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-cm<sup>2</sup> 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. This is a service provided by NASA HEASARC .
ARI's "Geschichte des Fixsternhimmels" is an attempt to collect all
astrometrically useful observations from before ca. 1970 in a way
comparable to what has been done to construct the FK* series of
fundamental catalogs. About 7e6 published positions are included.
In GAVO's DC, we provide tables of identified and non-identified stars
together with the master catalog that objects were identified against.
ARI's "Geschichte des Fixsternhimmels" is an attempt to collect all
astrometrically useful observations from before ca. 1970 in a way
comparable to what has been done to construct the FK* series of
fundamental catalogs. About 7e6 published positions are included.
In GAVO's DC, we provide tables of identified and non-identified stars
together with the master catalog that objects were identified against.
The catalogue ARIHIP has been constructed by selecting the 'best
data' for a given star from combinations of HIPPARCOS data with Boss'
GC and/or the Tycho-2 catalogue as well as the FK6. It provides 'best
data' for 90 842 stars with a typical mean error of 0.89 mas/year
(about a factor of 1.3 better than Hipparcos for this sample of
stars).
This service provides the data for the TGAS catalogue (Tycho-Gaia Astrometric Solution ; a subset of the Gaia DR1 catalogue providing parallaxes and proper motions from Tycho2 for a little more than 2 million sources).
This service provides Gaia data (currently DR1, DR2 and EDR3), with full-sky catalogues of high-precision positions down to about 20 mag, as a mirror of the original ESA archive with extra features (e.g., tables and column metadata).
