TITLE: GCN GRB OBSERVATION REPORT NUMBER: 80 SUBJECT: GRB980519 Optical Observations DATE: 98/05/20 15:11:30 GMT FROM: Jules Halpern at Columbia U. The MDM Observatory GRB team (J. Kemp, J. Halpern) reports followup photometry of the variable optical candidate discovered by Jaunsen et al. (GCN #78) in the BeppoSAX error box of GRB 980519. In a series of CCD images taken with the MDM 1.3m telescope, centered around May 20.31 UT, the candidate had I=20.1+/-0.3, R=20.9+/-0.2. These magnitudes were measured differentially with respect to stars A, B, and C of Jaunsen et al., which we recalibrated using Landolt standards. Preliminary photometry of those reference stars is as follows: RA(2000) Dec(2000) R I A 23 22 17.74 +77 15 51.2 17.93 17.28 B 23 22 27.29 +77 15 43.5 (19.26) (18.56) C 23 22 28.50 +77 15 25.4 18.15 17.43 Parentheses indicate values that are less certain. Note the large discrepancy between our I-band measurements and those of Jaunsen et al.; the latter may instead refer to the V band. MDM images will be posted at http://cba.phys.columbia.edu/jonathan/grb/. This note can be cited.