[vsnet-grb-info 16099] GRB 150202A: GROND Upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17381
SUBJECT: GRB 150202A: GROND Upper limits 
DATE:    15/02/03 05:23:59 GMT
FROM:    Corentin Delvaux at MPE  <delvaux at mpe.mpg.de>

C. Delvaux, K. Varela and J. Greiner (all MPE Garching) report on behalf
of the GROND team:

We observed the field of GRB 150202A (SWIFT-629547; Krimm et al., GCN
#17376) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started on February 3rd, 2015, at 00:43 UT, 1.5 hrs after the
GRB trigger. They were performed at an average seeing of 1.1" and at an
average airmass of 1.7.

We do not detect a source inside the 2.1” error circle reported by Krimm
et al. (GCN #17376). Based on a total exposure of 2.07 hours in
g'r'i'z'and 1.73 hours in JHK, at a midtime of 2 hours after the burst, we
measure the following preliminary upper limits (AB magnitudes system):

g' > 24.2 mag,
r' > 24.7 mag,
i' > 24.4 mag,
z' > 24.4 mag,
J  > 22.1 mag,
H  > 21.5 mag, and
K  > 18.0 mag.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V) = 0.02 mag in the
direction of the burst (Schlegel et al. 1998).