Gamma‐ray burst optical follow ups with robotic telescopes

Abstract

Abstract Gamma‐ray bursts (GRBs) are the most energetic phenomenon in the universe, emitting their energy throughout the electromagnetic spectrum. Due to their initial brightness and highly transient nature, they are ideally suited for rapid followup observations with robotic telescopes. From the sample of 30 GRBs with known redshift and detected optical afterglow, it is found that the 8 robotic detections are obtained at brighter apparent magnitudes. The U‐band luminosity function (LF) in the restframe at 1 day for this sample of 30 GRBs is derived and found to be broad (–19 < U < –25). For high‐ z GRBs, the faint end of the LF is undetected, implying that dark bursts are at least partly explained by a broad LF. For the robotically detected afterglows the LF and redshift distribution is indistinguishable from the full sample. The implication is that also rapid response robotic facilities have to be moderately large to probe the intrinsic GRB afterglow LF. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)