TITLE: GCN CIRCULAR NUMBER: 21996 SUBJECT: GRB 171011A: TAROT Calern observatory optical observations DATE: 17/10/11 21:25:44 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Noysena.K., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Eymar, L. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report: We imaged the field of GRB 171011A detected by SWIFT (trigger 778154) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 41.5s after the GRB trigger (12.6s after the notice). The elevation of the field decreased from 7 degrees above horizon and weather conditions were good. 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+41.5s to t0+101.5s : Rlim = 16.3 The second image is 30.0s exposure in tracking mode: t0+114.1s to t0+144.1s : Rlim = 16.6 We co-added a series of exposures: t0+114.1s to t0+405.3s : Rlim = 17.4 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.