The first ever high-resolution gamma-ray image above 1 MeV produced with the coded mask technique during the calibration of INTEGRAL's spectrometer SPI.
This image was obtained during the INTEGRAL SPI calibration campaign in April 2001. The calibration was carried out on the night of 18-19 April using a sodium-24 source. This image of a simulated star-like source produced with the coded mask technique is the first of its kind with such a high angular resolution (less than 2 degrees) and was obtained at 2.75 MeV.
Credit: CESR, Toulouse.