TITLE: GCN CIRCULAR NUMBER: 9684 SUBJECT: GRB 090715B: Lick observations DATE: 09/07/17 17:28:04 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley, J. Choi, A. Morton and M. Ganeshalingam (UC Berkeley) report: We obtained a series of R-band exposures of the optical transient associated with GRB 090715B (GCN 9668, Vetere et al.; GCN 9670, Smith et al.) at the 1-meter Nickel telescope at Lick Observatory under clear skies and good seeing. The transient is detected in individual frames. We report the following magnitudes relative to the calibration star of Malesani et al. (GCN 9671): t_start(UT) exp(s) mag t-t0(hr) 06:17:06.10 120 R = 20.23 +/- 0.21 9.23 06:27:36.17 200 R = 20.27 +/- 0.16 9.41 06:31:53.21 200 R = 20.06 +/- 0.14 9.48 06:42:53.80 300 R = 20.48 +/- 0.17 9.66 06:54:57.78 300 R = 20.40 +/- 0.16 9.86 07:01:01.97 300 R = 20.39 +/- 0.20 9.96 07:07:07.30 300 R = 20.24 +/- 0.14 10.07 07:19:01.36 300 R = 20.47 +/- 0.18 10.26 07:32:15.82 300 R = 20.71 +/- 0.23 10.44 A stack of all images gives an average magnitude of R = 20.23 +/- 0.07.