Search

GRB 030320 is the 5th gamma-ray burst (GRB) detected by INTEGRAL in the field of view (FoV). It is so far the GRB with the largest off-axis angle with respect to the INTEGRAL pointing direction, near to the edge of the FoV of both main instruments, IBIS and SPI. Nevertheless, it was possible to determine its position and to extract spectra and fluxes. The GRB nature of the event was confirmed by an IPN triangulation. It is a ~60 s long GRB with two prominent peaks separated by ~35 s. The spectral shape of the GRB is best represented by a single power law with a photon index $\Gamma \simeq 1.7$. The peak flux in the 20–200 keV band is determined to ~5.7 photons cm-2s-1and the GRB fluence to $ 1.1 \times 10^{-5}$erg cm-2. Analysing the spectral evolution of the GRB, a “hard-to-soft” behaviour emerges. A search for an optical counterpart has been carried out, but none was found.

In this paper we discuss the methods developed for the production of the INTEGRAL/SPI instrument response. The response files were produced using a suite of Monte Carlo simulation software developed at NASA/GSFC based on the GEANT-3 package available from CERN. The production of the INTEGRAL/SPI instrument response also required the development of a detailed computer mass model for SPI. We discuss our extensive investigations into methods to reduce both the computation time and storage requirements for the SPI response. We also discuss corrections to the simulated response based on our comparison of ground and inflight calibration data with MGEANT simulations.

Context.Motivated by the recent proposal that one can obtain quasi-periodic oscillations (QPOs) by photon echoes manifesting as non-trivial features in the autocorrelation function (ACF), we study the ACFs of the light curves of three accreting black hole candidates and a neutron star already known to exhibit QPOs namely, GRS 1915+105, XTE J1550-564, XTE J1859+226 and Cygnus X-2.