TITLE: GCN CIRCULAR NUMBER: 46097 SUBJECT: GRB 261029A: FRAM-ORM and FRAM-Auger optical afterglow light curve DATE: 26/10/29 17:15:07 GMT FROM: Filip Novotný at Masaryk University Filip Novotny, Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ), Martin Masek, Sergey Karpov, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza (Institute of Physics, Prague, CZ) report: The 25 cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically to the SVOM/ECLAIRs alert of GRB 261029A (Goto et al., GCN 46072; Fermi GBM Team, GCN 46071), obtaining a series of 120 x 60 s unfiltered images between 01:38:35 and 03:55:27 UT, i.e. from ~11.5 min to ~148 min post trigger. We clearly detect the optical afterglow (O'Neill et al., GCN 46073; He et al., GCN 46078; Wang et al., GCN 46079; De et al., GCN 46080; Cotter et al., GCN 46081; Sanchez Alvarez et al., GCN 46083; Yin et al., GCN 46084; Shi et al., GCN 46088; Kang et al., GCN 46090; Ma et al., GCN 46092) in single images up to ~T0+42 min and in combined frames thereafter. Forced aperture photometry at the GOTO position yields, for the first image and the last combined frame: T-T0[mid] Images Filter Mag (AB) 12.0 min 1 x 60 s CR 13.30 +/- 0.03 138.0 min 18 x 60 s CR 17.42 +/- 0.10 CR denotes unfiltered magnitudes calibrated to the r band. The 30 cm robotic telescope FRAM-Auger at the Pierre Auger Observatory (Malargue, Argentina) also reacted to the alert. The images obtained before 02:53 UT are not usable due to a technical problem. Combining 14 x 60 s R-band images obtained between 02:57:57 and 03:15:44 UT at an elevation of ~20 deg, we detect the afterglow with R(Vega) = 16.34 +/- 0.10 at T0+99 min. A preliminary fit suggests a steeper decay before ~T0+50 min, followed by a shallower power-law decline, F ~ t^-alpha, with alpha ~ 1.3. Our late-time magnitudes are consistent with those reported by NOT, LCO and TRT (Cotter et al., GCN 46081; Yin et al., GCN 46084; He et al., GCN 46078). The photometry was reduced with the PyRT pipeline and is calibrated against the ATLAS-REFCAT2 catalogue (Tonry et al. 2018, ApJ, 867, 105). It is not corrected for Galactic extinction.