The HEAO-1 Satellite
Beginning in 1977, NASA launched a series of
very large scientific payloads called High Energy Astronomy
Observatories (HEAO). The first of these missions, HEAO-1 surveyed the
X-ray sky almost three times over the 0.2 keV - 10 MeV energy band,
provided nearly constant monitoring of X-ray sources near the ecliptic poles.
More detailed studies of a number of objects were made through pointed
observations lasting typically 3-6 hours.
August 1977 - 9 January 1979
0.2 keV - 10 MeV
- A1 - Large Area Sky Survey experiment (LASS) :
0.25-25 keV, eff. area 7 modules each of 1350 - 1900 cm2,
FOV varied between 1° X 4° to 1° x 0.5° for finest collimators.
- A2 - Cosmic X-ray Experiment (CXE) :
six separate proportional counters
MED and HEDs had various FOV settings, 1.5° x 3°, 3° x
3° and 3° x 6°
- Low Energy Detectors (LED) 0.15-3.0 keV, eff. area 2 detectors
of 400 cm2 each
- Medium Energy Detector (MED) 1.5-20 keV, eff. area 1 detector at
- High Energy Detector (HED) 2.5-60 keV, eff. area 3 detectors at
800 cm2 each
- A3 - Modulation Collimator (MC) :
eff. area 2 collimators 400 cm2 (MC1) & 300 cm2 (MC2), FOV 4° X 4°
- A4 - Hard X-Ray / Low Energy Gamma Ray Experiment :
seven inorganic phoswich scintillator detectors
- Low Energy Detectors 15-200 keV, eff. area 2 detectors 100
cm2 each, FOV 1.7° x 20°
- Medium Energy Detectors 80 keV - 2 MeV, eff. area 4 detectors 45
cm2 each, FOV 17°
- High Energy Detector 120 keV - 10 MeV, eff. area 1 detector 100
cm2, FOV 37°
Archive: Catalogs, Spectra, Lightcurves, Maps and Raw
- Complete flux-limited High Galactic Latitude Survey (Piccinotti
et al. 1982).
- Measurement of X-ray background from 3-50 keV (Marshall et al. 1980, ApJ, 235, 4.)
- Comprehensive catalog of X-ray sources (one for each experiment).
- Several hundred optical companions and source
classifications based on X-ray source positions.
- Monitored variability of a variety of objects from AGNs to X-ray
- Studied aperiodic variability in Cyg X-1 on timescales on a
- Discovered the first eclipse seen in a low-mass X-ray binary.
Not all are available for all experiments.
[About HEAO-1] (http://heasarc.gsfc.nasa.gov/docs/heao1/heao1_about.html)