[vsnet-grb-info 19754] GRB170827A: Further GROND follow-up observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21743
SUBJECT: GRB170827A: Further GROND follow-up observations
DATE:    17/08/29 07:29:05 GMT
FROM:    Patricia Schady at MPE/Swift  <pschady at mpe.mpg.de>

P. Schady (MPE Garching) reports

I re-observed the field of GRB 170827A (Swift trigger 769567; Marshall et
al., GCN #21718) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) on 29-08-2017, 1.8 days after the GRB trigger and 1
day after the first set of GROND observations (Schady, GCN #21729) .
Observations were performed at an average seeing of 1.4" and at an average
airmass of 1.0.

The two point sources detected within the 4.9" XRT error circle (Marshall
et al., GCN #21718) in the first epoch of GROND observations (Schady, GCN
#21729) are still seen in the second epoch of GROND observations and they
remain at the same magnitude. Neither of these sources are therefore
likely to be the optical counterpart of GRB 170827A.

I acknowledge the excellent help provided by the support astronomer in La
Silla, Markus Rabus, in obtaining these data.