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A3 - HEAO 1 A3 MC LASS Catalog



This database table contains information from the HEAO 1 A3 MC LASS Catalog of X-ray Sources. The MC experiment contained two four-grid modulation collimators with an egg-crate collimator with an overall FOV of 4 x 4 degrees (FWHM). The objects in the catalog are possible HEAO 1 A1 sources. The HEAO 1 experiment began on day 224, 19 August 1977 and ended on day 739, 9 January 1979.


The HEAO 1 MC-LASS Catalog was prepared by Ron Remillard of MIT.

The instrument is described in "Measurements of X-ray Source Positions by the Scanning Modulation Collimator on HEAO 1", H. Gursky et al., Ap.J., 223:973-978, 1978 August.


One of the primary goals of the HEAO 1 MC LASS experiment was to measure the positions of X-ray sources over the whole sky with high angular precision in order to permit their optical or radio identification.

The identified sources fall into several categories. The catalog includes:

 * 180 emission-line AGNs
 * 131 stars with active coronae (RSCVn)
 * 120 clusters of galaxies
 * 81 XRBs
 * 42 cataclysmic variables
 * 32 Be-type binary systems
 * 31 BL Lac objects
 * 22 SNRs
 * 21 miscellaneous classifications
There are 660 total identifications, 631 Large Area sky survey sources (1st HEAO 1 scan), and 29 transients in HEAO 1 2nd and 3rd scans.


Name from identification by cross-referencing with other catalogs.

The NRL 1H source name --- the catalog number from the HEAO 1 Large Area Sky Survey (Wood, et al 1984).

The Right Ascension of the center of concurrent overlapping A3 error boxes.

The Declination of the center of concurrent overlapping A3 error boxes.

The Galactic longitude.

The Galactic latitude.

The astrophysical type of the object.

The HEASARC Browse classification assigned to the object, based on the contents of the 'type' field.

Contact Person

Questions regarding the A3 database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 18-Mar-2015 19:53:21 EDT