INTEGRAL and XMM-Newton Observations of the Weak Gamma-Ray Burst GRB 030227

We present International Gamma-Ray Astrophysical Laboratory (INTEGRAL) and XMM-Newton observations of the prompt γ-ray emission and the X-ray afterglow of GRB 030227, the first gamma-ray burst for which the quick localization obtained with the INTEGRAL Burst Alert System has led to the discovery of X-ray and optical afterglows. GRB 030227 had a duration of about 20 s and a peak flux of ~1.1 photons cm^-2 s^-1 in the 20-200 keV energy range. The time-averaged spectrum can be fitted by a single power law with photon index ~2, and we find some evidence for a hard-to-soft spectral evolution. The X-ray afterglow has been detected starting only 8 hr after the prompt emission, with a 0.2-10 keV flux decreasing as t^-1 from 1.3×10^-12 to 5×10^-13 ergs cm^-2 s^-1. The afterglow spectrum is well described by a power law with photon index 1.94+/-0.05 modified by a redshifted neutral absorber with column density of several 10²² cm^-2. A possible emission line at 1.67 keV could be due to Fe for a redshift z~3, consistent with the value inferred from the absorption.

Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, and Spain), the Czech Republic, and Poland and with the participation of Russia and the US, and XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and the US.