GRB 071122
GCN Circular 7121
Subject
GRB 071122: Swift detection of a burst
Date
2007-11-22T01:45:10Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
M. Stamatikos (NASA/ORAU), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), P. J. Brown (PSU),
M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), S. Immler (GSFC/UMCP),
J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD),
F. E. Marshall (NASA/GSFC), C. Pagani (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 01:23:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 071122 (trigger=297114). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 276.581, +47.063 which is
RA(J2000) = 18h 26m 20s
Dec(J2000) = +47d 03' 47"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). As is typical with image triggers, there is
nothing obvious in the TDRSS lightcurve. In these cases, the bursts often
have long duration.
The XRT began observing the field at 01:25:45 UT, 140 seconds after the
BAT trigger. Using prompt downlinked data, we find an uncatalogued fading
X-ray source located at RA, Dec 276.6056, 47.0770 which is
RA(J2000) = 18 26 25.34
Dec(J2000) = +47 04 37.2
with an uncertainty of 4.1 arcsec (radius, 90% containment).
This location is 79 arcseconds from the BAT on-board position,
within the BAT error circle. The initial flux in the 2.5s image
was 6.9e-10 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 145 seconds after the BAT trigger. No 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 3-sigma upper limit is 19.4 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.05.
Burst Advocate for this burst is M. Stamatikos (michael 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.)
GCN Circular 7122
Subject
GRB 071122: ROTSE-III Optical Limits
Date
2007-11-22T02:00:31Z (18 years ago)
From
Eli Rykoff at UCSB <erykoff@physics.ucsb.edu>
E.S. Rykoff (UCSB), W. Rujopakarn (Steward), B. E. Schaefer (Louisiana
State), T.A. McKay (U Mich), H. Swan (U Mich), report on behalf of the
ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
071122 (Swift trigger 297114; Stamatikos et al., GCN 7121), producing
images beginning 8.5 s after the GCN notice time. An automated response
took the first image at 01:24:51.5 UT, 85.9 s after the burst, under
fair conditions. These observations were affected by proximity to the
full moon. We took 10 5-sec, and 30 20-sec exposures. These unfiltered
images are calibrated relative to USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle or the XRT error circle, for both single
images and coadding into sets of 10. Individual images have limiting
magnitudes ranging from 15.7-16.8; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
01:24:51.5 01:24:56.5 5 15.8 85.9 N
01:24:51.4 01:25:58.5 67 17.3 85.8 Y
01:26:12.0 01:30:54.8 282 17.8 166.4 Y
GCN Circular 7123
Subject
GRB 071122: P60 Optical Afterglow Candidate
Date
2007-11-22T03:29:24Z (18 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko (Caltech), D. B. Fox (Penn State), and Eran Ofek (Caltech)
report on behalf of a larger collaboration:
We have imaged the field of GRB071122 (Stamatikos et al., GCN 7121) with
the automated Palomar 60-inch telescope. Observations began at
approximately 01:41 UT 22 November (~ 18 min after the burst). Just
outside the XRT error circle, we detect a stationary, faint point source
not present in the Digital Sky Survey images of the field at coordinates
(J2000.0):
RA: 18:26:25.34
Dec: +47:04:37.2
Using nearby USNO-B stars for photometric calibration, the object appears
to increase in brightness from I ~ 20.2 (01:54 UT) to I ~ 19.8 (02:33 UT).
We therefore consider it likely this is the optical afterglow of
GRB071122.
Further observations to confirm the variable nature of this source are
encouraged.
GCN Circular 7124
Subject
GRB071122: Gemini Absorption redshift
Date
2007-11-22T06:36:13Z (18 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara, D. B. Fox (Penn State) and S. B. Cenko (Caltech)
on behalf of a large collaboration:
Starting on 2007 November 22.19 UT we used the GMOS spectrograph on
the Gemini North telescope to obtain two spectra of 900 each of the
optical afterglow of GRB071122 (GCN 7121, 7123).
The spectrum covers the wavelength range 5900-10000A. We clearly
detect absorption features corresponding to MgII doublet, MgI, Ca H&K
at a redshift of z=1.14, which we identify as the redshift of the grb.
GCN Circular 7125
Subject
GRB 071122: Corrected P60 Coordinates
Date
2007-11-22T08:18:59Z (18 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko (Caltech) reports:
In our previous circular (GCN 7123), I incorrectly transcribed the
coordinates of the proposed afterglow candidate of GRB071122. The correct
coordinates are (J2000.0):
RA: 18:26:25.23
Dec: +47:04:31.3
I would like to thank Phil Evans for pointing out this typo and apologize
for any inconvenience this may have caused.
GCN Circular 7126
Subject
GRB 071122 Swift-XRT refined analysis
Date
2007-11-22T10:23:32Z (18 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans, K.L. Page, R.L.C. Starling (U. Leicester) and M. Stamatikos
(NASA/ORAU) report on behalf of the Swift-XRT team:
We have analysed 1.4 ks of Swift XRT data for GRB 071122 (Stamatikos et
al. GCN Circ 7121), comprising 125 s in Windowed Timing (WT) mode and
1.3 ks in Photon Counting (PC) mode. The observations started 146 s
after the BAT trigger. Using 778 s of overlapping XRT Photon Counting
mode and UVOT V-band data, 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 = 276.60547, 47.07504 which is
equivalent to:
RA (J2000): 18 26 25.31
Dec (J2000): +47 04 30.1
with an uncertainty of 1.7 arcsec (radius, 90% confidence). This
position is 1.5 arcsec from the optical afterglow reported by Cenko (GCN
Circ 7125), 74 arcsec from the initial BAT position, within the BAT
error circle, and 7.1 arcsec from the initial XRT position.
The XRT light curve follows a power-law decay with alpha=2.52
(+0.10/-0.09). There is also a small flare at approximately T0+400 s.
The WT mode spectrum can be fitted with an absorbed power-law, with the
absorption column fixed at the Galactic value of 4.75e20 cm^-2. Adding a
redshifted absorber at z=1.14 (Cucchiara et al. GCN Circ 7124) improved
the fit marginally, with chi-squared decreasing from 36.14 for 39
degrees of freedom, to 32.83 for 38 degrees of freedom. An f-test
indicates that the probability of this being a chance improvement is
~5%. The redshifted absorber has a column density of 9.9e20
(+10.0e20/-9.0e20) cm^-2, and a power-law index, gamma of 2.00
(+0.14/-0.13). The observed (unabsorbed) 0.3-10 keV flux is 2.52e-10
(3.04e-10) erg cm^-2 s^-1.
The predicted count-rate at T+24 hours is 1.69e-6 s^-1, which
corresponds to an observed (unabsorbed) 0.3-10 keV flux of 6.11e-17
(7.37e-17) erg cm^-2 s^-1.
Due to the proximity of this GRB to the sun, no further observations are
planned.
This circular is an official product of the Swift-XRT team.
GCN Circular 7127
Subject
GRB 071122 Swift XRT position update sent in error.
Date
2007-11-22T14:23:35Z (18 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans reports,
The GCN Swift XRT position update notice sent at 12:44:49 UT was sent in error
during the testing of some software modifications. This message should be
disregarded. The best XRT position is still that of GCN Circular 7126.
GCN Circular 7128
Subject
GRB 071122, Swift-BAT refined analysis
Date
2007-11-22T14:28:37Z (18 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+723 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 071122 (trigger #297114)
(Stamatikos, et al., GCN Circ. 7121). The BAT ground-calculated position is
RA, Dec = 276.576, 47.102 deg which is
RA(J2000) = 18h 26m 18.2s
Dec(J2000) = 47d 6' 6"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 69%.
The mask-weighted lightcurve shows a single, rougly symmetrical peak
starting at ~T-30 sec, peaking at ~T+5 sec, and ending at ~T+60 sec.
T90 (15-350 keV) is 68.7 +- 14.4 sec (estimated error including systematics).
The time-averaged spectrum from T-29.4 to T+47.3 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.77 +- 0.31. The fluence in the 15-150 keV band is 5.8 +- 1.1 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+3.00 sec in the 15-150 keV band
is 0.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
GCN Circular 7129
Subject
GRB 071122: MASTER optical observation
Date
2007-11-22T18:55:13Z (18 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy,
A.Krylov, N.Shatskiy, A.Sankovich, G.Borisov, V.Vladimirov,
P.Gritsyk, V.Vibornov, A.Kuznetsov
Sternberg Astronomical Institute, Moscow Union 'Optic'
A. Tlatov, I.Golubov
Kislovodsk Solar Station of the Pulkovo observatory
Krushinski V., I.Zalozhnih
Ural State University
MASTER robotic system (http://observ.pereplet.ru) responded to
GRB 071122.1 (GRB_TIME is 2007-11-22 01:23:25.62, M. Stamatikos et al.,
GCN Circ N 7121).
The first image was at 2007-11-22 01:25:57 UT, 69 s after the GCN notice
time and 151 s after the GRB time.
These observations were affected by proximity to the full moon.
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).
The robot not find OT-candidate in error box brighter then 15.6 (s/n=10).
Individual images have limiting magnitudes about 16.
We set the following specific limits for S. B. Cenko (GCN Circ 7125)
OT position.
start UT t_start-t_GRB mean t_GRB t_exp(s) mlim Coadd?
--------------------------------------------------------------------
01:25:57.6 151 s 166 s 30 16.0 N
01:25:57.6 151 s 266 s 5x30 16.8 Y
01:30:06.6 6 min 42 s 14 min 53 s 20x30 17.7 Y
01:34:15.9 11 min 00 s 15 min 02 s 10x30 17.2 Y
01:42:40.3 19 min 15 s 23 min 15 s 10x30 17.2 Y
01:50:59.5 27 min 35 s 31 min 38 s 10x30 17.2 Y
The reduction is continuing.
The delay of the given telegram is connected with participation and
successful end of national Russia football teem on a selection cycle
EURO' 08. Our collective is especially grateful to national Croatia-teem
for the help during the difficult moment!
The reduction is continuing.
This message can be cited.
Mailto: lipunov@sai.msu.ru
GCN Circular 7131
Subject
GRB071122: Swift/UVOT Observations
Date
2007-11-23T18:27:22Z (18 years ago)
From
Peter Brown at PSU <pbrown@astro.psu.edu>
P. J. Brown, M. M. Chester (PSU), R. L. C. Starling
(U. Leicester), and M. Stamatikos (NASA/ORAU)
report on behalf of the Swift/UVOT team:
Swift/UVOT observed the field of GRB 071122 (trigger
#297114) starting 145 s after the BAT trigger
(Stamatikos et al., GCN Circ. 7121). A faint source
is detected in the first white exposure at a position
of 18h 26m 25.38s, Dec = +47d 4m 30.8s, consistent
with the optical afterglow found by Cenko (GCN Circ.
7125) and the revised XRT position (Evans et al.,
GCN Circ. 7126). The afterglow is detected at a
level of 4 sigma and has a magnitude of
white=20.8 +- 0.3 (one sigma error), with an exposure
midpoint time of 196 s after the trigger. It is
not detected in subsequent exposures in white
or the other 6 filters. The detection and 3-sigma
upper limits in the coadded frames are summarized
in the following table:
Filter T_start(s) T_stop(s) Exp(s) Mag/3-sigma UL
white 145 245 100 20.8 +- 0.3
white 748 1483 119 >21.3
v 252 1517 823 >21.2
b 733 1469 30 >19.6
u 708 1444 40 >19.4
uvw1 684 703 20 >19.2
uvm2 658 1395 59 >18.7
uvw2 763 1508 40 >18.8
The values quoted above are not corrected for the
expected Galactic extinction corresponding to a
reddening of E(B-V) = 0.048 mag towards the direction
of the burst (Schlegel et al. 1998).
GCN Circular 7132
Subject
VLA radio detection of GRB 071122
Date
2007-11-25T20:32:23Z (18 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of the
Caltech-NRAO-Carnegie GRB Collaboration:
"We observed the Swift burst GRB 071122 (GCN 7121) using the VLA at a
frequency of 8.46 GHz. The observations were taken at 22.46 UT on 2007,
November 24. We detect a radio emission at the P60 afterglow position (GCN
7123, 7125). The flux density at the P60 position is 255 +/- 45 uJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."