{
  "bibcode": "1998GCN....87....1B",
  "body": "GRB 980519 Optical Observations\n\nJ. S. Bloom, S. G. Djorgovski, R. R. Gal, S. R. Kulkarni, and\nA. Kelly, on behalf of the Caltech GRB Collaboration, report:\n \n\"We obtained CCD images of the field of GRB 980519 using COSMIC on the\nPalomar Observatory 200-inch on UT May 20.  In particular, we imaged the\nGRB field for 500 s (Cousins R) and 600 s (Gunn i). We photometrically\ncalibrated our Gunn i-band and Cousins R-band images against standard\nLandolt 1992 (AJ 104, 340) stars (in SA 113).  We accounted for atmosphere\nextinction and included a color correction term in the fit to account for\nthe fact that Landolt reports magnitudes in a different R and I band\nsystem. Derived magnitudes of the following 10 secondary stars are thus in\nthe Londolt RI system (we kept the naming the convention of Jansen et al.\nGCN 78): \n \nObject   RA          DEC       I_landolt err    R_landolt err \n  A   23:22:20.0  +77:15:52   17.34 +/- 0.05   17.94 +/- 0.05\n  B         29.6         44   18.64 +/- 0.05   19.41 +/- 0.05\n  C         28.7         26   17.57 +/- 0.05   18.10 +/- 0.05\n  E         20.6         24   18.85 +/- 0.05   20.19 +/- 0.06\n  F         31.8         45   18.48 +/- 0.05   19.91 +/- 0.06\n  G         33.2  +77:14:59   17.25 +/- 0.05   19.02 +/- 0.05\n  H         20.7      14:55   18.13 +/- 0.05   19.44 +/- 0.05\n  I         09.2  +77:15:51   19.27 +/- 0.06   19.80 +/- 0.06\n  J         07.6  +77:16:01   19.05 +/- 0.06   20.08 +/- 0.06\n  L         35.0      16:15   18.57 +/- 0.05   19.21 +/- 0.05\n \nUncertainty in optimum aperture size for each star is the dominate source\nof statistical error. There is an overall zero-point systematic error (not\nincluded above) in each band which amounts to 0.150 mag (I) and 0.151 (R).\nThe approximate RA and DEC are measured in J2000 from the Digital Sky\nSurvey (DSS).\n \nWe note our derivation for A,B, and C magnitudes are highly discrepant\nfrom that of Jansen et al. GCN #78, but agree quite well with that of Kemp\nand Halpern (GCN #80) and Diercks et al. (GCN #82).  At the time of\nobservations we find the OT has magnitudes of May 20.43 UT, I_landolt =\n20.86 +/- 0.11; May 20.48 UT, R_landolt = 21.57 +/- 0.09.\n \nA finding chart with the secondary stars noted may be found at\nhttp://astro.caltech.edu/~jsb/grb980519.ps\n \nThis message may be cited.\"",
  "circularId": 87,
  "createdOn": 895798038000,
  "email": "jsb@astro.caltech.edu",
  "subject": "GRB 980519 Optical Observations",
  "submitter": "Josh Bloom at CIT  <jsb@astro.caltech.edu>",
  "eventId": "GRB 980519"
}