GCN Circular 12912

N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick),
L. Dom��nguez Palmero (ING), S. Leggett (Gemini) & T. Wold (JACH)
report on behalf of a larger collaboration:

We imaged the field of GRB120202A (Mereghetti et al. GCN12909
Not found
 
 
) using the
WHT/ACAM and Gemini-N/GMOS.�� At the location of the X-ray source identified
by Holland et al. (GCN12911
Not found
 
 
) we find a faint source at position:

13:34:00.80�� +22:46:24.3

with the following provisional magnitudes (both photometry and astrometry are
calibrated against SDSS DS8):

WHT
r= 25.00 +/- 0.15�� (approx 7:40 hours post-burst)

Gemini-N
r=24.84 +/- 0.09 (approx 16:10 hours post-burst)

Thus there is no clear evidence for variability.��
There is however another point source close to the reported Swift XRT
source at position:

13:34:01.27 +22:46:29.0

slightly outside the reported 90% error circle, for which
we find magnitudes:

WHT:������
r=24.68 +/- 0.09,���� z=22.93 +/- 0.18

Gemini:����
r=24.26 +/- 0.06,���� z=22.64 +/- 0.08

Thus, there is evidence of brightening for this source by about
0.3-0.4 mag between the two epochs, making it likely associated with
the GRB, albeit with unusual afterglow behaviour.�� For this source we also
have a K-band magnitude from UKIRT/WFCAM:

K=18.35 +/- 0.18�� (calibrated against 2MASS, taken at 15:00 hours post-burst)

indicating a very red colour from the provisional photometry.