GRB 050813
GCN Circular 3857
Subject
GRB050813: Maidanak I-band observations
Date
2005-08-22T19:39:34Z (20 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
D. Sharapov, M. Ibrahimov (MAO), A.Pozanenko (IKI), V.Rumyantsev (CrAO) on
behalf of larger GRB follow up collaboration report:
We observed the error box of GRB050813 (GCNs 3788, GCN 3790) with 1.5m
telescope of Maidanak Astronomical Observatory. Set of I images were taken
between (UT) 16:47 - 17:44, on August 13, 2005 under poor weather conditions
(seeing of ~ 1.15"). Limiting magnitude of stacked image (6x300 s) is I ~
21.
Detailed photometry of the field objects which is required variable
background accounting is underway.
The stacked image can be found in
http://grb.rssi.ru/GRB050813/grb050813_AZT22_I.jpg.
This message may be cited.
GCN Circular 3815
Subject
GRB 050813: Radio Observations
Date
2005-08-15T23:19:20Z (20 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
P. B. Cameron (Caltech) and D. A. Frail (NRAO) report on behalf of the
Caltech-NRAO-Carnegie collaboration:
"We have undertaken VLA observations at a frequency of 8.46 GHz toward
the short-hard burst GRB050813 (GCN 3790, 3793) centered on 2005
August 14.92 UT. No significant radio emission is seen within the XRT
error radius to a 3-sigma level of 55 microJy. No further observations
are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 3808
Subject
GRB 050813: Gemini Spectra Revisited
Date
2005-08-15T07:11:14Z (20 years ago)
From
Josh Bloom at Harvard/CFA <jbloom@cfa.harvard.edu>
GRB 050813: Gemini Spectra Revisited
R. J. Foley, J. S. Bloom (University of California, Berkeley), and H.-W.
Chen (MIT) report:
"We have performed an independent reduction and analysis of the spectra of
galaxies B and C in the XRT error circle of GRB 050813 (GCN 3788), and a
as yet unnamed galaxy to the north-east (referred to as X below) obtained
on Aug 14.35 UT with GMOS on Gemini-North under program GN-2005B-Q-6 and
originally reported in GCN 3801 by Berger. Inspection of the spectrum of
galaxy X shows it to be at redshift z = 0.722 (consistent with the
redshift listed in GCN 3801 for galaxies B and C) with obvious Ca H&K and
G-band absorption but no signs of H gamma or H beta absorption.
Inspection of the spectrum of galaxy B shows it to be at redshift z =
0.718 with obvious Ca H&K absorption, but again, no signs of H gamma or H
beta absorption. Inspection of the spectrum of galaxy C shows it to not
definitively be at z = 0.722. Although there are broad dips in the
spectrum which may correspond to Ca H&K at z = 0.722, there are other
features which conflict with this conclusion. There are narrow emission
lines at 7353 and 7519 A observed (which would be 4270 and 4367 A at z =
0.722).
The Ca H&K lines of galaxy X have a velocity width of 591 +/- 97 km/s.
The presence of G-band absorption and a lack of emission lines points
towards an old stellar population. The Ca H&K lines of galaxy B have a
width of 340 +/- 93 km/s. There is also a strong (EW_observed = -6.0 A)
unidentified absorption line at 7402 A. If we place this line at the
redshift of the galaxy, we notice that this could be Ti I 4305. There is
an offset of 116 km/s between the line and the fiducial redshift if this
is the correct identification. Another possibility is this line is due to
Mg II 4481 at z = 0.65."
This message may be cited.
GCN Circular 3806
Subject
GRB 050813: Non-fading of afterglow candidate
Date
2005-08-15T02:00:21Z (20 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
Edo Berger and Mike Gladders (Carnegie Observatories) report:
"We imaged the field of GRB 050813 (GCN 3788) with IMACS on the
Magellan/Baade telescope on Aug 14.98 UT. Observations were obtained in
R-band under mostly clear but non-photometric conditions. In addition to
galaxies B and C we also detect an object at the position of the source
proposed as a possible afterglow by Bloom (GCN 3802). Since the object
has not faded away in over 14 hours (and in addition appears to be
extended) we consider it unlikely that this is the afterglow of GRB
050813."
GCN Circular 3802
Subject
GRB050813: Gemini Imaging
Date
2005-08-14T20:28:39Z (20 years ago)
From
Josh Bloom at UC Berleley <jbloom@astron.berkeley.edu>
GRB 050813: Gemini Imaging
J. S. Bloom reports:
"Imaging acquired in i-band with GMOS/Gemini-N on Aug 14.4 UT under
program GN-2005B-Q-6 reveals a compact faint source 2.3 arcseconds to the
South-East of the centroid of galaxy C (Gorosabel et al.; GCN #3796). We
cannot confirm variability at this time but if it is at the redshift of
this galaxy (z=0.722; Berger GCN #3801) then it lies 16.5 kpc in
projection from the galaxy center, suggesting it is a viable counterpart
to the short-hard GRB 050813 (Retter et al., GCN 3788)."
An image will be posted shortly at
http://astro.berkeley.edu/~jbloom/grb050813-gemini.jpg
We thank K. Roth and the Gemini Observing Staff for assistance in
acquiring this data.
GCN Circular 3801
Subject
GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
Date
2005-08-14T20:07:21Z (20 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
E. Berger (Carnegie Observatories) reports:
"We reduced and analyzed spectra of galaxies B and C in the XRT error
circle of GRB 050813 (GCN 3788) obtained on Aug 14.35 UT with GMOS on the
Gemini north telescope under program GN-2005B-Q-6. Two 1800-sec exposures
were obtained with a 0.75" slit using the R400 grating. We find that both
galaxies exhibit clear Ca H&K, H-beta, and H-gamma absorption at a
redshift of z=0.722. The identical redshifts and the nature of the
galaxies (early types dominated by old stellar populations) support the
conclusion of Gladders et al. (GCN 3798) from Magellan imaging that the
position of GRB 050813 is centered on a galaxy cluster at z~0.5-1. At
this redshift, given K~19 mag, galaxies B and C are about 0.5 L* compared
to the 2MASS luminosity function.
Assuming that this is the redshift of GRB 050813, we find an isotropic
equivalent gamma-ray energy of 1.7e50 erg (fluence = 1.24e-7 erg/cm^2;
GCN 3793), which is somewhat larger than that of GRB 050724."
GCN Circular 3798
Subject
GRB 050813: Magellan detection of a high redshift galaxy cluster
Date
2005-08-14T05:28:50Z (20 years ago)
From
Edo Berger at Carnegie Obs <eberger@ociw.edu>
Mike Gladders, Edo Berger (Carnegie Observatories), Nidia Morrell, and
Miguel Roth (Las Campanas Observatory) report:
"We imaged the field of GRB 050813 (GCN 3788) with the PANIC IR camera on
the Magellan/Baade 6.5-m telescope starting on 2005 Aug. 14.017 UT.
Observations were obtained with the K-s and Y-Carnegie filters, under poor
conditions (variable thick clouds, bright moonlight, and poor seeing of
~1"). Initial processing of these data suggest that this line of sight is
centered on a high-redshift galaxy cluster. A composite Y-K color image,
as well as a greyscale image of the stacked K frame is shown at:
http://www.ociw.edu:/~eberger/grb050813_panic.jpg
The apparent centrally concentrated population of faint galaxies with red
and uniform colors is strongly suggestive of a galaxy cluster, and looks
similar to extensive data taken with this instrument on known high-z
galaxy clusters from the Red-Sequence Cluster Survey (Gladders & Yee
2005). The apparent size of the core of this distribution (~1 arcmin) and
the magnitude of the objects suggest this putative cluster is at high
redshift (above z=0.5, and likely at z~1). The objects noted as B and C by
Gorosabel et al. (GCN 3796) in the XRT error circle are both red and
likely cluster ellipticals, and both are approximately K=19, based on an
initial calibration of the image to the 2MASS magnitude of the bright star
to the immediate SE of these objects.
Given the low probability of a chance coincidence we suggest that GRB
050813 most likely occurred in the cluster environment. This supports
recent associations of short GRBs with old galaxies (050509b: Bloom et al.
astro-ph/0505480; 050724: Berger et al. astro-ph/0508115). The likely
higher redshift compared to the latter two events may also explain the
faintness of the X-ray afterglow (GCN 3790)."
Further observations are planned.
GCN Circular 3797
Subject
GRB050813: RTT150 optical observations
Date
2005-08-14T00:23:08Z (20 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
I. Bikmaev, A. Galeev, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Aslan, I. Khamitov, U. Kiziloglu (METU), A. Alpar (SabUni),
report:
We have observed the error box of GRB 050813 (GCN 3788 and GCN 3790)
with Russian-Turkish 1.5-m telescope (Bakyrlytepe, Turkey), using TFOSC
(the imaging and spectroscopic camera of the TUBITAK National
Observatory, Turkey). We made series of 60s exposures in R during UT
18:35 - 20:25, August 13, 2005.
We found almost all faint objects shown in GCN 3796