GRB 030227: The first multiwavelength afterglow of an INTEGRAL GRB

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 α R = -0.95 ± 0.16. The spectral index βopt/NIR yielded -1.25 ± 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.