{
  "bibcode": "2003GCN..2139....1L",
  "body": "D. Q. Lamb, M. Nysewander, D. Reichart, D. G. York, J. Barentine, R.\nMcMillan, J. Dembicky, and B. Ketzeback report on behalf of the ARC\nand UNC GRB teams of the FUN GRB collaboration:\n\nWe observed the 14 arcminute diameter HETE-2 WXM localization error\ncircle for GRB030324 (Donaghy et al., GCN 1954, 1955) in i* on the\nnight of March 24 UT, beginning 6.22 hours after the burst (Moran, GCN\n2037).  We also observed the WXM localization error circle in i* on the\nnight of April 5 UT, approximately 12 days after the burst.  On both\nnights, we took two 1200-second exposures centered at the origin of the\nWXM error circle and a mosaic of four overlapping 1200-second exposures\ncovering the entire WXM error circle.  The limiting magnitude of the\nfirst observation thus ranged from i* = 24.3 (3 sigma) at the center of\nthe WXM error circle to i* = 23.8 (3 sigma) at the edge of the mosaic.\nSimilarly, the limiting magnitude of the second observation ranged from\ni* = 24.0 (3 sigma) at the center of the WXM error circle to 23.5 (3\nsigma) at the edge of the mosaic.\n\nSubtraction of the two images, using the image subtraction routine\nISIS2 (Alard 2000), reveals a single candidate optical afterglow at\n\nRA = +13h 37m 04.418s,  Dec = -00d 15' 33.56\"  (J2000).\n\nThe candidate optical afterglow is i* = 23.4 +/- 0.2 (S/N = 4.3) in the\nfirst epoch image, using the calibration of Henden (GCN 1860), whereas\nno object is detected at the same location down to a limiting magnitude\nof i* = 23.9 (2 sigma) in the second epoch image.  The first and second\nepoch images, with the location of the candidate optical afterglow\ncircled, can be found at\n\nhttp://astro.uchicago.edu/candidate_optical_afterglow.jpg,\n\nand a sky map showing the HETE-2 WXM localization error circle and the\nlocation of the candidate optical afterglow can be found at\n\nhttp://astro.uchicago.edu/wxm_loc_and_candidate.gif.\n\nWe cannot rule out that the candidate is a variable star.  However, a\ntypical cataclysmic variable or an RR Lyrae variable would have to be\n~ 0.5 Mpc away and a typical Cepheid variable would have to be ~2 Mpc\naway to be as faint as i* = 23.4.  In either case, the object can not\nbe associated with the Milky Way galaxy, making the likelihood very\nsmall that the object that we have detected is a variable star.\n\nIf this object is indeed the optical afterglow of GRB030324, it would\nbe the faintest optical afterglow ever detected.\n\nAlard, C. 2000, A&AS, 114, 363",
  "circularId": 2139,
  "createdOn": 1050454850000,
  "email": "lamb@oddjob.uchicago.edu",
  "subject": "GRB030324: Candidate Optical Afterglow",
  "submitter": "Don Lamb at U.Chicago  <lamb@oddjob.uchicago.edu>",
  "eventId": "GRB 030324"
}