TITLE: GCN GRB OBSERVATION REPORT NUMBER: 749 SUBJECT: GRB981226, HST/STIS observations of the host galaxy DATE: 00/07/07 15:38:22 GMT FROM: Stephen Holland at IFA, U of Aarhus GRB981226, HST/STIS observations of the host galaxy Stephen Holland, Bjarne Thomsen (University of Aarhus), Michael Andersen (University of Oulu), Gunnlaugur Bjornsson (University of Iceland), Johan Fynbo, 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 7865 seconds of HST/STIS images with the 50CCD (clear) aperture and 7909.63 seconds of HST/STIS images with the F28X50LP (long pass) aperture of the host galaxy of GRB 981226. These data was taken as part of the Survey of the Host Galaxies of Gamma-Ray Bursts (Holland et al. GCN 698) approximately 555 (clear) and 558 (long pass) days after the burst. Combined (drizzled) images are now available at "http://www.ifa.au.dk/~hst/grb_hosts/data/index.html". The galaxy identified by Frail et al. (1999, ApJL, 525, L81) is the only object within the error circle of the radio transient (VLT J232937.2-235553) associated with GRB 981226. This galaxy is located at (X,Y) = (1033,1056) on the drizzled STIS clear image, has an ellipticity of approximately 0.65, and its major axis has a position angle of approximately -75 degrees east of north. We measured the following AB magnitudes for this galaxy using an aperture with a 1.1 arcsecond radius: CL = 25.04 +/- 0.07 in the STIS clear aperture and LP = 24.50 +/- 0.10 in the STIS long pass aperture. We used the photometry of Walker (1994, PASP, 106, 828) to calibrate our data (see Holland et al. 2000, in preparation, for details) and found V-R = 0.50 +/- 0.14, V = 24.80 +/- 0.08, and R = 24.30 +/- 0.11 in the Johnson and Kron-Cousins systems. We note that the northeast side of the galaxy is significantly bluer than the rest of the galaxy (see "http://www.ifa.au.dk/~hst/grb_hosts/data/grb981226_colour.gif"). We estimate that the blue structure on the north side of the galaxy has V-R = 0.1 and the south edge of the galaxy has V-R = 1.5. There is a compact source at each end of the blue structure. The west source corresponds to the photometric centre of the galaxy. Frail et al. (1999) found that the galaxy was located 0.55 +/- 0.53 arcseconds west and 0.41 +/- 0.43 arcseconds south of the radio afterglow. This error ellipse encompasses the eastern half of the galaxy and the eastern compact source in the blue structure. We also note the presence of a faint point source (V ~= 28.4, V-R ~= 0.3), at (X,Y) = (1015,1064) in the drizzled STIS clear image, approximately 1.0 arcseconds from the nominal position of the radio afterglow.