{
  "bibcode": "2002GCN..1542....1G",
  "body": "J. Gorosabel (IAA-CSIC), J. Fynbo (Univ. of Aarhus), I. Burud (STScI),\nA. Fruchter (STScI), J. Hjorth (Univ. of Copenhagen), report for the\nlarger GOSH (GRB Optical Studies with HST) collaboration:\n\nWe have observed the position of the optical afterglow (GCN 1267) of\nGRB 020305 (GCN 1262) with HST/STIS. The GRB field was visited four\ntimes; on April 12.7-12.9 UT (Clear filter), April 14.1-14.4 UT\n(Long-Pass), June 16.4-16.5 UT (Clear filter), and June 16.6-16.8 UT\n(Long-Pass).\n\nSubtraction of the two epoch HST/STIS images taken for each filter\nreveals a fading point source. The centroids of the Long-Pass and\nClear filter residuals are consistent with the afterglow position\nindependently derived registering an afterglow NOT image (taken on\nMarch 16) on our HST/STIS frames.\n\nThe magnitudes of the afterglow (AB system) are: 24.693+/-0.008\n(Clear, April 12.7-12.9 UT), 24.452+/-0.013 (Long-Pass, April\n14.1-14.4 UT), 26.197+/-0.027 (Clear, June 16.4-16.5 UT) and\n25.951+/-0.047 (Long-Pass, June 16.6-16.8 UT). The decay indexes\nassociated to the Clear and Long-Pass filters are, respectively;\nAlpha_Clear = 1.40+/-0.03, Alpha_Long-Pass = 1.45+/-0.05. So, the\noptical decay is consistent with being achromatic.\n\nThe afterglow position is consistent with an extended (~1.2\"x0.5\")\nfaint galaxy which shows a complex morphology. A preliminary aperture\nphotometry (AB system, considering a 0.675\" aperture radius and the\ncorresponding aperture correction) of the whole host galaxy system\nyields 25.771+/-0.054 (Clear filter) and 25.464+/-0.087 (Long-Pass\nfilter), respectively.\n\nSeveral gifs of the HST/STIS images and the afterglow light curve can\nbe seen at:\n\nhttp://www.stsci.edu/~fruchter/GRB/020305/\n\nThe optical measurements reported to date (our HST/STIS data points\nand the ones given in the GCNs; 1264, 1265, 1267, 1270, 1271, 1275,\n1279, 1283) might suggest the presence of a break ~10 days after the\nburst.  However, a final confirmation would require a more careful\nanalysis.",
  "circularId": 1542,
  "createdOn": 1032190044000,
  "email": "burud@stsci.edu",
  "subject": "GRB 020305: HST/STIS observations",
  "submitter": "Ingunn Burud at Space Telescope Science Inst  <burud@stsci.edu>",
  "eventId": "GRB 020305"
}