Columbia University Astronomy and 

MDM Observatory GRB Team

GRB 990806: R-band CCD image, CTIO 0.9m, Aug. 8
180 minutes exposure, 1' radius NFI circle (GCN #401)
R-band image
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

This message may be cited."

Jonathan Kemp
Robert Uglesich
Nestor Mirabal
Jules Halpern
Columbia University Astronomy and Astrophysics and MDM Observatory

MDM Observatory