{
  "bibcode": "2000GCN...585....1H",
  "body": "J. P. Halpern, N. Mirabal, & S. Lawrence (Columbia U.) report\non behalf of the MDM Observatory GRB follow-up team:\n\n\"We also obtained B-band images of GRB 000301C on March 4.52 UT\nusing the MDM 1.3m telescope.  By employing the Henden et al.\n(GCN #583) photometry of the comparison stars A and D of \nGarnavich et al. (GCN #573), we measure B = 21.41 +/- 0.04,\nand we determine that B-R = 0.77 +/- 0.06 at this time.\nCorrecting for the Schlegel et al. (1998) Galactic extinction at \nthis location, A_B = 0.23 and A_R = 0.14, we find an intrinsic\nB-R = 0.68 +/- 0.06, which corresponds to a spectral slope\nbeta = -0.87 +/- 0.14.  This value, together with the temporal\ndecay slope alpha = -1.07 +/- 0.09 (GCN #581,582), is consistent\nwithin the errors with the canonical alpha = (3/2)beta behavior\nof a spherical afterglow in an uniformly dense medium.\nLittle intrinsic extinction is required to explain the color.\n\nThe B-band image is posted at http://www.astro.bio2.edu/grb/\n\nThis message may be cited.\"\n\n\n[GCN OPS NOTE (05Mar00 04:25 UT):  This archived copy has the typo\n\"B-R = 0.68 +/- 0.6,\" fixed to correctly read \"B-R = 0.68 +/- 0.06,\".]",
  "circularId": 585,
  "createdOn": 952229523000,
  "email": "jules@astro.columbia.edu",
  "subject": "GRB 000301C, Optical Color",
  "submitter": "Jules Halpern at Columbia U.  <jules@astro.columbia.edu>",
  "eventId": "GRB 000301C"
}