{
  "bibcode": "2015GCN.17700....1G",
  "body": "Kosmas Gazeas and Konstantinos Sapountzis (National Univ. of Athens) report:\n\nOn 13 April 2015, we observed the GRB candidate optical counterpart\nGRB150413A, as reported by Markwardt et al., GCN 17688 and Serino et al., GCN\n17691. The observations have been obtained with the 0.40 m f/8 robotic\ntelescope at the University of Athens in R-band (Bessell specifications). Data\ncollection has started on Apr., 13 (UT) 17:38:58 and finishing on Apr. 13 (UT)\n18:08:08 (mid-exposure time). A sum of 15 exposures of 120 sec each was\ncollected and all data were combined into a single image, although the optical\nafterglow was barley seen in each individual exposure. Photometry with a 3\npixel (approximately 4 arcsec) radius aperture yields an R magnitude\nestimation of R = 17.9 +- 0.3 mag for GRB150413A, as compared with respect to\nthe nearby USNO-B1.0 stars, which lie within a radius of 3-4 arcminutes around\nthe source. No absolute photometric calibration has been applied on these data.\n\nThis message is quotable in publications.",
  "circularId": 17700,
  "createdOn": 1429019836000,
  "email": "kgaze@phys.uoa.gr",
  "subject": "GRB150413A, optical observations",
  "submitter": "Kosmas Gazeas at U of Athens  <kgaze@phys.uoa.gr>",
  "eventId": "GRB 150413A"
}