{
  "bibcode": "2005GCN..3090....1T",
  "body": "V. Tilvi, L. Shamir, W. Pereira, D. Cordell, V. Muzzin, M. Merlo & \nR. Nemiroff (Michigan Tech)  report on behalf of the greater Night Sky \nLive Collaboration\n\nThe NightSkyLive.net CONCAM2 operating on Mauna Kea has recorded\nfisheye images including the location of GRB050309, being sensitive\nto the GRB location starting about 28 minutes before Swift trigger.  No bright\noptical transient was found consistent with the GRB location on any frame.  \nA 170-second exposure including the GRB region was in progress during \nthe trigger time and prompt optical emission can be limited as being more \nfaint than unfiltered optical CCD magnitude 3.8.  The MK CONCAM image \nat the time of trigger is here: \nhttp://nightskylive.net/mk/mk050309/mk050309ut104239a.jpg\n\nA table of observation times and approximate limiting magnitudes follows:\n\nDate            From (UT)    To (UT)       m_limit     Remarks\n2005-03-09  10:15:03       10:17:53     2.5           28 minutes before trigger\n2005-03-09  10:19:00       10:21:50     2.8           Before trigger\n2005-03-09  10:22:56       10:24:46     3.0           Before trigger\n2005-03-09  10:26:53       10:28:43     3.1           Before trigger\n2005-03-09  10:30:47       10:32:37     3.2           Before trigger\n2005-03-09  10:38:41       10:40:31     3.5           Before trigger\n2005-03-09  10:42:39       10:44:29     3.8           During!  Swift trigger: 10:43:21 UT\n2005-03-09  10:46:34       10:48:24     4.0           After trigger\n2005-03-09  10:50:32       10:52:22     4.0           After trigger\n2005-03-09  10:54:29       10:56:19     4.0           After trigger",
  "circularId": 3090,
  "createdOn": 1110658898000,
  "email": "nemiroff@mtu.edu",
  "subject": "GRB050309: CONCAM pre-trigger and trigger coincident optical",
  "submitter": "Robert Nemiroff at Michigan Tech.  <nemiroff@mtu.edu>",
  "eventId": "GRB 050309"
}