{
  "bibcode": "2009GCN..9220....1H",
  "body": "A. Henden (AAVSO), J. Gross (SRO), B. Denny (DC-3),\nD. Terrell (SwRI), and W. Cooney (SRO) report:\n\nWe observed the field of GRB 090423 (Krimm et al., GCN 9198)\nusing the 35cm telescope of Sonoita Research Observatory\nwith an automated VOevent trigger for an R-band image\nsequence.  Images began at 07:58:09UT on 2009-04-23,\n170 seconds after the burst, under good conditions.\n\nThe afterglow candidate reported by Tanvir et al. (GCN 9202),\nLevan et al. (GCN 9206), Cucchiara et al. (GCN 9209),\nand shown by Olivares et al. (GCN 9215) to have both faded\nand to have a photo-z of 8.0, is not detected in our images.\nWe place 3-sigma constraints of\n\n200 seconds midpoint (1min image)  Rc < 18\n350 seconds midpoint (6min stack)  Rc < 20\n\nusing USNO-A red magnitudes.  The 19 total images, covering\nthe period 07:58:09 through 08:47:34, can be obtained from\nftp://ftp.aavso.org/public/sro/grb090423/",
  "circularId": 9220,
  "createdOn": 1240572975000,
  "email": "arne@aavso.org",
  "subject": "GRB 090423 limiting magnitudes",
  "submitter": "Arne A. Henden at AAVSO  <arne@aavso.org>",
  "eventId": "GRB 090423"
}