TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  767
SUBJECT: GRB000801, VLT-Antu R-band observations
DATE:    00/08/11 12:20:31 GMT
FROM:    Nicola Masetti at ITeSRE,CNR,Bologna  <masetti@tesre.bo.cnr.it>

E. Palazzi, N. Masetti (ITESRE, CNR, Bologna), E. Pian (OATs, Trieste), 
E. Rol, E.P.J. van den Heuvel (Univ. of Amsterdam), J.P.U. Fynbo (Univ. 
of Copenhagen), A.J. Castro-Tirado (LAEFF, IAA), J. Greiner (AIP), 
C. Kouveliotou (USRA), C. Lidman (ESO), on behalf of a larger
collaboration, report:


"We obtained optical R-band images on three different positions at two
different epochs each in order to mosaic the IPN error box (Cline et al.,
GCN #763) of GRB000801 (Hurley et al., GCN #761, #762) between 2000 Aug
2.972 and Aug 7.976 UT with Antu (VLT-UT1) plus FORS1 at ESO - Paranal
(Chile). This mosaic covered 98% of the IPN error box (see the page on
GRB000801 at http://www.aip.de/~jcg/grb.html).


The following table contains the main information on each pointing of the
mosaic:

   pointing    mid-exp date   hours    exptime   seeing  limiting R mag
                   (UT)     after GRB   (sec)     (")      (3-sigma)
  ----------------------------------------------------------------------
  central       Aug 2.972      42.4      360      1.0         24.4
  southeastern  Aug 2.981      42.6      360      1.0         24.5
  northwestern  Aug 2.991      42.8      360      1.0         24.5
  central       Aug 3.986      66.7      240      0.8         24.4
  southeastern  Aug 3.992      66.9      190      0.8         24.0
  northwestern  Aug 7.976     162.5      600      0.9         24.7


Photometric calibration was performed using standard stars in the Landolt
field PG1657+078 (Landolt 1992, AJ 104, 340). The comparison between pairs
of images does not reveal any object with significant brightness variation
down to a 3-sigma limiting R magnitudes 24.4, 24.0 and 24.5 over the
central, southeastern and northwestern parts of the GRB error box,
respectively.".


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