TITLE: GCN CIRCULAR NUMBER: 3891 SUBJECT: GRB 050826: Optical Candidate DATE: 05/08/27 12:09:34 GMT FROM: Jules Halpern at Columbia U. J. P. Halpern (Columbia U.) reports on behalf of the MDM Observatory GRB follow-up team: "I observed the error box of GRB 050826 (Swift trigger #152113, GCN #3884) in the R band with the MDM 1.3m telescope for 75 minutes on each of two consecutive nights. A fading object not visible on the Digitized Sky Survey is present at coordinates (J2000) 05:51:01.59, -02:38:35.4 (+/- 1") which is 8" from the revised Swift XRT position (error radius 6", GCN #3889). The epochs and magnitudes are: --------------------------------------------------- Date(UT) Time(UT) t-t0(hours) R(mag) --------------------------------------------------- Aug. 26 10:42-11:57 4.40- 5.65 21.0 +/- 0.2 Aug. 27 10:43-11:58 28.42-29.67 21.6 +/- 0.2 --------------------------------------------------- The indicated errors are systematic at this stage of the analysis, but the difference between the two observations is not affected by systematics. Improvements in precision of position and magnitudes will be forthcoming from these data. These preliminary magnitudes should not be used in formal analyses. I also note that this location suffers from significant Galactic extinction, E(B-V)=0.59, A(R)=1.57, according to Schlegel et al. (1998)."