GCN Circular 428
R. Uglesich, J. Halpern (Columbia U.), & J. Thorstensen (Dartmouth) report: "In addition to the MDM observations reported in GCN #423, we reobserved the entire 6' radius error circle of the BeppoSAX WFC (Gandolfi, GCN #417) with the 1.3m because it is not known if either of the reported NFI X-ray sources (in 't Zand et al. GCN #427) is associated with the GRB. The 1.3m observations were centered on Oct. 15.45 UT and Oct. 16.48 UT, and reach a 5-sigma limiting magnitude of R = 22.6 on the first night, and R = 22.8 on the second night. We used a non-standard, broad R filter which nevertheless calibrates very well with Landolt (1992) standards that we obtained. We find R = 17.64 for the star mentioned in GCN #423, which is consistent with the USNO calibration (R = 17.61 +/- 0.02). Although we have not yet carried out a detailed photometric analysis of the entire WFC circle, careful visual inspection reveals no variable object to a limit of approximately R > 22.6 at 13 hours after the burst. The images from the MDM 2.4 reported in GCN #423 cover the error circles of both of the NFI sources, and our previously reported limit of R > 23.1 at 11.2 hours still applies. We also note that Galactic extinction in this direction is estimated to be E(B-V) = 0.202 from IRAS dust maps (Schlegel et al. 1998), so A_R is a modest 0.54 magnitudes. A CCD image of the field of the NFI sources is posted at http://www.astro.bio2.edu/grb/ This message may be cited."