GRB 970828

For the recent GRB on 28 Aug 97, Shri Kulkarni et al. report the following:

   S. C. Odewahn, S. G. Djorgovski, S. R. Kulkarni (Caltech) and D. A.
   Frail (NRAO) report:  "We have examined CCD images of the field of GRB
   970828 obtained at the Palomar 200-inch Hale telescope by T. Herter,
   F. Fang and O. Pevunova on August 29, UT and compared them to images
   obtained by Steidel, Adelberger and Kellog on August 30, 31 and
   September 1 UT (and reported in IAUC 6370).  Our preliminary analyis
   shows no objects brighter than about R magnitude of 24.5 within the
   ASCA/RXTE/IPN error-box (see IAUC 6728, 6731), which changed
   significantly by more than 0.2 magnitudes per day within this time
   interval.  This places severe limit on the peak brightness of any
   possible optical transient associated with this burst."

GRB 970828: HST Observations of the Host Galaxy

J. S. Bloom, S. R. Kulkarni, T. J. Galama, D. A. Frail and S. G.
Djorgovski report on behalf the larger Caltech-NRAO-CARA GRB
Collaboration:

"We observed the field of GRB 970828 (Remillard et al., IAUC 6726;
Murakami et al., IAUC 6732; Groot et al. 1998, ApJ, 493, 27) on 2001
August 16-18 UT using the WFPC F450W, F606W, F814W filters on the Hubble
Space Telescope.  The 3-component host system seen in deep Keck imaging
(Djorgovski et al. 2001, astro-ph/0107539, accepted) appears to be
spatially resolved, with no detected emission connecting the components.
However, given the signal-to-noise, we would be unable to detect
low-surface brightness features and cannot therefore make a strong claim
about the geometry of dust and stars in the system.

Astrometrically comparing the F606W images with the Keck localization, we
identify component "B" (from figure 3 of Djorgovski et al.) as the host
galaxy.  The offset location and uncertainty (which is large due to poor
astometric tie between radio and optical images) are the consistent with
that reported in Bloom, Kulkarni & Djorgovski (2001; astro-ph/0010176).

An image of the host may be found at:

   http://www.astro.caltech.edu/~jsb/GRB/grb970828-host-reg.ps

The 3-sigma uncertainty contour of the OT position is shown in this
image as well as the galaxy component labels from Djorgovski et al."

This message may be cited.

GRB 970828: HST Observations of the Host Galaxy

J. S. Bloom, S. R. Kulkarni, T. J. Galama, D. A. Frail and S. G.
Djorgovski report on behalf the larger Caltech-NRAO-CARA GRB
Collaboration:

"We observed the field of GRB 970828 (Remillard et al., IAUC 6726;
Murakami et al., IAUC 6732; Groot et al. 1998, ApJ, 493, 27) on 2001
August 16-18 UT using the WFPC F450W, F606W, F814W filters on the Hubble
Space Telescope. The total integration time in each filter was 8800 s.
The 3-component host system seen in deep Keck imaging (Djorgovski et al.
2001, astro-ph/0107539, accepted) appears to be spatially resolved, with
no detected emission connecting the components. However, given the
signal-to-noise, we would be unable to detect low-surface brightness
features and cannot therefore make a strong claim about the geometry of
dust and stars in the system.

Astrometrically comparing the F606W images with the Keck localization, we
identify component "B" (from figure 3 of Djorgovski et al.) as the host
galaxy.  The offset location and uncertainty (which is large due to the
poor astrometric tie between radio and optical images) are consistent with
those reported in Bloom, Kulkarni & Djorgovski (2001; astro-ph/0010176).

An image of the host may be found at:

   http://www.astro.caltech.edu/~jsb/GRB/grb970828-host-reg.ps

The 3-sigma uncertainty contour of the OT position is shown in this
image as well as the galaxy component labels from Djorgovski et al."

This message may be cited.