|GCN Circular #397: GRB 990806 Optical Observations|
J. Kemp, R. Uglesich, N. Mirabal, J. Halpern (Columbia), D. Harkavy (Harvard), E. Costa (IAS/CNR, Rome) report on behalf of the BeppoSAX team and the MDM Observatory GRB follow-up team's southern extension: "We reobserved the BeppoSAX WFC error circle of GRB 990806 (Piro GCN 392; Gandolfi GCN 393) in the R band using the CTIO 0.9m. A total exposure of 180 minutes was obtained starting on Aug. 8.31 UT. Seeing was 1".3. The 5-sigma limiting magnitude of the summed R-band image is 23.8. No variable object is detected in comparison with images obtained on the previous night (GCN 395). Using a sensitive difference imaging technique, we set a limit of R > 23.3 on Aug. 7.3 for any fading optical transient in the WFC error circle. This is consistent with the R-band limit of 23.5 set by the ESO 2.2m (Greiner et al. GCN 396). The new image is posted at http://www.astro.bio2.edu/grb/ This message may be cited."
|Columbia University Astronomy and Astrophysics and MDM Observatory|