The GRANAT payload mainly includes
two types of instruments :
GRANAT payload
The GRANAT payload mainly includes
two types of instruments :
Three narrow field
telescopes, SIGMA, ART-P and ART-S, which are to observe
point-like sources in the sky in various energy ranges from 3 keV to 1.3 MeV.
Several detectors,
PHEBUS, KONUS, TOURNESOL and WATCH, which are to observe the
entire celestial sphere to detect transient phenomena like gamma bursts.
GRANAT orbit
The five-ton GRANAT satellite was
launched from Baïkonour on 1 december 1989 into a highly eccentric orbit,
going from 2000 to 200000 km, and inclined 51 degrees.
Its orbital period is four days but
the payload is only in service for three days out of each orbit. There is no
observation during the fourth day because of the passage of the satellite
through the Earth's radiation belts.
In fact at less than 60000 km, the
charged particles trapped in the radiation belts induce a considerable
background noise in the detector.
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