TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4596 SUBJECT: GRB 060124: ART optical limits during the burst DATE: 06/01/25 12:45:04 GMT FROM: Ken ichi Torii at RIKEN K. Torii (Osaka U.) reports on behalf of the ART collaboration: The error region of GRB 060124 (Holland et al., GCN 4570) was imaged with the two Automated Response Telescopes in Toyonaka, Osaka, under cloudy condition. The observations started before the arrivals of the three major gamma-ray pulses (Fenimore et al. GCN 4586). The older 14 inch telescope, ART-3a, imaged the field starting at 15:55:59 UT (67 s after the BAT trigger). 60 s integrations were repeated through each of the four linear polarizers (effective in 400-700 nm) in the filter wheel. The relative position angles between the filters are 45 degrees. We did not detect any optical flare at the position of the optical afterglow (Kann, GCN 4577; Kann, Henze, & Laux, GCN 4579), in the first two frames, before the field was completely clouded after ~15:58 UT (3.5 minutes after the trigger). A new 0.35m f/6 telescope, ART-3b, observed the field starting at 15:56:11 UT (79 s after the BAT trigger). Repeated 60 s integrations were made through the standard Ic filter. We did not detect any optical flare either, in the first two frames, and the later frames were clouded. The following 3-sigma limits are derived for an optical transient during the gamma-ray burst. The ART-3a and ART-3b magnitudes were calculated with reference to USNO-B1.0 R2 and I magnitudes, respectively. ----------------------------- StartUT Limits ============================= 15:55:59 >14.6R 15:56:11 >14.9I =============================