INTEGRAL observations of the gamma-ray burst on March 11, 2007

On March 11, 2007, the INTEGRAL observation discovered and localized a gamma-ray burst in the sky from which an early infrared afterglow was then detected. We present our timing and spectral analyses of the data from the ISGRI detector of the IBIS telescope. The burst consists of one ∼40-s-long peak during which a fluence of ∼3 × 10−6 erg cm−2 was released in the energy range 20–200 keV. The 18–300-keV spectrum is characterized by a slope Γ ≈ −0.8 at the rise phase and Γ ≈ −1.4 at the maximum and decay phase. The basic characteristics of GRB 070311 suggest that it is a typical cosmological gamma-ray burst.