HST/STIS Images of GRB 991208

An image of the host of GRB 991208 taken on August 3, 2000, or about 8 months after outburst using the 50CCD (clear) mode of STIS. The green line shows the one-sigma error circle of the position of the GRB based on earlier ground-based observations. The field-of-view is approximately 2.5" on a side. North is up; East is to the left.

On this page the HST GRB Collaboration presents the Hubble Space Telescope image of GRB 991208.

We observed the field of GRB 991208 with the HST STIS CCD on August 3, 2000, or approximately 8 months after outburst. A total exposure times of 5210s was obtained in the (50CCD) clear aperture. At the position of the burst we find a very compact galaxy with a magnitude of V= 24.6 +/- 0.15, where a conservative error bar is given due to the strong color dependence of the filter. The full-width at half-maximum (FWHM) of the galaxy is measured as 0."095, only marginally larger than the intrinsic 0."08 of the STIS PSF. Thus the true intrinsic width of the core of the galaxy is significantly smaller than the measured value. However, curve-of-growth analysis also indicates that the object is indeed resolved.

Comparison of the HST image with ground-based images (Castrado-Tirado et al., A&A submitted, see also GCN 452) shows the position of the optical transient to be offset from the center of the host by less than the 0."1 error in the relative positions.

We believe the ellipticity and position angle reported for the host by Bloom et al. (GCN 764) is due to the presence of a fainter, small object located approximagely 1" to the SE of the host. It is not clear from the HST image whether these are two objects are randomly superimposed or whether they are indeed physically related.

A wider view of the field about the GRB and its host. North is up, East to the left. The field is about 40" on a side

The wider (50") field of the STIS CCD shows a rich association of spiral galaxies surrounding the position of the OT. While some of the spirals show grand designs or prominent bulges, and are up to 5" across, we cannot rule out the possibility that the host of the GRB (which is at a redshift of 0.7, Sokolov et al., GCN 475) is a member of this apparent group of galaxies.