GRB 080915A
GCN Circular 8248
Subject
GRB 080915a, SMARTS optical/IR observations
Date
2008-09-16T19:57:08Z (17 years ago)
From
Bethany Cobb at Yale U <cobb@astro.yale.edu>
B. E. Cobb (UC Berkeley), reports:
Using the ANDICAM instrument on the SMARTS 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 080915a
(GCN 8227, Oates et al.) with a mid-exposure time of
2008-09-15 01:54 UT (~1.9 hrs post-burst). We then re-observed
the field at 2008-09-16 6:12 UT (~30.2 hrs post-burst). Total summed
exposure times for each observation amounted to 36 minutes in I
and 30 minutes in J.
A comparison of our two epochs of imaging reveals no variable source
at the position of the X-ray afterglow reported by Evans et al. (GCN
8231). Our limiting magnitudes are I>21.9 and J>20.1.
(Optical photometry is calibrated against Landolt standard stars
and IR photometry is calibrated against 2MASS stars in the field.)
GCN Circular 8268
Subject
GRB 080915A: GROND upper limits
Date
2008-09-18T15:09:18Z (17 years ago)
From
Thomas Kruehler at MPE/MPI <kruehler@mpe.mpg.de>
A. Rossi (Tautenburg Obs.), T. Kruehler, J. Greiner, A. Yoldas,
C. Clemens, R. Filgas (all MPE Garching), A. Kupcu Yoldas (ESO)
and G. Szokoly (Eoetvoes Univ., Budapest), report on behalf of
the GROND team:
GROND (Greiner et al. 2008, PASP 120, 405), mounted at the
2.2m ESO/MPI telescope at La Silla Observatory (Chile), started
observations of the field of GRB 080915A (Oates et al. GCN #8227)
in g'r'i'z'JHK at 00:07:25 UT on 2008-09-15, 4.6 minutes after the burst
and continued for 130 minutes.
The observations were resumed in the following night, starting at
05:18:45 UT and continued for 70 minutes.
We detect 2 sources, one inside the XRT error circle (Evans et al.GCN #8231)
at coordinates RA, DEC (J2000) = 01:11:47.83, -76:01:13.7,
the other at the edge of the XRT error circle at coordinates
RA, DEC (J2000) = 01:11:45.4, -76:01:10.5.
A comparison of the two observing runs does not reveal any evidence for
variability. We conclude that most likely none of them is associated with
GRB 080915A.
The co-added images from the first run then yield the following upper
limits measured at a mid-time of 0.038 days after the trigger and
calibrated on the SDSS standard star SA95-190:
g' > 23.8
r' > 23.7
i' > 23.5
z' > 23.1
J > 20.5
H > 19.3
K > 18.3