GCN Circular 397
Subject
GRB 990806, Optical Observations
Date
1999-08-08T23:59:42Z (25 years ago)
From
Jonathan Kemp at Biosphere 2 Ctr/Columbia U <jonathan@astro.bio2.edu>
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."