Observations of the First Electromagnetic Counterpart to a Gravitational-wave Source by the TOROS Collaboration

MARIO C. DÍAZ; LUCAS M. MACRI; DIEGO GARCÍA LAMBAS; C. MENDES DE OLIVEIRA; J. L. NILO CASTELLÓN; T. RIBEIRO; BRUNO O SANCHEZ; W. SCHOENELL; L. R. ABRAMO; S. AKRAS; R. ARTOLA; MARTÍN BEROIZ; S. BONOLI; JUAN CABRAL

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2017

0004-637X

We present the results of prompt optical follow-up of the electromagnetic counterpart of the gravitational-wave event GW170817 by the Transient Optical Robotic Observatory of the South Collaboration. We detected highly significant dimming in the light curves of the counterpart ( mag,  mag,  mag) over the course of only 80 minutes of observations obtained ~35 hr after the trigger with the T80-South telescope. A second epoch of observations, obtained ~59 hr after the event with the EABA 1.5 m telescope, confirms the fast fading nature of the transient. The observed colors of the counterpart suggest that this event was a "blue kilonova" relatively free of lanthanides.