GCN Circular 3015
G.Bourban, C.Vuissoz, F.Carrier, G.Burki and L.Weber (Geneva Observatory, Switzerland) report: We have carried out optical observations of the 12'x 12' field centered on the error circle of HETE trigger #11568 (~93% of the whole uncertainty area provided by HETE/WXM) using the C2 CCD Camera mounted on the Swiss 1.2-meter telescope located at the ESO La Silla Observatory (Chile). The observations began on 2005 Feb 09 at 03:57:30 UT (129s after the alert sent by HETE team, i.e 2.43 h after the burst) and four different sets of measurements were performed during the night at 03:57 UT, 04:57 UT, 06:07 UT and 07:12 UT (1.5 < Fz < 2.7). A total of 3 R-filtered images with exposure time of 180s as well as 8 R-filtered 480s exposures were obtained under good wheather conditions. The division of these images as well as their comparison with the USNO-A2 catalog did not reveal any new or fainting source inside the field of view of the C2 camera, down to a limiting magnitude of R < 20.5. This message may be cited.