Astron. Astrophys. Suppl. Ser. 138, 461-462

GRB afterglow studies at the Nordic Optical Telescope

J. Hjorth¹ - H. Pedersen¹ - A.O. Jaunsen² - M.I. Andersen³

Send offprint request: J. Hjorth; jens@astro.ku.dk

1 - Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark
2 - Institute of Theoretical Astrophysics, University of Oslo, Blindern, N-0315 Oslo, Norway
3 - Nordic Optical Telescope, Ap. 474, St. Cruz de La Palma, E-38700 Canarias, Spain

Received December 29, 1998; accepted April 21, 1999

Abstract:

Using the 2.56-m Nordic Optical Telescope (NOT) on La Palma we have observed most of the known optical afterglows to gamma-ray bursts (GRBs). We here briefly report on the discoveries of the optical afterglows of two recent SAX GRBs (GRB 980519 and GRB 980613) and the detection of their host galaxies. GRB 980519 was bright upon discovery ($R\approx20$) and occurred in a faint ($R\approx26$) galaxy whereas GRB 980613 was faint upon discovery ($R\approx23$) but occurred in a bright galaxy ($R\approx23$). Both host galaxies may show signs of interaction. GRB 980519 led to the earliest reported optical identification to date. We describe our continued efforts to produce optical identifications soon after optical observations have begun.

Key words: cosmology: observations -- gamma-rays: bursts