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X-ray Reduced Scanning Data


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

Time span: 1977-08-18 to 1979-09-08


These data represent the Scanning Modulation Collimator (MC) data binned around trial positions at which X-ray sources were thought to exist. The data are exposure units and raw counts separately saved for each satellite rotation, each energy channel (0.9 to 2.5 keV, 2.5 to 5.5 keV, and 5.5 to 13.5 keV), and each of the two collimator banks (MC1 is 30 arc-s FWHM with 4 arc-min periodicity, MC2 is 2 arc-min FWHM with 16 arc-min periodicity). Data for the two or three different 6-month intervals in which the satellite scanned a fixed celestial location are collated into one file for each source. The data are binned according to the phase of the peak response of the collimator from the trial position of the given source and are coadded by the precise periodicity of the collimator. Data are binned along azimuths within plus and minus 3 deg of the trial position. Along with the primary X-ray counts and time data, each scan contains the elevation of that scan circle from the source, the "jitter" angle measuring how much the actual scan deviated from an ideal great circle when passing the source, the orbit number and minor frame number that allow a calculation of universal time, and some detailed parameters used by software that performs analysis processing. For data analysis, the files are used to determine when the MC has, in fact, detected a source and then are used to produce the allowed locations of the source on the sky. In using the files, one can choose various combinations of energy channels, individual scans or passes, jitter angle, detector count rate, etc., in order to maximize the signal to noise. This data set is contained on magnetic tape. For further information on the A-3 data archive, contact Dr. Daniel Schwartz, Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138.

Alternate Names


    • Astronomy: X-Ray


    • 77-075A-03B

    Additional Information



    Questions and comments about this data collection can be directed to: Coordinated Request and User Support Office



    NameRoleOriginal AffiliationE-mail
    Dr. Daniel A. SchwartzGeneral ContactSmithsonian Astrophysical
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