{
  "bibcode": "2001GCN..1125....1L",
  "body": "D. Q. Lamb, B. C. Lee, D. L. Tucker, D. E. Vanden Berk, P. Newman,\nJ. Krzesinski and A. N. Kleinman, on behalf of the SDSS GRB team,\nreport:\n\nWe observed the HETE error box for GRB 010921 (GCN 1096) using the SDSS\n0.5-m \"Photometic Telescope\" at APO under partly cloudy conditions on\n2001 September 22 beginning at UT 02:36 and on 2001 September 23\nbeginning at UT 05:23.  Images of the entire improved HETE error box\n(GCN 1097) were acquired in the SDSS u, g , r, i, and z filters on both\nnights.\n\nThe optical transient (OT) reported by Price et al. (GCN 1107; see also\nGCN 1108 and GCN 1113) was r'=19.6 +/-0.3 on September 22 and\nsignificantly fainter on September 23 (we place an upper limit on r' of\nroughly 20.0).  The OT is marginally visible (at perhaps the 1 to 2\nsigma level) in g and i on September 22 and in g and r on September 23.\nWe place upper limits on u, g, i, and z of roughly 20.5, 18.5, 17.5,\nand 15.0 on September 22, with the completeness limit of the i and z\nfilters heavily degraded by clouds, and 19.5, 20.0, 18.5, and 18.5 on\nSeptember 23, again impacted by clouds.  These upper limits are\nconsistent with a ~ nu^{-2.3} spectrum over u, g, r, i, and z (GCN\n1107).  Images can be found at http://sdss.fnal.gov:8000/grb/.\n\nThis message is quotable.",
  "circularId": 1125,
  "createdOn": 1004638014000,
  "email": "lamb@oddjob.uchicago.edu",
  "subject": "GRB010921, optical observations",
  "submitter": "Don Lamb at U.Chicago  <lamb@oddjob.uchicago.edu>",
  "eventId": "GRB 010921"
}