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 (TOROS). We detected highly significant dimming in the light curves of the counterpart (Delta g=0.17+-0.03 mag, Delta r=0.14+-0.02 mag, Delta i=0.10 +- 0.03 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 1.5m 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.
@article{arxiv.1710.05844,
title = {Observations of the first electromagnetic counterpart to a gravitational wave source by the TOROS collaboration},
author = {M. C. Díaz and L. M. Macri and D. Garcia Lambas and C. Mendes de Oliveira and J. L. Nilo Castellón and T. Ribeiro and B. Sánchez and W. Schoenell and L. R. Abramo and S. Akras and J. S. Alcaniz and R. Artola and M. Beroiz and S. Bonoli and J. Cabral and R. Camuccio and M. Castillo and V. Chavushyan and P. Coelho and C. Colazo and M. V. Costa-Duarte and H. Cuevas Larenas and D. L. DePoy and M. Domínguez Romero and D. Dultzin and D. Fernández and J. García and C. Girardini and D. R. Gonçalves and T. S. Gonçalves and S. Gurovich and Y. Jiménez-Teja and A. Kanaan and M. Lares and R. Lopes de Oliveira and O. López-Cruz and J. L. Marshall and R. Melia and A. Molino and N. Padilla and T. Peñuela and V. M. Placco and C. Quiñones and A. Ramírez Rivera and V. Renzi and L. Riguccini and E. Ríos-López and H. Rodriguez and L. Sampedro and M. Schneiter and L. Sodré and M. Starck and S. Torres-Flores and M. Tornatore and A. Zadrożny},
journal= {arXiv preprint arXiv:1710.05844},
year = {2017}
}
Comments
Accepted for publication in The Astrophysical Journal Letters