GCN Circular 6525
Subject
GRB 070612A: P60 Confirmation of Afterglow and An Underlying, Nearby
Event
Date
2007-06-12T22:15:19Z (19 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko, E. O. Ofek (Caltech) and D. B. Fox (Penn State) report on
behalf of a larger collaboration:
We have imaged the field of GRB 070612A (Grupe et al., GCN 6509) with the
automated Palomar 60-inch telescope. Images were taken in the Sloan i'
filter beginning at 4:27:29 12 June UT (~ 1.8 hr after the burst) at large
airmass (> 2.5).
Inside the BAT error circle we identify a bright, stationary, variable
source located at coordinates (J2000.0):
RA: 08:05:29.61
Dec: +37:16:15.2
The object increases in brightness over the duration of our exposure,
ranging from i' = 16.97 in our first image to i' = 16.27 approximately 2.2
hours after the burst.
Given the brightness, we consider it likely this is the same candidate
proposed by Updike et al. (GCN 6515), despite the fact that their position
differs from ours by ~ 14". Furthermore, as first noted by this group,
there is a faint galaxy underlying the OT visible in the SDSS images of
this field (Cool et al., GCN 6510) located at RA: 08:05:29.64, Dec:
+37:16:14.6 (J2000.0). The photometric redshift, taken from the SDSS
database, for this putative host is z = 0.096 +/- 0.023.
Altogether, GRB 070612A has 1) a very long duration (t90 ~ 370 s;
Barthelmy et al., GCN 6522), 2) a bright, rising optical afterglow at t ~
2 hr, and 3) an underlying, nearby (z ~ 0.1) putative host galaxy. In all
these ways it is similar to XRF 060218. Despite its proximity to the
sun (~ 38 degrees away and setting), we encourage follow-up observations
at all wavelengths while still possible to further investigate this
interesting source and search for signs of an associated supernova.