{
  "bibcode": "2002GCN..1429....1G",
  "body": "J. Gorosabel (IAA-CSIC Granada), J. Hjorth, B. L. Jensen, H. Pedersen,\nP. Jakobsson (Univ. of Copenhagen), J. Fynbo (IFA Aarhus), \nM. I. Andersen (Univ. of Oulu), report:\n\n We have carried out optical observations of the GRB 020604 IPN error box\n (GCN 1417) with the 1.54 Danish Telescope (+DFOSC) on three epochs;\n June 8, 9 and 10. The observations were done following a mosaic as\n detailed below:\n\n =====================================================================\n  Date UT         Filter   R.A.       Dec    Seeing Time since ExpTime \n  June 2002              (J2000)    (J2000)   (\")   GRB (days)   (s)   \n ---------------------------------------------------------------------\n  8.07874--8.11230   R  16:27:42.0 -29:48:43  1.2     3.50      4x600   \n  8.11259--8.14516   R  16:28:39.8 -29:43:44  1.2     3.54      4x600   \n  8.14642--8.16250   R  16:29:19.8 -29:39:44  1.1     3.56      2x600   \n  8.16629--8.21525   R  16:28:01.7 -29:48:22  1.2     3.60      6x600** \n  8.21554--8.23159   R  16:27:18.4 -29:55:38  1.1     3.63      2x600   \n  8.23186--8.23973   R  16:26:45.4 -29:52:52  1.0     3.64        600   \n  8.27211--8.31829   I  16:28:01.7 -29:48:22  1.1     3.70      6x500** \n  8.32037--8.34111   I  16:28:39.8 -29:43:44  1.4     3.74      3x500   \n  8.34216--8.36298   I  16:27:18.4 -29:55:38  1.8     3.76      3x500   \n ---------------------------------------------------------------------\n  9.12684--9.21986   R  16:28:01.7 -29:48:22  1.1     4.58     10x600** \n  9.22098--9.26678   R  16:28:39.8 -29:43:44  1.2     4.65      4x600   \n  9.27909--9.30354   R  16:27:18.4 -29:55:38  1.3     4.70      4x600   \n  9.30392--9.31180   R  16:26:45.4 -29:52:52  1.3     4.72        600   \n  9.31378--9.32165   R  16:27:42.0 -29:48:43  1.2     4.72        600   \n  9.32416--9.33202   R  16:29:19.8 -29:39:44  1.5     4.74        600   \n ---------------------------------------------------------------------\n 10.16572--10.24745  R  16:28:01.7 -29:48:22  1.0     5.61      6x900** \n 10.26606--10.30406  R  16:28:39.8 -29:43:44  1.3     5.69      3x900   \n 10.30569--10.34051  R  16:27:18.4 -29:55:38  1.5     5.73      4x600   \n ---------------------------------------------------------------------\n ** Central part\t\t\t\t   \t              \n =====================================================================\n\n The first and the second epoch observations cover the whole error box, \n whereas the third epoch images contain ~80% of it.\n\n A gif of the performed mosaic can be seen at:\n http://www.dsri.dk/~jgu/grb020604/FCs/grb020604.R.8-9.06.02.1.54D.gif\n\n The limiting magnitude depends on the error box position. For the central\n pointing (covering ~50% of the error box), the R-band limiting magnitude \n (3 sigma) at the three epochs are R=24.5, R=24.7 and R=24.9. For the rest\n of the error box the limiting magnitude are R=23.8, R=23.6 and R=24.0,\n respectively. In the I-band the limiting magnitude ranges from I=22.5 to\n I=23.4.\n\n Albeit the severe Galactic extinction (AR=1.18, AI=0.86 mag), many\n extragalactic objects are detected in our images. Among the unsaturated\n objects, marginal variability (< 0.2 mag) is detected for 12 of them. \n None of these objects shows flux variability consistent with a decay, as\n expected for an optical afterglow 3.5-5.7 days after the gamma ray event.",
  "circularId": 1429,
  "createdOn": 1023993501000,
  "email": "jgu@laeff.esa.es",
  "subject": "GRB 020604, optical observations",
  "submitter": "Javier Gorosabel at LAEFF-INTA, Madrid  <jgu@laeff.esa.es>",
  "eventId": "GRB 020604"
}