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GCN Circular 18618

GRB 151118A: ISON-NM early optical limit
2015-11-18T14:44:20Z (9 years ago)
Alexei Pozanenko at IKI, Moscow <>
L. Elenin (KIAM),  A. Volnova (IKI), E. Mazaeva (IKI),  I. Molotov 
(KIAM), A. Pozanenko (IKI) report on behalf of larger GRB  follow-up 

We observed the field of the Swift GRB 151118A (Amaral-Rogers et  al., 
GCN 18611) with 0.4-m telescope of ISON-NM observatory in robotic mode 
starting on Nov., 18 (UT) 03:08:32  i.e. 122 seconds after burst 
trigger. We obtained 6 unfiltered images of 30 s exposure under 
unfavorable weather conditions. We do not detect any source within 
enhanced XRT error circle (Evans et al., GCN 18614):

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

2015-11-28 03:08:32   0.00158  None    1*30   17.4
2015-11-28 03:08:32   0.00265  None    5*30   18.0

The photometry is based on nearby USNO-B1.0 stars:
USNO-B1.0 id R2
1559-0079254 15.66
1558-0078601 16.03
1558-0078636 14.62
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