X-ray satellites

X-ray satellites

Artificial Earth satellites devoted to cosmic X-ray observations, the first of which was NASA's Uhuru, launched in Dec. 1970. Up to this date, i.e. throughout the period 1962–70, X-ray astronomy was carried out exclusively with sounding rockets and balloon experiments. Uhuru produced the first all-sky survey for cosmic X-ray sources and increased the catalog of known sources to 161 by 1974. The second X-ray astronomy satellite was the British satellite Ariel V, which was launched in Oct. 1974 and occupied a similar 500-km circular equatorial orbit to Uhuru. It successfully extended the Uhuru sky map and made detailed spectral and temporal studies of individual sources.

Although X-ray experiments were also carried on other satellites principally devoted to the research fields (Copernicus, OSO-7, ANS, OSO-8), the next two dedicated X-ray astronomy satellites were SAS-3 and HEAO-1, launched respectively in 1975 and 1977. Both included modulation collimator experiments in their payloads and these provided the first accurate positions of many X-ray sources, leading to additional and more reliable optical identifications. In Nov. 1978 HEA0-2 (the Einstein Observatory) was launched; its large grazing incidence telescope produced major advances. After the Einstein Observatory ceased operation in Apr. 1981 only two small satellites, Ariel VI and Hakucho, remained before the launch in 1983 of the Japanese Tenma and the European EXOSAT spacecraft. Subsequent X-ray satellites, of increasing sophistication, were the Japanese Ginga (launched 1987), German ROSAT (1990), and Japanese Asca (1993), with still larger missions in preparation, including the Russian Spectrum–X (1995), NASA's XTE (1997) and AXAF (1998/99), and ESA's XMM (1999).

References in periodicals archive ?
These would make it superior to a number of existing X-ray satellites, including China's own Hard X-ray Modulation Telescope (HXMT), (http://www.
HXMT (also called Insight) was China's first X-ray satellite, and after five months of calibrations and testing while in orbit, it began its science operations Jan.
237-second pulses are mainly seen with gamma- and X-ray satellites, but only weakly with ground-based radio telescopes.
We would like to tackle these unresolved problems by using the new X-ray observations by ASTRO-H, planned to be launched early next year, and by more sensitive future X-ray satellites, together with multi-wavelength observations of ULXs and SS 433," he said.
Infrared and X-ray satellites have seen a powerful 'wind' (outflow) of material from this central region.
In fact it was their bright X-ray emissions that led to the discovery of this type of binary star system by the first X-ray satellites about 30 years ago.
The group compared observations from four separate X-ray satellites and found the same variations over the years.
Within an hour, Schaefer set in motion the global network of observatories, and by the end of the morning, two X-ray satellites (the Rossi X-Ray Timing Observatory and the INTEGRAL satellite) had already made observations.
X-ray satellites such as NASA's Energetic X-ray Imaging Survey Telescope (EXIST) are being designed with the sensitivity, large field of view, and trigger capability to discover hundreds of supernovae each year in the act of exploding, thanks to their powerful X-ray outbursts.
Specializing in X-ray astronomy and high-energy solar physics, the Institute of Space and Astronautical Science (ISAS) drew international attention with its X-ray satellites Ginga (1987) and ASCA (1993).
Data obtained from X-ray satellites such as Einstein, Rosat, and more recently ASCA have shown that the amount of cluster gas is comparable to, or even greater than, the mass contained in all of the visible constituent galaxies (S&T: September 1995, page 15).