{
  "bibcode": "2009GCN..9918....1H",
  "body": "E. A. Hoversten (PSU) and T. Sakamoto (NASA/UMBC) report on behalf of  \nthe\nSwift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 090915\n44647 s after the BAT trigger (Cummings & Markwardt, GCN Circ. 9912).\nA faint source is detected with 5.6-sigma confidence in the summed\nUVOT observations at the position RA, Dec (J2000) = 238.02016,15.48772\nwhich is equivalent to:\n\n      RA (J2000) = 15:52:04.84\n     Dec (J2000) = 15:29:15.8\n\nwith an estimated uncertainty of 0.8 arcsec (radius, 90% confidence).\nThis position is 0.2 arcsec from the UVOT-enhanced XRT position\n(Beardmore, et al. GCN Circ. 9914) and the two positions agree within\nthe error bars.  It is unclear at this point if the source is fading,\nbut follow-up Swift observations are being planned.\n\nThe observed magnitudes using the UVOT photometric system (Poole et\nal. 2008, MNRAS, 383, 627) for the initial exposures are:\n\nFilter   T_start(s)   T_stop(s)   Exp(s)          Mag\n=======================================================================\nwhite      45492       52117       1647     22.15 +/- 0.24 (4.7 sigma)\nv          46338       52837       1583     21.08 +/- 0.39 (2.8 sigma)\nu          44647       51275       1647     21.40 +/- 0.43 (2.5 sigma)\n\n\nThe values quoted above are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.05 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 9918,
  "createdOn": 1253138484000,
  "email": "hoversten@astro.psu.edu",
  "subject": "GRB 090915: Swift/UVOT detection of an optical afterglow candidate",
  "submitter": "Erik Hoversten at Swift/Penn State  <hoversten@astro.psu.edu>",
  "eventId": "GRB 090915"
}