TITLE: GCN CIRCULAR NUMBER: 16800 SUBJECT: GRB 140907A: T100 observations DATE: 14/09/08 16:49:15 GMT FROM: Eda Sonbas at NASA/GSFC E. Sonbas (Adiyaman Univ.), U. Temiz, H. Avdan (Cukurova Univ.), T. Guver (Istanbul Univ.), E. Gogus (Sabanci Univ.), S. Eryilmaz (TUG), K. Yakut (Ege Univ.), H. Kirbiyik (TUG) report on behalf of a larger collaboration We observed the field of Swift GRB 140907A (Krimm et al., GCN#16788) with the 1.0 meter T100 telescope (Bakirlitepe, TUBITAK National Observatory, Turkey), starting September, 7, 23:54:47 UT (~ 7.794 hours after the trigger). Observations were carried out in the R filter. The afterglow is clearly detected in 300 s in the R band images. Using USNO-B1 star USNO-B1 1366-0072923 (R.A.=48.155, Dec=+46.614) in the field, the magnitude of the OT was estimated as follows; t-t0 (hr) exp.(s) filt mag err (+/-) 7.794 300 R 19.65 0.20 We are grateful to TUBITAK National Observatory for prompt scheduling the observations and technical support.