GRB 981220
Optical observations of the error box of GRB 981220
The error box of GRB 981220 was observed with the Tautenburg Schmidt
telescope on Dec. 23/24.
For any optical transient at the position of the radio counterpart
of GRB 981220 (Galama et al. 1998, GCN
168; Frail et al. 1998, GCN
170) the following preliminary data point can be provided:
Dec. 23.717 UT, Gunn z >17 +/- 1 mag
(observations from 16:48 to 17:36 UT;
Fig. 1). A more accurate limit will be published here,
when photometric standards are available (presumably in January).
Observations have also been performed in the I-band
(Fig. 2), but do not reach the limiting magnitude reported by Vrba et
al. (1998, GCN 171).
Fig. 1: Gunn z-band image of the GRB 981220 error box taken with
the
Tautenburg Schmidt telescope equipped with a 2048 x 2048 CCD chip
(see
http://www.tls-tautenburg.de/schmidt/schmiccd.html). During the
observations the weather conditions were poor.
The image is an excerpt from a composite of 7 frames a' 2 minutes
exposure time. The position of the proposed radio counterpart
of GRB 981220 is indicated. No source is visible on our image.
Fig. 2: The same as Figure 1, but in the I-band.
No source is visible at the position of the proposed
radio counterpart of GRB 981220.
Any use of these data should be accompanied by a reference.
S. Klose, Thüringer Landessternwarte Tautenburg.
Last modified: December 31, 1998