GRB 181103A
GCN Circular 23402
Subject
GRB 181103A: Swift detection of a burst
Date
2018-11-03T04:58:42Z (7 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
A. Tohuvavohu (PSU), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
K. L. Page (U Leicester), M. H. Siegel (PSU) and T. N. Ukwatta (LANL)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 04:22:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181103A (trigger=870201). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 197.109, +52.230 which is
RA(J2000) = 13h 08m 26s
Dec(J2000) = +52d 13' 50"
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 ~600 counts/sec (15-350 keV), at ~ 2 sec after the trigger.
The XRT began observing the field at 04:24:00.8 UT, 90.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 197.1161,
52.2254 which is equivalent to:
RA(J2000) = 13h 08m 27.86s
Dec(J2000) = +52d 13' 31.4"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 22 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 (1.31 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.5
(+3.93/-3.31) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 92 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.01.
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.)
GCN Circular 23403
Subject
GRB 181103A: Enhanced Swift-XRT position
Date
2018-11-03T09:58:38Z (7 years ago)
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 997 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 181103A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 197.11587, +52.22587 which is equivalent
to:
RA (J2000): 13h 08m 27.81s
Dec (J2000): +52d 13' 33.1"
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.
GCN Circular 23404
Subject
GRB 181103A: Swift-XRT refined Analysis
Date
2018-11-03T12:15:07Z (7 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
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), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB) and A. Tohuvavohu report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 181103A (Tohuvavohu et al.
GCN Circ. 23402), from 76 s to 18.3 ks after the BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Evans et al. (GCN Circ.
23403).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.40 (+/-0.04).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.14 (+0.21, -0.20). The
best-fitting absorption column is 6.0 (+1.3, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 1.3 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 3.9 x 10^-11 (7.3 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6.0 (+1.3, -1.1) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 8.5 sigma
Photon index: 2.14 (+0.21, -0.20)
If the light curve continues to decay with a power-law decay index of
0.40, the count rate at T+24 hours will be 0.032 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x
10^-12 (2.3 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/00870201.
This circular is an official product of the Swift-XRT team.
GCN Circular 23405
Subject
GRB 181103A: Swift-BAT refined analysis
Date
2018-11-03T13:47:23Z (7 years ago)
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 181103A (trigger #870201)
(Tohuvavohu, et al., GCN Circ. 23402). The BAT ground-calculated position is
RA, Dec = 197.093, 52.220 deg which is
RA(J2000) = 13h 08m 22.3s
Dec(J2000) = +52d 13' 11.8"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.
The mask-weighted light curves shows a single FRED-shaped peak from
T0-1 sec, peaking at T0, and decaying to background by T0+10 sec.
T90 (15-350 keV) is 8.38 +- 2.41 sec (estimated error including systematics).
The time-averaged spectrum from T-0.89 to T+10.18 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.90 +- 0.27. The fluence in the 15-150 keV band is 2.8 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.46 sec in the 15-150 keV band
is 0.8 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/870201/BA/
GCN Circular 23406
Subject
GRB 181103A: Nanshan-1m optical upper limit
Date
2018-11-04T11:51:29Z (7 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
J.H. Liu (XAO), Z.P. Zhu, D. Xu (NAOC), X. Zhang, F.F. Song, Z.X. Li,
J.Y. Bai, H.B. Niu, J.Z. Liu, A. Esamdin, L. Ma, Y. Zhang (XAO) report:
We observed the field of GRB 181103A (Tohuvavohu et al., GCN 23402)
using the Nanshan-1m telescope located at Nanshan, Xinjiang, China. We
optained 5��300s, 1��400s, 1��600s R-band frames, starting at 23:07:05 UT
on 2018-11-03, i.e, 18.73 hr after the Swift trigger.
No optical source was detected in the stacked image at the XRT position
(Evans et al, GCN 23403), down to a limiting magnitude of R ~ 21.3 mag
at the median time of 19.31hr post-burst, calibrated with the nearby
SDSS field.
GCN Circular 23407
Subject
GRB 181103A: Swift/UVOT Detection
Date
2018-11-04T14:47:19Z (7 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 181103A: Swift/UVOT Detection
S. J. LaPorte (PSU) and A. Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 181103A
92 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 23402).
A fading source is detected in the initial UVOT exposures at a position
consistent with the XRT position (Evans et al., GCN Circ. 23403).
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
b 534 898 58 >19.08
uvm2 632 1126 57 >18.19
u 279 874 530 19.58+-0.25
v 608 1103 58 >18.21
uvw1 657 849 38 >18.16
uvw2 584 1079 58 >18.36
white_FC 121 271 294 20.47+-0.29
white 559 6763 579 >21.12
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).
GCN Circular 23408
Subject
GRB 181103A: MITSuME Okayama optical upper limits
Date
2018-11-05T04:35:48Z (7 years ago)
From
Katsuhiro L. Murata at Nagoya U <murata@u.phys.nagoya-u.ac.jp>
K. L. Murata, R. Itoh, Y. Tachibana, S. Harita, K. Morita, K. Shiraishi, K.
Iida, M. Oeda, M. Niwano, R. Adachi, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 181103A (A. Tohuvavohu et
al., GCN Circular #23402) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Okayama Astrophysical
Observatory, Japan.
The observation started on 19:38:58 UT. We did not find any new point
source within enhanced XRT circle (P.A. Evans et al., GCN Circular #23403)
in all three bands. We obtained following limits for the magnitudes.
T0+[hour] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------------------------------------------------
15.352 20:15:29 3240 >18.5 >18.0 >17.5
-------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
GCN Circular 23410
Subject
GRB 181103A: AbAO optical upper limit
Date
2018-11-05T08:51:38Z (7 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (IKI), A. Pozanenko (IKI), R. Inasaridze (AbAO), E.
Mazaeva (IKI), S. Belkin (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 181103A (Tohuvavohu et al., GCN
23402) with AS-32 (0.7m) telescope of Abastumani Observatory starting on
Nov. 3 (UT) 15:02:42. We do not detect any object within enhanced
XRT position (Evans et al., GCN 23403). In particular we do not detect
the source reported by LaPorte et al. (GCN 23407). Preliminary
photometry of the field is following:
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2018-11-03 15:02:42 0.47151 R 63*60 n/d n/d 20.5
The photometry is based on nearby SDSS-DR12 stars (R, Lupton
transformation).