ar X iv : 0 80 4 . 17 27 v 1 [ as tr o - ph ] 1 0 A pr 2 00 8 Multiwavelength analysis of the intriguing GRB 061126 : the reverse shock scenario and magnetization

We present a detailed study of the prompt and afterglow emission from Swift GRB 061126 using BAT, XRT, UVOT data and multi-color optical imaging from ten ground-based telescopes. GRB 061126 was a long burst (T90 = 191 s) with four overlapping peaks in its γ-ray light curve. The X-ray afterglow, observed from 26 min to 20 days after the burst, shows a simple power-law decay with αX = 1.290 ± 0.008. Optical observations presented here cover the time range from 258 s (Faulkes Telescope North) to 15 days (Gemini North) after the burst; Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia. Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Birkenhead, CH41 1LD, UK. INAF Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate (LC), Italy. INAF Instituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, via Ugo La Malfa 153, 90146 Palermo, Italy. The UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK. Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA. Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany. Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 129, India. Inter University Center for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune 411 007, India. Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK. Space Research Institute (IKI), 84/32 Profsoyuznaya Str, Moscow 117997, Russia. Instituto de Astrof́ısica de Andalućıa (CSIC), P.O. Box 03004, E-18080 Granada, Spain. Indian Institute of Astrophysics, Bangalore, 560 034, India. Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA. Ulugh Beg Astronomical Institute, Tashkent 700052, Uzbekistan. Department of Physics, University of Warwick, Coventry CV4 7AL, UK. CNRS-CTBT, Grenoble 38000, France. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK. Center for Research and Education in Science & Technology, Hosakote, Bangalore, 562 114, India.