{
  "bibcode": "2007GCN..6508....1S",
  "body": "A. Stefanescu (1), A. Slowikowska (2)(3), G. Kanbach (1), S. Duscha (1),\nF. Schrey (1), H. Steinle (1), Z. Ioannou (4) of the OPTIMA-Burst Team\nreport the following:\n(1)=MPE, Garching, (2)=FORTH, Heraklion (3)=NCAC, Torun (4)=Univ. of Crete\n\n\"OPTIMA-Burst at the 1.3m Skinakas Observatory, of the University of\nCrete, Greece continued observations of the source reported on earlier\nin GCN  6492 (Stefanescu et al.), GCN 6501 (de Ugarte Postigo et al.)\nand GCN 6505 (Kann et al.)\n\nObservations started at 20:40 UT, 0.991 days after the burst. Taking the\nsame reference star as Kann et al. (GCN 6505), we detect the source with\nthe following magnitudes in our CCD frames:\n\nUT_mid     T_GRB [d]     t_exp    I mag\n20:42:38    0.99319      300      19.2\n20:57:26    1.00347      1200     17.0\n21:25:37    1.02304      300      20.7\n21:31:19    1.02700      300      21.2\n\nAfter this time, observations with the high-time-resolving main\ninstrument of OPTIMA-Burst commenced. The following describes a\nquick-look analysis of 83min of data, binned to a time-resolution of 10s.\n\nDuring it's low brightness periods, the source was not detected above\nthe noise in our photon counting detectors. However, we detected bright\nflares with pronounced substructure around the following times:\n\nUT      T_GRB [d]   duration (approx)    peak brightness (preliminary!)\n22:09   1.052       3.0 min              18.0 mag\n22:20   1.060       7.5 min              17.4 mag\n22:40   1.074       5.9 min              17.6 mag\n\nIn addition to these we detected 5 smaller flares at the 2.5 to 3 sigma\nlevel, each lasting for about 1 minute and having a peak brightness of\nabout 19.7 mag.\nFurther observations and further analysis is in progress.\n\nSince it seems strong variability is still in progress, we strongly\nrecommend further observations.\"\n\nThis message may be cited.",
  "circularId": 6508,
  "createdOn": 1181612838000,
  "email": "astefan@mpe.mpg.de",
  "subject": "GRB 070610: OPTIMA-Burst detection of continued strong flaring activity",
  "submitter": "Alexander Stefanescu at MPE  <astefan@mpe.mpg.de>",
  "eventId": "GRB 070610"
}