GRIS (Gamma-Ray Imaging Spectrometer)

Developed by NASA - Goddard Space Flight Center (GSFC)

Balloon launched on 4/26/1992, from Australian Balloon Launching Station, Alice Springs, Australia

Purpose of the flight and payload description

The GRIS instrument consists of an array of seven coaxial n-Type germanium detectors surrounded by a thick active NaI shield/collimator. Located above this assembly is an active NaI coded-aperture mask for imaging and precise source location. The seven germanium detectors are each enclosed in individual cryostats. This design (rather than a single large multi-detector cryostat) was chosen for two principal reasons: to minimize the internally produced background and for easier replacement of individual detectors, as well as upgrades and modifications.

The instrument is mounted in a gondola offering a conventional azimuth-over-elevation pointing system with a momentum wheel for azimuth control. Coarse pointing control used the earth's magnetic field as a reference. A CID camera was used to image star fields and the sun to obtain an independent and more accurate measure of the absolute pointing direction.

Details of the balloon flight

Balloon launched on: 4/26/1992 at 8:17 utc
Launch site: Australian Balloon Launching Station, Alice Springs, Australia  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon SF3-480.10-080-NSCHR-03-ST
Balloon serial number: W39.96-3-07
Flight identification number: 327N
End of flight (L for landing time, W for last contact, otherwise termination time): 4/26/1992 at 23:01 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 14 h
Landing site: 20 miles NNE of Clermont, Queensland, Australia

Observations of 4U1543-47 and the Galactic center.

External references

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