GRB 110107A
GCN Circular 11565
Subject
GRB 110107A: Swift-XRT afterglow confirmation
Date
2011-01-13T17:23:16Z (15 years ago)
From
Giulia Stratta at ASDC <giulia.stratta@gmail.com>
G. Stratta (ASDC) reports on behalf of the Swift-XRT team:
Swift performed a second target of opportunity observation of GRB 110107A on
January 12, 2011.
The XRT began observing the field at 2011-01-12 18:07:47 UT, that is T+420.7
ks (4.87 days) (Cummings, GCN Circ. 11545).
Using 2.1 ks of Photon Counting mode data we find that the source has faded
down to a 3-sigma upper limit of 0.007 counts/s.
Assuming a power law decay starting from the first source detection (Stratta
et al., GCN Circ. 11547), the upper limit
is consistent with a decay index steeper than alpha = -0.4.
The fading nature of the source confirms its afterglow origin.
This circular is an official product of the Swift-XRT team.
GCN Circular 11551
Subject
GRB 110107A: Swift/UVOT upper limits
Date
2011-01-10T19:20:46Z (15 years ago)
From
Stefan Immler at NASA/GSFC <stefan.m.immler@nasa.gov>
S. Immler (CRESST/UMCP/GSFC) and G. Stratta (ASDC) report on behalf
of the Swift/UVOT team:
Swift UVOT started observing the field of GRB 110107A on January 8,
2011 at 15:12 UT, approximately T+17.9 hours (Cummings, GCN Circ 11545).
No optical afterglow consistent with the XRT position (Stratta et al.,
GCN Circ. 11547) is detected in individual or merged UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) are:
Filter T_start T_stop Exp(s) Mag
-----------------------------------------------
v 64,646 75,090 2247 >20.5
u 64,609 74,538 1638 >21.2
-----------------------------------------------
The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight corresponding to a
reddening of E_{B-V} = 0.459 mag (Schlegel et al., 1998, ApJS, 500, 525).
GCN Circular 11547
Subject
GRB 110107A: Swift-XRT Afterglow Candidate
Date
2011-01-08T22:09:10Z (15 years ago)
From
Valerio D'Elia at ASDC <delia@asdc.asi.it>
G. Stratta (ASDC), V. D'Elia (ASDC), P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team:
Swift began a target of opportunity observation of GRB 110107A
on January 8, 2011 at 15:07 UT, approximately 17.8 hours
after the burst detected by Fermi. The GRB was deteced during a Swift
slew with BAT event capture. Swift data for these
observations utilize Target ID 20157.
The XRT began observing the field at 15:12:43 UT, 64.8 ks after the
Fermi trigger.
Using 2517 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 =
299.90910, 41.91400 which is equivalent to:
RA (J2000): �19 59 38.20
Dec (J2000): +41 54 50.3
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
This position is 1.7 arcminutes distant from the BAT position.
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).
The count rate level is (1.2+/-0.2)10^-2 counts/s.
We cannot state if the source is fading at this stage and
we need to wait for more data.
This circular is an official product of the Swift-XRT team.
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GCN Circular 11546
Subject
GRB 110107A: Swift-BAT refined analysis
Date
2011-01-08T19:45:24Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-70 to T+22 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 110107A (a ground-found burst)
(Cummings, GCN Circ. 11545).
The mask-weighted light curve shows low level multiple overlapping peaks
starting at ~T-70 sec and ending at ~T+22 sec. The event-by-event data captured
during the slew stops at T+22 sec. Using the on-board raw rates, there is
a weak indication that the burst continued out to ~T+45 sec.
The time-averaged spectrum from T-70 to T+22 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.58 +- 0.03. The fluence in the 15-150 keV band is at least
5.8 +- 0.5 x 10^-6 erg/cm2. All the quoted errors are at the 90% confidence
level.
GCN Circular 11545
Subject
GRB 110107A detected in ground analysis of BAT slew data
Date
2011-01-08T11:50:43Z (15 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
J. R. Cummings (GSFC/UMBC) on behalf of the Swift-BAT team
GRB 110107A occurred at 21:15:51 UTC. It was observed by Fermi GBM (trigger
316127753) and occurred during a Swift slew with BAT event capture. There is a
strong source in a mosaic of BAT images at RA, Dec 299.890, 41.889, which is
RA (J2000) 19h 59m 33.6s
Dec (J2000) +41d 53m 19s
with an estimated 90% uncertainty of 3 arcmin radius.
The burst was about 100 seconds long, starting at about T-70 sec and lasting
until about T+40 sec. The BAT event data ended at about T+21 sec. The burst
had multiple peaks, with the largest flux at about T0, the time of the Fermi
GBM trigger. The peak count rate in BAT was about 4000 counts/sec.
A Swift Target of Opportunity observation has been requested and approved.