HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.
SAS-2 (also refered to as SAS-B and Explorer 48) was launched on 19 November
1972. To minimize the background flux from cosmic-rays, SAS-2 was placed in a
low Earth equatorial orbit having a 2 degree orbital inclination. Its apogee
and perigee were 610 km and 440 km respectively, with an orbital period of
about 95 minutes.
During the ~6 months of the mission, 27 pointed observations (typically a week
in duration) were made, resulting in about 55 percent of the sky being
observed, including most of the galactic plane.
On 1973 June 8, a failure of the low-voltage power supply ended the collection
of data.
The SAS-2 satellite carried a single instrument: a gamma-ray telescope that
used a 32-level wire spark-chamber. The telescope covered the energy range
20 MeV - 1 GeV. The instrument was the work of Fichtel et. al. at
NASA-GSFC. During the short lifetime of the mission, there was some noticeable
decrease in sensitivity due to deterioration of the spark-chamber gas.
An extensive calibration program was carried out on the gamma-ray telescope
before SAS-2 was launched. The National Bureau of Standards (NBS) Synchrotron
accelerator in Gaithersburg, Maryland was used to study the performance of the
telescope in the 20 - 114 MeV range. The performance between 200 - 1000 MeV
was studied at the Deutsches Elektronen-Synchrotron (DESY) accelerator in
Hamburg, West Germany.
It is generally acknowledged that SAS-2 provided the first detailed
information about the gamma-ray sky and demonstrated the ultimate promise of
gamma-ray astronomy.
SAS-2 revealed that the galactic plane gamma-radiation was strongly
correlated with galactic structural features, especially when the known
strong discrete sources of gamma-radiation were subtracted from the total
observed radiation. The SAS-2 results clearly established a high energy
(> 35 MeV) component to the diffuse celestial radiation. High-energy
gamma-ray emission was also seen from discrete sources such as the Crab and
Vela pulsars.
Last modified: Wednesday, 08-Oct-2003 18:59:46 EDT
HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.
