{
  "bibcode": "2003GCN..2082....1H",
  "body": "A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:\n\nWe have acquired additional UBVRcIc all-sky photometry for\nan 11x11 arcmin field centered at the coordinates\nof the optical transient (Peterson and Price, GCN 1985)\nfor the HETE burst GRB030329 (GCN 1997) with the USNOFS\n1.0-m telescope.  Stars brighter than V=13.5 are saturated and\nshould be used with care.  We have replaced the photometric data\nwith the same file name on our anonymous ftp site:\nftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb030329.dat\nThe astrometry in this file is based on linear plate solutions\nwith respect to UCAC2.  The external errors are less than 100mas.\nThe second night of photometry shows that the first night was\nacceptable, and that the external error is now about 0.02mag.\n     For those of you not used to doing high-accuracy\nphotometry, here are some comments.  Star \"A\" of Martini et al.\n(GCN2012) has been used with either its USNO-A magnitude of\nR=16.2, or the more correct Rc=16.06, in various GCNs.  This\nwill lead to confusion when trying to fit light curves.  However,\nthe larger problem is that this star is red (B-V=1.19,\nV-I=1.41), while the afterglow itself is blue (B-V=0.35,\nV-I=0.77).  Using this star as a comparison and following\nit over a large airmass will generally lead to fading/brightening\ntrends that correlate with airmass due to differential\ncolor corrections unless proper transformations are made.\nThis will be even more apparent when comparing Johnson R,I\nmagnitudes with the Cousins Rc,Ic values reported here.\nYou should also be aware of the nice eclipsing binary discovered\nby Fitzgerald and Orosz (GCN 2056), as this is the brightest\nobject near the afterglow and might be used when performing\nearly-time photometry or U-band photometry.  Finally, as\nseveral observers have mentioned, there are not many real stars\nin this field; most of the objects are extended.  You should\nlook at the good-seeing finding charts that have been posted\nbefore selecting comparison stars, especially as the afterglow\nfades.  Many extended objects are near-enough to stellar that\nthey will appear in our field photometry file.\n\nWe intend to extend this file with more nights and to fainter\nmagnitudes as the afterglow fades.  As always, you should check\nthe dates on the .dat file prior to final publication to get the\nlatest photometry.",
  "circularId": 2082,
  "createdOn": 1049387978000,
  "email": "aah@nofs.navy.mil",
  "subject": "GRB030329, new UBVRcIc field photometry",
  "submitter": "Arne A. Henden at USNO/USRA  <aah@nofs.navy.mil>",
  "eventId": "GRB 030329"
}