TITLE: GCN CIRCULAR NUMBER: 19383 SUBJECT: GRB 160504A: TAROT Calern observatory optical observations DATE: 16/05/04 20:02:56 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Laugier, R. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report: We imaged the field of GRB 160504A detected by SWIFT (trigger 685124) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 57.1s after the GRB trigger (16.5s after the notice). The elevation of the field increased from 77 degrees above horizon and weather conditions were good but during twilight. The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT with a limiting magnitude of: t0+57.1s to t0+117.1s : R > 15.3 The second image is 30.0s exposure in tracking mode: t0+132.5s to t0+162.5s : R > 15.7 We co-added a series of exposures: t0+132.5s to t0+426.0s : R > 17.2 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.