Author/Authors :
Covino، S. نويسنده , , Malesani، D. نويسنده , , Gotz، D. نويسنده , , Mereghetti، S. نويسنده , , Rau، A. نويسنده , , Molinari، E. نويسنده , , Zerbi، F. M. نويسنده , , Beckmann، V. نويسنده , , Lichti، G. G. نويسنده , , Kienlin، A. von نويسنده , , Sturner، S. J. نويسنده , , Shrader، C. R. نويسنده ,
Abstract :
We present multiwavelength observations of a gamma-ray burst detected by INTEGRAL (GRB 030227) between 5.3 hours and ~1.7 days after the event. Here we report the discovery of a dim optical afterglow (OA) that would not have been detected by many previous searches due to its faintess (R~ 23). This OA was seen to decline following a power law decay with index (alpha)(R)=-0.95 (plus-minus) 0.16. The spectral index (beta)opt/NIR yielded 1.25 (plus-minus) 0.14.These values may be explained by a relativistic expansion of a fireball (with p = 2.0) in the cooling regime. We also find evidence for inverse Compton scattering in X-rays.
Keywords :
GRB , gamma-ray bursts , SPI , IBIS , INTEGRAL , gamma-ray astronomy