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.
Prognoz 9 was launched 1 July 1983 into a highly
eccentric orbit (apogee 720,000 km; perigee 380 km). The orbital inclination
was 65.5 degrees and the orbital period was 26.7 days. The spacecraft was spin
stabilized with a period of 113 s. The spin axis pointed towards the Sun, and
was repointed every few days.
The SIGNE II M P-9 experiment aboard the Prognoz 9 satellite operated for 8
months, after being turned on 2 July 1983. It was designed to study cosmic and
solar gamma-ray bursts in the 40-8000 keV energy range. The experiment
included 2 identical 15 cm diameter by 2 cm thick NaI (Tl) scintillators. One
faced in the solar direction, and the other faced the anti-solar direction.
Thus, 4-pi steradians were under simultaneous observation. With a surface area
of ~178 cm2, these detectors were some 3 times larger than the
previously flown SIGNE detectors. The energy resolution was 20% at 662 keV.
The output pulses from each photomultiplier were analyzed simultaneously in
11 energy channels. Background counts were accumulated over 64 s intervals. A
trigger signal was generated for the solar-pointed detector when the count rate
exceeded the background by 8-sigma over a 0.5 s interval. For the anti-solar
detector, a trigger signal was generated when the countrate in either a 0.5 s
or a 2 s interval exceeded the background by 8-sigma. This led to a trigger
threshold of ~3 X 10-7 erg/cm2/s for a gamma-ray burst
spectrum of E-2. Typically, data were integrated in 164 s bins, 11
energy channels when not triggered. Once a burst trigger occurred, data could
be taken in 1/64 s bins, 4-7 energy channels. The total allocated bit rate was
6 b/s.
Data from Prognoz 9 confirmed the existence of soft, repeating sources
(along with ISEE-3 and PVO). Prognoz 9 also discovered an extremely intense
burst (fluence 1 X 10-3 erg/cm2) on 1 August 1983. The
energy spectrum was observed up to over 8 MeV, with rapid variability in the
high energy spectra.
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.
