TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1408 SUBJECT: GRB 020531 optical observations with TAROT DATE: 02/06/05 11:01:05 GMT FROM: Jean-Luc Atteia at Lab d Astrophys.,OMP,Toulouse M. Boer, A. Klotz (CESR/CNRS) J.L. Atteia (LAT/OMP), C. Pollas (OCA) and H. Pinna (CEMES/CNRS) communicate: "We have observed the entire IPN error box for GRB020531 (Ricker et al, GCN 1399 and Hurley et al., GCN 1402) with the 25cm robotic TAROT telescope starting on May 31 01:55:12 UT (89 minutes after the burst and 50 seconds after the GCN notice) under clear sky conditions. 11 unfiltered 30s exposures were acquired between 01:55:12 and 02:06:30 UT and were coadded. Limit of magnitude is about R=18.0. The coadded image can be seen at URL : http://alain.klotz.free.fr/tarot/GRB020531 Two very faint sources were found that do not appear on the POSS I : source A : Ra(J2000.0) = 15h14min51s (+/- 1s) Dec(J2000.0) = -19d25'06" (+/- 2") R = 17.4 (+/- 0.4) This could be asteroid 2 of GCN #1405. source B: Ra(J2000.0) = 15h14min57s (+/- 1s) Dec(J2000.0) = -19d28'12" (+/- 2") R = 17.1 (+/- 0.4) Since we have no images taken at later times for comparison, it is difficult to conclude on the nature of sources A and B. We consider however that A is a likely asteroid. Source B, if real, is a possible candidate for the GRB counterpart. This message is citeable