{
  "bibcode": "2015GCN.17751....1M",
  "body": "F. E. Marshall (NASA/GSFC) and A. P. Beardmore (U. Leicester)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 150424A\n99 s after the BAT trigger (Beardmore et al., GCN Circ. 17743).\nA source consistent with the position\nof the suggested optical afterglow\n(Perley and McConnell, GCN Circ. 17745)\nis detected in the initial UVOT exposures.\nThe source remains nearly constant in 6 exposures with the \nwhite filter starting 99 s after the trigger and ending\n6786 s after the trigger. The magnitude is approximately that\nreported by Perley and McConnell. This may be a detection\nof the host galaxy.\n\nThe preliminary UVOT position is:\n   RA  (J2000) =  10:09:13.38 = 152.30577 (deg.)\n   Dec (J2000) = -26:37:51.1  = -26.63086 (deg.)\nwith an estimated uncertainty of 0.6 arcsec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limit using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite               99         6786          609         20.38 +/- 0.07\nv                  641         5881          432        >19.8\nb                  567         6701          432         20.71 +/- 0.21\nu                  311         5061          462         20.13 +/- 0.20\nw1                 690         6291          413         20.00 +/- 0.24\nm2                4452         6086          393         19.91 +/- 0.29\nw2                 616         5677          216         20.03 +/- 0.31\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.06 in the direction of the burst\n(Schlegel et al. 1998).\n\n[GCN OPS NOTE(24apr15): Per author's request the missing minus sign\non the hh:mm:ss format of the value was added; the decimal-deg value was correct.]",
  "circularId": 17751,
  "createdOn": 1429887798000,
  "email": "femarsha@khamseen.gsfc.nasa.gov",
  "subject": "GRB 150424A: Swift/UVOT Observations",
  "submitter": "Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>",
  "eventId": "GRB 150424A"
}