TITLE: GCN CIRCULAR NUMBER: 18939 SUBJECT: GRB 160127A: TAROT La Silla observatory optical light curve DATE: 16/01/27 12:14:43 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Turpin D. (IRAP-CNRS-OMP), Boer M., Gendre B., Bardho O. (UNS-CNRS-OCA), Gendre B. (Etelman Observatory-UVI), Atteia J.L. (IRAP-CNRS-OMP) report: We imaged the field of GRB 160127A detected by SWIFT (trigger 671828) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 25.1s after the GRB trigger (13.4s after the notice). The elevation of the field increased from 42 degrees above horizon and weather conditions were good. We detected the candidate couterpart mentioned by Amaral-Rogers et al. (GCNC 18938). The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We detect the OT increasing its optical flux from t0+25s to t0+45s (R~16.9) and fading until the end of the trail at t0+85s. Following images were acquired in tracking mode: t1(s) t2(s) Rmag d_Rmag 99 129 17.9 0.6 141 171 17.4 0.1 182 212 17.1 0.7 223 253 17.1 0.0 306 396 17.1 0.2 407 497 17.4 0.4 610 700 17.6 0.1 711 801 17.6 0.2 914 1004 17.6 0.1 1015 1105 17.4 0.0 1742 1922 >18.4 0.6 Magnitudes were estimated with the stars: NOMAD1 0900-0248256 ra=225.9885561 dec=+00.0840197 R=14.83 NOMAD2 0901-0246538 ra=225.9533572 dec=+00.1320336 R=14.83 Magnitudes are not corrected for galactic dust extinction. After the first deacay observed in the trailed image from t0+45s to t0+85s, we observed a bump (maximum flux at t0+220s R~17.1) and we suspect a second bump (maximum flux at t0+1100s R~17.3) followed by a steep decay. The OT become fainter than 18.4 after t0+2000s.