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Cosmic X-Ray Experiment (A-2) MAP Database


Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1977-08-14 to 1979-01-09


The HEAO-1 A-2 MAP database consists of a detailed map of both the entire X-ray sky and the X-ray background only. Only X-ray counting rates data in scan mode for the HED and MED detectors are used. Each 360 degree scan of the sky is broken into 1440 scan angle bins and the data is accumulated for a period of ~12 hours, and written into a file of nine records. This maps the sky into bins of ~0.5 deg ecliptic longitude by ~0.25 deg ecliptic latitude bins. The X- ray sky map contains rates (discovery scaler) data which passed tests of "clean" criteria, and with a McIllwain-L value less than 1.2. The X-ray background map contains only rates data which passed tests of "superclean" criteria. A data analysis package is available on the microVAX of the GSFC Laboratory for High Energy Astrophysics.

Alternate Names

  • A-2 MAP Database


  • Astronomy: X-Ray


  • 77-075A-02M

Additional Information



Questions and comments about this data collection can be directed to: Dr. Cynthia Y. Cheung



NameRoleOriginal AffiliationE-mail
Dr. Laura A. WhitlockData ProviderNASA Goddard Space Flight
Dr. Jean H. SwankGeneral ContactNASA Goddard Space Flight
Mr. Brendan H. PerryProgrammerNASA Goddard Space Flight

Selected References

  • Piccinotti, G., et al., A complete X-ray sample of the high latitude (1b1 greater than 20 degree) sky from HEAO -1 A-2: Log N - log S and luminosity functions, NASA-GSFC, TM-82168, Greenbelt, MD, Aug. 1981.
  • Boldt, E., et al., Cosmic X-ray background: 1. The discrete source component, in (COSPAR) X-Ray Astronomy, 443-448, W.A. Baity, Pergamon Press, New York, NY, 1979.
  • Nugent, J. J., et al., HEAO A-2 soft X-ray source catalog, Astrophys. J. Suppl. Ser., 51, 1-28, doi:10.1086/190838, Jan. 1983.
  • Rothschild, R. E., et al., The cosmic X-ray experiment aboard HEAO-1, Space Sci. Instrum., 4, 269-301, 1979.
  • Marshall, F. E., et al., New hard X-ray sources observed with HEAO A-2, Astrophys. J. Suppl. Ser., 40, No. 3, 657-666, doi:10.1086/190600, July 1979.
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