{
  "bibcode": "2021GCN.29638....1S",
  "body": "P.S. Smith, Z. Chen, P. Milne, D. Sand, N. Smith, D. Stark, and G.G.\nWilliams (Steward Observatory, University of Arizona)\n\nObservations of the optical counterpart of GRB 210306A using the B&C\nSpectrograph and the University of Arizona, Steward Observatory 2.3m Bok\nTelescope located on Kitt Peak, Arizona began at 07:07:50 on March 6, 2021\nUTC and ended at 08:23:13 UT.  Three, 1500 s exposures were obtained\ncentered at 3.384, 3.859, and 4.279 hours after the Swift/BAT detection of\nthe burst (D�Elia et al.; GCN Circ. 29597).  Comparison with a\nspectrophotometric standard star observed immediately after the optical\nafterglow observations suggest that the counterpart was at an approximate\nV magnitude of 19.18, 19.33, and 19.46 for the three exposures,\nrespectively. All spectra show a featureless blue continuum from 350-760nm.\nA fit to the least noisy portion (450-750nm) of the scaled median spectrum\nfrom the three observations yields a slope of about -1.25 in log(F_lambda)\nvs. log(wavelength). No corrections for Galactic extinction and reddening\nhave been made.",
  "circularId": 29638,
  "createdOn": 1615314939000,
  "email": "psmith@as.arizona.edu",
  "subject": "GRB 210306A: Early Spectroscopy of the Optical Afterglow",
  "submitter": "Paul S. Smith at Steward Observatory  <psmith@as.arizona.edu>",
  "eventId": "GRB 210306A"
}