Columbia University Astronomy and 
Astrophysics


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 http://www.astro.bio2.edu/grb/

This message may be cited."

Jonathan Kemp
jonathan@astro.bio2.edu
Robert Uglesich
rru@astro.columbia.edu
Nestor Mirabal
abulafia@astro.columbia.edu
Jules Halpern
jules@astro.columbia.edu
Columbia University Astronomy and Astrophysics and MDM Observatory


MDM Observatory