TITLE: GCN GRB OBSERVATION REPORT NUMBER: 57 SUBJECT: GRB980326, optical observations DATE: 98/04/23 05:30:47 GMT FROM: George Djorgovski at Caltech/Palomar S. G. Djorgovski, S. R. Kulkarni, P. Cote, J. Blakeslee, J. S. Bloom, and S. C. Odewahn (Caltech), on behalf of the Caltech GRB collaboration, report: We obtained R band images of the field of GRB 980326, using Keck-II 10-m telescope, on the night of 17 April 1998 UT. We clearly detect a galaxy coincident to within the astrometric errors (less than 0.3 arcsec) with the previously reported optical transient (cf. Groot et al. IAUC 6852, and Kulkarni et al. GCN Circ. 33). Using the magnitudes of stars 2 and 3 from Groot et al., we derive for this galaxy R = 25.5 +- 0.5 mag (preliminary reductions). This is about 0.6 magnitudes fainter than the tentative detection by Grossan et al. (GCN Circ. 35), and is consistent with the upper limits reported by Valdes et al. (GCN Circ. 56). We interpret this object as the host galaxy of GRB 980326, probably with a negligible contamination from the OT itself. The difference in brightness from the measurements by Grossan et al. on 30 March 1998 UT suggests that some contribution from the OT was still present at that time, with the estimated OT magnitude of R ~ 25.8 at that epoch. Images of the field can be found at: http://astro.caltech.edu/~george/grb/grb980326.html Further observations of this field are in progress. This note can be cited.