TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1351 SUBJECT: GRB020406(?), optical observations DATE: 02/04/10 21:40:53 GMT FROM: Arne A. Henden at USNO/USRA D. Durig and A. McDermott (Cordell-Lorenz) and B. Gary (Santa Barbara) report on behalf of the International AAVSO GRB Network: We observed the RXTE/ASM revised error box for the possible GRB 020406 (Smith et al. GCN 1332, 1341) with the Cordell-Lorenz Observatory 30cm telescope (ST-9E/AO-7 CCD) and Gary 25cm telescope (ST-8E). coverage lim mag UTD entire box CR=17 020407.356 western half CR=20 020407.356 central 80% Rc=17.5 020407.500 remaining 20% Rc=17.1 020407.500 entire box CR=20 020410 Where CR = unfiltered, using R-band zeropoint, and Rc = taken with a standard Cousins R filter. No new objects were found in the revised error box to the limiting magnitudes listed above. In addition, the entire original box was covered to CR=17 on 020407.4 with no new source detected. The candidate mentioned in Durig and McDermott (GCN 1338) was reobserved on 020410 and has shown no fading over the past 72 hours; it can be eliminated as a possible afterglow candidate.