TITLE: GCN GRB OBSERVATION REPORT NUMBER: 185 SUBJECT: GRB981226 Optical Observations DATE: 98/12/31 11:37:38 GMT FROM: Brad Schaefer at Yale Bradley E. Schaefer (Yale U.), Jonathan Kemp, Irina Feygina, Jules Halpern (Columbia U.) report: "We have obtained B, V, and R images with the 0.9-m and 1.0-m telescopes on Cerro Tololo of the GRB981226 position on the nights of 26/27, 27/28, and 30/31 December 1998. We find no variable sources, and no significant changes from the Digitized Sky Survey. This includes the entire BeppoSAX WFC error circle (Di Ciolo et al. IAUCirc. 7074) as well as the BeppoSAX NFI error circle (Frontera et al. IAUCirc. 7078). A journal of our observations, the corresponding magnitudes, and limits are presented in the table below. Our limiting magnitudes are quoted for a signal-to-noise ratio of 4. For the three variables that have been proposed previously, we find as follows: (1) No source is visible at the position of the proposed infrared variable (Castro-Tirado et al. GCN 173) to the limits stated below. This implies R-J > 1.7 for this source if it is the afterglow. (2) There is no significant evidence for variability of the proposed candidate of Galama et al. (GCN 172). (3) The source identified by Wozniak et al. (GCN 177) is clearly visible, but we have no significant evidence of its variability." ------------------------------------------------------------------- Telescope UT start Band Limit Mag(Galama) Mag(Wozniak) ------------------------------------------------------------------- CTIO 1.0m Dec 27.044 R 21.6 20.74+-0.13 21.20+-0.20 CTIO 0.9m Dec 27.064 V 21.8 >21.8 >21.8 CTIO 0.9m Dec 27.071 B 21.5 >21.5 >21.5 CTIO 1.0m Dec 28.034 R 21.7 21.06+-0.15 21.15+-0.24 CTIO 0.9m Dec 28.065 V 21.7 >21.7 >21.7 CTIO 0.9m Dec 28.072 R 21.0 20.8 +-0.3 21.03+-0.24 CTIO 0.9m Dec 31.052 R 22.1 21.10+-0.10 21.61+-0.20 ------------------------------------------------------------------