GRB 030227: The first multiwavelength afterglow of an INTEGRAL GRB

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 ( $R\sim 23$). This OA was seen to decline following a power law decay with index $\alpha_{R} = -0.95 \pm 0.16$. The spectral index $\beta_\mathrm{opt/NIR}$ yielded $-1.25 \pm 0.14$. 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.