{
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>",
  "body": "J. Gorosabel (IAA-CSIC/STScI), A.  Levan (U. Leicester/STScI),\nA. Fruchter, J. Rhoads, J.M.  Castro Cerón (STScI), T. Tripp (Princeton)\nreport for a larger collaboration:\n\nWe have imaged  the optical candidate (GCN 1857) of  the INTEGRAL burst GRB\n030131 (GCN 1836, GCN 1838, GCN 1847) with the 4-m KPNO telescope (equipped\nwith  Mosaic,  FOV=36'x36').  The  observations  were  carried  out on  Feb\n1.526-1.542 UT 2003 (~29 hours after the GRB) with a total exposure time of\n4x500s and a seeing of 0.85\".\n\nWe find a marginal detection  (~3.5 sigma above the detection threshold) at\nRA(J2000)=13:28:22.27  DEC(J2000)=30:40:23.7.  The  astrometry is  based on\nthe  USNO  catalog and  shows  an internal  uncertainty  of  0.5\" for  each\ncoordinate. We have compared the offset of the object in our image from the\nnearest USNO  star with  that found by  D. Fox (personal  communication) in\ntheir   discovery  image.   These  offsets   agree  within   0.2\",  further\nstrengthening the association.\n\nPreliminary aperture photometry centered on the object yields B=25.4+/-0.3.\nOur photometric calibration is based on  11 USNO stars in the field.  Under\nthe  zero   point  obtained   the  star  located   at  RA(J200)=13:28:18.16\nDEC(J2000)=30:38:20.79 has B=18.18.\n\nA smoothed image of the field can be seen at:\nhttp://www.stsci.edu/~fruchter/GRB/030131/kpno/grb030131.kpno.gif\n\nWe thank D. Fox for providing valuable astrometric information.",
  "subject": "GRB 030131: marginal optical detection",
  "editedOn": 1731923358010,
  "bibcode": "2003GCN..1866....1G",
  "submitter": "Javier Gorosabel at LAEFF-INTA, Madrid  <jgu@laeff.esa.es>",
  "eventId": "GRB 030131",
  "email": "jgu@laeff.esa.es",
  "createdOn": 1045149933000,
  "format": "text/plain",
  "version": 2,
  "circularId": 1866
}