is equivalent to:
   RA(J2000)  = 17h 54m 52.42s
   Dec(J2000) = -25d 47' 56.8"
with an uncertainty of 5.8 arcseconds (radius, 90% containment). No
event data are yet available to determine the column density using
X-ray spectroscopy. 

UVOT took a finding chart exposure of  30 seconds with the White filter
starting 123 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. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the large, but uncertain, extinction
expected. 

Due to its location in the Galactic Bulge (3.8 degrees from Sgr A*,  
0.14 degrees below the plane), this trigger may be due to a previously
unknown X-ray transient. If this source is an X-ray transient, we 
name it Swift J1754.9-2548. Although the initial GCN Notice 
identified this as possibly related to Swift J1753.7-2544, the XRT 
position of this transient is 16.5 arcmin away from Swift 
J1753.7-2544, and therefore it is unrelated. 

Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB180828A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23183
SUBJECT: GRB 180828A: Fermi GBM observation
DATE:    18/08/29 04:19:38 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

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

"At 18:57:26.58 UT on 28 August 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180828A (trigger 557175451 / 180828790),
which was also detected by Swift (Beardmore et al. 2018, GCN 23182).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time using the
Swift-XRT position is 77 degrees.

The GBM light curve consists of multiple bright pulses with a duration
(T90) of 8.3 s (50-300 keV). The time-averaged spectrum from T0+1.5s to 
T0+11 s is best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.46 +/- 0.02 and the 
cutoff energy, parameterized as Epeak, is 358 +/- 9 keV.

A Band function fits the interval equally well, with 
Epeak =346 +/- 12 keV, alpha = -0.44 +/- 0.03 and
beta = -3.01 +/- 0.33.

The event fluence (10-1000 keV) over the T90 interval is
(3.39 +/- 0.5)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0 +8s in the 10-1000 keV band is 38 +/- 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: GRB180828A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23184
SUBJECT: GRB 180828A / Swift J1754.9-2548: Enhanced Swift-XRT position
DATE:    18/08/29 07:03:44 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Using 973 s of XRT Photon Counting mode data and 1 UVOT
images, 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 = 268.71784, -25.79805 which is equivalent to:

RA (J2000):  17 54 52.28
Dec (J2000): -25 47 53.0

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 athttp://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).

Preliminary analysis of the XRT light curve (http://www.swift.ac.uk/xrt_curves/00856977/)
suggests that this object is likely a GRB, not a Galactic transient. Analysis is ongoing.

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


GRB_name: GRB180828A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23185
SUBJECT: GRB 180828A: Swift-XRT refined Analysis
DATE:    18/08/29 07:33:58 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S. J. LaPorte (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), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU) and A.P. Beardmore report on behalf of the Swift-XRT
team:

We have analysed 6.6 ks of XRT data for GRB 180828A (Beardmore et al.
GCN Circ. 23182), from 121 s to 28.1 ks after the  BAT trigger. The
data comprise 1.8 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. Using 2040 s of PC mode data and 4 UVOT
images, we find an enhanced XRT position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
268.71817, -25.79815 which is equivalent to:

RA (J2000): 17h 54m 52.36s
Dec(J2000): -25d 47' 53.3"

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

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.22 (+/-0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+1.3, -1.1). The
best-fitting absorption column is  2.5 (+1.3, -1.0) x 10^23 cm^-2, in
excess of the Galactic value of 1.4 x 10^22 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 1.2 x 10^-10 (7.0 x 10^-10) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      2.5 (+1.3, -1.0) x 10^23 cm^-2
Galactic foreground: 1.4 x 10^22 cm^-2
Excess significance: 4.0 sigma
Photon index:      2.1 (+1.3, -1.1)

If the light curve continues to decay with a power-law decay index of
1.22, the count rate at T+24 hours will be 2.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x
10^-13 (1.8 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/00856977.

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


GRB_name: GRB180829A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23187
SUBJECT: GRB 180829A: Tiled Swift observations
DATE:    18/08/29 15:49:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 180829A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00073

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 MAXI 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: GRB180828A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23188
SUBJECT: GRB 180828A: Swift-BAT refined analysis
DATE:    18/08/29 16:00:35 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), 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+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180828A (trigger #856977)
(Beardmore et al., GCN Circ. 23182).  The BAT ground-calculated position is
RA, Dec = 268.704, -25.791 deg which is
  RA(J2000)  =  17h 54m 49.1s
  Dec(J2000) = -25d 47' 28.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 19%.

The mask-weighted light curve shows a few overlapping pulses that starts at
~ T-7 s and ends at ~T+2 s, with some weak tail emission that lasts till
~ T+30 s. T90 (15-350 keV) is 14.0 +- 8.0 sec (estimated error including systematics).

The time-averaged spectrum from T-7.29 to T+28.71 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.89 +- 0.06.  The fluence in the 15-150 keV band is 8.8 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.29 sec in the 15-150 keV band
is 17.8 +- 0.9 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The BAT temporal and spectral characteristics are consistent with
those of a GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/856977/BA/


GRB_name: GRB180828A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23189
SUBJECT: GRB 180828A: RATIR Optical and NIR Observations
DATE:    18/08/29 16:14:03 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 180828A (Beardmore, et al., GCN 23182) 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 2018/08 29.14 to 2018/08 29.28 UTC (8.29 to
11.70 hours after the BAT trigger), obtaining a total of 1.73 hours
exposure in the r and i bands and 0.79 hours exposure in the Z, Y, J, and H
bands.

We find one uncatalogued source within the Swift-XRT error circle
(Beardmore at at., GCN 23182) at RA, Dec = 17:54:52.5 -25:47:56.3 (J2000,
+/-0.5").  This source is outside the enhanced XRT error region (Evans et
al., GCN 23184), within which we find no new sources.  In comparison with
the 2MASS catalog, we obtain the following detection and 3-sigma upper
limit:

 J > 21.4
 H = 20.8 +/- 0.3

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.  We note that this field has high
extinction, with E[B-V]~16.

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


GRB_name: GRB180828A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23190
SUBJECT: GRB 180828A: Swift/UVOT Upper Limits
DATE:    18/08/29 17:21:47 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

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

The Swift/UVOT began settled observations of the field of GRB 180828A
124 s after the BAT trigger (Beardmore et al., GCN Circ. 23182).
No optical afterglow consistent with the XRT position
(LaPorte et al., GCN Circ. 23185) or the position of the source 
detected outside the enhanced XRT error region by RATIR 
(Butler et al., GCN Circ. 23189)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

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

white              124        23102         1057         >21.8
v                16882        39624         1367         >20.3
b                 5752        28839         1439         >21.7
u                 5547        34577         1709         >21.1
uvw1              5342        33925         1082         >20.7
uvm2              5137        40314         1756         >21.0
uvw2             11215        38709         2087         >21.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 23.65 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180828A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23191
SUBJECT: GRB 180828A: AstroSat CZTI detection
DATE:    18/08/29 21:32:04 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

T. Khanam, 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 180828A, which was also detected by Swift (Beardmore A. P. et al., GCN 23182) and Fermi-GBM (Roberts O. J. et al., GCN 23183).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 18:57:35.500 UT. The measured peak count rate is 947 cts/s above the background in combined data of four quadrants, with a total of 3607 cts. The local mean background count rate was 557 cts/s. Using cumulative rates, we measure a T90 of 8.9 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: GRB180829A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23192
SUBJECT: GRB 180829A: Swift-XRT observations
DATE:    18/08/30 08:10:55 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), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
D.N. Burrows (PSU) and P.A. Evans (U. Leicester) report on behalf of
the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 180829A (Yamada et al. GCN Circ. 23186) in a series of
observations tiled on the sky. The total exposure time is 1.4 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 420 s. The data were collected between T0+56.4 ks and T0+57.9 ks,
and are entirely in Photon Counting (PC) mode. 

No X-ray sources have been detected. The 3-sigma upper limit in the
field (not including the regions where the tiles overlap) ranges from
~0.03 to ~0.11 ct s^-1, corresponding to a 0.3-10 keV observed flux of
1.1e-12 to 4.4e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

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_GRB00073.

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


GRB_name: GRB180828A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23193
SUBJECT: Konus-Wind observation of GRB 180828A
DATE:    18/08/30 20:51:39 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 180828A (Swift-BAT detection:
Beardmore et al., GCN 23182; Markwardt et al., GCN 23188;
Fermi-GBM observation: Roberts & Meegan, GCN 23183;
AstroSat-CZTI detection: Khanam et al., GCN 23191)
triggered Konus-Wind at T0=68250.016 s UT (18:57:30.016).

The burst light curve shows a multipeaked structure
which starts at ~T0-6 s and has a duration of ~14.7 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst
had a fluence of 4.41(-0.17,+0.17)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+7.456 s,
of 1.57(-0.24,+0.26)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+15.104 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.50(-0.12,+0.12)
and Ep = 341(-21,+24) keV (chi2 = 72/88 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 70/87 dof).

The spectrum near the maximum count rate
(measured from T0+6.912 to T0+15.104 s)
is best fit in the 20 keV - 10 MeV range
by the CPL model with  alpha = -0.36(-0.23,+0.26)
and Ep = 395(-45,+59) keV (chi2 = 61/86 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.5
(chi2 = 61/85 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180828_T68250/

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


GRB_name: GRB180904A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23194
SUBJECT: GRB 180904A: Swift detection of a burst
DATE:    18/09/04 21:42:57 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. D'Ai (INAF-IASFPA), J.D. Gropp (PSU), J. A. Kennea (PSU),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
M. J. Moss (George Washington University), D. M. Palmer (LANL),
B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 21:28:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180904A (trigger=859282).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 274.250, +46.623 which is 
   RA(J2000) = 18h 17m 00s
   Dec(J2000) = +46d 37' 24"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 20 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. 

The XRT began observing the field at 21:30:35.3 UT, 123.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source with an enhanced position: RA, Dec 274.2495,
46.6298 which is equivalent to:
   RA(J2000)  = 18h 16m 59.87s
   Dec(J2000) = +46d 37' 47.4"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 24 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 in excess of the Galactic value (3.37 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.3
(+3.26/-2.80) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 4.47e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 131 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. D'Ai (antonino.dai AT ifc.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB180904A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23195
SUBJECT: GRB 180904A: NOT optical observations, candidate host galaxy
DATE:    18/09/04 23:04:27 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), Sune Dyrbye (NOT), report on behalf of a largert 
collaboration:

We observed the field of GRB 180904A (D'Ai' et al., GCN 23194) with the 
Nordic Optical Telescope (NOT) equipped with the AlFOSC camera.

In an image of 300 s exposure taken with the SDSS r filter and 
commencing on Sep 4.9057 UT (15.6 min after the GRB), we detect a single 
object consistent with the currently available XRT position 
(http://www.swift.ac.uk/xrt_positions/). Its coordinates are (J2000):

RA = 18:16:59.74
Dec = +46:37:47.1

Compared to nearby stars from the Pan-STARRS survey, we measure for this 
object a magnitude r = 22.56 +- 0.08 AB.

We note that the same object is visible in the archival Pan-STARRS image 
of this field, with a measured magnitude r = 22.84 +- 0.15 AB. There is 
thus only marginal indication of excess flux in the NOT image. If this 
object is related to GRB 180904A, as suggested by the spatial 
coincidence with the X-ray position, it is largely or entirely dominated 
by the host galaxy.

Further observations are planned.


GRB_name: GRB180904A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23196
SUBJECT: GRB 180904A: Enhanced Swift-XRT position
DATE:    18/09/04 23:19:01 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 468 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180904A, 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 = 274.24978, +46.62971 which is equivalent
to:

RA (J2000): 18h 16m 59.95s
Dec (J2000): +46d 37' 46.9"

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: GRB180904A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23197
SUBJECT: GRB 180904A: OSN observations
DATE:    18/09/05 00:16:23 GMT
FROM:    Luca Izzo at IAA-CSIC  <Luca.Izzo@ICRA.it>

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

We observed the field of GRB 180904A (Dâ€™Ai et al., GCN #23194) with the 1.5-m OSN telescope in Granada, Spain. We obtained 12 x 300 s images in the Ic band centered at 1.23 hours after the GRB.

At the enhanced XRT position of the GRB (Osborne et al., GCN #23196), we find no source inside the Swift-XRT error circle down to a limit of Ic (AB) > 22.4. We note, however, that the object reported in Malesani et al., GCN #23195, lies just outside the XRT position reported by Osborne et al., and may therefore be unrelated to the GRB.

The calibration was performed using i-band magnitudes of nearby stars in the Pan-STARRS catalog, transformed into Ic magnitudes according to the Lupton (2005) transformations.


GRB_name: GRB180904A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23198
SUBJECT: GRB 180904A: SAO RAS optical observations
DATE:    18/09/05 00:46:37 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

Moskvitin, A. S., Spiridonova O. I., Maslennikova O. A. (SAO RAS),
report on behalf of larger GRB follow-up team.

We observed the field of the GRB 180904A (D'Ai et al., GCNC 23194)
with the Zeiss-1000 telescope of SAO RAS (+ CCD UBVRcIc photometer)
on the 2018 September, 4.926 (mid. time).

The observations started since 7.2 minutes after the Swift trigger
(21:35:44--22:46:03 UT). 12 x 300 sec. exposures in Rc band
were obtained. We can not see any object inside the XRT enhanced
1".8 error circle (Osborne et al., GCNC 23196) down to
the limiting magnitude of R_lim = 22.7, but at the edge
of the circle we detected the object mentioned by Malesani et al.
(GCNC 23195). The preliminary magnitude of the object is
R = 21.9 +/- 0.2 (Vega system) compared to nearby USNO-B1 stars.

The finding chart can be found at
ftp://ftp.sao.ru/pub/grb/GRB/GRB180904A_SAORAS.png


GRB_name: GRB180904A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23199
SUBJECT: GRB 180904A: LT early observations
DATE:    18/09/05 09:57:11 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 robotic Liverpool Telescope automatically began observing Swift 
GRB 180904A (D'Ai et al. GCN 23194) with the polarimeter RINGO3 and the 
IO:O camera on September 04, 21:32:12 UT (219 seconds from the GRB 
trigger time). Within the enhanced Swift-XRT error circle (Osborne et 
al. GCN 23196) we do not detect any object down to a limit of r' > 21.2 
mag in a 6x10s exposure at a mid time of 37 minutes post burst, as 
calibrated against nearby Pan-STARRS objects, in agreement with previous 
reports (Malesani et al. GCN 23195; Izzo et al. GCN 23197; Moskvitin et 
al. GCN 23198).


GRB_name: GRB180904A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23200
SUBJECT: GRB 180904A: Swift-XRT refined Analysis
DATE:    18/09/05 13:04:23 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), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), P.A. Evans (U.
Leicester) and A. D'Ai report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 180904A (D'Ai et al. GCN
Circ. 23194), from 129 s to 45.0 ks after the  BAT trigger. The data
comprise 91 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. 23196).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=0.9 (+0.4, -0.6). At T+179 s  the decay
steepens to an alpha of 7.84 (+0.16, -1.21) before breaking again at
T+247 s to a final decay with index alpha=1.19 (+/-0.15).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.61 (+0.24, -0.22). The
best-fitting absorption column is  4.6 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 3.4 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.19 (+0.26, -0.24)
and a best-fitting absorption column of 4.3 (+1.2, -1.1) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.6 x 10^-11 (6.4 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.3 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 3.4 x 10^20 cm^-2
Excess significance: 6.0 sigma
Photon index:      2.19 (+0.26, -0.24)

If the light curve continues to decay with a power-law decay index of
1.19, the count rate at T+24 hours will be 7.3 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x
10^-14 (4.6 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/00859282.

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


GRB_name: GRB180905A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23201
SUBJECT: GRB 180905A: Swift detection of a burst
DATE:    18/09/05 14:07:32 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

V. D'Elia (SSDC), A. D'Ai (INAF-IASFPA), J.D. Gropp (PSU),
J. A. Kennea (PSU), M. J. Moss (George Washington University),
K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 13:57:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180905A (trigger=859421).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 91.035, -4.591 which is 
   RA(J2000) = 06h 04m 08s
   Dec(J2000) = -04d 35' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual for an image trigger, no obvious
variation is visible in the immediately-available lightcurve. 

The XRT began observing the field at 14:00:12.3 UT, 145.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 91.0602, -4.5724 which is equivalent to:
   RA(J2000)  = 06h 04m 14.45s
   Dec(J2000) = -04d 34' 20.6"
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This
location is 112 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 2.03e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 135 seconds with the White filter
starting 153 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
0.60. 

Burst Advocate for this burst is V. D'Elia (delia AT ssdc.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: GRB180904A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23203
SUBJECT: GRB 180904A: Swift-BAT refined analysis
DATE:    18/09/05 15:28:50 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), A. D'Ai (INAF-IASFPA),
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 180904A (trigger #859282)
(D'Ai et al., GCN Circ. 23194).  The BAT ground-calculated position is
RA, Dec = 274.260, 46.640 deg which is
  RA(J2000)  =  18h 17m 02.4s
  Dec(J2000) = +46d 38' 23.3"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 56%.

The mask-weighted light curve shows a weak structure that starts at ~T0
and ends at ~T+6 s. T90 (15-350 keV) is 5.40 +- 0.89 sec (estimated error
including systematics).

The time-averaged spectrum from T+0.28 to T+6.18 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.02 +- 0.30.  The fluence in the 15-150 keV band is 2.4 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+5.14 sec in the 15-150 keV band
is 0.5 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/859282/BA/


GRB_name: GRB180904A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23204
SUBJECT: GRB 180904A: RATIR Optical and NIR Observations
DATE:    18/09/05 15:49:17 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 180904A (D'Ai, et al., GCN 23194) 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 2018/09 5.13 to 2018/09 5.32 UTC (5.66 to
10.26 hours after the BAT trigger), obtaining a total of 2.91 hours
exposure in the r and i bands and 1.33 hours exposure in the Z, Y, J, and H
bands.

Within the XRT error circle (Osborne, et al., GCN 23196), we detect the
source reported by Malesani, et al. (GCN 23195) at a consistent brightness
level.  In comparison with the USNO-B1 and 2MASS catalogs, we obtain the
following detections and upper limit (3-sigma):

 r = 22.61 +/- 0.08
 i = 22.06 +/- 0.05
 Z = 22.13 +/- 0.16
 Y = 21.64 +/- 0.18
 J = 21.72 +/- 0.21
 H > 21.86

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: GRB180904A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23205
SUBJECT: GRB 180904A: Swift/UVOT Upper Limits
DATE:    18/09/05 15:58:34 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180904A
131 s after the BAT trigger (D'Ai et al., GCN Circ. 23194).
No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 23196)
is detected in the initial UVOT exposures, consistent with the non-detections
of Malesani et al. (GCN Circ. 23195), Izzy et al. (GCN Circ 23197), 
Moskvitin et al. (GCN Circ. 23198) and Guidorzi et al. (GCN Circ. 23199).
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           131          281          147         >21.1
u_FC               289          539          246         >20.1
white              131          589          167         >21.1
v                  620          640           19         >20.1
b                  545          565           19         >19.4
u                  289          539          246         >20.1
w1                 670          690           19         >18.1
w2                 595          615           19         >18.6

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: GRB180904A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23206
SUBJECT: GRB 180904A: AbAO optical upper limit
DATE:    18/09/05 16:18:22 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Volnova  (IKI),  A. Pozanenko (IKI), R. Inasaridze (AbAO),  E. 
Mazaeva (IKI),  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 the Swift GRB 180904A (D'Ai et al., GCN 23194) 
with AS-32 (0.7m) telescope of Abastumani Observatory starting on 
September 04 (UT) 21:52:23.   We do not detect any object within 
enhanced XRT position (Osborne et al., GCN 23196). Preliminary 
photometry of the field is following:

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

2018-09-04  21:52:23   0.05731   CR     70*60  n/d   n/d  21.5

The photometry is based on nearby USNO-B1.0 stars (R2 magnitude)
USNO-B.1_id    R2
1366-0296056   14.72
1366-0296068   15.43
1365-0287325   15.62
1366-0296106   15.21
1366-0296088   14.95
1366-0296093   14.37


GRB_name: GRB180905A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23207
SUBJECT: GRB 180905A: Enhanced Swift-XRT position
DATE:    18/09/05 18:09:33 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 1840 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 180905A, 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 = 91.06265, -4.57015 which is equivalent
to:

RA (J2000): 06h 04m 15.04s
Dec (J2000): -04d 34' 12.6"

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: GRB180905A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23208
SUBJECT: GRB 180905A: BOOTES-3/YA optical observations
DATE:    18/09/05 20:41:11 GMT
FROM:    Youdong HU at IAA-CSIC, UGR  <youdong@iaa.es>

Y.-D. Hu, E. Fernandez-Garcia, J. C. Tello, A. Ayala and A. J. 
Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de 
Malaga), M. D. Caballero-Garcia (ASU-CAS, CZ) and R. Querel (NIWA), on 
behalf of a larger collaboration, report:

The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New 
Zealand) automatically responded to the Swift trigger of GRB 180905A 
(D'Elia et al. GCNC 23201) ~0.55 h after the burst as soon as it became 
few degrees above the horizon. The first image (clear filter) were 
obtained starting at 14:30:52 UT. At the position of the Swift/XRT 
enhanced X-ray position (Beardmore et al. GCNC 23207), no optical 
afterglow is detected down to 20 mag on a 720s co-added image at 
14:38:31 (mid-exposure), in agreement with the non-detection by 
Swift/UVOT.
Further analysis is ongoing.

We thank the staff at NIWA for its excellent support.


GRB_name: GRB180904A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23209
SUBJECT: GRB 180904A: BOOTES-2/TELMA early observations
DATE:    18/09/05 22:11:32 GMT
FROM:    Youdong HU at IAA-CSIC, UGR  <youdong@iaa.es>

C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), Y.-D. 
Hu, E. Fernandez-Garcia, J. C. Tello, A. Ayala, A. J. Castro-Tirado 
(IAA-CSIC), and M. Jelinek (ASU-CAS), on behalf of a larger 
collaboration, report:

The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) 
in Algarrobo Costa (Spain) automatically responded in 56s (and 116s 
after the GRB onset) to the Swift trigger of GRB 180904A (D'Ai et al. 
GCNC 23194). The first image (11s exposure, unfiltered) was obtained at 
21:30:28 UT. At the position of the enhanced Swift X-ray afterglow 
(Osborne et al. GCNC 23196), no optical afterglow is detected down to 19 
mag at a mid time of 6 minutes post burst. This is consistent with the 
limits reported by Malesani et al. (GCNC 23195), Izzo et al. (GCNC 
23197), Moskvitin et al. (GCNC 23198, Guidorzi et al. (GCNC 23199), 
Butler et al. (GCNC 23204), Siegel et al. (GCNC 23205), Volnova et al. 
(GCNC 23206).


GRB_name: GRB180905A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23210
SUBJECT: GRB 180905A: Swift-XRT refined Analysis
DATE:    18/09/06 02:40:59 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 9.0 ks of XRT data for GRB 180905A (D'Elia et al. GCN
Circ. 23201), from 152 s to 35.0 ks after the  BAT trigger. The data
comprise 135 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. 23207).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.556 (+0.029, -0.027).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.45 (+0.11, -0.10). The
best-fitting absorption column is  5.7 (+1.1, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 3.5 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.68 (+0.28, -0.26)
and a best-fitting absorption column of 5.5 (+2.2, -1.8) 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 (6.9 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.5 (+2.2, -1.8) x 10^21 cm^-2
Galactic foreground: 3.5 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index:      1.68 (+0.28, -0.26)

If the light curve continues to decay with a power-law decay index of
1.556, the count rate at T+24 hours will be 1.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x
10^-14 (1.2 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/00859421.

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


GRB_name: GRB180905A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23211
SUBJECT: GRB 180905A: MITSuME Akeno optical upper limits
DATE:    18/09/06 05:53:52 GMT
FROM:    Katsuhiro L. Murata at Nagoya U  <murata@u.phys.nagoya-u.ac.jp>

M. Niwano, R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita,
K. Shiraishi, K. Iida, R. Adachi, M. Oeda,
Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We searched for the optical counterpart of GRB 180905A
(V. D'Elia et al., GCN Circular #23201)
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 2018-09-05 17:29:51.08 UT.
We did not find any point source at the enhanced position of the
XRT error circle (A.P. Beardmore et al., GCN Circular #23207) in all three
bands.
We obtained following 5-sigma upper limits for the magnitudes.

T0+[min]    MID-UT      T-EXP[sec]    g'       Rc        Ic
-------------------------------------------------------------------------------------------------------
202.32     18:46:39  8,100   >18.9   >18.6   >18.4
-------------------------------------------------------------------------------------------------------

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


GRB_name: GRB180905A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23212
SUBJECT: GRB 180905A: RATIR Optical and NIR Observations 
DATE:    18/09/06 13:30:04 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 180905A (D'Elia et al., GCN Circ. 23201)
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 2018/09 6.42 to
2018/09 6.51 UTC (20.07 to 22.23 hours after the BAT trigger), obtaining
a total of 1.17 hours exposure in the r and i bands and 0.57 hours
exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT enhanced error circle (Beardmore et
al., GCN Circ. 23207), in comparison with the USNO-B1 and 2MASS
catalogs, we obtain the following upper limits (3-sigma):

  r > 23.26
  i > 23.10
  Z > 22.21
  Y > 22.06
  J > 21.60
  H > 21.25

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: GRB180905A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23213
SUBJECT: GRB 180905A, Swift-BAT refined analysis
DATE:    18/09/06 16:12:08 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), V. D'Elia (SSDC),
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+250 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180905A (trigger #859421)
(D'Elia et al., GCN Circ. 23201).  The BAT ground-calculated position is
RA, Dec = 91.038, -4.592 deg which is
  RA(J2000)  =  06h 04m 09.2s
  Dec(J2000) = -04d 35' 31.9"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 29%.

The mask-weighted light curve shows a weak long pulse that starts
at ~T-60 s and ends at ~T+150 s. Note that the burst came into the BAT
field of view at T-84 s, and BAT entered the SAA after ~ T+250 s. Therefore,
there might be additional burst emission before and after the available event
data range. T90 (15-350 keV) is 165.3 +- 28.9 sec (estimated error including
systematics).

The time-averaged spectrum from T-58.9 to T+146.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.60 +- 0.12.  The fluence in the 15-150 keV band is 4.2 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-2.09 sec in the 15-150 keV band
is 1.0 +- 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/859421/BA/


GRB_name: GRB180905A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23215
SUBJECT: GRB 180905A: Swift/UVOT Upper Limits 
DATE:    18/09/09 19:37:38 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

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

The Swift/UVOT began settled observations of the field of GRB 180905A
154 s after the BAT trigger (D'Elia et al., GCN Circ. 23201).
No optical afterglow consistent with the XRT position
(D'Elia et al. GCN Circ. 23201) is detected in the initial UVOT exposures,
as confirmed by Bootes (Hu et al., GCN Circ. 23208), MITSUME (Niwano
et al., GCN Circ. 23211) and RATIR (Watson et al., GCN Circ. 23212).
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           154          289          133         >20.4
white              154         6385          373         >21.1
v                 5316         5515          197         >19.1
b                 4700         6335          393         >20.5
u                 4495         6130          393         >20.3
w1                5726         5925          197         >19.6
m2                5520         5720          197         >19.8
w2                5111         5311          197         >19.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.60 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB180718A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23216
SUBJECT: GRB 180718A: 15 GHz upper limits from the AMI Short GRB Program
DATE:    18/09/10 06:44:13 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 short GRB 180718A (Svinkin et al., GCN 22959) 
with the AMI Large Array at 15 GHz. Our observation on 2018 Jul 22.03 
(UT) (3.95 d post-burst) does not reveal any potential afterglow 
candidate consistent with the BAT location (Svinkin et al., GCN 22959), 
and our 3sigma upper limit to the flux density is 180 uJy.

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: GRB180715A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23217
SUBJECT: GRB 180715A: 15 GHz upper limits from the AMI Short GRB Program
DATE:    18/09/10 06:54:19 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 short GRB 180718A (Ukwatta et al., GCN 22947) 
with the AMI Large Array at 15 GHz. Our observations on 2018 Jul 16.80, 
Jul 17.73, Jul 19.80 and Jul 23.80 (UT) (1.05 d, 1.98 d, 4.05 d and 7.05 
d post-burst) does not reveal any potential afterglow candidate 
consistent with the BAT location (Ukwatta et al., GCN 22947), and our 
3sigma upper limit to the flux density are 137 uJy, 186 uJy, 106 uJy and 
146 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: GRB180914A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23225
SUBJECT: GRB 180914A: Fermi-LAT detection
DATE:    18/09/14 19:27:09 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico & INFN Bari), D. Kocevski (NASA/MSFC),
and N. Omodei (Stanford Univ) report on behalf of the Fermi-LAT team:


At 12:31:47.25 UT on September 14, 2018 Fermi-LAT detected
high-energy emission from GRB 180914A, which was also detected by
Fermi-GBM (trigger 558621112 / 180914522).

The best LAT on-ground location is found to be

RA, Dec = 52.74, -5.26 (J2000)

with an error radius of 0.40 deg (90 % containment,
statistical error only). This was 87 deg from the LAT boresight
at the time of the trigger.

The data from the Fermi-LAT show a significant increase in the event
rate that is spatially correlated with the trigger with high significance.
The highest-energy photon is a 5.1 GeV event which is
observed 630 s after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is
Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it).


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


GRB_name: GRB180914B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23226
SUBJECT: GRB 180914B: AGILE/MCAL detection of a burst
DATE:    18/09/14 22:37:55 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

GRB 180914B: AGILE/MCAL detection of a burst

A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata),
A. Argan, M. Cardillo, Y. Evangelista, G. Minervini, G. Piano (INAF/IAPS),
F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and INAF/OAR),
A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS), M.
Marisaldi (INAF/OAS, and Bergen University), M. Pilia, A. Trois
(INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN
Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a long burst at T0 = 2018-09-14
18:23:02.22 +/- 0.01 s (UTC).

The event lasted T90 = 5.8 s (in the 0.4-100 MeV energy range), consisting
of two broad pulses, and released a total number of ~25,000 counts in the
detector, above an average background rate of ~1250 counts / s.

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: GRB180914A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23227
SUBJECT: GRB 180914A: Fermi GBM detection
DATE:    18/09/14 23:47:15 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

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

"At 12:31:47.25 UT on 14 September 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180914A (trigger 558621112/ 180914522),
which was also detected by the Fermi LAT (E. Bissaldi et al. 2018, GCN
23225).
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight
at the GBM trigger time is 86 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 122.4 s (50-300 keV).
The time-averaged spectrum from T0+1.0 s to T0+156.7 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.70 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 296 +/- 7 keV.

The event fluence (10-1000 keV) in this time interval is
(9.152 +/- 0.128)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+21.37 s in the 10-1000 keV band
is 12.73 +/- 0.36 ph/s/cm^2.

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


GRB_name: GRB180914A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23228
SUBJECT: GRB 180914A: Tiled Swift observations
DATE:    18/09/14 23:48:16 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 180914A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00074

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

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

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


GRB_name: GRB180914A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23229
SUBJECT: GRB 180914A: Swift-XRT observations
DATE:    18/09/15 07:59:26 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

V. D'Elia (ASDC), 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) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 180914A (Bissaldi et al. GCN Circ. 23225)
in a series of observations tiled on the sky. The total exposure time
is 1.8 ks, distributed over 7 tiles; the maximum exposure at a single
sky location was 546 s. The data were collected between T0+40.9 ks and
T0+43.0 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):  53.0804  =  03:32:19.29
  Dec (J2000): -5.6243  =  -05:37:27.5
  Error: 5.0 arcsec (radius, 90% conf.)
  Count-rate: 0.162 [+0.048, -0.040] ct s^-1   
  Distance: 1791 arcsec from Fermi/LAT position.
  Flux: (7.7 [+2.3, -1.9])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)

We note the presence of a bright star (with magnitude R~12.7, as
reported in the USNOB1 catalogue) about 14" away from Source 1.

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_GRB00074.

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


GRB_name: GRB180914A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23230
SUBJECT: GRB 180914A: MASTER automatic inspection 
DATE:    18/09/15 08:31:45 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, D. Vlasenko, N.Tiurina,
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI

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

D.Svinkin (Ioffe Institute, Sankt Petersburg)

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

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

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

MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru,
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located near 
Bykal Lake (Irkutsk University Astrophysical Center) was starting survey
on the FERMI  GRB180914.52  error-box  (Poolakkil et al., GCN #23227).

17768 sec after trigger time at 
2018-09-14 17:27:55 UT. The 5-sigma upper limit on our first (180s 
exposure)  set is about 16.0 mag

No OT found.

MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
South Africa (South African Astronomical Observatory) was starting survey 
on the LAT  GRB180914.52  error-box (ra=03 30 
57 dec=-05 15 35 r=0.4, (Bissaldi et al., GCN #23225)). 
15521 sec after notice time and 38331 sec after trigger time at 2018-09-14 
23:10:38 UT. The 5-sigma upper limit on our first (180s exposure)  set is 
about 18.5 mag

The cover map is available at 
http://observ.pereplet.ru/images/GRB180914A.png

No new objects brighter than 18.5 mag  were found after the human analysis 
of automatic candidates.


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


The galacitc latitude b =  0 deg.

The observations made on zenit distance = 54 deg.The moon (31 % bright 
part) below the horizon (The altitude of the Moon is -19 deg. ).
The sun  altitude  is -59.4 deg.
The object can be observed till sunrise at 2018-09-15 04:35:52



THIS BLOCK FOR MASTER-Team USERS ONLY.

Link to GRB180914.52 page: 
https://196.21.94.34//master2/grb.php?not=2018-09-14+18%3A51%3A56.63329&sat=LAT&gcrd=%2852.7375d%2C-5.25972d%29&eb=0.4&trig=2018-09-14+12%3A31%3A47.25&n=GRB180914.52
Long     transients in E.B. 
https://196.21.94.34//master2/trans.php?wh=transients.coord2000@%27%3C%2852.7375d%2C-5.25972d%29%2C0.8d%3E%27%3A%3Ascircle+and+transients.datetime%3E%3D%272018-09-14+12%3A31%3A47.25%27&class=9&t2=LAT+GRB180914.52+optical+counterpart+candidate
Short    transients in E.B. 
https://196.21.94.34//master2/trans3.php?wh=transients3.coord2000@%27%3C%2852.7375d%2C-5.25972d%29%2C0.8d%3E%27%3A%3Ascircle+and+transients3.datetime%3E%3D%272018-09-14+12%3A31%3A47.25%27&class=-1&t2=LAT+GRB180914.52+optical+counterpart+candidate
Two tube transients in E.B. 
https://196.21.94.34//master2/trans2.php?wh=transients2.coord2000@%27%3C%2852.7375d%2C-5.25972d%29%2C0.8d%3E%27%3A%3Ascircle+and+transients2.datetime%3E%3D%272018-09-14+12%3A31%3A47.25%27&class=0&t2=LAT+GRB180914.52+optical+counterpart+candidate
Undef. objects 1 image 
https://196.21.94.34//master2/aobj.php?wh=stars.coord2000@%27%3C%2852.7375d%2C-5.25972d%29%2C0.8d%3E%27%3A%3Ascircle+and+stars.class=0+and+stars.status+and+stars.proc_id=578290&t2=LAT+GRB180914.52+1+image+optical+counterpart+candidate

This message can be cited


GRB_name: GRB180914B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23231
SUBJECT: GRB 180914B: AGILE/GRID detection
DATE:    18/09/15 14:06:01 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

GRB 180914B: AGILE/GRID detection

F. Verrecchia (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), F. Longo (Univ. Trieste and INFN
Trieste), A. Argan, M. Cardillo, A. Giuliani (INAF/IASF-Mi), Y.
Evangelista, G. Minervini, G. Piano (INAF/IAPS), F. Lucarelli, C.
Pittori (SSDC,
and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, M. Marisaldi
(INAF/OAS, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari),
I. Donnarumma (ASI),
report on behalf of the AGILE Team:

The Gamma-Ray Imaging Detector (GRID) of AGILE detected the long bright
GRB 180914B reported Ursi et al., GCN 23226.
A preliminary GRID analysis in the energy range 30 - 420 MeV shows a
detection
with a statistical significance of about 9 sigma, at the sky position
L,B: 85,-26 +/- 5 deg.

The gamma-ray emission detected by the AGILE-GRID lasted about 16 seconds,
and the preliminary estimated position is between 50 and 70 deg off-axis
angle.

These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress.


GRB_name: GRB180914B
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23232
SUBJECT: GRB 180914B: Fermi-LAT detection
DATE:    18/09/15 14:32:01 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico & INFN Bari) and F. Longo (Univ & INFN Trieste)
report on behalf of the Fermi-LAT team:


At 18:23:02 UT on September 14, 2018 Fermi-LAT detected high-energy emission
from GRB 180914B, which was also detected by AGILE/MCAL (Ursi et al., GCN #23226)
and by AGILE/GRID (Verrecchia et al., GCN #23231).

The best LAT on-ground location is found to be

RA, Dec = 332.45, 24.88 (J2000)

with an error radius of 0.33 deg (90 % containment, statistical error only).
This was 94 deg from the LAT boresight at the time of the trigger.
The Fermi-LAT position is consistent with the AGILE/GRID one.

The data from the Fermi-LAT show a significant increase in the event rate
that is spatially correlated with the trigger with high significance.
The highest-energy photon is a 12.6 GeV event
which is observed 1662 s after the AGILE trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is
Elisabetta Bissaldi (elisabetta.bissaldi@ba.infn.it).


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


GRB_name: GRB180914B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23233
SUBJECT: GRB 180914B: AGILE/GRID detection
DATE:    18/09/15 14:51:10 GMT
FROM:    Francesco Verrecchia at ASDC  <francesco.verrecchia@ssdc.asi.it>

F. Verrecchia (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), F. Longo (Univ. Trieste and INFN
Trieste), A. Argan, M. Cardillo, A. Giuliani (INAF/IASF-Mi), Y. Evangelista,
G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, A. Bulgarelli, V. Fioretti,
F. Fuschino, M. Marisaldi (INAF/OAS, and Bergen University), M. Pilia, A.
Trois (INAF/OA-Cagliari), I. Donnarumma (ASI),
report on behalf of the AGILE Team:

The Gamma-Ray Imaging Detector (GRID) of AGILE detected the long bright
GRB 180914B reported in Ursi et al., GCN 23226.
A preliminary GRID analysis in the energy range 30 - 420 MeV shows a detection
with a statistical significance of about 9 sigma, at the sky position
L,B: 85.0, -26.0 +/- 5 deg.

The gamma-ray emission detected by the AGILE-GRID lasted about 16 seconds,
and the preliminary estimated position is between 50 and 70 deg off-axis.

These measurements were obtained with AGILE observing a large portion of
the sky in spinning mode. Additional analysis of AGILE data is in progress.


GRB_name: GRB180914B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23234
SUBJECT: GRB 180914B: Tiled Swift observations
DATE:    18/09/15 17:34:21 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 180914B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00075

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

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

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


GRB_name: GRB180914A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23235
SUBJECT: GRB 180914A: RATIR Optical and NIR Observations
DATE:    18/09/15 19:44:14 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), 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), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:

We observed the field of the LAT GRB 180914A (Bissaldi, et al., GCN
23225) with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronomico Nacional on Sierra San Pedro Martir from 2018/09 15.29 to
2018/09 15.50 UTC (18.54 to 23.57 hours after the Fermi trigger),
obtaining a total of 3.00 hours exposure in the r and i bands and
1.24 hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (D'Elia, et al.,
GCN 23229), in comparison with the SDSS DR9 and 2MASS catalogs, we
obtain the following upper limits (3-sigma):

   r    > 24.2
   i    > 24.1
   Z    > 22.7
   Y    > 22.5
   J    > 22.0
   H    > 21.6

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 Astronomico Nacional in San Pedro
Martir.


GRB_name: GRB180914B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23236
SUBJECT: GRB 180914B: Swift-XRT afterglow detection
DATE:    18/09/15 22:21:41 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU),
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/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 (U. Leicester) report on behalf
of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 180914B (Bissaldi et al. GCN Circ. 23232)
in a series of observations tiled on the sky. The total exposure time
is 4.1 ks, distributed over 6 tiles; the maximum exposure at a single
sky location was 1.3 ks. The data were collected between T0+82.8 ks and
T0+93.8 ks, and are entirely in Photon Counting (PC) mode. 

An uncatalogued X-ray source is detected and is above the RASS limit,
and is therefore likely the GRB afterglow. Using 579 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 = 332.35648, +25.06314 which is equivalent to:

RA (J2000): 22h 09m 25.56s
Dec(J2000): +25d 03' 47.3"

with an uncertainty of 3.4 arcsec (radius, 90% confidence). This
position is 12.1 arcmin from the Fermi/LAT position.  The source has a
mean count rate of 6.2e-02 ct/sec; we cannot determine at the present
time whether it is fading.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00075/Source2.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00075.

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


GRB_name: GRB180914B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23237
SUBJECT: GRB 180914B: KAIT Optical Afterglow Candidate
DATE:    18/09/16 04:23:18 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 AGILE/MCAL GRB 180914B (Ursi et al.,
GCN 23226 starting at Sep. 16, 03:47:39 UT, namely ~1.392 days
after the burst. Observations were performed with a sequence in the
clear (roughly R), B, V, R, and I filters, and the exposure time was
60 s per image. Inside the reported Swift/XRT afterglow error circle
(D'Ai et al., GCN 23236) we detected an optical afterglow candidate
at position:
RA:  22:09:25.55 (J2000)
Dec: +25:03:43.90 (J2000)
We estimate the clear band magnitude ~19.2. At this time, we can not
estimate the changes of the brightness. But the object was not presented
in the SDSS image, we therefore suggest it to be the optical  afterglow of
GRB 180914B.
Observation are on going, multi-band follow-ups are encouraged.


GRB_name: GRB180914B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23238
SUBJECT: GRB 180914B: RATIR Optical and NIR Observations
DATE:    18/09/16 05:48:12 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), 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), , Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:

We observed the field of GRB 180914B, detected by AGILE/MCAL (Ursi,
et al., GCN 23226) AGILE/GRID (Verrecchia, et al., GCN 23231), and
Fermi/LAT (Bissaldi, et al., GCN 23232) with the Reionization and
Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold
Johnson Telescope at the Observatorio Astronomico Nacional on Sierra
San Pedro Martir from 2018/09 16.14 to 2018/09 16.16 UTC (32.90 to
33.43 hours after the burst), obtaining 0.36 hours exposure in the
r and i bands and 0.15 hours exposure in the Z, Y, J, and H bands.

Within the Swift-XRT error circle (D'Ai, et al., GCN 23236),
we detect the object reported by Zheng & Filippenko (GCN 23237).
In comparison with the SDSS DR9 and 2MASS catalogs, we obtain
the following detections:

r = 19.51 +/- 0.01
i = 19.20 +/- 0.01
z = 18.93 +/- 0.03
Y = 18.75 +/- 0.03
J = 18.60 +/- 0.05
H = 18.28 +/- 0.04

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

The source position is consistent with a catalogued SDSS galaxy with
photometric redshift z~0.58. However, its brightness is significantly
higher than the values reported in the catalogue,suggesting that the
emission may be dominated by the GRB afterglow and that the SDSS
object may be the GRB host galaxy.

Further observations to establish the source variability are planned.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.


GRB_name: GRB180914B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23239
SUBJECT: GRB 180914B: Optical counterpart observation from OAJ
DATE:    18/09/16 08:58:16 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (HETH/IAA-CSIC), 
D.A. Kann (HETH/IAA-CSIC), C.C. Thoene (HETH/IAA-CSIC), H. Vazquez 
Ramio (CEFCA), N. Maicas (CEFCA) and V. Tilve (CEFCA) report:

We have observed the field of GRB 180914B (Ursi et al., GCN 23226; 
Verrecchia et al., GCN 23231; Bissaldi et al. GCN 23232; Dâ€™Ai et al., GCN 23236) 
with the 0.8m T80 telescope of the Javalambre Astrophysical Observatory 
(Teruel, Spain). The observation consisted of 12x300s i-band exposures, each 
covering the complete LAT error box. The exposures started at 22:03:46 UT of 
the 15th September, 27.68 hr after the burst. The counterpart identified by Zheng 
& Filippenko (GCN 23237) and Troja et al. (GCN 23238) is well detected in the 
individual images. Photometry of the first epoch, as compared with SDSS 
reference stars yields i(AB)=18.84+/-0.03.

Comparing with the RATIR photometry (roja et al. GCN 23238), our photometry 
implies a decay rate of alpha ~ -1.9 (where F_nu ~ t^alpha), indicating that the 
afterglow has possibly entered a post-jet-break regime evolution.


GRB_name: GRB180914B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23240
SUBJECT: Konus-Wind of the very bright GRB 180914B
DATE:    18/09/16 14:34:47 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long, very bright GRB 180914B
(Agile/MCAL detection: Ursi et al., GCN 23226;
Fermi-LAT detection: Bissaldi & Longo, GCN 23232,
Agile/GRID detection: Verrecchia et al., GCN 23233)
triggered Konus-Wind (KW) at T0=66182.692 s UT (18:23:02.692).

The burst light curve shows multiple pulses in the interval from
T0 - 30 s to T0+250 s. A total duration of the burst (T100)
is ~280 s. The emission is seen up to ~15 MeV.

As observed by Konus-Wind, the burst had a fluence of
(1.15 Â± 0.05)x10^-3 erg/cm2 and a 64-ms peak energy flux,
measured from T0+5.824, of (1.14 Â± 0.24)x10^-4 erg/cm2
(both in the 20 keV - 10 MeV energy range).
The fluence of GRB 180914B is among the highest measured
for the Konus-Wind sample of >3000 GRBs detected since 1994.

The time-integrated spectrum (measured from T0 to T0+168.192 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 = -0.81 (-0.04,+0.04),
the high energy photon index beta = -2.12 (-0.7,+0.08),
the peak energy Ep = 466 (-27,+29) keV
(chi2 = 104/97 dof).

The spectrum near the peak count rate (measured from T0+5.632 s
to T0+6.144 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
alpha = -0.64 (-0.08,+0.10),
beta = -1.98 (-0.16,+0.12),
Ep = 1285 (-249,+287) keV
(chi2 = 68/69 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180914_T66182/

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


GRB_name: GRB180914B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23241
SUBJECT: GRB180914B: Swift UVOT detection of an optical afterglow
DATE:    18/09/16 16:05:06 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. Paul M. Kuin reports on behalf of the Swift-UVOT team:

Swift-UVOT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 180914B (Bissaldi et al. GCN Circ. 23232)
in a series of observations tiled on the sky.
Within the error of the location of the XRT source (D'Ai, GCN Circ. 23236)
we detect a source that appears to be fading.
The UVOT source location is RA = 332.2609, Dec = 24.5823 deg which is

RA = 22:09:25.53 (J2000)
Dec = +25:03:43.8 (J2000)

which is consistent with Zheng and Filipenko (GCN Circ. 23237).
The preliminary magnitude using the UVOT photometric calibration
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) is

filter Tstart  Tend   exposure magnitude
 u     8.35e4  8.37e4   76.5   18.90 +- 0.23
 u     8.70e4  8.74e4  373.0   18.87 +- 0.11
 u     9.27e4  9.29e4  1.93.8  19.05 +- 0.17A

Times in seconds since Tzero=2018-09-14 18:22:40 UT.

No correction has been made for Galactic interstellar reddening of
E(B-V) = 0.07 (Schlafy&Finkbeiner, 2011 ApJ 737, 103).


GRB_name: GRB180914B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23242
SUBJECT: GRB 180914B: AGILE/MCAL refined analysis
DATE:    18/09/16 18:26:38 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

GRB 180914B: AGILE/MCAL refined analysis

A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani
(INAF/IAPS, and Univ. Roma Tor Vergata), F. Longo (Univ. Trieste and INFN
Trieste), A. Argan, M. Cardillo, Y. Evangelista, G. Piano (INAF/IAPS), F.
Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F.
Fuschino, N. Parmiggiani (INAF/OAS), M. Marisaldi (INAF/OAS, and Bergen
University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), A.
Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:

We present a refined analysis of the long GRB 180914B detected by
AGILE/MCAL (Ursi et al., GCN #23226), AGILE/GRID (Verrecchia et al., GCN
#23231), Fermi/LAT (Bissaldi et al., GCN #23232), and Konus-Wind (Frederiks
et al., GCN #23240), whose afterglow has been so far detected by Swift/XRT
(D'Ai et al., GCN #23236) and Swift/UVOT (Kuin et al., GCN #23241), KAIT
(Zheng & Filippenko, GCN #23237), RATIR (Troja et al., GCN #23238), and OAJ
(de Ugarte Postigo et al., GCN #23239).

The AGILE Mini-CALorimeter (MCAL) detector high time resolution data
acquisition was triggered twice by the GRB on sub-millisecond and 16 ms
timescales.

A first GRB peak triggered complete MCAL data acquisition, starting at T1 =
2018-09-14 18:23:02.22 +/- 0.01 s (UTC) and ending at about T1+6.4 s, and
lasted the whole duration of the acquisition. The time-integrated spectrum
measured between T1 and T1+6.4 s can be fitted in the energy range 0.5-40
MeV with a power law with photon index 1.74 -0.13/+0.06 and a cut-off
energy of 2.35 -2.2/+1.54 MeV, with a reduced chi-square of 1.13 (66
d.o.f.). The burst fluence in the same energy range and time interval is
2.4e-04 erg/cm^2 (90% confidence level).

After ~85 s, a second GRB peak triggered complete MCAL data acquisition,
starting at T2 = 2018-09-14 18:24:27.84 +/- 0.01 s and ending at about
T2+6.4, and lasted about 2.7 s. The time-integrated spectrum measured
between T2 and T2+2.7 s can be fitted in the 0.5-40 MeV energy range with a
simple power law with ph.ind. = 2.13 -0.07/+0.08 and a reduced chi-square
of 1.23 (68 d.o.f.). The corresponding fluence is 1.94e-05 erg/cm^2 (90%
confidence level).

The AGILE-MCAL detector has a full solid angle acceptance, and is
operational in the range 0.4 - 100 MeV. This observation was done with the
MCAL trigger capability set to a reduced mode with substantial TM
constraints, and the Super-AGILE imaging being turned-off. A substantially
enhanced AGILE instrument configuration is foreseen to be implemented
shortly.


GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23243
SUBJECT: GRB 180914B: Continued RATIR Optical and NIR Observations
DATE:    18/09/17 07:20:02 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), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.),
and Vicki Toy (UMD) report:

We re-observed the field of GRB 180914B (Ursi, et al., GCN  23226)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astronomico Nacional on Sierra San Pedro Martir from
2018/09 17.12 to 2018/09 17.28 UTC (56.53 to 60.22 hours after the
burst), obtaining a total of 2.49 hours exposure in the r and i
bands and 1.04 hours exposure in the Z, Y, J, and H bands.

At the position of the optical/nIR counterpart (Zheng & Filippenko,
GCN 23237; Troja, et al., GCN 23238), in comparison with the
SDSS DR9 and 2MASS catalogs, we obtain the following detections:

r = 20.46 +/- 0.01
i = 20.08 +/- 0.01
z = 19.74 +/- 0.02
Y = 19.57 +/- 0.02
J = 19.33 +/- 0.02
H = 19.08 +/- 0.03

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

Compared to our first night of observations (Troja, et al., GCN 23238),
the source significantly faded at an approximate decay rate of t^(-1.4),
shallower than the value found by De Ugarte Postigo, et al. (GCN 23239)
at earlier times.

Further observations are planned.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.


GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23244
SUBJECT: GRB 180914B : TSHAO optical observations
DATE:    18/09/17 10:26:49 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Kusakin 
(FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger 
GRB follow-up collaboration:

We observed the field of GRB 180914B (Ursi, et al., GCN  23226; Bissaldi 
et al., GCN 23232;  Frederiks et al., GCN 23240) with Zeiss-1000 1-m 
telescope of Tien Shan Astronomical Observatory starting on September 16 
(UT) 19:44:34, obtaining a total of 46.5 minutes exposure in the 
Rc-band. Within XRT position (D'Ai et al., GCN 23236)  we detect the 
object reported by Zheng & Filippenko (GCN 23237), Troja et al. (GCN 
23238),  (Paul & Kuin, GCN 23241). Preliminary photometry of the objext 
is following.

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

2018-09-16 19:44:34 2.07692 R      31*90 19.89 0.05 21.9

The photometry is based on several nearby SDSS-DR9 stars.
SDSS-DR9_id            R(Lupton)
J220926.80+250130.1    15.705
J220922.87+250206.0    16.156
J220929.88+250257.7    15.812
J220928.05+250309.0    17.230
J220928.90+250327.6    15.524
J220924.12+250415.7    15.485
J220920.37+250610.6    15.050
J220902.04+250312.5    15.321




-- 
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GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23245
SUBJECT: GRB 180914B: MASTER OT automatic dtection 
DATE:    18/09/17 11:10:54 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, N.Tiurina, D. Vlasenko, 
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI

D.Svinkin (Ioffe Institute, Sankt Petersburg)

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

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

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


MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Tunka Astrophysical Center (Baykal Lake,  Applied Physics Institute, 
Irkutsk State University, Russia)  was starting 
survey on the LAT  GRB180914.77 error-box (ra=22 09 47 dec=+24 52 47 
r=0.33)  9409 sec after notice time and 79012 sec after trigger time at 
2018-09-15 16:19:55 UT. The 5-sigma upper limit on our first (180s 
exposure)  set is about 19.7 mag

MASTER OT J220925.53+250343.3  - Afterglow

MASTER-Tunka auto-detection system discovered OT source at (RA, Dec) = 22h 
09m 25.53s +25d 03m 43.3s on 2018-09-15 16:19:55.393UT. Error is 0.7 
arcsec. This position is coincident with late XRT (P. A. Evans, GCN 23234) 
and KAIT  (WeiKang Zheng and Alexei V.  Filippenko, GCN 23237) positions. 
The OT magnitude in clear filter is 19.2m (limit 19.7m).
This is the first optical magnitude ( see also Eleonora Troja GCN 23238, 
A. de Ugarte Postigo et al., GCN 23239; N. Paul M. Kuin et al., GCN 23241; 
Eleonora Troja et al., GCN 23243).

The OT is seen in 2 images. There is no minor planet at this place.

We have reference image without OT on 2011-12-15.46200 UT with unfiltered 
magnitude limit 20.0m.

The discovery and refernces images are available at
http://master.sai.msu.ru/static/OT/MASTEROTJ220925.53+250343.3.jpg

The galactic latitude b = -25 deg.

The observations made on zenit distance = 28 deg.The moon (38 % bright 
part) below the horizon (The altitude of the Moon is -17 deg. ).
The sun  altitude  is -34.5 deg.
The object can be observed till sunrise at 2018-09-15 22:42:06


GRB_name: GRB180914B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23246
SUBJECT: GRB 180914B: VLT/X-shooter spectroscopic redshift
DATE:    18/09/17 15:15:17 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

P. D'Avanzo (INAF/OABr), K. E. Heintz (Univ. Iceland and DAWN/NBI), A. 
de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), A. J. Levan (Univ. 
Warwick), L. Izzo (HETH/IAA-CSIC), D. B. Malesani (DAWN/NBI and 
DARK/NBI), D. A. Kann (HETH/IAA-CSIC), N. R. Tanvir (Univ. Leicester), 
report on behalf of the Stargate collaboration:

We observed the optical counterpart (e.g. Zheng & Filippenko, GCN 23237) 
of GRB 180914B, detected by AGILE (Ursi et al., GCN 23226; Verrecchia et 
al., GCN 23231), Fermi/LAT (Bissaldi & Longo, GCN 23232), and Konus-Wind 
(Frederiks et al., GCN 23240). We used the X-shooter spectrograph on the 
ESO VLT UT2 (Kueyen), for a total exposure of 2x600 s, starting on 2018 
September 17.07 UT (2.30 days after the GRB). The covered wavelength 
range is 3000-21000 AA, and the seeing was relatively poor, around 1.5".

 From a 15-s acquisition image, we measure the magnitude of the 
afterglow as r = 20.37 +- 0.04 (AB), calibrated against the Pan-STARRS 
catalog.

Several absorption features are detected superimposed on the afterglow 
continuum. Among them, we identify Mn II, Al III, Fe II, Mg II, Mg I, Ca 
II, all at the common redshift of z = 1.096. At the same redshift, 
fine-structure lines from Fe II are also identified, thus firmly 
establishing this value as the GRB redshift. A few emission lines from 
the underlying host are also visible. We identify the [O II] doublet and 
[O III] 5008, while other commonly observed features lie at this 
redshift in regions of poor atmospheric transparency or low S/N.

We note that our spectroscopic value is larger than the photometric 
redshift of the putative host galaxy as listed in the SDSS catalog 
(https://skyserver.sdss.org/dr14/en/tools/explore/Summary.aspx?id=1237680331629267013), 
which is however based on low-S/N photometry. At z = 1.096, the 
isotropic-equivalent energy radiated in gamma-rays is 3.6*10^54 erg, 
using the Konus-Wind fluence (1.15*10^-3 erg cm^-2; Frederiks et al., 
GCN 23240). This ranks among the highest measured values for GRBs.

We acknowledge the ESO staff at Paranal for their support, in particular 
Willem-Jan de Wit, Romain Thomas and Rodrigo Palominos.


GRB_name: GRB180914A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23247
SUBJECT: IPN Triangulation of GRB 180914A (long)
DATE:    18/09/17 18:26:55 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

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

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

A. 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 180914A (Bissaldi et al., GCN Circ.23225;
Poolakkil et al., GCN Circ. 23227) was detected by
Fermi (GBM trigger 558621112), INTEGRAL (SPI-ACS), Konus-Wind,
and Mars-Odyssey (HEND) at about 45107 s UT (12:31:47).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    53.107 (03h 32m 26s)  -5.687 ( -5d 41' 14")
  Corners:
    52.535 (03h 30m 08s)  -5.415 ( -5d 24' 53")
    53.948 (03h 35m 48s)  -8.072 ( -8d 04' 21")
    53.677 (03h 34m 42s)  -5.954 ( -5d 57' 13")
    52.197 (03h 28m 47s)  -3.090 ( -3d 05' 23")
  ---------------------------------------------
The error box area is 2.36 sq. deg, and its maximum
dimension is 5.28 deg (the minimum one is 45.48 arcmin).
The Sun distance was 119 deg.

This box may be improved.

The distance between the XRT source (D'Elia et al., GCN circ. 23229) and 
the box center is 4.1 arcmin, supporting the association of the 
transient and the GRB.

We thank Robert Wilson for noticing this.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180914_T45107/IPN

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


GRB_name: GRB180914A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23248
SUBJECT: GRB 180914A: AstroSat CZTI detection
DATE:    18/09/17 18:46:42 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma, T. Khanam 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 180914A, which was also detected by Fermi (LAT: Bissaldi E. et al., GCN 23225 and GBM: Poolakkil S. et al., GCN 23227), Swift (XRT: D'Elia V. et al., GCN 23229) and IPN Triangulation (Hurley K. et al., GCN 23247).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 12:32:08.500 UT. The measured peak count rate is 874 cts/s above the background in combined data of four quadrants, with a total of 27940 cts. The local mean background count rate was 609 cts/s. Using cumulative rates, we measure a T90 of 125.4 s. In preliminary analysis, we find that 2142 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: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23249
SUBJECT: GRB 180914B : continued TSHAO optical observations
DATE:    18/09/17 20:04:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Kusakin 
(FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger 
GRB follow-up collaboration:

We observed the field of GRB 180914B (Ursi, et al., GCN  23226; Bissaldi 
et al., GCN 23232;  Frederiks et al., GCN 23240) with Zeiss-1000 1-m 
telescope of Tien Shan Astronomical Observatory starting on September 17 
(UT) 14:28:30.  We observed the object reported e.g. (Zheng & Filippenko 
GCN 23237; Troja et al. GCN 23238;  de Ugarte Postigo et al., GCN 23239; 
Paul & Kuin, GCN 23241). Preliminary photometry of the object is following.

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

2018-09-17 14:28:30 2.87843 R      60*60 20.53 0.07 22.2

The photometry is based on several nearby SDSS-DR9 stars
SDSS-DR9_id            R(Lupton)
J220926.80+250130.1    15.705
J220922.87+250206.0    16.156
J220929.88+250257.7    15.812
J220928.05+250309.0    17.230
J220928.90+250327.6    15.524
J220924.12+250415.7    15.485
J220920.37+250610.6    15.050
J220902.04+250312.5    15.321


GRB_name: GRB180914B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23250
SUBJECT: GRB 180914B: AstroSat CZTI detection
DATE:    18/09/17 20:55:04 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

T. Khanam, 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 180914B, which was also detected by AGILE (MCAL: Ursi A. et al., GCN 23226 and GRID: Verrecchia F. et al., GCN 23231), Fermi-LAT (Bissaldi E. et al., GCN 23232), Swift-XRT (D'Ai A. et al., GCN 23236) and Konus-Wind (Frederiks D. et al., GCN 23240).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 18:23:02.500 UT. The measured peak count rate is 3258 cts/s above the background in combined data of four quadrants, with a total of 105168 cts. The local mean background count rate was 657 cts/s. Using cumulative rates, we measure a T90 of 146.8 s. In preliminary analysis, we find that 7300 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: GRB180914B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23251
SUBJECT: GRB180914B: Swift UVOT position correction to circ. 23241
DATE:    18/09/17 21:25:15 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N.Paul M. Kuin (MSSL/UCL) reports on behalf of the Swift-UVOT Team:

In GCN Circ. 23241 the position of the transient was correct in sexadecimal
units, but
incorrect in the degree units, where it should read:

The UVOT source position is RA= 332.35638, Dec =  25.06217 (J2000).

My apologies for any confusion caused by this mistake.


GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23252
SUBJECT: GRB 180914B: GOTO optical detection
DATE:    18/09/17 22:22:19 GMT
FROM:    Danny Steeghs at U.of Warwick/GOTO  <D.T.H.Steeghs@warwick.ac.uk>

G.Ramsay (Armagh O.), K.Ulaczyk, D.Steeghs, J.Lyman (U. Warwick),
M.Dyer (U. Sheffield),  B.Gompertz, A.Levan, R.Cutter (U. Warwick)
K. Ackley, D.Galloway, E.Rol (Monash U.), V.Dhillon (U. Sheffield),
P.O'Brien, R.Starling (U. Leicester), S.Poshyachinda (NARIT),
D.Pollacco (U. Warwick), E.Thrane (Monash U.), E.Palle (IAC)

report on behalf of the GOTO collaboration:

The Gravitational-wave Optical Transient Observer observed the field
of the long GRB 180914B (Ursi et al. GCN Circ. 23226, Bissaldi et al. GCN
Circ. 23232) from Roque de los Muchachos Observatory.

In a combined L-band image (400-700nm passband), with a total exposure
time of 600s at a mid-time 2018-09-16 21:57:04 UT, 2.149 days since
burst, we detect the optical counterpart (Zheng et al. GCN
Circ. 23237; Troja GCN Circ. 23238; de Ugarte Postigo et al. GCN
Circ. 23239; Mazaeva et al. GCN Circ. 23244; Lipunov et al. GCN
Circ. 23245) with a preliminary magnitude of g=20.9 +/- 0.2 based on a
comparison to Panstarrs g-band calibrators.


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: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23253
SUBJECT: GRB 180914B: DDOTI/OAN Detection and Confirmation of Fading 
DATE:    18/09/18 00:55:28 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (GSFC), Rosa L.
Becerra (UNAM), William H. Lee (UNAM), and Alexander Kutyrev (GSFC)
report:

We observed the field of GRB 180914B (Ursi et al., GCN Circ. 23226) with
the DDOTI/OAN wide-field imager at the Observatorio Astronomico
Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from
2018-09-16 02:54 to 06:02 (32.5 to 35.7 hours after burst) and
2018-09-17 02:58 to 04:17 (56.6 to 57.9 after burst) obtaining 7200 and
3060 seconds exposure with no filter.

We detect the optical counterpart (Zheng & Filippenko, GCN Circ. 23237;
Troja, et al., GCN Circ. 23238) with the following magnitudes:

w = 19.45 +/- 0.10 (on 2018-09-16) 
w = 20.25 +/- 0.31 (on 2018-09-17)

These AB magnitudes are calibrated against the Pan-STARRS1 catalog and
are not corrected for Galactic extinction in the direction of the GRB.

We confirm the fading reported by de Ugarte Postigo et al. (GCN Circ.
23239), Troja et al. (GCN Circ. 23243), and Mazaeva et al. (GCN Circ.
23249).

DDOTI/OAN imaged the entire Fermi/LAT error region (Bissaldi et al., GCN
Circ. 23232). We confirm that there were no other uncatalogued sources
in the region on 2019-09-16 to a 10-sigma limit of w = 19.4.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir.


GRB_name: GRB180914A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23254
SUBJECT: Konus-Wind observation of GRB 180914A
DATE:    18/09/18 15:46:59 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 GRB 180914A (Fermi-LAT detection:
Bissaldi, Kocevski & Omodei , GCN 23225;
Fermi GBM detection: Poolakkil, Meegan & Bissaldi, GCN 23227;
IPN Triangulation: Hurley et al., GCN 23247;
AstroSat CZTI detection: Sharma at al., GCN 23248)
triggered Konus-Wind at T0=45119.268 s UT (12:31:59.268).

The burst light curve shows multiple pulses
in the interval from T0 - 11 s to T0+143 s.
A total duration of the burst (T100) is ~154 s.
The emission is seen up to ~20 MeV.

As observed by Konus-Wind, the burst
had a fluence of 9.08(-0.51,+0.57)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+13.408 s,
of 6.05(-1.28,+1.29)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+147.200 s)
is best fit in the 20 keV - 20 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.68(-0.12,+0.13),
and Ep = 301(-25,+30) keV (chi2 = 136/98 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.43 (chi2 = 134/97 dof).

The spectrum near the peak count rate
(measured from T0+7.936 to T0+16.128 s)
is best fit in the 20 keV - 20 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.51(-0.13,+0.14),
and Ep = 356(-31,+37) keV (chi2 = 112/98 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.82 (chi2 = 112/97 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180914_T45119/

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


GRB_name: GRB180914B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23255
SUBJECT: GRB 180914B: OAJ multi-color follow-up
DATE:    18/09/19 18:32:38 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

L. Izzo, M. Blazek (both HETH/IAA-CSIC), A. de Ugarte Postigo 
(HETH/IAA-CSIC, DARK/NBI), D. A. Kann, C. C. Thoene, K. Bensch (all 
HETH/IAA-CSIC), R. Martone (U. Ferrara), W. Schoenell (Federal U. of Rio 
Grande do Sul), H. Vazquez Radio, M. C. Diaz-Martin, and S. 
Rodriguez-Llano (all OAJ) report:

We have continued to monitor GRB 180914B (Ursi et al., GCN 23226; 
Verrecchia et al., GCN 23231; Bissaldi et al. GCN 23232; D'Ai et al., 
GCN 23236) with the 0.8m T80 telescope of the Javalambre Astrophysical 
Observatory (Teruel, Spain). Observations consisted of a series of 3x300 
s griz exposures, starting at 22:47:49 UT  on September 16 (2.18 days 
after the GRB detection). The afterglow is clearly detected in all 
stacked images. We measure the following magnitudes (AB system):

g' = 20.73 +/- 0.05 mag at 2.1875 days,
r' = 20.27 +/- 0.08 mag at 2.2003 days,
i' = 19.94 +/- 0.07 mag at 2.2260 days,
z' = 19.62 +/- 0.07 mag at 2.2413 days,

as compared to nearby PANSTARRS stars.


GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23256
SUBJECT: GRB 180914B: OSN Detection and light curve/SED analysis
DATE:    18/09/19 18:33:37 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

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

We observed the location of the extremely bright AGILE/Fermi GRB 180914B 
(Ursi et al., GCN #23226; Bissaldi et al., GCN #23232) with the T150 
telescope of the Sierra Nevada Observatory (OSN). We obtained 3 x 180 s 
images in the Ic band, centered 3.157 days after the GRB.

The afterglow (e.g., Zheng & Filippenko, GCN #23237; Troja et al., GCN 
#23238; de Ugarte Postigo et al., GCN #23239) is clearly detected, and 
we derive Ic (AB) = 20.28 +/- 0.06 mag vs. several SDSS comparison 
stars, using the transformation equations of Lupton (2005).

Using the photometry given in the GCNs so far (Zheng & Filippenko, GCN 
#23237; Troja et al., GCN #23238, #23243; de Ugarte Postigo et al., GCN 
#23239; Kuin, GCN #23241; Mazaeva et al., GCN #23244, #23249; Lipunov et 
al., GCN #23245; D'Avanzo et al., GCN #23246; Ramsay et al., GCN #23252; 
Watson et al., GCN #23253, Izzo et al., GCN #23255), we find the optical 
afterglow can be fit by an achromatic simple power-law with a decay 
slope alpha = 1.65 +/- 0.02 (taking host-galaxy magnitudes from SDSS 
into account). The SED (from u to H band) is well-fit with a small 
amount of SMC extinction, we find beta = 0.94 +/- 0.11, A_V = 0.09 +/- 
0.07 (assuming F_nu ~ t^(-alpha)*nu^(-beta) ). Note the earliest 
detection, from MASTER, lies significantly below the back-extrapolation 
of the later decay slope, indicating a rebrightening may have taken 
place.


GRB_name: GRB180923A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23257
SUBJECT: GRB 180923A: MAXI/GSC detection
DATE:    18/09/23 06:57:35 GMT
FROM:    Motoko Suzuki at RIKEN  <motoko@crab.riken.jp>

W. Maruyama, H. Negoro (Nihon U.), M. Serino (AGU),
M. Nakajima, A. Sakamaki (Nihon U.),
T. Mihara, S. Nakahira, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, Y. Kawakubo, T. Hashimoto, A. Yoshida (AGU),
N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita (Tokyo Tech),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA),
Y. Ueda, A. Tanimoto, T. Morita, S. Yamada (Kyoto U.),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.),
H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.),
M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.),
M. Shidatsu (Ehime U.) 
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source 
at 2018-09-23T04:08:25 UT .
We obtain the source position at
(R.A., Dec) = (38.304 deg, 6.301 deg) = (02 33 12, +06 18 03) (J2000)
with a rectangular error box with the following corners:
(R.A., Dec) = (37.429, 7.302) deg = (02 29 42, +07 18 07) (J2000)
(R.A., Dec) = (37.165, 6.998) deg = (02 28 39, +06 59 52) (J2000)
(R.A., Dec) = (39.010, 5.456) deg = (02 36 02, +05 27 21) (J2000)
(R.A., Dec) = (39.274, 5.760) deg = (02 37 05, +05 45 35) (J2000) .
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 162 +- 26 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 02:35
and in the next transit at 05:41 UT with an upper limit of 20 mCrab for each.


GRB_name: GRB180923A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23258
SUBJECT: GRB 180923A: MASTER inspection MAXI/GSC error box
DATE:    18/09/23 08:38:06 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, D. Vlasenko, N.Tiurina,
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

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

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

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 starting 
survey on the MAXI  GRB180923.17 error-box (ra=02 33 12 dec=+06 18 02 r=1) 
2777 sec after notice time and 7954 sec after trigger time at 2018-09-23 
06:21:04 UT. The 5-sigma upper limit on our first (60s exposure)  set is 
about 17.9 mag

No OT detected.

The galacitc latitude b =  0 deg.

The observations made on zenit distance = 39 deg.The moon (97 % bright
part) is 42 deg. above the horizon. The distance between  moon and  object
is 59
The sun  altitude  is -48.6 deg.
The object can be observed till sunrise at 2018-09-23 10:25:33
  .


The cover map is availavle at 
http://observ.pereplet.ru/images/GRB180923A_cover_map.png

Only for MASTER-team:

The OT candidate available here 
https://200.123.254.238:49004//master2/trans.php?wh=transients.coord2000@%27%3C%2838.3d%2C6.30056d%29%2C2d%3E%27%3A%3Ascircle+and+transients.datetime%3E%3D%272018-09-23+04%3A08%3A30%27&class=9&t2=MAXI+GRB180923.17+optical+counterpart+candidate

The full information about this GRB180923.17 available here 
https://200.123.254.238:49004//master2/grb.php?not=2018-09-23+05%3A34%3A46.484065&sat=MAXI&gcrd=%2838.3d%2C6.30056d%29&eb=1&trig=2018-09-23+04%3A08%3A30&n=GRB180923.17


The message may be cited.


GRB_name: GRB180923A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23259
SUBJECT: GRB 180923A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/09/24 00:10:40 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

A. V. Penacchioni, A. Yoshida, T. Sakamoto, V. Pal'shin,
S. Sugita, Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa,
T. Ito, H. Morita, Y. Sone (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), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The MAXI GRB 180923A (Maruyama et al., GCN Circ. 23257) was detected
in ground analysis of the CALET Gamma-ray Burst Monitor (CGBM) data
near the MAXI/GSC trigger time at T0=04:08:25 UT on 23 September 2018.
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked structure which starts
at T-18 sec and ends at T+107 sec.
The T90 and the T50 durations measured by the SGM data are
122 +- 15 sec and 95 +- 58 sec (40-1000 keV), respectively.
The significant emission is seen only below ~100 keV.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1221710834/

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


GRB_name: GRB180924A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23261
SUBJECT: GRB 180924A: Swift detection of a burst
DATE:    18/09/24 15:39:23 GMT
FROM:    Caryl Gronwall at PSU/Swift-UVOT  <caryl@swift.psu.edu>

T. N. Ukwatta (LANL), A. P. Beardmore (U Leicester),
A. A. Breeveld (UCL-MSSL), P. A. Evans (U Leicester),
C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU),
A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), M. H. Siegel (PSU)
and R. L. C. Starling (U Leicester) report on behalf of the Neil
Gehrels Swift Observatory Team:

At 15:22:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180924A (trigger=863186).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 49.161, -58.505 which is 
   RA(J2000) = 03h 16m 39s
   Dec(J2000) = -58d 30' 19"
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 130 sec.  The peak count rate
was ~1492 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 15:23:39.1 UT, 76.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
49.2002, -58.5321 which is equivalent to:
   RA(J2000)  = 03h 16m 48.05s
   Dec(J2000) = -58d 31' 55.6"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 122 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 2.03
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 1.35e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 82 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. 

This source lies within the current (Sector 2) field-of-view of TESS camera 3. 

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


GRB_name: GRB180924A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23262
SUBJECT: GRB 180924A: Enhanced Swift-XRT position
DATE:    18/09/24 19:29:29 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 1363 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 180924A, 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 = 49.19945, -58.53258 which is equivalent
to:

RA (J2000): 03h 16m 47.87s
Dec (J2000): -58d 31' 57.3"

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: GRB180923B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23263
SUBJECT: GRB 180923B: Fermi GBM detection
DATE:    18/09/24 19:51:56 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

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

"At 22:20:30.53 UT on 23 September 2018, the Fermi 
Gamma-Ray Burst Monitor triggered and located 
GRB 180923B (trigger 559434035 / 180923931).
The on-ground calculated location, using the GBM trigger
data, is

RA, Dec = 310.6, -0.7 (J2000 degrees)

with an uncertainty of 1.0 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic error which we 
have characterized as a core-plus-tail model, with 90% of GRBs 
having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).

The initial angle from the Fermi LAT boresight to
the best location is 86 degrees.

The GBM light curve shows/consists of two bright peaks
with a duration (T90) of about 8.2 s (50-300 keV).
The time-averaged spectrum from T0+0 s to T0+8.9 s is
best fit by a Band function with Epeak = 44.5 +/- 0.5,
alpha index = -0.77 +/- 0.03 and beta index = -3.02 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(1.880 +/- 0.003)E-05 erg/cm^2. The 1s peak photon flux 
measured starting from T0+4.0 s in the 10-1000 keV band
is 53 +/- 1 ph/s/cm^2.

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

[GCN OPS NOTE(24sep18): Based on CIrcular 23265, the name
of the GRB used in this circular (23263) was changed
from "180923A" to "180923B".]


GRB_name: GRB180924A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23264
SUBJECT: GRB 180924A: Swift-BAT refined analysis
DATE:    18/09/24 20:32:53 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.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+304 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180924A (trigger #863186)
(Ukwata, et al., GCN Circ. 23261).  The BAT ground-calculated position is
RA, Dec = 49.207, -58.524 deg, which is 
   RA(J2000)  =  03h 16m 49.7s 
   Dec(J2000) = -58d 31' 27.6" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows a couple peaks starting at ~T-90 sec,
peaking at ~T=50 and ~T0 sec, and returning to baseline ~T+30 sec.
T90 (15-350 keV) is 95.1 +- 10.9 sec (estimated error including systematics).
 
The time-averaged spectrum from T-85.15 to T+26.35 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.94 +- 0.14.  The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.73 sec in the 15-150 keV band
is 0.6 +- 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/863186/BA/


GRB_name: GRB180923B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23265
SUBJECT: GRB 180923B - GBM Correction to GCN 23263
DATE:    18/09/24 20:46:13 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

O.J. Roberts (USRA) reports on behalf of the GBM Team:

In GCN 23263, the incorrect GRB ID was used. 

All references to GRB 180923A in this GCN are incorrect and should read as 180923B. 

GRB 180923A was already detected by MAXI earlier that day (GCN 23257), 
and used in subsequent GCNs (23258 and 23259).

My apologies for any confusion this error may have caused. 


GRB_name: GRB180924A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23266
SUBJECT: GRB 180924A: Swift-XRT refined Analysis
DATE:    18/09/25 08:20:02 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Melandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (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 T.N. Ukwatta report on behalf of the
Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 180924A (Ukwatta et al. GCN
Circ. 23261), from 82 s to 52.3 ks after the  BAT trigger. The data
comprise 141 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. 23262).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.23 (+0.11, -0.09), followed by a break at T+485 s to
an alpha of 0.70 (+0.06, -0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.96 (+0.14, -0.13). The
best-fitting absorption column is  1.0 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.88 (+0.20, -0.19)
and a best-fitting absorption column of 6.9 (+5.2, -4.5) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.5 x 10^-11 (4.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.9 (+5.2, -4.5) x 10^20 cm^-2
Galactic foreground: 2.0 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index:      1.88 (+0.20, -0.19)

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 0.017 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.8 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/00863186.

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


GRB_name: GRB180924A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23267
SUBJECT: GRB 180924A: MASTER inspection
DATE:    18/09/25 09:29:21 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, D. Vlasenko, N.Tiurina, V.Kornilov, 
A.Kuznetsov, V.Chazov, I.  Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

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

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

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 Swift  GRB 180924A (Ukwatta  et al. GCN 23261, Evans et al. GCN 23262, Stamatikos et al. GCN 23264, Melandri et al. GCN 23266)
57128 sec after notice time and 57128 sec after trigger time at 2018-09-25 07:14:30 UT.

There is no new astrophysical sources detected brighter then 19.3m (unfiltered)
inside Swift XRT error-box (03h 16m 47.87s -58d 31' 57.3", r=1.7arcsec Evans et al. GCN 23262)

The message may be cited.

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

The galacitc latitude b =  -49.7 deg.
The observations made on zenit distance = 27 deg.
The moon (99.8 % bright part) was 40 deg. above the horizon. The distance 
between  moon and  object is 66
The sun  altitude  was -35.5 deg.


GRB_name: GRB180925A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23268
SUBJECT: GRB 180925A: Swift detection of a burst
DATE:    18/09/25 14:51:09 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), A. P. Beardmore (U Leicester),
P. A. Evans (U Leicester), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (PSU),
M. H. Siegel (PSU), R. L. C. Starling (U Leicester) and
A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 14:37:31 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180925A (trigger=863421).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 315.213, -64.443 which is 
   RA(J2000) = 21h 00m 51s
   Dec(J2000) = -64d 26' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of at least 30 sec.  The peak count rate
was ~3500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 14:39:20.8 UT, 108.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 315.20546, -64.45727 which
is equivalent to:
   RA(J2000)  = 21h 00m 49.31s
   Dec(J2000) = -64d 27' 26.2"
with an uncertainty of 4.5 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.  We
cannot determine whether the source is fading at the present time. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 3.19e-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
0.03. 

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: GRB180923A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23269
SUBJECT: Konus-Wind observation of GRB 180923A
DATE:    18/09/25 15:02:50 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 180923A localized by MAXI/GSC (Maruyama et al., GCN
23257) and observed by CALET (GBM: Penacchioni et al., GCN 23259) was
detected by Konus-Wind (KW) in the waiting mode.

The burst light curve shows two episodes, started at ~T0(MAXI)-19 s
with a total duration of ~ 127 s.

As observed by KW, the burst had a fluence of
5.42(-0.65,+1.26)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(MAXI)+93.3 s, of 3.47(-0.92,+1.15)x10^-7 erg/cm2/s
(both in the 20 - 1000 keV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from ~T0(MAXI)-18.6 s to ~T0(MAXI)+108 s)
by a simple power-law model yields a power law
index of -2.2(-0.2,+0.2), chi2=0.2/1 dof.

The KW light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB180923A

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


GRB_name: GRB180925A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23270
SUBJECT: GRB 180925A: Prompt enhanced Swift-XRT position
DATE:    18/09/25 15:22:50 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 180925A, we find an
enhanced XRT position of the afterglow: RA, Dec: 315.2038, -64.4569
which is equivalent to:
   RA (J2000)  = 21 00 48.92
   Dec (J2000) = -64 27 24.9
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/863421.

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: GRB180925A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23271
SUBJECT: GRB 180925A: Enhanced Swift-XRT position
DATE:    18/09/25 22:20:42 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 1212 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 180925A, 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 = 315.20075, -64.45690 which is equivalent
to:

RA (J2000): 21h 00m 48.18s
Dec (J2000): -64d 27' 24.8"

with an uncertainty of 3.8 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: GRB180925A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23272
SUBJECT: GRB 180925A: Swift-XRT refined Analysis
DATE:    18/09/26 02:14:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.8 ks of XRT data for GRB 180925A (Gropp et al. GCN
Circ. 23268), from 115 s to 19.2 ks after the  BAT trigger. The data
comprise 191 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. 23270).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.1 (+/-0.4). At T+169 s  the decay
steepens to an alpha of 2.55 (+0.49, -0.22). The light curve breaks
again at T+296 s to a decay with alpha=7.7 (+0.3, -1.3),  and  again at
T+388 s s to alpha=0.71 (+0.26, -0.51),  before a final break at T+1241
s s after which the decay index is 1.42 (+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 1.42 (+/-0.08). The
best-fitting absorption column is  1.4 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 3.3 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.77 (+/-0.17) and a
best-fitting absorption column of 1.5 (+0.6, -0.5) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.9 x 10^-11 (4.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.5 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^20 cm^-2
Excess significance: 3.7 sigma
Photon index:      1.77 (+/-0.17)

If the light curve continues to decay with a power-law decay index of
1.42, the count rate at T+24 hours will be 8.2 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.2 x
10^-14 (3.9 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/00863421.

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


GRB_name: GRB180925A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23273
SUBJECT: GRB 180925A: Swift-BAT refined analysis
DATE:    18/09/26 03:39:29 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (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), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180925A (trigger #863421)
(Gropp et al., GCN Circ. 23268).  The BAT ground-calculated position is
RA, Dec = 315.212, -64.450 deg which is
  RA(J2000)  =  21h 00m 50.9s
  Dec(J2000) = -64d 26' 59.2"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 15%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-5 s and ends at ~T+105 s. The main peak occurs at ~ T+1 s.
T90 (15-350 keV) is 81.70 +- 23.25 sec (estimated error including systematics).

The time-averaged spectrum from T-4.44 to T+103.96 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.53 +- 0.13.  The fluence in the 15-150 keV band is 4.1 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.87 sec in the 15-150 keV band
is 3.1 +- 0.6 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/863421/BA/


GRB_name: GRB180925A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23274
SUBJECT: GRB 180925A: Swift/UVOT Detection
DATE:    18/09/26 12:53:04 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180925A
119 s after the BAT trigger (Gropp et al., GCN Circ. 23268).
A fading source consistent with the XRT position
(Goad et al. GCN Circ. 23271)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  21:00:48.70 = 315.20292 (deg.)
    Dec (J2000) = -64:27:24.82 = -64.456894 (deg.)
with an estimated uncertainty of 0.22 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              119          269          147         19.73 +/- 0.17
white              557         6943          674         20.32 +/- 0.13
v                  607         7354          549         >19.66
b                  533         6739          347         20.89 +/- 0.37
u                  277         6533          579         19.78 +/- 0.21
uvw1               657         7755          540          20.07 +/- 0.29
uvm2              1062         7559          413         >20.14
uvw2               583         7149          510         >20.60

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: GRB180925A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23275
SUBJECT: GRB 180925A: Insight-HXMT/HE detection
DATE:    18/09/27 06:44:05 GMT
FROM:    Qi Luo at IHEP  <luoqi@ihep.ac.cn>

Q. Luo,Y. Huang,G. Li,S. L. Xiong,X. B. Li, C. K. Li, C.Z. Liu,

X.F. Li, Z. W. Li, Z. Chang, J. L. Zhao, A. M. Zhang,

Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin,

Z. Zhang (THU), T. P. Li (IHEP/THU),F. J. Lu, L. M. Song,

H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),

report on behalf of the Insight-HXMT team:




At 2018-09-25T14:37:27.900 (T0), the Insight-HXMT/HE detected

GRB 180925A(trigger ID: HEB180925609) in a routine search of the data,

which was also triggered by Swift-BAT (Gropp et al.,GCN 23268).




The Insight-HXMT/HE light curve mainly consists of a bright

pulse with a duration (T90) of 23.23 s measured from T0-2.82 s.

The 1-s peak rate, measured from T0+1.8640 s, is 1845.76 cnts/sec.

The total counts from this burst is 10107.89 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB180925609_lc.jpg




All measurements above are made with the CsI detectors operating in the

regular mode with the energy range of about 80-800 keV (record energy).

Only gamma-rays with energy greater than about 200 keV can penetrate

the spacecraft and leave signals in the CsI detectors installed inside

of the telescope.




The analysis results presented above are preliminary,

final results will be published elsewhere.




Insight-HXMT is the first Chinese space X-ray telescope, which was

fundedjointly by the China National Space Administration (CNSA) and

the Chinese Academy of Sciences (CAS).

More information about it could be found at:

http://www.hxmt.org.


GRB_name: GRB180925A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23276
SUBJECT: GRB 180925A: VLT optical observations
DATE:    18/09/27 19:52:07 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

D. B. Malesani (DAWN/NBI and DARK/NBI), P. Schady (Univ. Bath), C. C. 
Thoene (HETH/IAA-CSIC), D. A. Kann (HETH/IAA-CSIC), and N. R. Tanvir 
(Univ. Leicester) report on behalf of the Stargate collaboration:

We observed the optical counterpart of GRB 180925A (Gropp et al., GCN 
23268; Emery & Gropp, GCN 23274) using the ESO VLT UT2 (Kueyen) equipped 
with the X-shooter instrument. A 60-seconds image in the SDSS r filter 
was taken with the acquisition camera, at approximate time 2018 
September 26.17 UT (0.56 days after the GRB).

At a location consistent with that of the UVOT afterglow (Emery & Gropp, 
GCN 23274), a faint source is marginally visible. Forced photometry, 
calibrated against nearby USNO-B1 stars, yields R = 22.9 +- 0.4 (Vega).

No further observations are planned.

We acknowledge support from the ESO staff at Paranal, in particular Joe 
Anderson and Jorge Lillo-Box.


GRB_name: GRB180924A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23277
SUBJECT: GRB 180924A: Swift/UVOT Upper Limits 
DATE:    18/09/28 04:16:50 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) and T. N. Ukwatta (LANL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180924A
83 s after the BAT trigger (Ukwatta et al., GCN Circ. 23261).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 23262)
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            83          233          147         >20.8
u_FC               241          491          246         >19.7
white               83          542          167         >20.9
v                  572          592           19         >17.1
b                  497          517           19         >18.4
u                  241          491          246         >19.7

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: GRB180914B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23278
SUBJECT: INTEGRAL detections of the prompt gamma-ray emission of GRB 180914B
DATE:    18/09/28 11:05:12 GMT
FROM:    Volodymyr Savchenko at ISDC,U of Geneve  <savchenk@in2p3.fr>

J. Rodi, A. Bazzano, P. Ubertini, L. Natalucci (IAPS-Roma)
C. Ferrigno, V. Savchenko (ISDC, University of Geneva, CH)
E. Kuulkers (ESTEC/ESA, The Netherlands)

We have analyzed the public INTEGRAL data of IBIS/PICsIT (200 - 2600 keV)
and SPI-ACS(>75 keV) in coincidence with the long, bright GRB 180914B,
which was initially reported by AGILE/MCAL (GCN 23226), AGILE/GRID (GCN
23231),
and Fermi/LAT(GCN 23232). The INTEGRAL orientation was 98.4 degrees from
the GRB location and implies a near optimal response for SPI-ACS and
a suppressed response for PICsIT (Savchenko et al. 2017, A&A 603, A46).

The GRB was clearly detected in SPI-ACS until about T0+250s
(T0=2018-09-14 18:23:02.22) and shows 8 flaring events, of which 7 show
large variability detected down to the 50 ms time-resolution of the
detector. 
It was also detected in PICsIT until approximately T0+130s, of which 5
flaring
events are clearly seen.  Because of the unfavorable viewing angle for
PICsIT,
the burst is predominately seen above 460 keV with significant
emission up to 1.2 MeV.

The SPI-ACS light curve can be found at:

https://www.isdc.unige.ch/integral/ibas/cgi-bin/ibas_acs_web.cgi/?trigger=2018-09-14T18-23-01.00-00000-00000-0


GRB_name: GRB180930A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23279
SUBJECT: GRB 180930A: Swift detection of a burst
DATE:    18/09/30 12:57:20 GMT
FROM:    David Burrows at PSU/Swift  <burrows@astro.psu.edu>

A. Tohuvavohu (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),
D. M. Palmer (LANL) and B. Sbarufatti (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 12:43:49 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180930A (trigger=864584).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 76.870, -25.138 which is 
   RA(J2000) = 05h 07m 29s
   Dec(J2000) = -25d 08' 17"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 20 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 12:47:17.6 UT, 208.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 76.86228, -25.11720 which is equivalent
to:
   RA(J2000)  = 05h 07m 26.95s
   Dec(J2000) = -25d 07' 01.9"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 78 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 (2.09 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.9
(+1.93/-1.74) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 211 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.02. 

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: GRB180930A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23280
SUBJECT: GRB 180930A: Prompt enhanced Swift-XRT position
DATE:    18/09/30 13:42:51 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 180930A, we find an
enhanced XRT position of the afterglow: RA, Dec: 76.8633, -25.1169
which is equivalent to:
   RA (J2000)  = 05 07 27.19
   Dec (J2000) = -25 07 00.8
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/864584.

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: GRB180930A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23281
SUBJECT: GRB 180930A: KAIT Optical Upper Limit
DATE:    18/09/30 18:07:48 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 180930A (Tohuvavohu et al.,
GCN 23279) starting at 12:45:41 UT, 112 seconds after the burst
under dawn twilight condition. 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 enhanced XRT position error
circle (Evans et al., GCN 23280) neither in single image, nor in
the co-add images. The typical limiting magnitude of our single
clear image is about 18.5 mag calibrated to the Pan-STARRS1 catalog.


GRB_name: GRB180930A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23282
SUBJECT: GRB 180930A: Enhanced Swift-XRT position
DATE:    18/09/30 18:10:03 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 2552 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 180930A, 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 = 76.86315, -25.11694 which is equivalent
to:

RA (J2000): 05h 07m 27.16s
Dec (J2000): -25d 07' 01.0"

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

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

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


GRB_name: GRB180930A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23283
SUBJECT: GRB 180930A: Swift/UVOT Upper Limits
DATE:    18/09/30 20:40:45 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and A. Tohuvavohu (PSU)

report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180930A
212 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 23279).
No optical afterglow consistent with the XRT position
(Evans GCN Circ. 23280)
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           212          362          147         >21.2
white              212         2818          602         >21.1
v                  517         2620          226         >20.1
b                  443         2718          240         >20.7
u                  418         2693          245         >19.7
w1                 394         2669          253         >20.8
m2                 369         2644          233         >19.3
w2                 659         2595          194         >19.9

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: GRB180930A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23284
SUBJECT: GRB 180930A: NOT optical upper limits
DATE:    18/10/01 08:00:35 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Daniele B. Malesani (DAWN/NBI and DARK/NBI) and Ana Sagues (NOT) report 
on behalf of a larger collaboration:

We observed the field of GRB 180930A (Tohuvavohu et al., GCN 23279) with 
the Nordic Optical Telescope (NOT) equipped with the AlFOSC camera. 
Observations were carried out as soon as the field became visible from 
La Palma, starting on 2018 Oct 1.153 UT (14.95 hr after the GRB). A 
total exposure of 1500 s in each of the SDSS r and z filters was secured.

Inside the UVOT-enhanced GRB position (Osborne et al., GCN 23282), we 
detect no sources down to r = 23.5, z = 22.8 (both AB, calibrated 
against nearby stars from the Pan-STARRS survey).


GRB_name: GRB180930A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23285
SUBJECT: GRB 180930A: Swift-XRT refined Analysis
DATE:    18/10/01 13:02:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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), S. J. LaPorte (PSU) and A.
Tohuvavohu report on behalf of the Swift-XRT team:

We have analysed 2.6 ks of XRT data for GRB 180930A (Tohuvavohu et al.
GCN Circ. 23279), from 212 s to 6.0 ks after the  BAT trigger. The data
comprise 47 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. 23280).

The light curve can be modelled with a power-law decay with a decay
index of alpha=2.04 (+/-0.09).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.01 (+/-0.15). The
best-fitting absorption column is  7.2 (+3.7, -3.3) x 10^20 cm^-2, in
excess of the Galactic value of 2.1 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 3.3 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.2 (+3.7, -3.3) x 10^20 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 2.6 sigma
Photon index:      2.01 (+/-0.15)

If the light curve continues to decay with a power-law decay index of
2.04, the count rate at T+24 hours will be 3.5 x 10^-5 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-15 (1.4 x 10^-15) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00864584.

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


GRB_name: GRB180930A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23286
SUBJECT: GRB 180930A: Swift-BAT refined analysis
DATE:    18/10/01 18:21:40 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.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-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180930A (trigger #864584)
(Tohuvavohu, et al., GCN Circ. 23279).  The BAT ground-calculated position is
RA, Dec = 76.894, -25.124 deg which is 
  RA(J2000)  =  05h 07m 34.6s 
  Dec(J2000) = -25d 07' 25.6" 
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 87%.

The mask-weighted light curve shows a single episode of weak emission from 
T-4 sec to T+4 sec with several peaks. T90 (15-350 keV) is 6.80 +- 0.95 sec 
(estimated error including systematics).

The time-averaged spectrum from T-3.24 to T+4.20 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.86 +- 0.28.  The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.14 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/864584/BA/


GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23287
SUBJECT: GRB 180914B: RTT150 optical observations
DATE:    18/10/01 20:36:17 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>

A. Lyapin, I. Zaznobin, R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), 
I. Bikmaev, E. Irtuganov, N. Sakhibullin (KFU/AST),
I. Khamitov, S. Ozdemir (TUG), E. Gogus (Sabanci Uni.)

report:

We observed the field of GRB 180914B (Ursi et al., GCN 23226, Bissaldi
et al., GCN 23232, Ai et al., GCN 23236) with the Russian-Turkish
1.5-m optical telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey) using the TFOSC instrument.

We obtained series of exposures in SDSS gri filters, starting at 18:30
UT on Sep 16, 2018. The optical transient (Zhen and Filippenko, GCN
23237, Troja et al., GCN 23238, de Ugarte Postigo et al., GCN 23239)
was detected in all images. We estimated the following magnitudes for
the OT:

g:  20.97 +- 0.02
r:  20.38 +- 0.02 
i:  20.04 +- 0.02

calibrated against SDSS secondary standards.


GRB_name: GRB180914B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23288
SUBJECT: GRB 180914B: RTT150 optical observations
DATE:    18/10/01 20:38:00 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>

E. Irtuganov, I. Bikmaev, N. Sakhibullin (KFU/AST),
A. Lyapin, I. Zaznobin, R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), 
I. Khamitov, S. Ozdemir (TUG), E. Gogus (Sabanci Uni.)

report:

We observed the field of GRB 180914B (Ursi et al., GCN 23226, Bissaldi
et al., GCN 23232, Ai et al., GCN 23236) with the Russian-Turkish
1.5-m optical telescope (RTT150, Bakirlitepe, TUBITAK National
Observatory, Turkey) using the TFOSC instrument.

We obtained direct images in SDSS r filter, on Sep 18, 19 and 21,
2018. The optical transient (Zhen and Filippenko, GCN 23237, Troja et
al., GCN 23238, de Ugarte Postigo et al., GCN 23239) was detected in
all images. We estimated the following magnitudes for the OT:

Sep 18:  21.21 +- 0.03
Sep 19:  21.99 +- 0.05
Sep 21:  22.28 +- 0.10

calibrated against SDSS secondary standards.

Therefore, approximately power law light curve is observed, with a
decay slope near -1.53, which is approximately consistent with the
slope measured earlier by Kann et al., GCN 23256. Note, that some
deviations from simple power law decay at the level of 0.2-0.3 mag are
also observed in our data.


GRB_name: GRB181002A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23290
SUBJECT: GRB 181002A: Swift detection of a burst
DATE:    18/10/02 11:41:28 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester) and
B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 11:26:43 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181002A (trigger=865036).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 64.736, +15.233 which is 
   RA(J2000) = 04h 18m 57s
   Dec(J2000) = +15d 13' 60"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~900 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 11:28:59.2 UT, 136.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
64.7464, 15.2136 which is equivalent to:
   RA(J2000)  = 04h 18m 59.13s
   Dec(J2000) = +15d 12' 48.8"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 78 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 2.79
x 10^21 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 7.41e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 144 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
0.60. 

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: GRB180925A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23291
SUBJECT: Konus-Wind observation of GRB 180925A
DATE:    18/10/02 12:49:43 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 180925A (Swift-BAT detection:
Gropp et al., GCN 23268; Ukwatta et al., GCN 23273;
Insight-HXMT/HE observation: Luo et al., GCN 23275)
triggered Konus-Wind at T0=52650.967 s UT (14:37:30.967).

The burst light curve shows a multipeaked structure
which starts at ~T0 and has a total duration of ~26 s.
The emission is seen up to ~6 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.44(-0.23,+0.32)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+5.088 s,
of 4.99(-1.51,+1.66)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.99(-0.17,+0.21)
and Ep = 528(-135,+239) keV (chi2 = 77/76 dof).
Fitting by a GRB (Band) model yields alpha = -0.84(-0.33,+0.40),
Ep = 374(-139,+403) keV, and beta = -2.0(-8.0,+0.3)
(chi2 = 77/75 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model
with  alpha = -0.85(-0.20,+0.23)
and Ep = 544(-125,+200) keV (chi2 = 93/76 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.8
(chi2 = 93/75 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180925_T52650/

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


GRB_name: GRB181002A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23292
SUBJECT: GRB 181002A: Enhanced Swift-XRT position
DATE:    18/10/02 13:44:29 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 336 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 181002A, 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 = 64.74661, +15.21290 which is equivalent
to:

RA (J2000): 04h 18m 59.19s
Dec (J2000): +15d 12' 46.4"

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: GRB181002A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23293
SUBJECT: GRB 181002A: MASTER optical observation
DATE:    18/10/02 16:13:52 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, D. Vlasenko, N.Tiurina,V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov,
Lomonosov Moscow State University,SAI

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

D. Buckley,
South African Astronomical Observatory (SAAO)

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

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

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

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

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

MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru,  Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located 
near Baykal lake in Russia (Applied Physics Institute, Irkutsk State University)
was pointed to the Swift GRB181002A (Gropp et al. GCN 23290, Beardmore et al. 
GCN 23292) 03h50min08sec after trigger time at 2018-10-02 2018-10-02 15:16:51 UT.

There is no astrophysical optical counterparts inside error-box
  (ra=04h 18m 59.19s dec=+15d 12' 46.4" r=2.0 arcsec) brighter than 20.3mag.

The message may be cited.

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

Galactic latitude: -23.628772, Galactic longitude: 179.675296

Observations started when
Object_Altitude was 17.32
Sun_Altitude: -37.57 
Moon_AAltitude: -0.05, Azimuth: 234.39


GRB_name: GRB181002A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23294
SUBJECT: GRB 181002A: Swift-BAT refined analysis 
DATE:    18/10/02 22:58:09 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. R. Cummings (CPI), S. D. Barthelmy (GSFC),
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-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181002A (trigger #865036)
(Gropp et al., GCN Circ. 23290).  The BAT ground-calculated position is
RA, Dec = 64.739, 15.248 deg which is
  RA(J2000)  =  04h 18m 57.4s
  Dec(J2000) = +15d 14' 51.6"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 70%.

The mask-weighted light curve shows a weak pulse that starts at ~T-30 s and
ends at ~T+45 s. T90 (15-350 keV) is 63.4 +- 12.4 sec (estimated error
including systematics).

The time-averaged spectrum from T-28.38 to T+43.62 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.15 +- 0.23.  The fluence in the 15-150 keV band is 8.8 +- 1.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+11.39 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/865036/BA/


GRB_name: GRB181003A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23295
SUBJECT: GRB 181003A: Swift detection of a burst
DATE:    18/10/03 05:25:47 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. P. Beardmore (U Leicester),
M. J. Moss (George Washington University), K. L. Page (U Leicester)
and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 05:11:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181003A (trigger=865179).  Swift did not slew immediately
to the burst due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 52.569, -34.023 which is 
   RA(J2000) = 03h 30m 17s
   Dec(J2000) = -34d 01' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~600 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+46.3
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)


GRB_name: GRB181003A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23296
SUBJECT: GRB 181003A: Swift-XRT observations
DATE:    18/10/03 06:56:48 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

The XRT began observing the field of GRB 181003A at 06:02:32.6 UT,
3089.4 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 52.52910,
-33.96445 which is equivalent to:
   RA(J2000)  = 03h 30m 06.98s
   Dec(J2000) = -33d 57' 52.0"
with an uncertainty of 4.5 arcseconds (radius, 90% containment). This
location is 242 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. As this position is
significantly outside the BAT error circle, it is probably 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 1.24
x 10^20 cm^-2 (Willingale et al. 2013). 


GRB_name: GRB181002A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23297
SUBJECT: GRB 181002A: Swift/UVOT Upper Limits
DATE:    18/10/03 10:48:04 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181002A
144 s after the BAT trigger (Gropp et al., GCN Circ. 23290).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 23292)
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           144          294          147         >20.8
u_FC               302          552          246         >20.3
white              144         1008          334         >20.7
v                  632         1058           58         >17.9
b                  558          751           39         >18.6
u                  302          726          265         >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.60 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB181002A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23298
SUBJECT: GRB181002A: GOTO optical limits
DATE:    18/10/03 13:34:51 GMT
FROM:    Danny Steeghs at U.of Warwick/GOTO  <D.T.H.Steeghs@warwick.ac.uk>

K.Ulaczyk, D.Steeghs, J.Lyman (U. Warwick), G.Ramsay (Armagh O.),
M.Dyer (U. Sheffield),  B.Gompertz, A.Levan, R.Cutter (U. Warwick)
K. Ackley, D.Galloway, E.Rol (Monash U.), V.Dhillon (U. Sheffield),
P.O'Brien, R.Starling (U. Leicester), S.Poshyachinda (NARIT),
D.Pollacco (U. Warwick), E.Thrane (Monash U.), E.Palle (IAC)

report on behalf of the GOTO collaboration:

In response to GRB 181002A (Gropp et al. GCN 23290), the
Gravitational-wave Optical Transient Observer (GOTO) observed the
field near the Swift BAT/XRT detection.

Observations started at 2018-10-03T01:19:02 UT (13.9 hours after the
burst) consisting of a set of 3x5x120s exposures in our wide L filter
(400-700nm). We do not detect any optical source within the error
circle of the enhanced XRT location (Beardmore et al. GCN 23292) with
a 5-sigma limit of g=20.8, using PanSTARRS calibrators on
the stacked image.

We note that our limits are deeper than those reported in Lipunov et al.
GCN 23293 and Emery et al. GCN 23297, albeit obtained 13.9 hours
post-burst.

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: GRB181003A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23299
SUBJECT: GRB 181003A: MASTER optical observation 
DATE:    18/10/03 13:57:37 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

Hugo Levato and Carlos 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

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

O. Gres, N.M. Budnev, Yu.Ishmuhametova
Applied Physics Institute of Irkutsk State University

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

MASTER-IAC robotic telescope  (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)
located in Spain (IAC Teide Observatory) was pointed to Swift GRB181003A (Beardmore et al. GCN 23295, Evans et al. GCN 23296)
  4 sec after notice time and 59 sec after trigger time at 2018-10-03 05:12:02 UT, with 
upper limit up to  19.1 mag.
The observations started on zenit distance = 65 deg.
The sun  altitude  was -23.8 deg.

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University)
was pointed to the  GRB181003A
10 sec after notice time and 64 sec after trigger time at 2018-10-03 05:12:08 UT, 
with upper limit up to  20.3 mag.
The observations started on zenit distance = 27 deg.
The sun  altitude  was -53.3 deg.

The galactic latitude b = -60 deg., longitude l = 98 deg.

We obtained the following upper limits:

Tmid-T0  |  MASTER observatory |Filt.| Exp.,s| m_lim | Comment
_________|_____________________|_____|_______|_______|________

       89 |          MASTER-IAC |  P- |    10 | 16.29 |
       89 |          MASTER-IAC |  P- |    50 | 17.38 |  Coadd
       89 |          MASTER-IAC |  P- |   710 | 19.12 |  Coadd
       96 |         MASTER-OAFA |   C |    10 | 16.88 |
       96 |         MASTER-OAFA |   C |    70 | 18.69 |  Coadd
       96 |         MASTER-OAFA |   C |   550 | 19.83 |  Coadd
      131 |          MASTER-IAC |  P- |    20 | 16.75 |
      176 |         MASTER-OAFA |   C |    20 | 17.54 |
      185 |          MASTER-IAC |  P- |    20 | 16.75 |
      242 |          MASTER-IAC |  P- |    30 | 17.31 |
      242 |          MASTER-IAC |  P- |   120 | 17.94 |  Coadd
      272 |         MASTER-OAFA |   C |    40 | 18.17 |
      312 |          MASTER-IAC |  P- |    40 | 17.05 |
      393 |         MASTER-OAFA |   C |    50 |  18.4 |
      393 |         MASTER-OAFA |   C |   210 |  19.3 |  Coadd
      399 |          MASTER-IAC |  P- |    50 | 17.53 |
      500 |          MASTER-IAC |  P- |    70 | 17.66 |
      500 |          MASTER-IAC |  P- |   250 | 18.41 |  Coadd
      531 |         MASTER-OAFA |   C |    70 |  18.7 |
      632 |          MASTER-IAC |  P- |    80 | 17.66 |
      701 |         MASTER-OAFA |   C |    90 | 18.81 |
      774 |          MASTER-IAC |  P- |   100 | 17.92 |
      900 |         MASTER-OAFA |   C |   120 | 19.05 |
      900 |         MASTER-OAFA |   C |   450 | 19.72 |  Coadd
      951 |          MASTER-IAC |  P- |   130 | 17.92 |
     1145 |         MASTER-OAFA |   C |   150 | 19.18 |
     1170 |          MASTER-IAC |  P- |   160 | 17.92 |
     1434 |         MASTER-OAFA |   C |   180 | 19.31 |
     1434 |         MASTER-OAFA |   C |  1800 | 20.16 |  Coadd
     1436 |          MASTER-IAC |  P- |   180 | 18.15 |
     1436 |          MASTER-IAC |  P- |  1800 | 19.11 |  Coadd
     1749 |          MASTER-IAC |  P- |   180 | 18.16 |
     1749 |          MASTER-IAC |  P- |   540 |    19 |  Coadd
     1764 |         MASTER-OAFA |   C |   180 | 19.26 |
     1764 |         MASTER-OAFA |   C |   540 | 19.84 |  Coadd
     2070 |          MASTER-IAC |  P- |   180 | 18.16 |
     2097 |         MASTER-OAFA |   C |   180 | 19.27 |
     2382 |          MASTER-IAC |  P- |   180 | 18.16 |
     2429 |         MASTER-OAFA |   C |   180 |  19.3 |
     2709 |          MASTER-IAC |  P- |   180 | 18.14 |
     2709 |          MASTER-IAC |  P- |   540 | 18.97 |  Coadd
     2760 |         MASTER-OAFA |   C |   180 | 19.26 |
     2760 |         MASTER-OAFA |   C |   540 | 19.81 |  Coadd
     3027 |          MASTER-IAC |  P- |   180 | 18.14 |
     3093 |         MASTER-OAFA |   C |   180 | 19.26 |
     3428 |         MASTER-OAFA |   C |   180 | 19.25 |
     3761 |         MASTER-OAFA |   C |   180 |  19.3 |
     3761 |         MASTER-OAFA |   C |   540 |  19.9 |  Coadd
     3887 |          MASTER-IAC |  P- |   180 | 17.93 |
     4094 |         MASTER-OAFA |   C |   180 | 19.27 |
     4203 |          MASTER-IAC |  P- |   180 | 17.89 |
     4203 |          MASTER-IAC |  P- |   540 | 18.43 |  Coadd
     4428 |         MASTER-OAFA |   C |   180 |  19.3 |
     4515 |          MASTER-IAC |  P- |   180 | 17.73 |
     4758 |         MASTER-OAFA |   C |   180 |  19.3 |
     4758 |         MASTER-OAFA |   C |   540 | 19.85 |  Coadd
     4758 |         MASTER-OAFA |   C |  1800 | 20.26 |  Coadd
     4835 |          MASTER-IAC |  P- |   180 | 17.45 |
     5093 |         MASTER-OAFA |   C |   180 |  19.3 |
     5151 |          MASTER-IAC |  P- |   180 | 17.08 |
     5151 |          MASTER-IAC |  P- |   540 | 17.39 |  Coadd
Filter C is unfiltred band (clear), calibrated by USNO B1 thousands field 
stars as 0.2B+0.8R.

The observation and reduction will continue.
The message may be cited.


GRB_name: GRB181003A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23300
SUBJECT: GRB 181003A: LCO Cerro Tololo observations
DATE:    18/10/03 14:56:21 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), A. Cucchiara, 
D. Morris (U. of Virgin Islands) on behalf of a large collaboration report:

We automatically observed Swift GRB 181003A (Beardmore et al. GCN 23295) 
with one LCO 1-m unit at Cerro Tololo from October 03, 05:26:07 UT 
(corresponding to 15 minutes from the GRB trigger time) with the SDSS r' 
filter. Within the Swift-XRT error circle (Evans et al. GCN 23296) we 
marginally detect an uncatalogued source with r'=22.11 +- 0.25 mag from 
a 9x60s exposure at a mid time of 0.35 hours post GRB, as calibrated 
against nearby Pan-STARRS objects, at the following position:

RA(J2000) = 03:30:06.86
DEC(J2000)= -33:57:54.2

with an error radius of about 1".


GRB_name: GRB181002A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23301
SUBJECT: GRB 181002A: Swift-XRT refined Analysis
DATE:    18/10/03 16:36:47 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

J.D. Gropp (PSU) reports on behalf of the Swift-XRT team:

We have analysed 935 s of XRT data for GRB 181002A (Gropp et al. GCN
Circ. 23290), from 142 s to 1.1 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. 23292).

The light curve can be modelled with a power-law decay with a decay
index of alpha=4.15 (+0.18, -0.16).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.60 (+0.18, -0.17). The
best-fitting absorption column is  4.0 (+0.7, -0.6) x 10^21 cm^-2, in
excess of the Galactic value of 2.8 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 2.8 x 10^-11 (6.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:      4.0 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 2.8 x 10^21 cm^-2
Excess significance: 3.2 sigma
Photon index:      2.60 (+0.18, -0.17)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00865036.

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


GRB_name: GRB180930A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23302
SUBJECT: GRB 180930A: TSHAO optical upper limit
DATE:    18/10/03 17:10:51 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 180930A (Tohuvavohu et al., GCN  23279) 
with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory 
starting on September 30 (UT) 21:55:14, obtaining a total of 31*120 s 
exposure in the Rc-band. Within enhanced XRT position (Osborne et al., 
GCN 23282)  we do not detect any object. Preliminary photometry of the 
field is following.

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

2018-09-30 21:55:14 0.41030 R      31*120 n/d   n/d 20.1

The photometry is based on several nearby USNO-B1.0 stars.


GRB_name: GRB181003A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23303
SUBJECT: GRB 181003A: Swift/UVOT Upper Limits
DATE:    18/10/03 17:47:56 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

GRB 181003A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181003A
3095 s after the BAT trigger (Beardmore et al., GCN Circ. 23295).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 23296)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

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

b              5040         5240           196            >20.83  
uvm2           3452         3652           196            >19.46 
u              3862         3902            39            >19.19 
v              3427         3447           196            >19.79 
uvw1           3658         3857           196            >19.85
uvw2           5451         5597           144            >19.37 
white          3091         3240           294            >21.73  

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: GRB180925A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23304
SUBJECT: GRB 180925A: Astrosat CZTI detection
DATE:    18/10/03 18:03:54 GMT
FROM:    Vidushi Sharma at IUCAA  <vidushi@iucaa.in>

V. Sharma and T. Khanam (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 180925A, which was also detected by Swift (Gropp J. D. et al., GCN 23268), Insight-HXMT/HE (Luo Q. et al., GCN 23275) and Konus-Wind (Kozlova A. et al., GCN 23291).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 14:37:33.5 UT. The measured peak count rate is 246 cts/s above the background in combined data of four quadrants, with a total of 2223 cts. The local mean background count rate was 506 cts/s. Using cumulative rates, we measure a T90 of around 34.7 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: GRB181003A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23305
SUBJECT: GRB 181003A: Swift-XRT afterglow detection
DATE:    18/10/03 18:08:13 GMT
FROM:    Andy Beardmore at U Leicester  <ab271@leicester.ac.uk>

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

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 181003A (Beardmore et al. GCN Circ.
23295), collecting 8.6 ks of Photon Counting (PC) mode data between
T0+3.1 ks and T0+34.3 ks. 

Six uncatalogued X-ray sources are detected consistent with being
within 296 arcsec of the Swift/BAT position, of which one ("Source 1")
is fading with 3-sigma significance, and is therefore likely the GRB
afterglow. Using 1905 s of PC mode data and 1 UVOT image, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 52.52869, -33.96466
which is equivalent to:

RA (J2000): 03h 30m 06.89s
Dec(J2000): -33d 57' 52.8"

with an uncertainty of 6.3 arcsec (radius, 90% confidence). This
position is 4.0 arcmin from the Swift/BAT position.  The source is
fading with alpha >0.8.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00865179.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00865179.

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


GRB_name: GRB181003A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23306
SUBJECT: GRB 181003A: Swift-BAT refined analysis
DATE:    18/10/03 22:34:55 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

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

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181003A (trigger #865179)
(Beardmore et al., GCN Circ. 23295).  The BAT ground-calculated position is
RA, Dec = 52.481, -33.991 deg which is
  RA(J2000)  =  03h 29m 55.4s
  Dec(J2000) = -33d 59' 25.8"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.

The mask-weighted light curve shows a weak structure that starts at ~T-10 s
and ends at ~ T+20 s. The burst went out of the BAT field of view at ~T+97 s.
T90 (15-350 keV) is 21.5 +- 4.8 sec (estimated error including systematics).

The time-averaged spectrum from T-11.20 to T+18.01 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index -0.20 +- 1.12,
and Epeak of 56.5 +- 14.4 keV (chi squared 52.40 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 4.2 +- 0.7 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+1.86 sec in the 15-150 keV band is
0.6 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.54 +- 0.19 (chi squared 63.13 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/865179/BA/


GRB_name: GRB181003A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23307
SUBJECT: GRB 181003A: RATIR Optical and NIR Observations 
DATE:    18/10/04 19:27:17 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 181003A (Beardmore et al., GCN Circ. 23295)
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 2018/10 4.32 to
2018/10 4.46 UTC (26.59 to 29.89 hours after the BAT trigger), obtaining
a total of 1.41 hours exposure in the r and i bands and 0.58 hours
exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (Tohuvavohu et al., GCN
Circ. 23305), in comparison with the USNO-B1 and 2MASS catalogs, we
obtain the following 3-sigma upper limits:

  r > 23.40
  i > 23.15
  Z > 22.01
  Y > 21.53
  J > 21.19
  H > 20.73

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: GRB181002A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23308
SUBJECT: GRB 181002A: Mondy optical upper limit
DATE:    18/10/05 07:28:44 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of the GRB 181002A (Gropp et al., GCN 23290) 
with AZT-33IK telescope of Sayan observatory (Mondy).  We obtained 
several images in R-filter starting on Oct. 02 (UT) 16:31:56.  We do not 
detect any object within enhanced Swift-XRT position  (Beardmore et al., 
GCN 23292). Preliminary photometry of the field is following.

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


2018-10-02  16:31:56  0.23281    R     58*60  n/d     n/d   22.9

The photometry is based on nearby SDSS-DR12 stars

SDSS-DR12_id        R(Lupton)
J041903.61+151252.8 18.69
J041903.16+151309.7 18.40
J041848.32+151242.2 16.52
J041904.57+151201.2 17.35
J041857.89+151107.8 17.14


GRB_name: GRB181010A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23309
SUBJECT: GRB 181010A: Swift detection of a burst with an optical counterpart
DATE:    18/10/10 06:07:32 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC),
M. J. Moss (George Washington University), K. L. Page (U Leicester)
and B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 05:55:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181010A (trigger=866434).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 52.557, -23.035, which is 
   RA(J2000)  =  03h 30m 14s
   Dec(J2000) = -23d 02' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple peaks
with a total duration of about 25 sec.  The peak count rate
was ~2200 counts/sec (15-350 keV), at ~8 sec after the trigger. 

The XRT began observing the field at 05:57:24.7 UT, 93.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 52.56984, -23.03721 which is equivalent
to:
   RA(J2000)  = 03h 30m 16.76s
   Dec(J2000) = -23d 02' 14.0"
with an uncertainty of 3.6 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. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.89 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.9
(+2.46/-2.18) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 96 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 03:30:16.89 =  52.57036
  DEC(J2000) = -23:02:15.4  = -23.03760
with a 90%-confidence error radius of about 0.78 arc sec. This position is 3.0
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.37 with a 1-sigma error of about  0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.03. 

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


GRB_name: GRB181010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23310
SUBJECT: GRB 181010A: MASTER-Argentina OT detection
DATE:    18/10/10 06:54:35 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

Hugo Levato 
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

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

O. Gres, N.M. Budnev, Yu.Ishmuhametova
Applied Physics Institute of Irkutsk State University

V. Yurkov, A. Gabovich, 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  GRB181010.25 19 sec after notice time and 42 sec after trigger 
time at 2018-10-10 05:56:33 UT. On our first (60s coadd exposure) coadd 
set we  found 1 optical transient within SWIFT error-box (ra=52.55 
dec=-23.0344 r=0.05) brighter than 18.24.


  T-Tmid      Date      Time       Expt.        Ra                Dec 
Mag
---------|---------------------|-------|-----------------|-----------------|-------
       72   2018-10-10 05:56:33      60   (  3h 30m 16.8s , -23d  2m 14.9s) 
18.05

The 5-sigma upper limit has been about 18.7 mag
The message may be cited.


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


The galactic latitude b = -53 deg., longitude l = 215 deg.
The observations made on zenit distance = 15 deg.The moon ( 2 % bright 
part) below the horizon (The altitude of the Moon is -50 deg. ).
The sun  altitude  is -45.7 deg.
The object can be observed till sunrise at 2018-10-10 10:03:45
  .



THIS BLOCK FOR MASTER-Team USERS ONLY.

Link to GRB181010.25 page: 
https://200.123.254.238:49004//master2/grb.php?not=2018-10-10+05%3A56%3A14&sat=SWIFT&gcrd=%2852.55d%2C-23.0344d%29&eb=0.05&trig=2018-10-10+05%3A55%3A51&n=GRB181010.25
Long     transients in E.B. 
https://200.123.254.238:49004//master2/trans.php?wh=transients.coord2000@%27%3C%2852.55d%2C-23.0344d%29%2C0.1d%3E%27%3A%3Ascircle+and+transients.datetime%3E%3D%272018-10-10+05%3A55%3A51%27&class=9&t2=SWIFT+GRB181010.25+optical+counterpart+candidate
Short    transients in E.B. 
https://200.123.254.238:49004//master2/trans3.php?wh=transients3.coord2000@%27%3C%2852.55d%2C-23.0344d%29%2C0.1d%3E%27%3A%3Ascircle+and+transients3.datetime%3E%3D%272018-10-10+05%3A55%3A51%27&class=-1&t2=SWIFT+GRB181010.25+optical+counterpart+candidate
Two tube transients in E.B. 
https://200.123.254.238:49004//master2/trans2.php?wh=transients2.coord2000@%27%3C%2852.55d%2C-23.0344d%29%2C0.1d%3E%27%3A%3Ascircle+and+transients2.datetime%3E%3D%272018-10-10+05%3A55%3A51%27&class=0&t2=SWIFT+GRB181010.25+optical+counterpart+candidate
Undef. objects 1 image 
https://200.123.254.238:49004//master2/aobj.php?wh=stars.coord2000@%27%3C%2852.55d%2C-23.0344d%29%2C0.1d%3E%27%3A%3Ascircle+and+stars.class=0+and+stars.status+and+stars.proc_id=626837&t2=SWIFT+GRB181010.25+1+image+optical+counterpart+candidate


The observation and reduction will continue.
This circular was generated automatically.
The message may be cited.


GRB_name: GRB181010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23311
SUBJECT: GRB 181010A: LCO Cerro Tololo observations
DATE:    18/10/10 07:35:32 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

We automatically began observing Swift GRB 181010A (Melandri et al. GCN 
23309) with one LCO 1-m unit at Cerro Tololo from October 10, 06:02:54 
UT (corresponding to 7.1 minutes from the GRB trigger time) with the 
SDSS r' filter. We clearly detect the optical counterpart reported by 
Swift-UVOT with r'=19.98 +- 0.12 mag from a 3x120s exposure at a mid 
time of 10.7 minutes post GRB, as calibrated against nearby Pan-STARRS 
objects.


GRB_name: GRB181010A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23312
SUBJECT: GRB 181010A: RATIR Optical and NIR Afterglow Detection
DATE:    18/10/10 08:02:49 GMT
FROM:    Eleonora Troja at GSFC  <eleonora.troja@nasa.gov>

Eleonora Troja (GSFC), 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), Owen Littlejohns
(ASU), Enrico Ramirez-Ruiz (UCSC), Jesus Gonzalez (UNAM),
Carlos RomÃ¡n-Zuniga (UNAM), Harvey Moseley (GSFC), John
Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD)
report:

We observed the field of GRB 181010A (Melandri, et al., GCN 23309)
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astronomico Nacional on Sierra San Pedro Martir from
2018/10 10.25 to 2018/10 10.29 UTC (4.2 min to 1.10 hours after
the BAT trigger), obtaining a total of 0.50 hours exposure in the
r and i bands and 0.24 hours exposure in the Z, Y, J, and H bands.

At the position of the optical afterglow (Melandri, et al.,
GCN 23309; Gorbovskoy, et al., GCN 23310), in comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following detections:

r    20.30 +/- 0.20
i    21.03 +/- 0.10
Z    20.67 +/- 0.24
Y    20.24 +/- 0.21
J    19.87 +/- 0.24
H    19.16 +/- 0.17

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 Astronomico Nacional in
San Pedro Martir.

Further observations are on-going.


GRB_name: GRB181010A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23313
SUBJECT: GRB 181010A: Enhanced Swift-XRT position
DATE:    18/10/10 10:29:09 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 441 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 181010A, 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 = 52.57030, -23.03844 which is equivalent
to:

RA (J2000): 03h 30m 16.87s
Dec (J2000): -23d 02' 18.4"

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: GRB181008A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23314
SUBJECT: GRB 181008A: Insight-HXMT/HE detection
DATE:    18/10/10 11:04:42 GMT
FROM:    Ce Cai at IHEP  <caice@ihep.ac.cn>

C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team: 

At 2018-10-08T06:28:13.500 (T0), the Insight-HXMT/HE detected 
GRB 181008A (trigger ID: HEB181008269) in a routine search of the data, 
which was also triggered by Fermi/GBM (trigger number 560672873). 

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 41.79 s measured from T0-28.03 s. 
The 1-s peak rate, measured from T0+0.10 s, is 1357.8 cnts/s. 
The total counts from this burst is 14288.3 counts. 
URL_LC: http://www.hxmt.org/images/GRB/HEB181008269_lc.jpg 

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (record energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
fundedjointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.


GRB_name: GRB181010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23315
SUBJECT: GRB 181010A: VLT/X-shooter redshift
DATE:    18/10/10 11:49:03 GMT
FROM:    Jean Baptiste at Paris Observatory  <jean.baptiste.vielfaure@gmail.com>

J-B. Vielfaure (CNRS - GEPI/Observatorie de Paris), J. Japelj (API, U.
Amsterdam), D. B. Malesani (DAWN/NBI and DARK/NBI), V. D'Elia (SSDC), J. P.
U. Fynbo (DAWN/NBI), N. R. Tanvir (Univ. Leicester), S. D. Vergani (CNRS -
GEPI/Observatorie de Paris), A. Rossi (INAF-OAS), P. Vreeswijk (Radboud
Univ. Nijmegen), L. Izzo (HETH/IAA-CSIC), D. A. Kann (HETH/IAA-CSIC), B.
Milvang-Jensen (DAWN/NBI), D. Xu (NAOC) and K. E. Heintz (Univ. of
Iceland), report on behalf of the Stargate collaboration:

We observed the optical counterpart of GRB 181010A (Melandri et al. GCN
23309; E. Gorbovskoy et al. 23310; R. Martone et al. 23311; E. Troja et al.
23312) with the ESO-VLT UT2 equipped with the X-shooter spectrograph. From
the acquisition image we measure a preliminary magnitude of 20.4 +/- 0.1
mag in the r-band, calibrated against local Pan-STARRS sources. Several
spectra with increasing exposure time were collected; in this analysis we
consider only one with 600s exposure obtained in a Rapid Response Mode at
06:18:24.9 UT (at the start of observation, 0.37 hr after the GRB).

A bright continuum is observed across the entire wavelength range covered
by X-shooter. Several absorption and emission features are detected, which
can be identified as due to H-alpha and [OIII]5007/4959 in emission at z =
1.39. At this same redshift we also detect AlII1854/1862, SiII1808, the
MgII doublet, and MgI in absorption. Fine-structure lines from FeII and
NiII are also detected at z = 1.39, which makes the redshift association
with the GRB secure. An intervening system at z = 0.67 with absorption
features due to the MgII doublet and MgI is also identified in the
spectrum.

We acknowledge the ESO observing staff at Paranal, in particular Jorge
Lillo-Box.


GRB_name: GRB181010A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23316
SUBJECT: GRB 181010A: Swift-XRT refined Analysis
DATE:    18/10/10 12:30:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 7.3 ks of XRT data for GRB 181010A (Melandri et al.
GCN Circ. 23309), from 96 s to 17.1 ks after the  BAT trigger. The data
comprise 77 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. 23313).

The light curve can be modelled with an initial power-law decay with an
index of alpha=0.741 (+/-0.021), followed by a break at T+11.9 ks to an
alpha of 3.6 (+4.4, -0.7).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.88 (+0.11, -0.10). The
best-fitting absorption column is  3.1 (+/-0.5) x 10^21 cm^-2, in
excess of the Galactic value of 1.9 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 4.0 x 10^-11 (5.6 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      3.1 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^20 cm^-2
Excess significance: 10.7 sigma
Photon index:      1.88 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
3.6, the count rate at T+24 hours will be 1.8 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.4 x
10^-15 (1.0 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/00866434.

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


GRB_name: GRB181010A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23317
SUBJECT: GRB 181010A: Swift/UVOT Detection
DATE:    18/10/10 12:55:25 GMT
FROM:    Sam Emery at MSSL-UCL  <samuel.emery.15@ucl.ac.uk>

S.W.K. Emery (UCL-MSSL) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181010A
96 s after the BAT trigger (Melandri et al., GCN Circ. 23309).
A source consistent with the XRT position
(Evans et al. GCN Circ. 23313)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  03:30:16.89 =  52.57038 (deg.)
    Dec (J2000) = -23:02:15.4  = -23.03761 (deg.)
with an estimated uncertainty of 0.49 arc sec. (radius, 90% confidence),

consistent with (MASTER-OAFA, Gorbovskoy et al., GCN Circ. 23310;
LCO Cerro Tololo, Martone et al., GCN Circ. 23311; RATIR, Troja et al., GCN Circ. 23312;
VLT/X-shooter, Vielfaure et al., GCN Circ. 23315)

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            96          246          147        19.42 +/- 0.09
white              589         6359          247        >21.0
v                 3867         5503          393        >19.4
b                  564         6323          413        >20.9
u                  309         6117          639        >20.6
uvw1              4277         5912          393        >20.1
uvm2              4072         5707          393        >20.7
uvw2              5098         5298          197        >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB181008B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23318
SUBJECT: IPN Triangulation of GRB 181008B (long)
DATE:    18/10/10 18:44:25 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

K. Hurley, on behalf of the IPN,

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

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

The long-duration GRB 181008B was detected by
Fermi (GBM; trigger 560725347), Konus-Wind, Swift (BAT)
and INTEGRAL (SPI-ACS), at about 75743 s UT (21:02:23).
The burst was outside the coded field of view of the BAT.

We have triangulated this GRB to a Konus-GBM annulus centered at 
RA(2000)=173.995 deg (11h 35m 59s)  Dec(2000)=+4.777 deg (+4d 46' 38"), 
whose radius is 70.040 +/- 2.099 deg (3 sigma).

The annulus combined with the Fermi-GBM final position
3 sigma error circle gives the following error box:
---------------------------------
  RA(2000), deg   Dec(2000), deg
---------------------------------
  Center:
    112.6582      -35.4039
  Corners:
    110.7043      -23.9434
    105.1913      -20.9537
    119.7336      -50.4173
    121.7709      -44.6724
--------------------------------
The error box area is 116 sq. deg, and its maximum
dimension is 31.6 deg (the minimum one is 4.2 deg).
The Sun distance was about 62 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180728_T76197/IPN

This box was submitted for observation by the MASTER-Net robotic
telescope network (http://observ.pereplet.ru; Lipunov et al., 2010,
Advances in Astronomy, vol. 2010, 30L).

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


GRB_name: GRB181010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23319
SUBJECT: GRB 181010A: ePESSTO NTT optical observations
DATE:    18/10/10 18:48:11 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

T. Reynolds (Turku), S. Moran (Turku/NOT), P. D'Avanzo (INAF-OAB), D. B. Malesani (DAWN/NBI and DARK/NBI), M. De Pasquale (Istanbul Univ.), 
S. Campana, A. Melandri (INAF-OAB), J. Harmanen, H. Kuncarayakti (Turku), R. Cartier (CTIO), M. Dennefeld (IAP), C. Inserra (Southampton), 
E. Kankare (QUB), K. Maguire (QUB), S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), I. Manulis (Weizmann) report:


We observed the optical counterpart of GRB 181010A (Melandri et al. GCN 23309; Gorbovskoy et al. GCN 23310; Martone et al. GCN 23311; 
Troja et al. GCN 23312; Vielfaure et al. GCN 23315; Emery et al. GCN 23317) 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 EFOSC2 instrument in imaging mode starting from 2018-10-10 at 08:37:50 UT (i.e. 2.7 hours from the burst). 
The observations ended at 08:53:03 UT and were carried out with the R and i filters. 
The optical afterglow is clearly detected in the R-band image. From preliminary photometry, we find a magnitude of R ~ 22.9 +/- 0.1 
(Vega, calibrated against the USNOB1 catalogue). The afterglow is marginally detected in the i-band. From preliminary forced photometry 
at the afterglow position, we derive a magnitude of i ~ 21.4 +/- 0.4 (AB, calibrated against the Pan-STARRS catalogue). These results, 
compared to previous reports (e.g. Martone et al. GCN 23311; Troja et al. GCN 23312; Vielfaure et al. GCN 23315), suggest for a significant fading 
of the optical afterglow flux. 


GRB_name: GRB181010A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23320
SUBJECT: GRB 181010A: Fermi GBM observation
DATE:    18/10/10 19:34:51 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

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

"At 05:55:59.39 UT on 10 October 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 181010A (trigger 560843764 / 181010247),
which was also detected by the Swift/BAT (Melandri et al. 2018, GCN 23309).
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 48.1
degrees.

The GBM light curve shows two structured pulses followed a weak tail with
an overall duration (T90) of about 60 s (50-300 keV). The time-averaged
spectrum
from T0-0.256s to T0+1.280s is best fit by a power law function with an
exponential
high-energy cutoff.  The power law index is -0.8 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 280 +/- 80 keV.

The event fluence (10-1000 keV) in this time interval is
(6.13 +/- 0.98)E-07 erg/cm^2. The 1.024 sec peak photon flux measured
starting from T0-0.128 s in the 10-1000 keV band
is 3.35 +/- 0.29 ph/s/cm^2.

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


GRB_name: GRB181010A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23321
SUBJECT: GRB 181010A: Swift-BAT refined analysis
DATE:    18/10/10 21:12:55 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), A. Melandri (INAF-OAB),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL)  (i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181010A (trigger #866434)
(Melandri, et al., GCN Circ. 23309).  The BAT ground-calculated position is
RA, Dec = 52.574, -23.023 deg, which is 
   RA(J2000)  =  03h 30m 17.7s 
   Dec(J2000) = -23d 01' 22.7" 
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 85%.
 
The mask-weighted light curve shows several overlapping peaks starting
at ~T-5sec, peaking at ~T+8 sec, and returning to baseline at ~T+15 sec.
T90 (15-350 keV) is 16.4 +- 2.2 sec (estimated error including systematics).
 
The time-averaged spectrum from T-4.04 to T+15.21 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.52 +- 0.15.  The fluence in the 15-150 keV band is 6.9 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+7.43 sec in the 15-150 keV band
is 1.4 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/866434/BA/


GRB_name: GRB181008B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23322
SUBJECT: GRB 181008B: Global MASTER Net optical inspection
DATE:    18/10/11 07:59:47 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

D.Svinkin (Ioffe Institute, Russia)

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

Hugo Levato 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

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

O. Gres, N.M. Budnev, Yu.Ishmuhametova
Applied Physics Institute of Irkutsk State University

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


MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
South Africa (South African Astronomical Observatory) was starting survey 
on the IPN  GRB181008.88  error-box (Svinkin et al., GCN 23318) 
26827 sec after notice time and 1 days 8072 sec after trigger time at 
2018-10-09 23:19:04 UT. The 5-sigma upper limit on our first (180s 
exposure)  set is about 19.0 mag
Link to GRB181008.88 page: 
https://master.sai.msu.ru/site/master2/ligo.php?af=1&wh=tabs(grbtime-'2018-10-08+21:04:32')%3C'1+minutes'::interval
The message may be cited.


The galactic latitude b = -60 deg., longitude l = 98 deg.
The observations made on zenit distance = 42 deg.The moon ( 1 % bright 
part) below the horizon (The altitude of the Moon is -52 deg. ).
The sun  altitude  is -49.0 deg.
The object can be observed till 2018-10-10 03:24:40



MASTER-Kislovodsk robotic telescope (MASTER-Net: 
http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, 
vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station 
of Pulkovo observatory) was starting survey on the IPN  GRB181008.88 
error-box   28923 sec after notice time 
and 1 days 10168 sec after trigger time at 2018-10-09 23:54:00 UT. The 
5-sigma upper limit on our first (180s exposure)  set is about 17.4 mag
Link to GRB181008.88 page: 
https://master.sai.msu.ru/site/master2/ligo.php?af=1&wh=tabs(grbtime-'2018-10-08+21:04:32')%3C'1+minutes'::interval
The message may be cited.

The observations made on zenit distance = 69 deg.The moon ( 1 % bright 
part) below the horizon (The altitude of the Moon is -43 deg. ).
The sun  altitude  is -36.1 deg.
The object can be observed till 2018-10-10 01:57:56

MASTER-Tavrida robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Russia (Lomonosov MSU, SAI Crimea astronomical station) was starting 
survey on the IPN  GRB181008.88 error-box   32631 sec after notice time and 1 days 13876 sec after trigger 
time at 2018-10-10 00:55:48 UT. The 5-sigma upper limit on our first (180s 
exposure)  set is about 17.9 mag

The galactic latitude b = -60 deg., longitude l = 98 deg.
The observations made on zenit distance = 74 deg.The moon ( 1 % bright 
part) below the horizon (The altitude of the Moon is -39 deg. ).
The sun  altitude  is -31.3 deg.
The object can be observed till 2018-10-10 02:32:31


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 starting 
survey on the IPN  GRB181008.88 error-box   1 days 33629 sec after trigger time at 2018-10-10 03:35:27 UT. 
The 5-sigma upper limit on our 3-th (180s exposure)  set is about 17.6 mag
Link to GRB181008.88 page: 
https://master.sai.msu.ru/site/master2/ligo.php?af=1&wh=tabs(grbtime-'2018-10-08+21:04:32')%3C'1+minutes'::interval
The message may be cited.


The galactic latitude b = -60 deg., longitude l = 98 deg.
The observations made on zenit distance = 32 deg.The moon ( 1 % bright 
part) below the horizon (The altitude of the Moon is -44 deg. ).
The sun  altitude  is -50.0 deg.
The object can be observed till 2018-10-10 09:24:14

The total MASTER cover map is available at 
http://master.sai.msu.ru/static//IPN/db/GRB181008.88/img/ligo_master_2018-10-10-08-31-15.eb.zoom.1.png

MASTER OT J075512.66-414512.0 detection - long variable star

MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L )
  discovered OT source at (RA, Dec) = 07h 55m 12.66s -41d 45m 12.0s on 
2018-10-09.99672 UT.
The OT unfiltered magnitude is 12.2m (mlim=19.0).
The OT is seen in 4 images.
This OT was observed at MASTER-OAFA on 2017-09-23 08:08:47 with unfiltered 
m_OT=12.4.
We have reference image on  on 2015-01-11 21:25:04.129 UT with  unfiltered 
m_OT=14.9m (MASTER-SAAO).

The discovery and reference images are available at
http://master.sai.msu.ru/static/OT/075512.66-414512.0.png

This message can be cited.


GRB_name: GRB181010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23323
SUBJECT: GRB 181010A: REM optical and NIR afterglow detection
DATE:    18/10/11 11:06:56 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

P. D'Avanzo, S.Covino, D. Fugazza, A. Melandri (INAF-OAB), on behalf of the REM team, report:

We observed the optical counterpart of GRB 181010A (Melandri et al. GCN 23309; Gorbovskoy et al. GCN 23310; Martone et al. GCN 23311; 
Troja et al. GCN 23312; Vielfaure et al. GCN 23315; Emery et al. GCN 23317; D'Avanzo et al. GCN 23319) with the REM 60cm robotic telescope 
located at the ESO premise of La Silla (Chile). The observations were performed starting on 2018 October 10 at 05:56:52 UT (i.e. 61 seconds 
after the burst) and were carried simultaneously in the g, r, i, z, and H bands. 

The GRB afterglow is detected in the first set of optical and NIR images. From preliminary photometry we estimate the following magnitudes:

r = 18.2 +/- 0.2 (AB; calibrated against the Pan-STARRS catalogue)
H = 14.4 +/- 0.2 (Vega; calibrated against the 2MASS catalogue) 

at a mean time of 4.1 minutes from the GRB time (Melandri et al. GCN 23309).


GRB_name: GRB180913A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23324
SUBJECT: GRB180913A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 558557292)
DATE:    18/10/11 15:49:25 GMT
FROM:    Michael Coughlin at Caltech/LIGO  <mcoughli@caltech.edu>

Michael W. Coughlin (Caltech), S. Bradley Cenko (NASA GSFC), TomÃ¡s
Ahumada (UMD), Leo P. Singer (NASA GSFC), Shaon Ghosh (UWM), Igor
Andreoni (Caltech), Mansi M. Kasliwal (Caltech), Eric C. Bellm (UW),
V. Zach Golkhou (UW), on behalf of the ZTF and GROWTH collaborations
and the KPED team

We observed the localization region of the short GRB 180913A (trigger
558557292) 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 (ZTF) camera. We obtained a
series of 180 second g-, r- and g-band images covering 546 square
degrees beginning at 3:06 UT on 2018 September 14 (8:18 hours after
the burst trigger time). Accounting for area lost to processing
failures due to the overlap of the region with the Galactic plane,
this corresponds to analyzing 72% of the probability enclosed.  Using
the IPN updated localization of GRB 180913B available the next day, we
observed the IPN region with ZTF beginning at 3:08 UT on 2018
September 15, using 300 second g-, r- and g-band exposures. The
observations covered 403 square degrees. Once again accounting for
processing failures, 53% of the enclosed probability was analyzed. A
third set of the same epochs was taken beginning at 3:06 UT on 2018
September 19, using 300 second g-band and 180 second r-band exposures.

The images were processed through the ZTF reduction and image
subtraction pipelines at IPAC to search for potential counterparts.
296 high-significance transient and variable candidates were
identified by our pipeline in the area observed,  most (284) of which
had previous detections with ZTF in the days and weeks prior to the
GRB trigger time (e.g., supernovae, active galactic nuclei). The 12
transients discovered the night of September 14 are listed in the
table below. These candidates were followed up with the Kitt Peak
EMCCD Demonstrator (KPED) on the Kitt Peak 84 inch telescope on
September 16 and with the fl05 Sinistro Camera at Las Cumbres
Observatory (LCO) node at McDonald Observatory on September 23. .

----------------------------------------------------------------------------------------------------------------------------

       ZTF ID             RA DEC      last non-detection discovery mag
     KPED mag

----------------------------------------------------------------------------------------------------------------------------


                       2018/09/14 2018/09/17

----------------------------------------------------------------------------------------------------------------------------
ZTF18abvzgms     354.4607 47.8892      2018/09/12 g>20.96 g = 21.96
       g = 19.65
ZTF18abwiios        348.0586 39.4641     2018/09/12 g>20.92 g = 22.04
         g = 20.24

ZTF18abvzfgy        349.0633 43.5331    2018/09/12 g>20.98  g = 20.98 g = 20.36

ZTF18abvzjwk       337.6354 39.8374     2018/09/12 g>20.72   g = 21.70 g = 21.80

ZTF18abvwkbw     344.1347 37.0509     2018/09/13 r>20.64    r = 21.19
  r > 23.12

ZTF18abvwhkl      346.4340 45.543      2018/09/12 r>20.60   r = 21.44 r = 21.15

ZTF18abvucnv       337.8832 39.501      2018/09/12 g>20.85 g = 21.15
         g = 20.88

ZTF18abwiitm        348.8650 39.9529    2018/09/12 g>20.91   g = 21.71 g = 20.9

ZTF18abvubdm     344.6185 47.1011     2018/09/12 g>20.86 g = 21.01
      g = 20.19

ZTF18abvzsld            3.988 49.4808 2018/09/13  g>20.99 g = 21.50 g = 21.14

ZTF18abwiivr         343.0658 37.3748      2018/09/14 g=21.73 2018/09/12 g>20.89

ZTF18abvzmtm     358.8045 48.3605        2018/09/14 g=21.65 2018/09/13 g>21.01

-------------------------------------------------------------------------------------------------------------------------

The median 5 sigma upper limit for an isolated point source in our
images was g > 21.8 and r > 22.2 mag for the observations made on
September 14 and g > 21.9 and g > 22.1 mag for the observations made
on September 15. For the LCO observations, the median 5 sigma upper
limit for an isolated point source in our images was g> 20.2 and
r>19.9 , no transient had risen to these magnitudes by September 23.

ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL
#11266), and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA;
UW, USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant
No 1440341. Alert distribution service provided by DIRAC@UW. Alert
filtering is being undertaken by the GROWTH marshal system, supported
by NSF PIRE grant 1545949.


GRB_name: GRB181010A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23326
SUBJECT: GROND afterglow detection of GRB 181010A
DATE:    18/10/11 16:01:19 GMT
FROM:    Patricia Schady at Swift  <p.schady@bath.ac.uk>

P. Schady (Uni. of Bath, UK) and J. Bolmer (MPE, Garching) report:


We observed the field of GRB 181010A (Swift trigger 866434; Melandri et al., GCN #23309) 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 were performed in rapid response mode, and started at 05:59 UT, 3 mins after the GRB trigger. They were performed at an average seeing of 1.4" and at an average airmass of 1.0.


We detect a new source at a position consistent with the X-ray and optical afterglow (Gorbovskoy et al., GCN #23310; Evans et al., GCN #23313; Emery, GCN #23317). Based on the first 3.3 min of total exposures in g'r'i'z' and 3 min in JHK, we measure the following preliminary AB magnitudes:


g' = 20.02 +/- 0.02 mag
r' = 19.33 +/- 0.01 mag
i' = 19.13 +/- 0.02 mag
z' = 18.56 +/- 0.01 mag
J = 17.78 +/- 0.03 mag
H = 17.02 +/- 0.03 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)=0.03 in the direction of the burst (Schlafly & Finkbeiner 2011).


We thank Markus Rabus for the excellend support from La Silla.


GRB_name: GRB181011A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23327
SUBJECT: GRB 181011A: MAXI/GSC detection
DATE:    18/10/12 09:35:00 GMT
FROM:    H. Negoro at Nihon U.  <negoro@phys.cst.nihon-u.ac.jp>

Y. Kawakubo (AGU), M. Nakajima, H. Negoro (Nihon U.), M. Serino (AGU), 
S. Nakahira (RIKEN), A. Sakamaki, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.),  
T. Mihara, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, 
T. Hashimoto, A. Yoshida (AGU), N. Kawai, M. Sugizaki, Y. Tachibana, 
K. Morita (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, 
R. Shimomukai, T. Midooka (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, 
S. Ogawa (Kyoto U.), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, 
T. Sato (Chuo U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), 
M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.), T. Kawamuro (NAOJ), 
K. Yamaoka (Nagoya U.), M. Shidatsu (Ehime U.) 
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray 
transient source at 2018-10-11T03:36:12 UT.
Assuming that the source flux was constant over the transit, we obtain 
the source position at

(R.A., Dec) = (93.500 deg, 20.837 deg) = (06 14 00, +20 50 13) (J2000) 

with a statistical 90% C.L. elliptical error region with long and short 
radii of 0.26 deg and 0.18 deg, respectively. The roll angle of the long axis 
from the north direction is 101.0 deg counterclockwise. There is an additional 
systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 167 +- 28 mCrab
(4.0-10.0keV, 1 sigma error).
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:

(R.A., Dec) = (94.338, 21.465) deg = (06 17 21, +21 27 53) (J2000)
(R.A., Dec) = (93.931, 21.742) deg = (06 15 43, +21 44 31) (J2000)
(R.A., Dec) = (92.419, 19.784) deg = (06 09 40, +19 47 02) (J2000)
(R.A., Dec) = (92.824, 19.511) deg = (06 11 17, +19 30 39) (J2000)

There was no significant excess flux in the next transit at 03:55 UT with 
an upper limit of 20 mCrab.

We note that this burst was detected just after the ISS maneuver, and 
the data arrived at JAXA/TKSC about about 8 hr late. 
This and the confirmation of the event result in the late notice of this burst.


GRB_name: GRB181011A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23328
SUBJECT: IPN Triangulation of GRB 181011A (long)
DATE:    18/10/12 12:47:30 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,

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 181011A
(MAXI/GSC detection: Kawakubo et al., GCN Circ. 23327)
was detected by Konus-Wind, INTEGRAL (SPI-ACS),
and Mars-Odyssey (HEND) at about 12979 s UT (03:36:19).

We have triangulated it to a preliminary error box
whose coordinates are:
---------------------------------
   RA(2000), deg   Dec(2000), deg
---------------------------------
   Center:
     93.1530       19.1552
   Corners:
     93.2025       23.5555
     94.8930       14.2497
     94.7356       11.0039
     91.9740       23.5347
--------------------------------
The error box area is about 10 sq. deg, and its maximum
dimension is 11.2 deg (the minimum one is 1.1 deg).
The Sun distance was about 171 deg.

This box may be improved.

The box is consistent with the MAXI/GSC localization.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB181011_T12979/IPN/

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


GRB_name: GRB181011A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23329
SUBJECT: GRB 181011A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/10/12 15:22:41 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto,
V. Pal'shin, S. Sugita, Y. Kawakubo, A. Tezuka, S. Matsukawa,
H. Onozawa, T. Ito, H. Morita, Y. Sone (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 MAXI GRB 181011A (Kawakubo et al., GCN Circ. 23327) was detected
in ground analysis of the CALET Gamma-ray Burst Monitor (CGBM) data
near the MAXI trigger time at T0=03:36:12 UT on 11 October 2018.
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single multi-peaked emission episode which 
starts at T+21 sec and ends at T+55 sec.
The T90 and the T50 durations measured by the SGM data are
31 +- 8 sec and 15 +- 8 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1223264170/

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


GRB_name: GRB181011A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23330
SUBJECT: GRB 181011A: Global MASTER Net optical inspection
DATE:    18/10/12 15:33:40 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

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

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

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)

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

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


MASTER-Kislovodsk robotic telescope (MASTER-Net: 
http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, 
vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station 
of Pulkovo observatory) was starting survey on the IPN  GRB181011.15 
error-box (K. Hurley et al GCN 23328)  33218 sec after notice time and 
61888 sec after trigger time at 2018-10-11 20:47:47 UT. The 5-sigma upper 
limit on our images is about 19 mag.


MASTER-Tavrida robotic telescope  located in 
Russia (Lomonosov MSU, SAI Crimea astronomical station) was starting 
survey on the IPN  GRB181011.15 error-box  45716 sec after notice time and 
74386 sec after trigger time at 2018-10-12 00:16:05 UT. The 5-sigma upper 
limit on our images is about 19 mag.

MASTER-Net cover full IPN (K. Hurley et al. GCN 23328) and MAXI (Kawakubo 
et al. GCN 23327)  error boxes.

Coverage map is available here:
http://master.sai.msu.ru/static//IPN/db/GRB181011.15/img/ligo_master_2018-10-12-05-03-00.eb.zoom.1.pngmlimit.png


GRB_name: GRB181013A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23332
SUBJECT: GRB 181013A: Swift detection of a probable burst
DATE:    18/10/13 03:16:19 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

P. D'Avanzo (INAF-OAB), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
D. M. Palmer (LANL), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 02:39:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181013A (trigger=866783).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 207.601, +40.179, which is 
   RA(J2000)  =  13h 50m 24s
   Dec(J2000) = +40d 10' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several peaks
with a duration of about 25 sec.  The peak count rate
was ~700 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 02:41:12.7 UT, 103.1 seconds after
the BAT trigger. No source was detected in 1.9 ks of promptly
downlinked data, which covered 96% of the BAT error circle. We are
waiting for the full dataset to detect and localise the XRT
counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 106 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of
the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
BAT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.01. 

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


GRB_name: GRB181013A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23333
SUBJECT: GRB 181013A: Global MASTER Net optical observations
DATE:    18/10/13 06:51:18 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

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

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

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)

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

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

MASTER-Kislovodsk robotic telescope (MASTER-Net: 
http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, 
vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station 
of Pulkovo observatory) was pointed to the  GRB181013A (D'Avanzo et al., 
GCN 23332) 21 sec after notice time and 54 sec after trigger time
at 2018-10-13 02:40:23 UT . On 
our first (10s exposure)  set we haven't found optical transient  within 
SWIFT error-box (ra=207.596 dec=40.1783 r=0.05).
The 5-sigma upper limit has been about 13.2 mag
The message may be cited.


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


The galactic latitude b = 72 deg., longitude l = 82 deg.
The observations made on zenit distance = 71 deg.The moon (18 % bright 
part) below the horizon (The altitude of the Moon is -50 deg. ).
Observations started at twilight.
The sun  altitude  is -7.8 deg.
The object can be observed till sunrise at 2018-10-13 03:20:48.


MASTER-Tavrida robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the 
GRB181013.11 129 sec after notice time and 202 sec after trigger time at 
2018-10-13 02:42:51 UT. On our first (40s exposure)  set we haven't found 
optical transient  within SWIFT error-box (ra=207.596 dec=40.1781 r=0.1).
The 5-sigma upper limit has been about 17.4 mag
The message may be cited.


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


The galactic latitude b = 72 deg., longitude l = 82 deg.
The observations made on zenit distance = 75 deg.The moon (18 % bright 
part) below the horizon (The altitude of the Moon is -54 deg. ).
Observations started at twilight.
The sun  altitude  is -13.6 deg.
The object can be observed till sunrise at 2018-10-13 03:56:18.



This message can be cited.


GRB_name: GRB181013A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23334
SUBJECT: GRB 181013A: Swift-XRT afterglow detection
DATE:    18/10/13 07:02:02 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

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

We have analysed 190 s of Photon Counting (PC) mode XRT data for the
Swift/BAT-detected burst GRB 181013A (D'Avanzo et al. GCN Circ. 23332),
collected between T0+115 s and T0+306 s. 

An uncatalogued X-ray source is detected consistent with being within
296 arcsec of the Swift/BAT position and is above the RASS limit and
fading with 3-sigma significance, and is therefore likely the GRB
afterglow.  The position of this source is RA, Dec=207.6518, +40.1082
which is equivalent to:

RA (J2000): 13:50:36.43
Dec(J2000): +40:06:29.5

with an uncertainty of 3.9 arcsec (radius, 90% confidence).  This
position is 4.8 arcmin from the Swift/BAT position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=7.6 (+0.4, -1.0).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 0.98 (+0.30, -0.19). The
best-fitting absorption column is  consistent with the Galactic value
of 9.4 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 6.2 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9 (+/-90) x 10^19 cm^-2
Galactic foreground: 9.4 x 10^19 cm^-2
Excess significance: <1.6 sigma
Photon index:      0.98 (+0.30, -0.19)

If the light curve continues to decay with a power-law decay index of
7.6, the count rate at T+24 hours will be 5.9 x 10^-21 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x
10^-31 (3.6 x 10^-31) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/ToO_GRBs/00866783/Source1.php.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00866783.

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


GRB_name: GRB181013A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23335
SUBJECT: GRB 181013A: Swift-BAT refined analysis
DATE:    18/10/13 18:36:22 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
P. D'Avanzo (INAF-OAB), 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+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181013A (trigger #866783)
(D'Avanzo, et al., GCN Circ. 23332).  The BAT ground-calculated position is
RA, Dec = 207.661, 40.107 deg, which is 
   RA(J2000)  =  13h 50m 38.5s 
   Dec(J2000) = +40d 06' 26.8" 
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 81%.
 
The mask-weighted light curve shows peaks starting at ~T-5 sec and ending
at ~T+120 sec.  T90 (15-350 keV) is 104.1 +- 53.5 sec (estimated error
including systematics).
 
The time-averaged spectrum from T+18.37 to T+123.97 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.82 +- 0.75.  The fluence in the 15-150 keV band is 3.0 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+18.80 sec in the 15-150 keV band
is 0.5 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/866783/BA/


GRB_name: GRB181013A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23336
SUBJECT: GRB 181013A: Swift/UVOT Upper Limits
DATE:    18/10/14 00:31:04 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181013A 106 s
after
the BAT trigger (D'Avanzo et al., GCN Circ. 23332). No optical afterglow
consistent
with the XRT position (Osborne et al. GCN Circ. 23334) 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           867         1017          147         >20.2
u_FC               266          516          246         >19.1
white              867         1017          147         >20.2
u                  266          516          246         >19.1
w1                 818         7875          471         >20.4
m2                6035         7669          393         >19.6
w2                5624         7260          393         >20.8

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: GRB181013A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23341
SUBJECT: GRB 181013A: AbAO optical upper limit
DATE:    18/10/15 18:04:31 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

 E. Mazaeva (IKI),  S. Belkin (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 the Swift GRB 181013A (D'Avanzoet al., GCN 23332) 
with AS-32 (0.7m) telescope of Abastumani Observatory starting on  Oct. 13 
(UT) 15:23:15 .   We do not detect any object within  XRT position (Osborne 
et al., GCN 23334). Preliminary  photometry of the field is following:

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

2018-10-13 15:23:15    0.54312    R      58*60  n/d   n/d  21.0

The photometry is based on nearby SDSS-DR12 stars
SDSS-DR12_id R(Lupton)
J135025.82+400818.8 16.99
J135102.99+401021.5 16.36
J135015.70+400244.5 13.69
J135009.92+400351.8 13.87
J135009.71+400308.0 14.87 


GRB_name: GRB181016A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23342
SUBJECT: GRB 181016A: Swift detection of a burst
DATE:    18/10/16 01:07:47 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF/USRA), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 00:55:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181016A (trigger=867252).  Due to an observing constraint,
Swift could not slew to the burst. 
The BAT on-board calculated location is 
RA, Dec 231.268, -35.279 which is 
   RA(J2000) = 15h 25m 04s
   Dec(J2000) = -35d 16' 43"
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 40 sec.  The peak count rate
was ~500 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 09:03 UT on 2019 January 03. There will thus be no XRT
or UVOT data for this trigger before this time. 

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


GRB_name: GRB181016A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23343
SUBJECT: GRB 181016A: Swift-BAT refined analysis
DATE:    18/10/16 14:44:39 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI), 
P. D'Avanzo (INAF-OAB),  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 181016A (trigger #867252)
(D'Avanzo, et al., GCN Circ. 23342).  The BAT ground-calculated position is
RA, Dec = 231.273, -35.307 deg which is 
  RA(J2000)  =  15h 25m 05.6s 
  Dec(J2000) = -35d 18' 23.6" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The mask-weighted light curve shows a single peak starting at ~T-20 sec, peaking
at T+0 sec, and declining to background around T+90 sec.
T90 (15-350 keV) is 111.6 +- 26.3 sec (estimated error including systematics).

The time-averaged spectrum from T-18.00 to T+110.14 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.51 +- 0.20.  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+0.39 sec in the 15-150 keV band
is 0.7 +- 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/867252/BA/


GRB_name: GRB181011A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23345
SUBJECT: GRB 181011A: MITSuME Akeno and Okayama optical upper limits
DATE:    18/10/17 10:02:24 GMT
FROM:    Adachi Ryo at Tokyo Institute of Tech  <adachi@hp.phys.titech.ac.jp>

R. Adachi, R. Itoh, K. L. Murata, Y. Tachibana, K. Morita,
K. Shiraishi, K. Iida, M. Oeda, M. Niwano,
Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:

We performed tiling observation for error region of GRB 181011A
(Kawakubo et al., GCN Circular #23327)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the two MITSuME 50cm telescopes at  Akeno Observatory
and Okayama Astrophysical Observatory, in Japan.

The observation started on 2018-10-12 13:51:34 UT.
Our tiling observation covers about 90% of MAXI error region.
We did not find any point source at the position of the
MAXI error box (Kawakubo et al., GCN Circular #23327)
in all three bands.
Unfortunately, thin cloud were passing during the observation therefore
we could not obtain uniform exposure for each data set between tiling.
Finally we obtained following 5-sigma upper limits for the magnitudes

35% region: g' > 18.0, Rc > 17.7, Ic > 17.0
40% region: g' > 16.5, Rc > 16.2, Ic > 15.7
15% region: g' > 15.0, Rc > 14.7, Ic > 14.2

We used UCAC-4 catalog for flux calibration.


GRB_name: GRB181014A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23347
SUBJECT: GRB 181014A: Insight-HXMT/HE detection
DATE:    18/10/19 01:08:01 GMT
FROM:    QiBin Yi at IHEP, HXMT  <yiqb@ihep.ac.cn>

Q.B. Yi, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team: 

At 2018-10-14T11:30:23.000 (T0), the Insight-HXMT/HE detected 
GRB 181014A (trigger ID: HEB181014479) in a routine search of the data, 
which was also triggered by Fermi/GBM (trigger number 561209419). 

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 17.64 s measured from T0-8.74 s. 
The 1-s peak rate, measured from T0-3.46 s, is 2675.0 cnts/s. 
The total counts from this burst is 24467.4 counts. 
URL_LC:  http://www.hxmt.org/images/GRB/HEB181014479_lc.jpg 

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (record energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
fundedjointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.


GRB_name: GRB181020A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23349
SUBJECT: GRB 181020A: Swift detection of a burst with an optical counterpart
DATE:    18/10/20 19:19:43 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

M. J. Moss (George Washington University), A. D'Ai (INAF-IASFPA),
V. D'Elia (SSDC), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and A. Tohuvavohu (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 19:00:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181020A (trigger=867987).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 13.967, -47.380 which is 
   RA(J2000) = 00h 55m 52s
   Dec(J2000) = -47d 22' 47"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 30 sec.  The peak count rate
was ~12000 counts/sec (15-350 keV), at ~7 sec after the trigger. 

The XRT began observing the field at 19:01:29.0 UT, 55.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 13.9837, -47.3796 which is equivalent to:
   RA(J2000)  = 00h 55m 56.09s
   Dec(J2000) = -47d 22' 46.6"
with an uncertainty of 4.8 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 6.04e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
121 seconds after the BAT trigger. There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 00:55:55.78 =  13.98240
  DEC(J2000) = -47:22:51.8  = -47.38105
with a 90%-confidence error radius of about 0.76 arc sec. This position is 6.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.51 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 M. J. Moss (mikejmoss3 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: GRB181020A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23350
SUBJECT: GRB 181020A: Fermi-LAT detection
DATE:    18/10/21 01:47:35 GMT
FROM:    Magnus Axelsson at Stockholm U.  <magaxe@kth.se>

M. Axelsson (KTH and Stockholm University) reports on behalf of the Fermi-LAT team:

On October 20, 2018, Fermi-LAT detected high-energy emission from GRB 181020A, which was also detected by Swift (Moss et al. 2018, GCN 23349) and by Fermi-GBM (trigger 561754838).

The best LAT on-ground location is found to be

RA, Dec = 14.1, -47.3 (J2000)

with an error radius of 1.1 deg (90 % containment, statistical error only). This is 0.19 deg from the Swift location.

This was 50 deg from the LAT boresight at the time of the GBM trigger: 19:00:33.30 UT.

The data from the Fermi-LAT in the time interval 0-50s after the GBM trigger show a significant increase in the event rate that is spatially and temporally correlated with the trigger with very high significance. The highest-energy photon is a 930 MeV event which is observed 18 seconds after the GBM trigger.


The Fermi-LAT point of contact for this burst is Masanori Ohno (ohno@astro.hiroshima-u.ac.jp<mailto:ohno@astro.hiroshima-u.ac.jp>).

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


GRB_name: GRB181020A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23351
SUBJECT: GRB 181020A: Enhanced Swift-XRT position
DATE:    18/10/21 03:35:37 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 1995 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 181020A, 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 = 13.98251, -47.38033 which is equivalent
to:

RA (J2000): 00h 55m 55.80s
Dec (J2000): -47d 22' 49.2"

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: GRB181020A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23352
SUBJECT: GRB 181020A: Fermi GBM detection
DATE:    18/10/21 04:22:04 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres (UAH) reports on behalf of the Fermi GBM Team:

"At 19:00:33.30 UT on 20 October 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 181020A (trigger 561754838 / 181020792).
which was also detected by Fermi/LAT (Axelsson GCN 23350) and Swift/BAT
(Moss et al., GCN 23349). The GBM on-ground location is consistent with the
Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 50
degrees.


The GBM light curve shows a single bright pulse
with a duration (T90) of about 15 s (50-300 keV).
The time-averaged spectrum from T0-2 s to T0+20.5 s is
best fit by a Band function with Epeak = 367 +/- 17 keV,
alpha = -0.70 +/- 0.02, and beta = -2.06 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(3.07 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+7.4 s in the 10-1000 keV band
is 16.6 +/- 0.3 ph/s/cm^2.

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


GRB_name: GRB181020A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23353
SUBJECT: GRB 181020A: Swift-XRT refined Analysis
DATE:    18/10/21 04:36:46 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 7.3 ks of XRT data for GRB 181020A (Moss et al. GCN
Circ. 23349), from 61 s to 18.3 ks after the  BAT trigger. The data
comprise 1.1 ks 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. 23351).

The late-time light curve (from T0+4.8 ks) can be modelled with a
power-law decay with a decay index of alpha=1.2 (+/-1.0).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.865 (+0.020, -0.019). The
best-fitting absorption column is  4.3 (+0.5, -0.4) x 10^20 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 1.97 (+0.09, -0.08)
and a best-fitting absorption column of 5.2 (+1.9, -1.8) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.3 x 10^-11 (3.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.2 (+1.9, -1.8) x 10^20 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 3.2 sigma
Photon index:      1.97 (+0.09, -0.08)

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 0.042 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x
10^-12 (1.6 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/00867987.

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


GRB_name: GRB181017A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23354
SUBJECT: GRB 181017A: Insight-HXMT/HE detection
DATE:    18/10/21 05:52:38 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team: 

At 2018-10-17T10:41:58.000 (T0), the Insight-HXMT/HE detected 
GRB 181017A (trigger ID: HEB181017445) in a routine search of the data. 

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 5.72 s measured from T0-0.25 s. 
The 1-s peak rate, measured from T0+1.23 s, is 992.0 cnts/s. 
The total counts from this burst is 3383.0 counts. 
URL_LC:  http://www.hxmt.org/images/GRB/HEB181017445_lc.jpg 

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (record energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.

[GCN OPS NOTE(21oct18): Per author's request, the "A" suffix was
corrected to be in english text.]


GRB_name: GRB181018A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23355
SUBJECT: GRB 181018A: Insight-HXMT/HE detection
DATE:    18/10/21 05:54:23 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team: 

At 2018-10-18T06:07:25.000 (T0), the Insight-HXMT/HE detected 
GRB 181018A (trigger ID: HEB181018255) in a routine search of the data. 

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 34.05 s measured from T0-4.06 s. 
The 1-s peak rate, measured from T0+24.33 s, is 1679.0 cnts/s. 
The total counts from this burst is 18937.0 counts. 
URL_LC:  http://www.hxmt.org/images/GRB/HEB181018255_lc.jpg 

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (record energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
fundedjointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.

[GCN OPS NOTE(21oct18): Per author's request, the "A" suffix was
corrected to be in english text.]


GRB_name: GRB181020A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23356
SUBJECT: GRB 181020A: VLT/X-shooter spectroscopy and redshift
DATE:    18/10/21 10:09:02 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani@dark-cosmology.dk>

Johan P. U. Fynbo (DAWN/NBI and DAWN/DTU), Antonio de Ugarte Postigo 
(HETH/IAA-CSIC and DARK/NBI), Valerio D'Elia (ASI-SSDC), Nial R. Tanvir 
(Univ. Leicester), Giovanna Pugliese (API/Univ. Amsterdam), D. Alexander 
Kann (HETH/IAA-CSIC), D. Malesani (DAWN/NBI, DAWN/DTU, and DARK/NBI), 
and Kasper E. Heintz (Univ. Iceland), report on behalf of the Stargate 
collaboration:

We observed the optical afterglow of the bright Swift and Fermi GRB 
181020A (Moss et al., GCN 23349; Axelsson, GCN 23350; Veres, GCN 23352) 
with the ESO VLT UT2 equipped with the X-shooter instrument. 
Spectroscopy covering the wavelength range 3000-21000 AA was carried out 
starting on 2018 Oct 21.030 UT (5.7 hr after the GRB), for a total of 
4x600 s exposure time.

In a 5-s image taken with the acquisition camera on 2018 Oct 10.023 UT, 
we measure for the afterglow R ~ 17.3 (Vega), assuming R = 18.34 for the 
USNO star at RA = 00:55:51.53, Dec = -47:23:14.5.

The spectrum has a very high S/N. A wide trough is easily visible around 
4780 AA, which we interpret as a DLA in the GRB host system. From 
detection of a plethora of absorption lines, including Al II, Al III, S 
II, O I, Si II, Si IV, C IV, Zn II, Cr II, Ni II, Fe II, Mn II, O I*, Si 
II*, Ni II*, Fe II*, we measure the redshift to be z = 2.938. The 
velocity structure of the lines spans the redshift range 2.9360-2.9407 
(2.938 corresponding to the strongest component). The detection of 
fine-structure lines makes the redshift association with the GRB host 
system secure. Intervening absorbers are also detected at z = 1.788 (Mg 
II), 2.172 (Mg II), and 2.822 (C IV).

We acknowledge the ESO observing staff in Paranal for conducting these 
observations, in particular Elizabeth Bartlett, Stephane Brillant, 
Marcelo Lopez, and Thomas Rivinius.


GRB_name: GRB181020A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23357
SUBJECT: GRB 181020A: Swift-BAT refined analysis
DATE:    18/10/21 14:50:33 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),
M. J. Moss (GWU), 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 181020A (trigger #867987)
(Moss et al., GCN Circ. 23349).  The BAT ground-calculated position is
RA, Dec = 13.987, -47.372 deg which is 
  RA(J2000)  =  00h 55m 56.9s 
  Dec(J2000) = -47d 22' 18.1" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.

The mask-weighted light curve shows a large pulse that starts at ~T-1 s, peaks
at ~T+8 s and ends at ~T+30 s. There is a second, much weaker, pulse that occurs
at ~T+200 s and lasts until ~T+270 s. T90 (15-350 keV) is 238.0 +- 11.6 sec 
(estimated error including systematics).

The time-averaged spectrum from T-1.45 to T+271.20 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.25 +- 0.06.  The fluence in the 15-150 keV band is 8.1 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+7.26 sec in the 15-150 keV band
is 7.7 +- 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/867987/BA/


GRB_name: GRB181020A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23358
SUBJECT: GRB 181020A: LCO Cerro Tololo observations
DATE:    18/10/21 15:54:44 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

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

We observed Swift GRB 181020A (Moss et al. GCN 23349) with one of the 
LCO 1-m unit at Cerro Tololo Observatory on October 20, from 23:55 to 
Oct 21, 00:49 UT (corresponding to 4.9 to 5.8 hours from the GRB trigger 
time) with the SDSS r' and i' filters. We clearly detect the optical 
afterglow (Moss et al. GCN 23349) in both filters with the following 
magnitudes for the first half of the observation run:

Mid time from GRB      Exposure         Filter          Magnitude
trigger time (hrs)     (s)
---------------------------------------------------------------------
5.0                   5x120             SDSS r'         17.55 +- 0.03
5.2                   5x120             SDSS i'         17.2  +- 0.1
---------------------------------------------------------------------

as calibrated against nearby USNO UCAC4 objects.


GRB_name: GRB181020A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  23359
SUBJECT: GRB 181020A: Global MASTER Net OT  observations 
DATE:    18/10/21 18:05:37 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

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

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

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

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

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

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)

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

MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
South Africa (South African Astronomical Observatory) was starting survey 
on the SWIFT  GRB181020.79 error-box (ra=00 55 55.78 dec=-47 22 52 
r=0.05; Moss et all., GCN #23349; Axelsson et al., Fermi LAT, GCN #23350) 
7550 sec after notice time and 7572 sec 
after trigger time at 2018-10-20 
21:06:45 UT. The delay connected with weather condition around trigeer 
time. The 5-sigma upper 
limit on our first (540s exposure) coadd set is about 19.5 mag

We see possible nonmonotonic behaviour OT detected UVOT ( Moss et all., 
GCN #23349;). More accurate (handmade) reduction will be coming.

The automatic OT LC is available at 
http://observ.pereplet.ru/images/GRB181020A_LC.jpg

The galactic latitude b = -70 deg., longitude l = 300 deg.
The observations made on zenit distance = 16 deg.The moon (85 % bright 
part) is 60 deg. above the horizon. The distance between  moon and  object 
is 45 degrees.
The sun  altitude  is -43.7 deg.
The object can be observed till sunrise at 2018-10-21 03:49:44

This message may be cited.


