TITLE: GCN CIRCULAR NUMBER: 18314 SUBJECT: GRB 150910A: T100 observations DATE: 15/09/15 08:24:52 GMT FROM: Eda Sonbas at NASA/GSFC E. Sonbas (Adiyaman Univ.), O. Basturk (Ankara Univ.), T. Guver (Istanbul Univ.), E. Gogus (Sabanci Univ.), S. Eryilmaz, O. Erece, H. Kirbiyik (TUG) report on behalf of a larger collaboration We observed the field of Swift GRB 150910A (Pagani et al., GCN#18264) with the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National Observatory, Turkey), starting September, 10, 20:08:16 UT (~ 11 hours after the trigger). Observations were carried out in the R filter. The afterglow is detected in the R band images with an exposure time of 300 s. Using USNO-B1 star USNO-B1 1234-0008068 (R.A.=5.65, Dec=+33.45) in the field, the magnitudes of the OT were estimated as follows; t-t0 (hr) exp.(s) filt mag err (+/-) 10.97 300 R 20.09 0.23 11.06 300 R 20.18 0.25 Analysis of further observations with the same filter is ongoing. We thank to TUBITAK National Observatory for a partial support in using T100 telescope with project number 10CT100-95 and technical support.