Imagine the Universe!

The HEAO-1 Satellite


artist
concept of HEAO-1
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.


Mission Characteristics

* Lifetime : 12 August 1977 - 9 January 1979
* Energy Range : 0.2 keV - 10 MeV
* Payload :
  • 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
    • 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 800 cm2
    • High Energy Detector (HED) 2.5-60 keV, eff. area 3 detectors at 800 cm2 each
    MED and HEDs had various FOV settings, 1.5° x 3°, 3° x 3° and 3° x 6°
  • A3 - Modulation Collimator (MC) :
    0.9-13.3 keV, 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°
* Science Highlights:
  • 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 binaries.
  • Studied aperiodic variability in Cyg X-1 on timescales on a few milliseconds
  • Discovered the first eclipse seen in a low-mass X-ray binary.
* Archive : Catalogs, Spectra, Lightcurves, Maps and Raw data.
Not all are available for all experiments.

[About HEAO-1] (http://heasarc.gsfc.nasa.gov/docs/heao1/heao1_about.html) [Archive] (http://heasarc.gsfc.nasa.gov/docs/heao1/archive/heao1_archive.html) [Software] (http://heasarc.gsfc.nasa.gov/docs/heao1/software/heao1_software.html) [Gallery] (http://heasarc.gsfc.nasa.gov/docs/heao1/heao1_images.html) [Publications] (http://heasarc.gsfc.nasa.gov/docs/heao1/bib/heao1_biblio.html)
Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Nicholas White (Director), within the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center.

The Imagine Team
Project Leader: Dr. Jim Lochner
All material on this site has been created and updated between 1997-2004.

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