GCN Circular 2539

H. Pedersen, Copenhagen University Observatory, on behalf of the GRACE team,
reports:

"The Descartes Optical Telescope, consisting of a parallactically mounted
F=24 mm, f/2.8 lens and a 1472 x 2184 pixel CCD (pixel size: 6.8 micron),
is currently undergoing tests at ESO, La Silla, during which serendipitous
observations of the GRB040228 error box (Nakagawa et al. GCN 2536
Not found
 
 
, see
also Hurley et al. GCN 2538
Not found
 
 
) were done on several nights starting February
22 d 1 h UTC. No filter was used, and all exposures lasted 30 s followed
by 30 s read-out. During each of the first five nights integrations
spanning several hours were obtained under mostly good conditions.
No observations were attempted on February 27. On the night of trigger 
no. H3066 a partial clearing started more than an hour later. A set of 24 
exposures obtained in the time interval from 75 to 99 minutes after the 
trigger are of fairly uniform quality and have been co-added. No candidate 
afterglow is seen in or near the error box to m(r) = 10.2, based on USNO 
photometry of U0825_07125568, a star near the centre of the error box. 
Observations taken in the time interval from 46 to 45 hours prior to the 
GRB likewise give no indication of 'preglow', to a limit of m(r) = 10.5.

All values are preliminary and should not be published before further
confirmation."