GRB 220101A
GCN Circular 31347
Subject
GRB 220101A: Swift detection of a burst with a bright optical counterpart
Date
2022-01-01T05:32:40Z (4 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. Tohuvavohu (U Toronto), J.D. Gropp (PSU), J. A. Kennea (PSU),
A. Y. Lien (U Tampa), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), B. Sbarufatti (PSU) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 05:09:55 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220101A (trigger=1091101). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 1.380, +31.753 which is
RA(J2000) = 00h 05m 31s
Dec(J2000) = +31d 45' 09"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT lightcurve shows a complex lightcurve
extending to at least T+170 with a peak of 7000 counts/s (15-350 keV),
at ~89 sec after the trigger.
The XRT began observing the field at 05:11:32.2 UT, 80.8 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 1.3561, 31.7702 which is equivalent to:
RA(J2000) = 00h 05m 25.46s
Dec(J2000) = +31d 46' 12.7"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 95 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 1.30e-08 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 89 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 00:05:24.82 = 1.35340
DEC(J2000) = +31:46:08.5 = 31.76903
with a 90%-confidence error radius of about 0.61 arc sec. This position is 9.3
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.60 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.056.
Burst Advocate for this burst is A. Tohuvavohu (aaron.tohu 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/)
GCN Circular 31348
Subject
GRB 220101A: Correction to GCN 31347
Date
2022-01-01T05:53:46Z (4 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
GCN circular 31347 incorrectly referred to the BAT trigger number of the burst.
The correct trigger number for GRB 220101A is 1091527.
I apologize for any confusion this may have caused.
Happy new year!
GCN Circular 31349
Subject
GRB 220101A: Enhanced Swift-XRT position
Date
2022-01-01T08:34:16Z (4 years ago)
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 1177 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 220101A, 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 = 1.35374, +31.76890 which is equivalent
to:
RA (J2000): 00h 05m 24.90s
Dec (J2000): +31d 46' 08.0"
with an uncertainty of 2.1 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 31350
Subject
GRB 220101A: Fermi-LAT detection
Date
2022-01-01T14:08:57Z (4 years ago)
From
Lorenzo Scotton at CNRS/IN2P3/LUPM <lorenzo.scotton@lupm.in2p3.fr>
M. Arimoto (Kanazawa Univ.), L. Scotton (CNRS/IN2P3/LUPM) and F. Longo
(University and INFN, Trieste)
report on behalf of the Fermi-LAT Collaboration:
On January 1st, 2022, Fermi-LAT detected high-energy emission from
GRB 220101A, which was also detected by Swift (trigger 1091527,
Tohuvavohu et al. GCN Circ. 31347)
The best LAT on-ground location is found to be
RA, Dec = 1.52, 31.75 (degrees, J2000)
with an error radius of 0.46 deg (90% containment, statistical error only).
This was 18 deg from the LAT boresight at the time of the Swift trigger:
T0 = ��05:10:11.5 UT.
The data from the Fermi-LAT show a significant increase
in the event rate after the Swift trigger that is spatially correlated
with the
Swift emission (0.14 degrees from the Swift-XRT location) with high
significance.
The photon flux above 100 MeV in the time interval 0-600s after the
Swift trigger is 2.5E-5 +/- 5E-6 ph/cm2/s.
The estimated photon index above 100 MeV is -2.46 +/- 0.25.
The Fermi-LAT point of contact for this burst is
Lorenzo Scotton (lorenzo.scotton AT lupm.in2p3.fr).
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV.
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
GCN Circular 31353
Subject
GRB 220101A: Xinglong-2.16m photometry and spectroscopy
Date
2022-01-01T15:51:07Z (4 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>