GCN Circular 1389
Subject
HST detection of the likely host galaxy of GRB 020124
Date
2002-05-12T22:29:36Z (23 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.