GCN Circular 6281
Subject
GRB 070412: further NOT observations
Event
Date
2007-04-12T09:01:56Z (19 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
Daniele Malesani (DARK/NBI) and Helene Uthas (NOT) report on behalf of a
larger collaboration:
We observed again the field of GRB 070412 (Romano et al., GCN 6273) with
the NOT. Observations were carried out at two epochs, ~0.9 and ~3.5 hr
after the GRB. R- and I-band images were secured at each epoch.
Inside the XRT error circle, we do not detect the sources reported by
Jelinek et al. (GCN 6279) and Berger (GCN 6280). The 3-sigma limiting
magnitudes are:
t-t0 I limit R limit
--------------------------
0.9 hr 22.9 24.0
3.5 hr 23.1 24.2
These numbers were computed assuming R = 17.38 and I = 17.17 for the USNO
star at RA = 12:06:02.17, Dec = +40:09:01.4. We note that the magnitude
reported by Berger (GCN 6280) is fainter than our limits. Our early
measurement implies a decay shallower than ~t^-0.7.
The object reported by Malesani & Uthas (GCN 6276) is detected only in the
first R-band image, thus leaving open the possibility that this source was
fading. However, we caution about the low significance of this detection.