TITLE:   GCN CIRCULAR
NUMBER:  17705
SUBJECT: GRB 150413A
DATE:    15/04/15 02:02:25 GMT
FROM:    Matteo M. M. Santangelo at OAC  <oac@irf.lu.it>

M.M.M. Santangelo and S. Gambogi report:

We performed R and I bands CCD imagery of the field of GRB 150413A
with the 0.60-meter f/9.83 Cassegrain reflector of Capannori Astronomical Observatory, Italy.
Weather conditions were good, the seeing was fairly good, and the night-sky brightness
at zenith was 20.15 mag/arcsec2 in V band.
We clearly detected the optical counterpart of GRB 150413A.
Magnitudes in Johnson/Cousins R and I bands derived by means of Mira professional 7 UE software are as follows:

Date           UT         Exposure   Band   mag ± sigma
2015-04-13   20:56:22   300 s	   I	  17.2 ± 0.2
2015-04-13   21:04:43   180 s	   R	  17.6 ± 0.1
2015-04-13   21:11:02   360 s	   I	  17.29 ± 0.04

Photometry is based on the nearby GSC 4397:1311 star, with magnitudes of comparison star from PPMXL.
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