[vsnet-grb-info 11909] GRB 120514A: GROND upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13298
SUBJECT: GRB 120514A: GROND upper limits
DATE:    12/05/14 16:45:37 GMT
FROM:    Vladimir Sudilovsky at MPE  <vsudilov at mpe.mpg.de>

A. Nicuesa Guelbenzu (TLS Tautenburg), S. Schmidl (TLS Tautenburg), V. 
Sudilovsky (MPE Garching), and J. Greiner (MPE Garching) report on 
behalf of the GROND team:

We observed the field of GRB 120514A (Mangano et al., GCN #13289) 
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 
405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile).

Observation started at 03:39 UT, 2.4 h after the trigger and ended at 
11:10 UT.

We detect two sources just outside of the enhanced 1.8" XRT error circle 
at RA,DEC 18:52:00.1, -04:15:50.8 and 18:52:00.2, -04:15:46.8 with a 
positional uncertainty of +/- 0.3". We note that neither source varies 
in r' brightness relative to USNO field stars over a period of 2 hours. 
Additionally, the southern source exhibits a thermal spectrum. 
Therefore, neither of these two sources are likely associated with the GRB.

Based on exposures of 1480 seconds in g'r'i'z' and 1200 seconds in JHK, 
we do not detect a source within the 1.8" XRT error circle of the X-ray 
counterpart candidate (Evans et al., GCN #13292) to the following 
3-sigma upper limits (AB system):

g' > 22.7,
r' > 23.0
i' > 23.0
z' > 23.0
J > 20.5
H > 19.6
K > 18.5

These magnitudes are calibrated against GROND zeropoints (g'r'i'z') and 
2MASS (JHK) and are not corrected for the expected Galactic foreground 
extinction corresponding to a reddening of E_(B-V)=1.7 mag in the 
direction of the burst (Schlegel et al. 1998).