GCN Circular 1614

A. Klotz and M. Boer, CESR/CNRS (Centre d'Etude Spatiale des
Rayonnements, Toulouse, France) report measurements obtained by members
of the AUDE network (Association des Utilisateurs de Detecteurs
Electroniques). As images were not filtered, the authors computed the
magnitudes in reference to the R band system which is expected to be the
most reliable for unfiltered CCD images. 

Magnitudes of GRB 021004 : 

2002 oct. 5, 01h04 UT : R=18.8 by R. Poncy (1) 
2002 oct. 5, 22h30 UT : R=19.70 +/- 0.1 (referenced to USNO) by P.
Martinez & P.M. Berger (2) 

(1) Diam. 254 mm 
    Integ. 30 x 60 sec. 
    Location : Le Cres, France (IAU station 177)

(2) Diam. 820 mm 
    Integ. 23 x 60 sec. 
    Location : ADAGIO observatory, Belesta, France (IAU station A05) 

Note also a detection of the optical counterpart at 2002 oct. 5, 21h30
UT, by A. Klotz using a telescope of only 200 mm diameter. Low signal to
noise did not allow to measure the magnitude, but the limiting magnitude
of the image is about 20.5 (addition of 60 frames of 60 sec). This
demonstrates that small telescopes can detect the afterglow of a GRB
even 1.4 days after the GRB event.

Images are available at the following URL:
http://www.cesr.fr/~klotz/grb021004/aude.html

These data are coherent with already reported magnitude in other
circulars, and fill some gaps in the light curve.