GRB 071010A
GCN Circular 6934
Subject
GRB 071010A: Late-time Keck/LRIS photometry - possible host galaxy and jet break
Date
2007-10-18T21:59:38Z (19 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, A. V. Filippenko, J. M. Silverman, R. J. Foley, M. Modjaz,
D. Kocevski, and J. S. Bloom report:
We acquired an additional series of imaging observations of the field of
GRB 071010A (Moretti et al., GCN 6859) with Keck I + LRIS starting at
5:01 UT, 2007-10-16 (6.05 days after the trigger), in g and R filters.
The optical afterglow (Klotz et al. GCN 6860) has faded substantially.
An object is observed at the GRB position, resolvable into two regions:
a brighter, redder source to the east and a fainter, bluer source to the
west. Comparison with our previous Keck imaging shows the afterglow
position to be consistent only with the fainter, western source. The
two sources may be a bright elongated host galaxy, a compact host galaxy
with the afterglow offset from the center, or a foreground star with the
afterglow coincidentally located very nearby. An image of the field is
posted at: http://lyra.berkeley.edu/~dperley/071010a/071010a_keck.png
Aperture photometry shows the combined complex of both sources to have a
magnitude of R=22.5, using the same calibration system in previous
circulars. The contribution from the afterglow is limited to R>23.3,
depending on the uncertain contribution of a possible bright host galaxy.
Refined photometry of our imaging starting at 2007-10-11 UT 04:47 (GCN
6885) shows the afterglow magnitude at that time to be R = 19.82+/-0.02.
This indicates that the afterglow decay underwent a sharp break, from
alpha < 0.5 between the first and second night to a minimum of alpha >
1.7 over the following five days.
Comparison with the XRT light curve at
http://astro.berkeley.edu/~nat/swift/00293707/bat_xrt.jpg shows the
X-ray afterglow to have undergone a break at 10^5 seconds (roughly
coincident with our measurement on 2007-10-11) from approximately flat
evolution before this point to a rapidly decaying power law of alpha ~
1.8 afterward. This suggests that this sharp break may be achromatic,
and possibly indicative of a jet break.
[GCN OPS NOTE(18oct07): The "and jet break" was added back on to the
Subject-line of this circular. It was chopped off during processing
because the mail sending/delivery system chopps wrapped Subject lines.]
GCN Circular 6901
Subject
VLA non-detection of GRB 071010A
Date
2007-10-12T14:46:05Z (19 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 field centered on the BAT position of the Swift burst
GRB 0701010A (GCN#6859) using the VLA at a frequency of 8.46 GHz
and starting at 0.09 UT on Oct 12, 2007. We do not detect any radio emission
Keck optical position of the afterglow (GCN#6861). The flux density at
afterglow position is -4 � 35 uJy.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 6885
Subject
GRB 071010A: Continued Keck Imaging
Date
2007-10-11T15:11:26Z (19 years ago)
From
Daniel Kocevski at UC Berkeley <kocevski@berkeley.edu>
D. Kocevski, D. A. Perley, and M. Modjaz (UC Berkeley) report:
Beginning at 04:47:42 UT (2007-10-11) we began a second series of
imaging on the field of GRB 071010A (GCN 6733) using the Keck I
telescope (+LRIS). We acquired 6 images with an effective exposure
of 270s in R band and 360s in V band.
The optical afterglow (GCN 6860) is still detected and has faded
since our previous imaging epoch (GCN 6872). Preliminary aperture
photometry of the source indicates that it has faded by 0.55
magnitudes since our previous imaging. Using the same calibration
system as in our previous circular, we estimate a preliminary
magnitude of R=19.42
GCN Circular 6880
Subject
Optical observations: GRB 071010A
Date
2007-10-11T12:12:29Z (19 years ago)
From
Kuntal Mishra at ARIES,Nainital,India <kuntal@aries.ernet.in>
Rupak Roy, K. Misra, and S. B. Pandey (ARIES, NainiTal, India, on behalf
of larger Indian GRB collaboration)
We have imaged the field of Swift GRB 071010 (Moretti et al. GCN6859)
with the 1.04m telescope at NainiTal ~ 0.5 days after the burst.
Observations were performed in R and I bands in poor sky conditions.
We observed the afterglow candidate in R and I bands reported by Klotz,
A. et al. (GCN 6860). Magnitude of the OT is R ~ 20 in comparison to
nearby USNO B1.0 stars.
This message can be cited.
GCN Circular 6876
Subject
GRB 071010A: bright NIR afterglow
Date
2007-10-11T01:07:21Z (19 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
D. Malesani (DARK), V. D'Elia (INAF/OAR), S. Covino (INAF/OABr), G.
Andreuzzi, A. Garcia de Gurtubai (INAF/TNG), and E. Maiorano (INAF/IASF
Bo), report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 071010A (Moretti et al., GCN
6859; Klotz et al., GCN 6860) with the TNG telescope located in the
Canary Islands. Observations were carried out with the NICS instrument
equipped with the H filter, with mean time Oct 10.82 UT (15.7 hr after
the GRB).
At the position reported by Bloom et al. (GCN 6861), we clearly detect a
pointlike object, with H = 16.62 +- 0.05. We note that this value is
remarkably bright. Assuming typical afterglow colors (Fnu propto nu^-1),
this corresponds to R ~ 19. When compared to the Keck photometry
reported by Perley et al. (GCN 6872), this may suggest a flat segment or
even a flaring behaviour. Alternatively, the afterglow may be very red.
We thus encourage further observations to characterize the afterglow
light curve and spectrum.
This message can be cited.
GCN Circular 6872
Subject
GRB 071010A: Keck/LRIS Photometry
Date
2007-10-10T21:16:37Z (19 years ago)
From
Josh Bloom at UC Berkeley <jbloom@astron.berkeley.edu>
D. A. Perley, J. S. Bloom, M. Modjaz, and D. Poznanski (UC Berkeley)
report:
"In addition to the spectroscopic followup reported by Prochaska et
al. (GCN 6864), we acquired imaging of the GRB 071010A field in g and
R band with the Keck I 10m telescope (+LRIS) starting in twilight and
continuing until the object set. The fading afterglow reported by
Klotz et al. (GCN 6860) is well-detected.
Photometry, calculated relative to the USNO B1.0 catalog, is as follows:
t_start(min) R err
67.497 18.025 +/- 0.03
71.041 18.080 +/- 0.03
189.225 18.784 +/- 0.02
194.482 18.806 +/- 0.02
199.457 18.827 +/- 0.02
201.544 18.846 +/- 0.02
203.794 18.873 +/- 0.02
This photometry supersedes the preliminary report in GCN 6861 (Bloom
et al.). In addition, starting at 213 minutes after the trigger we
obtained a rapid series of 26 simultaneous g+R integrations of
typically 30 sec duration, lasting until 239 minutes after the
trigger. Analysis is ongoing."
This message may be cited.