GRB 051021A
GCN Circular 4180
Subject
GRB 051021A: RTT150 optical observations
Date
2005-10-30T06:41:30Z (20 years ago)
From
Rodion Burenin at IKI, Moscow <rodion@hea.iki.rssi.ru>
R. Burenin, D. Denisenko, M. Pavlinsky, R. Sunyaev (IKI), I. Khamitov,
Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.),
I. Bikmaev, N. Sakhibullin (KSU/AST)
report:
The optical transient associated with GRB 051021A (Yoshida et al., GCN
4116; Fox et al., GCN 4120) was observed with Russian-Turkish 1.5-m
telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory, Turkey) in
BVR filter set, starting at Oct. 21, 18:15 UT, 4.88 hours after the
burst.
Compared to USNOB, the magnitudes are about:
t-t0,h
5.34 R=21.1
9.95 R=21.8
5.70 V=22.2
10.18 V=22.6
In B the object was detected only marginally.
This message may be cited.
GCN Circular 4159
Subject
GRB051021a: optical observations
Date
2005-10-24T13:59:34Z (20 years ago)
From
Vasilij Rumjantsev at CrAO <rum@crao.crimea.ua>
V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), and A.Pozanenko (IKI) on behalf
of larger GRB follow up collaboration report:
We observed the SXC error box of HETE-2 GRB051021a (Yoshida et al.,
GCN4116) with 0.6 m telescope (Crimean laboratory of SAI) equipped with FLI
IMG-1001E camera. The series of 60 sec R-band exposures were taken between
October 21, 21:19:01 and October 22, 00:23:24. We clearly detect the
optical afterglow (Fox et al. GCN4120, Swan et al. GCN4120) on stacked
image. Coordinates of the source are RA=01 56 36.37 Dec=+09 04 03.27 (J2000)
with uncertainty of 0.5 arcsec. Preliminary photometry of the stacked image
is following:
Mid time (UT) Exposure R
Oct. 21 22:51 146x60 21.9 +/-0.2
Photometry and astrometry of the source are based on USNO-A2.0.
Stacked image can be found in http://grb.rssi.ru/GRB051021a/.
Taken R-band magnitudes (GCNs 4120, 4123) and upper limit reported in
GCN4138 (Eastman et al.) our results is compatible within statistical error
with single power-law decay light curve alpha ~ -1.6. Also extrapolating
backward J-band (Reichart et al., GCN 4144) observations to our epoch (Oct.
21 22:51) we found R-J ~ 1.0 which do not imply a high redshift source.
This message may be cited.
GCN Circular 4151
Subject
GRB051021A: Swift XRT refined analysis
Date
2005-10-23T18:34:01Z (20 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. Racusin, D. Fox, D. Burrows (PSU), N. Gehrels (GSFC) on behalf of the
Swift XRT team:
We have analyzed the first four orbits of data after XRT began observing
the field of GRB051021A (Yoshida et al., GCN 4116) at 16:28:28 UT. The
refined XRT coordinates are:
RA(J2000): 01 56 36.5
Dec(J2000): +09 04 6.1
with an estimated uncertainty of 4 arcseconds (90% containment), including
corrections for the XRT boresight offset. This position is 1 arcsecond
from the position we quoted in Racusin et al. (GCN 4125), and 2.9
arcseconds from the optical afterglow candidate reported by Fox et al.
(GCN 4120).
The XRT light curve shows a steady decline with a power-law fit decay
index of 1.06+/-0.16.
The Photon Counting mode spectra can be fit with an absorbed power-law
with a photon index of 2.17+/-0.18 and a column density of 1.4+/-0.5 E21
cm-2 which is in excess of the Galactic column density of 0.56E21 cm-2 in
this direction. The observed 0.2-10 keV flux is 2.02E-12 ergs cm-2 s-1,
corresponding to an unabsorbed flux of 2.28E-12 ergs cm-2 s-1.