TITLE: GCN GRB OBSERVATION REPORT NUMBER: 35 SUBJECT: GRB980326 optical observations DATE: 98/03/31 19:11:38 GMT FROM: Bruce Grossan at LBNL Addendum to GCN #34 Bruce Grossan, Robert Knop, Saul Perlmutter (Lawrence Berkeley National Laboratory and CfPA, U.C. Berkeley), and Isobel Hook(ESO) report that in the observations of UT Mar 30.2 using the LRIS instrument on Keck II (see GCN#34), OT980326 (see IAUC6582) is irregular in shape, with some elongation roughly NE to SW. We have therefore analyzed the OT photometry with a 1.5" aperture to include all the light up to the point where the curve-of-growth flattens. The OT, with 900 seconds of exposure, was delta R= 3.1 and 4.7 mag fainter than stars 2 and 3 of IAUC6582, where these reference stars were measured with a larger 3.0" aperture. This yields R = 24.8 or 25.0 mag for the OT using the absolute calibrations for stars 2 and 3. Note that the OT has a neighboring object currently 0.7 mag brighter, approximately 1.4" E, 0.7" S of the OT.