GRB 071008
GCN Circular 6856
Subject
GRB 071008: Swift detection of a burst
Date
2007-10-08T22:04:30Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
A. Moretti (INAF-OAB), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC),
V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), M. Stamatikos (NASA/ORAU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 21:55:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 071008 (trigger=293587).
The BAT on-board calculated location is
RA, Dec 151.548, +44.334 which is
RA(J2000) = 10h 06m 11s
Dec(J2000) = +44d 20' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single peak
with a duration of about 15 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger.
Because Swift is in the process of returning to normal operations,
automatic slewing to GRBs is currently disabled outside of
business hours (US EDT). Therefore, there
are no prompt XRT or UVOT observations of this burst.
Burst Advocate for this burst is A. Moretti (moretti AT merate.mi.astro.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.)
GCN Circular 6857
Subject
GRB071008: IAC80 observation
Date
2007-10-09T17:15:01Z (18 years ago)
From
Martin Jelinek at Inst.Astrophys.Andalucia,Granada <mates@iaa.es>
Martin Jelinek, Alberto J. Castro-Tirado, Javier Gorosabel
(IAA-CSIC Granada) and R. Piontek (AIP Potsdam) report on
behalf of larger collaboration:
We observed the Swift-BAT errorbox of a GRB 071008
(trigger=293587, Moretti et al., GCN 6856), with an IAC 80cm
telescope at La Palma starting at 05:43 UT (7.8h after the
GRB). Our 3 x 180s combined R-band image has a limiting
magnitude of R < 21.5 and does not show any new source in
comparison to a DSS-Red, implying a DSS-equivalent limit to
the afterglow detection.
GCN Circular 6866
Subject
GRB071008: Swift-XRT observation
Date
2007-10-10T10:37:43Z (18 years ago)
From
Alberto Moretti at Obs Brera Merate <alberto.moretti@brera.inaf.it>
A. Moretti (INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB),
P. Romano (Univ. Bicocca & INAF-OAB), report on behalf of the
Swift-XRT team:
Swift XRT observed the GRB 071008 (trigger=293587, Moretti et al., GCN
Circ. 6856) beginning 57 ks after the BAT trigger. In 6857s of Photon
Counting mode data spanning 57-65 ks after the trigger in the BAT
error circle we found 2 faint sources at RA,Dec =151.58851,44.32071
and RA,Dec =151.55340, 44.34459 which are
RA(J2000) = 10 06 21.24 Dec(J2000)= +44 19 14.5
RA(J2000) = 10 06 12.82 Dec(J2000)= +44 20 40.5
with error circles of radius 6.5 and 7.5 arcseconds (90%, including
boresight uncertainties) respectively.
They are at 116 and 40 arcseconds from the BAT position, respectively.
At present, due to the paucity of the observed events, we are unable
to determine whether these sources are fading. Further observations
will be planned when the distance to the Sun will be larger.
This circular is an official product of the Swift-XRT team.
GCN Circular 6869
Subject
GRB 071008, Swift-BAT refined analysis
Date
2007-10-10T15:47:08Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
E. Fenimore (LANL), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
A. Moretti (INAF-OAB), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
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+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 071008 (trigger #293587)
(Moretti, et al., GCN Circ. 6856). The BAT ground-calculated position is
RA, Dec = 151.571, 44.303 deg which is
RA(J2000) = 10h 6m 17.0s
Dec(J2000) = 44d 18' 13"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 88%.
The mask-weighted light curve shows a symmetrical peak starting at ~T-11 sec,
peaking at ~ T-1 sec, and ending at ~T+10 sec.
T90 (15-350 keV) is 18 +- 1 sec (estimated error including systematics).
The time-averaged spectrum from T-11.0 to T+14.0 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.23 +- 0.27. 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-2.04 sec in the 15-150 keV band
is 0.5 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
GCN Circular 6874
Subject
GRB071008: optical observations
Date
2007-10-11T00:43:38Z (18 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the error box of short GRB071008 (Moretti et al., GCN 6856)
with Shajn 2.6m telescope of CrAO on Oct. 9. Series of images were obtained
between (UT) 00:15:12 and 01:30:43 in R filter. The limiting magnitude (3
sigma) of a combined image calibrated against USNO-A2.0 is 24.3 mag. The
combined image of a total exposure of 4020 s (67x60 s) covers entire of the
refined BAT error box (Fenimore et al., GCN 6869).
Within error circles of the two XRT sources (Moretti et al., GCN 6866) we
found following optical objects.
Within XRT source at RA(J2000) = 10 06 21.24 Dec(J2000)= +44 19 14.5 there
is a galaxy S1 which also can be detected in SDSS images. However the galaxy
S1 is out of the refined BAT error box (Fenimore et al., GCN 6869).
Within XRT source at RA(J2000) = 10 06 12.82 Dec(J2000)= +44 20 40.5 we
marginally detect S2 object.
It is necessary a second epoch observation to decide about nature of the S2
object.
The combined image can be found at http://grb.rssi.ru/GRB071008.
The message can be cited.
GCN Circular 7113
Subject
Swift XRT follow-up observations of GRB071008
Date
2007-11-19T14:50:58Z (18 years ago)
From
Alberto Moretti at Obs Brera Merate <alberto.moretti@brera.inaf.it>
A. Moretti (INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB), report
P. Romano (Univ. Bicocca & INAF-OAB) on behalf of the Swift XRT team:
The Swift XRT re-observed the field of GRB 071008 (trigger=293587,
Moretti et al., GCN Circ. 6856) on 2007 November 15-19 for a total
exposure of 10.7 ks.
The first source listed in GCN Circ 6866 (Moretti et al., 2007), which
is the only one in the refined BAT error circle (GCN Circ. 6869
Fenimore et al. 2007) is no more detectable. The chance probability of
no variation between the two epochs is < 1E-4. We conclude that this
source is the X-ray afterglow of GRB 071008 and its position is
RA(2000)=151.58851, Dec(2000)=44.3207 which corresponds to
RA(2000) = 10h06m21.24s
Dec(2000) = +44 19 14.6
with a 5.8" radius error circle (90% confidence).
The 3-sigma upper count rate limit at the position of the burst at
3.1E6 seconds after the trigger is 7e-4 counts/s which converts roughly
to 4e-14 ergs/s/cm2.
This circular is an official product of the Swift team