Abstract
The 2-m robotic Liverpool Telescope automatically discovered the optical afterglow of the INTEGRAL gamma-ray burst GRB 050502a 3 min after the GRB onset. The automatic identification of a bright optical transient of r′ ∼ 15.8 triggered for the first time a multi-colour observation sequence in the BVr′i′ filters during the first hour after a GRB. All the four light curves are fitted by a simple power law with index of 1.2 ± 0.1. We also find evidence for an achromatic bump rising at t ∼ 0.02 days. We investigate different scenarios compatible with the data. We find possible evidence for a uniform circumburst medium with clumps in density, as in the case of GRB 021004. The alternative case of a wind environment cannot be ruled out, although it can hardly account for our observations. The alternative interpretation of the bump, as the result of a refreshed shock, appears to be more problematic, although it cannot be ruled out either.
Original language | English |
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Pages (from-to) | 330-334 |
Number of pages | 5 |
Journal | Chinese Journal of Astronomy and Astrophysics |
Volume | 6 |
Issue number | SUPPL. 1 |
DOIs | |
Publication status | Published - 1 Jan 2006 |
Event | 6th International Workshop on Multifrequency Behaviour of High Energy Cosmic Sources: Frascati Workshop 2005 - Vulcano, Italy Duration: 23 May 2005 → 28 May 2005 |
Keywords
- Gamma-rays: bursts
- Techniques: photometric
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science