TITLE: GCN CIRCULAR NUMBER: 36680 SUBJECT: GRB 240615A: FLWO-1.2m optical upper limits DATE: 24/06/17 02:24:03 GMT FROM: Harsh Kumar at Center for Astrophysics | Harvard & Smithsonian H. Kumar (CFA) D. Hiramatsu (CFA), and E. Berger (CFA) report on behalf of the FLWO team: We observed GRB 240615A detected by Fermi GBM (GCN #36671)and Swift/BAT-GUANO (GCN #36672), with the FLWO 1.2m (48”) robotic telescope. We obtained multiple 300-sec exposures in the g, r, and i filters and did not detect any new source in our stacked images within 4 arcmin of BAT position: RA (J2000) = 21:44:33.91, Dec(J2000) = 38:35:41.3. We obtained the following upper limits: --------------------------------------------------------------------------------- JD (mid) | T-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) --------------------------------------------------------------------------------- 2460477.78778 | 13.04 | 900 (stacked) | r | > 21.92 2460477.79915 | 13.32 | 900 (stacked) | g | > 21.33 2460477.81047 | 13.59 | 900 (stacked) | i | > 21.47 --------------------------------------------------------------------------------- The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. We thank the FLWO staff for their support.