ARIEL3A Catalog
The 3rd Ariel-V SSI Catalog contains a list of X-ray sources detected by the
University of Leicester's Sky Survey Instrument (SSI) on the Ariel-V satellite,
and published (in 2 papers) as the Ariel-V (3A) Catalog: Warwick et al. 1981,
MNRAS, 197, 865 (the low galactic latitude sources) and McHardy et al. 1981,
MNRAS, 197, 893 (the high galactic latitude sources). The catalog is
based on observations extending over a 5.5 year period from 1974 October
until 1980 March. The SSI had a field of view of 0.75 by 10.6 degrees (FWHM)
and had an energy range from 2 to 18 keV. A detailed description of the SSI
is given by Villa et al. 1976, MNRAS, 176, 609. For a more detailed
discussion of how the 3A Catalog was created, please refer to the Warwick et
al. (1981) and McHardy et al. (1981) papers.
ARIEL5 Catalog
The All Sky Monitor was one of six X-ray instruments on the Ariel 5 satellite.
The satellite was launched into a low inclination (2.8 degrees), nearly
circular orbit (altitude ~520 km) on 15 October 1974. Ariel 5 was actively
pointed so that objects of interest could be observed by the four instruments
aligned along its spin axis. The ASM was mounted 90 degrees from the spin
axis; the satellite had a spin period of 6 seconds. The ASM operated from
October 18, 1974 to March 10, 1980.
The ASM instrument, built by the Lab for High Energy Astrophysics at NASA-
Goddard Space Flight Center, provided continuous coverage of the entire sky,
except for a 20 degree band straddling the satellite's equator. The ASM was
intended to act as an early detection system for transients, and to monitor
the variability of bright ( > 0.2 Crab) galactic sources. The instrument
consisted of a pair of X-ray pinhole cameras, each covering opposite halves of
the sky, with gas-filled imaging proportional counters. Position
determination of sources was accomplished through position-sensitive anode
wires and satellite rotation. Each camera had a 1-cm2 aperture. Overall
telemetry constraints limited the duty cycle for any given source to 1 percent.
With the low telemetry rate provided for this instrument (1 bit/s), temporal
and spectral information were sacrificed for the sake of all-sky coverage.
Hence, spectral information was limited to a single 3 - 6 keV bandpass, and
temporal resolution was limited to the satellite orbital period, ~100 minutes.
