The scanning modulation collimator experiment on the HEAO-1
Abstract
The purpose of this experiment is to localize celestial sources of X-rays to a precision of 5 to 20 arcsec, so that they may be identified with optical or radio counterparts. We also study their angular size and structure, to elucidate the X-ray emission mechanism. Four grids, wound with nickel alloy wires, are aligned to produce a modulated X-ray signal when the spacecraft rotation carries the collimator field of view across an X-ray source. An image dissector star camera and rate integrating gyroscopes are used to deduce the celestial position from which a peak X-ray signal arises. On-orbit performance and thermal stability have been very good. Based on the first six weeks of quick look data, we have the following results: the location of an X-ray burst source within a globular cluster; the location of 4U1608-52, a unique object which shows bursting, transient, and steady X-ray behavior and is also an optical source; the location of the X-ray transient H1705-25, which provided Anglo-Australian astronomers the basis for an optical identification with a nova-like object; the location of the X-ray transient H1743-32 in the galactic center; and a precise measurement of the angular extent of the Crab Nebula.
- Publication:
-
AIAA, Aerospace Sciences Meeting
- Pub Date:
- January 1978
- Bibcode:
- 1978aiaa.meetS....S
- Keywords:
-
- Collimators;
- Heao;
- Satellite-Borne Instruments;
- X Ray Astronomy;
- Calibrating;
- Crab Nebula;
- Histograms;
- Novae;
- Proportional Counters;
- Astronomy