TITLE: GCN GRB OBSERVATION REPORT NUMBER: 472 SUBJECT: GRB 991216, Optical Afterglow DATE: 99/12/17 12:48:46 GMT FROM: Jules Halpern at Columbia U. Robert Uglesich, Nestor Mirabal, J. Halpern (Columbia U.), Susan Kassin, & Sebastino Novati (Ohio State U.) report on behalf of the MDM Observatory GRB follow-up team: "We find a probable afterglow of the extremely bright BATSE burst GRB 991216 (Kippen et al. GCN #463) in a series of R-band observations taken by S. Kassin and S. Novati on the MDM 1.3m telescope. An object at (J2000) 05:09:31.2, +11:17:07.2 faded from approximately R = 18.8 on Dec. 17.142 to R = 19.4 on Dec 17.372. The corresponding power-law decay index is -1.4. This object is not visible on the digitized POSS II plate. Its position is consistent with the latest RXTE scan (Markwardt et al. GCN/RXTE_PCA notice). This preliminary photometry is based on several USNO stars. We used a nonstandard broad R filter which transforms very well with Landolt R. A finding chart is posted at http://www.astro.columbia.edu/~rru/GRB991216.html This message may be cited."