[vsnet-grb-info 16503] GRB 150413A: CrAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17784
SUBJECT: GRB 150413A: CrAO optical observations
DATE:    15/04/28 19:47:55 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

V. Rumyantsev (CrAO), K. Antoniuk  (CrAO), E. Mazaeva (IKI),  A. 
Pozanenko (IKI) report on  behalf of larger GRB follow-up collaboration:

We observed the field of the GRB 150413A (Markwardt  et al., GCN 17688) 
  with AZT-11 telescope of CrAO observatory starting on Apr. 13 (UT) 
17:39:02. Several images were take in R-filter. The afterglow   (Ivanov 
et al., GCN 17689) is clearly detected in all single images of 180 s 
exposure. Preliminary photometry is following

Date,       UT start,    OT,    OT_err

2015-04-13  17 40 32.11  16.56  0.12
2015-04-13  17 43 36.17  16.97  0.30
2015-04-13  17 46 40.21  16.48  0.07
2015-04-13  17 49 44.26  16.73  0.11
2015-04-13  17 52 48.30  16.48  0.15
2015-04-13  17 55 52.37  16.62  0.13
2015-04-13  17 58 56.41  16.74  0.09
2015-04-13  18 02 00.58  16.63  0.13
2015-04-13  18 05 04.68  16.78  0.10
2015-04-13  18 08 08.76  16.77  0.09
2015-04-13  18 11 12.83  16.63  0.07
2015-04-13  18 14 16.87  16.74  0.06
2015-04-13  18 17 20.95  16.74  0.04
2015-04-13  18 20 25.30  16.76  0.06
2015-04-13  18 23 29.10  16.77  0.10
2015-04-13  18 26 33.15  16.90  0.08
2015-04-13  18 29 37.20  16.74  0.07
2015-04-13  18 32 41.25  16.71  0.05
2015-04-13  18 35 45.30  16.78  0.04
2015-04-13  18 38 49.36  16.77  0.03
2015-04-13  18 44 31.44  16.88  0.03
2015-04-13  18 47 35.48  16.81  0.03
2015-04-13  18 50 39.57  16.87  0.03
2015-04-13  18 53 43.66  16.92  0.03
2015-04-13  18 56 47.73  16.98  0.03
2015-04-13  18 59 51.90  17.02  0.03
2015-04-13  19 02 55.98  16.95  0.04
2015-04-13  19 06 00.64  16.94  0.04
2015-04-13  19 09 04.22  17.08  0.07
2015-04-13  19 12 08.35  17.05  0.06

The photometry is based on nearby USNO-B1.0  1618-0098185 (Xu et al., 
GCN 17693) assuming R=15.59.