{
  "bibcode": "2015GCN.18270....1M",
  "body": "L. M. McCauley (PSU) and C. Pagani (U Leicester)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 150910A\n154 s after the BAT trigger (Pagani et al., GCN Circ. 18264).\nA source consistent with the XRT position\n(Pagani et al. GCN Circ. 18264)\nis detected in the initial UVOT exposures.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  00:22:40.11 =   5.66713 (deg.)\n    Dec (J2000) = +33:28:21.9  =  33.47274 (deg.)\nwith an estimated uncertainty of 0.58 arc sec. (radius, 90% confidence).\n\nPreliminary detections using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) show a very rapid and steep\nrise in the luminosity of the afterglow over the first 1 ks of observation.\nFurther investigation is strongly encouraged.\nPreliminary detections for the early exposures are:\n\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite                 153            303         147         19.90\nwhite                 156            303         144         19.93\nwhite                 592            612          19         17.09\nwhite                 765            785          19         16.67\nwhite                 866           1016         147         16.30\nv                     135            145           9        >17.23\nv                     642            662          19         16.64\nv                     815            835          19         16.91\nv                    1046           1066          19         16.11\nb                     568            588          19         17.56\nb                     741            761          19         16.87\nu                     312            561         245         18.03\nu                     312            561         245         18.02\nu                     716            736          19         16.14\nuvw1                  692            712          19         16.76\nuvw2                 1022           1041          19        >17.97\n\nThe magnitudes in the table 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": 18270,
  "createdOn": 1441901509000,
  "email": "marissamc@swift.psu.edu",
  "subject": "GRB 150910A: Swift/UVOT Detection of a Brightening Afterglow",
  "submitter": "Marissa McCaule at PSU  <marissamc@swift.psu.edu>",
  "eventId": "GRB 150910A"
}