GRB 020124
GCN Circular 1452
Subject
GRB 020124, HST observations of the fading afterglow
Date
2002-07-12T17:08:20Z (23 years ago)
From
Edo Berger at Caltech <ejb@astro.caltech.edu>
J. S. Bloom, E. Berger, and S. R. Kulkarni (Caltech), on behalf of the
larger HST Collaboration, report:
"After thorough analysis of the three epochs of HST STIS/Clear imaging
observations of GRB 020124, we now find that the faint source reported in
Bloom et al. (GCN #1389) has faded between epoch 1 (11 Feb 2002 UT) and
epoch 3 (25 Feb 2002 UT). This source ("S1"), is astrometrically
consistent with the rapidly fading optical transient reported from Palomar
200-inch imaging (Bloom, GCN #1225). We therefore conclude that S1 is the
afterglow, rather than the host. The source was R=28.6+/-0.2 mag on Feb
11.09 UT, and fainter than R~29.2 mag on Feb 25.71 UT. See the associated
figure at:
http://www.astro.caltech.edu/~jsb/GRB/grb020124/grb020124-hst.gif
This figure shows the first epoch (9972 sec) and the combined images from
18 Feb and 25 Feb (14836 sec) with the same flux scaling.
When combined with ground-based data, these observations reveal that the
rate of decay of the afterglow has steepened from a value of -1.6 to <-1.9
approximately 15 days after the burst.
Furthermore, we do not detect a persistent source (i.e. a host galaxy)
within 1.75 arcsec of the OT position down to R~29.5 mag. Thus, a
positionally-coincident host galaxy of GRB 020124 is the faintest host to
date."
This message may be cited.
GCN Circular 1389
Subject
HST detection of the likely host galaxy of GRB 020124
Date
2002-05-12T22:29:36Z (24 years ago)
From
Josh Bloom at CIT <jsb@astro.caltech.edu>
HST detection of the likely host galaxy of GRB 020124
J. S. Bloom, P. A. Price, D. Fox, S. R. Kulkarni (Caltech), on behalf
of the larger HST Collaboration, report:
"As part of our large HST Cycle 10 program (#9180) we triggered a
series of STIS/Clear imaging visits on GRB 020124 (Ricker et al., GCN
#1220; Hurley et al.; GCN #1223). The imaging, spanning three epochs
(epoch 1: 2002 Feb 11.09, epoch2: 2002 Feb 18.30, epoch 3: 2002 Feb
25.71), was centered at the position of the fading optical transient
(OT) (Price et al.; GCN #1221). Differential astrometry from our
earlier Palomar imaging (Bloom et al., GCN #1225) reveals a faint
source, consistent with the position of the OT, near the detection
limit of the images. A view of region near the OT, as well as the
uncertainty position of the OT relative to the HST image (about 300
mas 1-sigma), may be found at:
http://www.astro.caltech.edu/~jsb/GRB/grb020124/Images/grb020124-host.gif
In that image, two sources ("A", near the center of the OT position
and "B" a faint ~2-sigma source near the outskirts of the OT position)
are consistent with the OT position. The majority of the mapping error
was due to the poor detection of the OT in the JCAM image, therefore,
we expect that the astrometry could be significantly improved using
better detection imaging of the OT.
Imaging differencing between epochs 1 and 3 does not reveal evidence
for fading; we therefore identify source "A" as the likely host of GRB
020124. The difference image may be viewed at:
http://www.astro.caltech.edu/~jsb/GRB/grb020124/Images/grb020124-diff.gif
Summing the epochs (total exposure time 6.8 hrs) we find that the
source was V=29.3 +/- 0.3 mag at a weighted mean time of 2002 Feb
17.6; this includes the estimated uncertainty due to the unknown
color. If the source is indeed the host, it is one of the faintest
known, along with the host of GRB 980326 (V=29.25, Fruchter et al.;
GCN #1029) and GRB 000301C (V=29.0 mag, Fruchter et al.; GCN #1063).
The first imaging epoch is now available in the HST archives and we
will supply reduced images of all three epochs upon request
(jsb@astro.caltech.edu). Additionally, we have made the summed image
from JCAM (see GCN #1225) available at the website:
http://www.astro.caltech.edu/~jsb/GRB/grb020124/
This message may be cited.
GCN Circular 1378
Subject
GRB 020124: Optical observations
Date
2002-04-19T12:32:47Z (24 years ago)
From
Ken ichi Torii at RIKEN <torii@crab.riken.go.jp>
K. Torii (RIKEN), T. Kato (Kyoto U.), H. Yamaoka (Kyushu U.), and
A. Yoshida (Aoyama Gakuin U., RIKEN) report:
Based on the GCN alert notice, the GRB 020124 (Ricker, et al. GCN
1220) was observed at RIKEN with the 0.25m f/3.4 hyperboloid
astro-camera equipped with unfiltered cooled CCD AP7p. The field of
view was 50'x50' which covered the HETE's entire error region of 12'
radius (GCN 1220