TITLE: GCN GRB OBSERVATION REPORT NUMBER: 88 SUBJECT: GRB980519 optical observations DATE: 98/05/22 22:19:07 GMT FROM: Roy Gal at CalTech GRB980519 Optical Observations with Keck and Palomar R. R. Gal, J. S. Bloom, C. Steidel, K. L. Adelberger, S. G. Djorgovski, and S. R. Kulkarni, on behalf of the Caltech GRB Collaboration, report: "We have obtained additional photometric CCD images of the field of GRB 980519. C. Steidel and K. Adelberberger have obtained 11 minutes of R-band data using the W.M. Keck Observatory 10-m, and R. Gal has obtained 800 sec. of i band data and 750 sec. of R band data with the Palomar Observatory 5-m on UT May 21. We measured magnitudes for the OT using the Landolt magnitude system derived by Bloom et al.(GCN #87) for the nearby stars. The OT is no longer visible in our i-band data, with an upper limit of I > 21.6 +/- 0.7, at UT May 21.43. The OT is still seen in the R band with R = 23.48 +/- 0.2 at UT May 21.469 (Palomar) and R = 23.10 +/- 0.13 at UT May 21.6 (Keck). The fainter Palomar magnitude at the earlier epoch is likely due to poor seeing conditions (>2") which place the object close to our detection limit. C. Steidel and K. Adelberger also report that in seeing conditions of 0.75" at Keck the OT is not distinguishable from a point source. We note that these observations place an upper limit on the magnitude of the OT host galaxy of not brighter than R ~ 24 mag. Our R-band magnitudes are consistent with the source still fading with a slope of approximately 2.0, while the I-band data do not provide additional constraints on the slope. This message may be cited."