Letter to the Editor

Detection of an optical transient following the 13 March 2000 short/hard gamma-ray burst^*

¹ Instituto de Astrofísica de Andalucía (IAA-CSIC), PO Box 03004, 18080 Granada, Spain
² Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF-INTA), 28080 Madrid, Spain
³ Real Instituto y Observatorio de la Armada, Sección de Astronomía, 11.110 San Fernando–Naval (Cádiz), Spain
⁴ Danish Space Research Institute, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
⁵ Czech Technical University, Faculty of Electronic Engineering, Department of Radioelectronics, 166 27 Prague, Czech Republic
⁶ Astronomical Institute of the Czech Academy of Sciences, 251 65 Ondřejov, Czech Republic
⁷ Centro de Experimentación del Arenosillo (CEDEA-INTA), 21130 Mazagón, Huelva, Spain
⁸ Departamento de Astrofísica, Universidad Complutense, Madrid, Spain
⁹ Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Alicante, Spain
¹⁰ Universities Space Research Association, Flagstaff station, AZ, USA
¹¹ U. S. Naval Observatory, Flagstaff station, AZ, USA
¹² Laboratoire d'Astrophysique de l'Observatoire de Grenoble, Grenoble, France
¹³ Lockheed Martin Solar & Astrophysics Lab, Palo Alto, 3251 Hanover St., Bldg. 252, CA 94304, USA
¹⁴ Dept. of Theoretical Physics and Astrophysics, Masaryk University, Brno, Czech Republic
¹⁵ División de Ciencias del Espacio (DCE-INTA), Torrejón de Ardoz, 28850 Madrid, Spain
¹⁶ NASA Goodard Space Flight Center, Greeebelt, MA, USA

Corresponding author: A. J. Castro-Tirado, ajct@iaa.es

Received: 14 June 2002
Accepted: 9 August 2002

Abstract

We imaged the error box of a gamma-ray burst of the short (0.5 s), hard type (GRB 000313), with the BOOTES-1 experiment in southern Spain, starting 4 min after the γ–ray event, in the I-band. A bright optical transient (OT 000313) with was found in the BOOTES-1 image, close to the error box (3σ) provided by BATSE. Late time -band deep observations failed to reveal an underlying host galaxy. If the OT 000313 is related to the short, hard GRB 000313, this would be the first optical counterpart ever found for this kind of events (all counterparts to date have been found for bursts of the long, soft type). The fact that only prompt optical emission has been detected (but no afterglow emission at all, as supported by theoretical models) might explain why no optical counterparts have ever been found for short, hard GRBs. This fact suggests that most short bursts might occur in a low-density medium and favours the models that relate them to binary mergers in very low-density environments.