[vsnet-grb-info 515] GRB 021004: optical observations

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1654
SUBJECT: GRB 021004: optical observations
DATE:    02/10/25 13:44:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E.A.Barsukova (SAO), V.P.Goranskij (Sternberg Institute),
G.M.Beskin (SAO), V.L.Plokhotnichenko (SAO), A.S.Pozanenko  (IKI).

We have observed GRB 021004 on October 8, 2002 four days after the burst,
using 1-m Zeiss telescope and CCD with Rc filter under good seeing
conditions. Five 20-min exposures were taken in the time interval between
20:49:56 and 22:35:14 UT. Object is seen near the frame limit in each of
these frames. The photometry and astrometry of images were performed. The
sum of all frames (total exposure is 100 minutes) gives the magnitude of OT

Rc = 20.9 +/- 0.3

relative to comparison star by Fox (GCN 1564) with Henden's (GCN 1630)
calibration magnitude of 15.538 Rc.

The astrometry of all the frames taken both on October, 4 (GCN 1606) and
October, 8 shows that the image of the object is displaced by 0".5 West on
October, 8 relative to that on October, 4. The accuracy of the astrometry is
0".2. One may suggest that the displacement results from influence of a host
galaxy.

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