{
  "bibcode": "2009GCN..8773....1C",
  "body": "S. B. Cenko (UC Berkeley), A. Rau and M. Salvato (Caltech) report on\nbehalf of a larger collaboration:\n\nWe have imaged the field of GRB090102 (Mangano et al., GCN 8762) with the\nautomated Palomar 60-inch telescope beginning at 03:46 on 2 Jan 2008 UT (~\n50 min after the burst).  Observations were taken in the R, i', and g'\nfilters and continued throughout the night until sunrise roughly 10 hours\nlater.\n\nThe optical afterglow (Klotz et al., GCN 8761, Covino et al., GCN 8763) is\nwell detected in all three filters.  All three bands exhibit a relatively\nsmooth power-law decay with index ~ 0.9, consistent with the value\nreported by Afonso et al. (GCN 8771).  We report here the following subset\nof our R-band observations:\n\nTmid (s)   Texp (s)   Mag    Err\n--------------------------------------\n3190.2     120.0      19.75  0.13\n5266.2     120.0      20.02  0.06\n7704.3     120.0      20.41  0.07\n9973.9     120.0      20.56  0.07\n11911.5    120.0      20.78  0.08\n14068.6    120.0      21.01  0.09\n16144.7    120.0      21.09  0.09\n18522.6    600.0      21.23  0.06\n20631.5    600.0      21.42  0.06\n22756.7    600.0      21.58  0.07\n24832.6    600.0      21.86  0.08\n27994.7   1200.0      21.72  0.05\n32188.5   1200.0      22.02  0.06\n36411.3   1200.0      21.93  0.11\n\nPhotometric calibration was performed relative to the SDSS DR7, with\nphotometric transformations from Jordi, Grebel, & Ammons (A&A, 460, 2006).\n\nIn addition, we have obtained a single 1800 s spectrum of the afterglow\nwith the Double Beam Spectrograph mounted on the Palomar 200\" Hale\ntelescope at a mean epoch of Jan 2.22.  The spectrograph was configured to\nprovide wavelength coverage from the atmospheric cutoff to ~ 8000 A.  We\nconfirm the results of de Ugarte Postigo (GCN 8766), finding a single\nstrong absorption system at z = 1.546.  Given the lack of strong\nLy-alpha absorption, we place a slightly stricter limit on the host\nredshift of z < 1.9.",
  "circularId": 8773,
  "createdOn": 1230947708000,
  "email": "cenko@srl.caltech.edu",
  "subject": "GRB 090102: P60 Imaging and P200 Spectroscopy",
  "submitter": "S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>",
  "eventId": "GRB 090102"
}