TITLE: GCN GRB OBSERVATION REPORT NUMBER: 161 SUBJECT: GRB 980326/Host Galaxy DATE: 98/12/23 02:48:56 GMT FROM: Shri Kulkarni at Caltech J. S. Bloom and S. R. Kulkarni report on behalf of the Caltech GRB effort: "On the nights of 17 and 18, December 1998 we carried out imaging observations of the field of GRB 980326 with LRIS instrument on Keck II. In the R-band we obtained 8 images each with an integration time of 300 s. These images were debiased, flat-fielded, registered and median stacked. In the resulting image we do not detect the host galaxy at the position of the optical transient of this GRB (Groot et al., ApJ 502, L123, 1998). We determined the zero-point calibration using the reference stars quoted in Groot et al. (1998). The faintest object that was readily detected and in the general vicinity of the OT was ~27.3 mag (with aperture radius of 1.5 arcsec). This object and others at similar brightness levels are clearly visible to the eye in the stacked image. We can place a firm lower limit on the magnitude of the host galaxy at this level. Previous magnitudes for the the magnitude of the host galaxy were derived using data when the OT was bright and could have been affected by the assumed decay model and photometric errors. The true host of GRB 980326 is thus fainter than R=27.3 mag or that the OT/GRB is not coincident with its host (e.g. the GRB was ejected from the host galaxy or is of intergalactic origin). If the former is true then the host galaxy of GRB 980326 is by far the faintest host and this faintness is unlikely due to dust extinction given the detection of the optical transient in the B band (Groot et al. 1998)."