GCN Circular 726

Stephen Holland, Johan Fynbo, Bjarne Thomsen (University of Aarhus),
Michael Andersen (University of Oulu),
Gunnlaugur Bjornsson (University of Iceland),
Jens Hjorth (University of Copenhagen),
Andreas Jaunsen (University of Oslo),
Priya Natarajan (University of Cambridge, & Yale), and
Nial Tanvir (University of Hertfordshire)

     We have obtained 7842 seconds of STIS images with the 50CCD
(clear) aperture of the sky where the optical afterglow associated
with GRB 990308 was detected.  This data was taken as part of the
Survey of the Host Galaxies of Gamma-Ray Bursts (Holland et al. GCN
698
Not found
 
 
) approximately 468 days after the burst occurred.  Combined images
are now available at
"http://www.ifa.au.dk/~hst/grb_hosts/data/index.html".

     We estimate that the uncertainty in the location of the optical
afterglow in our drizzled STIS image is approximately 1.2 arcsec,
mostly due to the uncertainty in transferring the Schaefer et
al. (1999, ApJL, 524, L103) coordinates for the afterglow to the STIS
image.  We do not detect any objects within this error circle, and
estimate that our five-sigma limiting magnitude is V ~ 28.5.  There
are two faint, extended sources located 1.448 arcseconds (1.2 sigma)
and 2.228 arcseconds (1.9 sigma) west of Schaefer et al. (1999)'s
position for the optical afterglow.  Some properties of these objects
are given below.

Object    X       Y       magnitude      FWHM(")  Ellipticity
  1    1081.77  909.91   26.9 +/- 0.1     0.10       0.09
  2    1086.91  879.21   27.0 +/- 0.1     0.11       0.36

The X and Y values are the pixel coordinates on our drizzled image and
the magnitude is the STIS 50CCD (clear) AB magnitude measured in an
aperture with a diameter of 0.75 arcsec.  The resolution limit of the
image is ~0.084 arcseconds.  There are no other objects within
approximately six arcseconds of the Schaefer et al. (1999) position
for the optical afterglow, so it is possible that one of these objects
is the host galaxy for GRB 990308.  A GIF image of the error circle,
and the two extended objects, is available at
"http://www.ifa.au.dk/~hst/grb_hosts/data/grb990308cd.gif".