[vsnet-grb-info 16930] GRB 150831A: optical upper limit ISON-SSO

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18211
SUBJECT: GRB 150831A: optical upper limit ISON-SSO
DATE:    15/08/31 13:02:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

L. Elenin (KIAM), A. Volnova (IKI), E. Mazaeva (IKI), I. Molotov (KIAM), 
A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:

We observed the field of Swift and INTEGRAL short GRB 150309A (Lien et 
al., GCN 18209; Mereghetti et al., GCN 18210) with with 0.4-m f/2.4 
telescope of ISON-SSO (Siding Spring Observatory) starting on Aug. 31 
(UT) 10:44:10 (i.e. 10 minutes after burst trigger). We obtained 30 
unfiltered images of 30 s exposure. We do not detect any optical source 
within XRT error circle (Lien et al., GCN 18209). Preliminary photometry 
of the filed is following


Date       UT start   t-T0     Filter   Exp.   UL (3 sigma)
                       (mid, days)       (s)

2015-08-31 10:44:10   0.01299  none    30*30   18.8


Photometry is based on nearby USNO-B1.0 stars (R2)