{
  "bibcode": "2009GCN..8993....1N",
  "body": "Markku Nissinen (Varkaus, Finland) reports to the AAVSO High Energy Network\nthe following optical observations of GRB 090313 (Chornock, Li, and\nFilippenko, GCN #8979; Mao et al., GCN #8980):\n\nMarkku Nissinen reports the detection of the optical counterpart of GRB\n090313 using the GRAS-04 telescope sited in Mayhill, NM, USA.  A number\nof unfiltered observations with varying exposure times were made using\nthe 0.25-meter telescope with an SBIG ST8XE CCD camera; observations began\napproximately 1 hour post burst.  The afterglow was detected in all frames\nwith astrometric positions matching those given by Chornock, Li, and\nFilippenko (GCN #8979) and Updike et al (GCN #8983) to within positional\nerrors.\n\nThe following unfiltered magnitudes were obtained from the observations\nusing USNO-A2.0 U0975_07146255 (R magnitude = 15.9) as the comparison:\n\n   obs midpoint(UT)   exptime  mag(CR)   mag.err\n\n2009-03-13 10:14:41  360 sec  16.5  +/-  0.3  (3 x 120 sec)\n2009-03-13 10:27:59  300 sec  16.7  +/-  0.3\n2009-03-13 10:39:53  600 sec  16.9  +/-  0.3\n\nA FITS image of the 300-second observation is available at the following URL:\nftp://ftp.aavso.org/grb/MarkkuNissinen_GRB090313_2454904.28608_.fits\n\nThe AAVSO thanks the Curry Foundation for their continued support of the\nAAVSO International High Energy Network.",
  "circularId": 8993,
  "createdOn": 1236995232000,
  "email": "matthewt@aavso.org",
  "subject": "GRB 090313 optical observations",
  "submitter": "AAVSO GRB Network at AAVSO  <matthewt@aavso.org>",
  "eventId": "GRB 090313"
}