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
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).