TITLE: GCN GRB OBSERVATION REPORT NUMBER: 702 SUBJECT: The Hosts of GRB 980703 and GRB 971214 DATE: 00/06/15 01:42:09 GMT FROM: Josh Bloom at CIT The Hosts of GRB 980703 and GRB 971214 J. S. Bloom and S. R. Kulkarni report on behalf of the larger Caltech-NRAO-CARA GRB Collaboration: "The Hubble Space Telescope (HST) has recently observed the hosts of GRB 971214 and GRB 980703 with STIS as part of the Survey of the Host Galaxies of Gamma-Ray Bursts (see S. Holland, B. Thomsen, H. Hjorth et al. GCN #698). Here we present our data reduction of this public data and relate the new STIS images to our previously obtained ground-based data and space-based data. GRB 980703: This remains one of the brightest GRB host galaxies at R~22.8 and the inferred GRB energy release is at the high end of the GRBs energy distribution. The optical astrometry tie from Bloom et al. (1998, ApJL 508, 21) revealed the GRB to be nearly coincident with its host galaxy. The GRB host was observed for a total of 5264 s with the STIS long-pass filter (central wavelength ~ 7230 Ang and FWHM 2720 Ang) beginning 12.42 June 2000 UT. The galaxy is compact (though resolved) and has a low ellipticity (~12%). The effective seeing of the drizzled image is 85 milliarcsec (FWHM) as measured from a bright star in the image and the host has a FWHM diameter of 250 milliarcsec. This is consistent with our report in Bloom et al. of an unresolved source in 0.5 arcsec seeing on July 18 (when the host was thought to dominate the total light of the source). At a redshift of z=0.966 (Djorgovski et al. ApJL 508, 17, 1998), this implies a half-light radius of ~1.1 kpc (assuming H_0 = 65 km/s/Mpc, Omega_0 = 0.3, Omega_lam = 0.7). For photometric zero-pointing of the HST image, we compared two compact objects in common to our deep Keck images from 18 July 1998 in V, R, I. We find the host galaxy has R = 22.8 +/- 0.3 and I = 22.6 +/- 0.3. The error is dominated by the uncertainty in the color correction. These magnitudes are both within 1-sigma of those predicted for the host galaxy in Bloom et al. from the light curve data. We conclude therefore there is no evidence for the presence of a second light source (e.g. a supernova component) in the early time light curve. GRB 971214: At z=3.418, this burst and its host remains the furthest of GRBs with spectroscopically confirmed redshifts and also had an implied energy release at the high end of the GRB energy distribution (Kulkarni et al. 1998, Nature, 393, 35). Using STIS imaging from 13 April 1998 we previously reported (Odewahn et al. 1998 ApJL, 509, 5) the host as compact core with an irregular envelope (half-light radius of 1.3 kpc). Morphologically and in all other observed physical properties the host is rather typical Lyman break galaxy at comparable redshifts. Further, we found a small but significant offset of the GRB from the nucleus of the galaxy. The GRB host was observed for 8599s using STIS clear mode beginning 12.21 Jun 2000 UT. The final image has achieved approximately the same depth as our previous STIS clear imaging. A visual comparison of the two epochs reveals no obvious new or fading component. Our conclusions about the nature of the host and its relation to the GRB remain unchanged from Odewahn et al." Our final reduced images can be obtained in .fits format at http://astro.caltech.edu/~jsb/GRB/Host/ This message may be cited.