GCN Circular 756
GRB 990510 Host Galaxy Discovery J. S. Bloom, on behalf of the larger Caltech-NRAO-CARA GRB Collaboration, reports: "We have discovered a faint extended source nearly coincident with the position of GRB 990510. This source, which we identify as the host galaxy of GRB 990510, is visible in new HST/STIS imaging taken on 29 April 2000 as part of the HST proposal #8189 (see Fruchter et al. GCN #386) and made public on 28 July 2000. The total integration time is 5840 s taken in 8 individual exposures. Registration of the early epoch (17 June 1999) where the OT was bright reveals the OT occurred (0.064" +/- 0.009") West and (0.015" +/- 0.012") North of the center of the host galaxy. This amounts to a significant displacement of (66 +/- 9) mas or ~600 pc at a distance of z=1.62 (Galama et al. 1999), though the OT does appear to reside within the detectable light of the galaxy. The galaxy extension is PA=80.5 +/- 1.5 deg with an ellipticity of about ~0.5. Preliminary magnitude estimates reveal that V_host = 28.5 +/- 0.5 mag (referenced to star C of Beuermann et al. 1999). The host does appear to be marginally detected in the July 1999 imaging as well (although see GCN #386)." An image of the field from both epochs as well as a close-up of the host and the 3-sigma location of the GRB can be found at: http://astro.caltech.edu/~jsb/grb990510-host.ps This message may be cited.