COLLECTION: The US Survey for Quasars and Faint Blue Stars (1981 - 2004)

The survey for Ultraviolet Starlike objects began at the behest of Allan Sandage. Observations were conducted with the 1.2 m Palomar Schmidt telescope. The survey lists 3987 objects in seven Schmidt fields in the North and South galactic polar caps. Superior statistical completeness was achieved by deriving instrumental color indices akin to B–V and U–B.
Selection effects for Quasars are fully quantified: the Ly α criterion z ≤ 2.2; the flux-limited criterion B ≤ 18.5; color indices bluer than halo subdwarfs; and starlike morphology for the Schmidt telescope according to the criterion B < 21.0 – 0.75 / z (Usher, Mitchell, & Huang, ApJ 454, 654, 1995; Fabian and Usher AJ 111, 645, 1996). The survey is named "US" for its Ultraviolet Starlike selection effects -- and whimsically not for a person or persons, or for a country. It is the first quantified multi-color generalization of the methods of Haro & Luyten and Jaidee & Lynga. Positional accuracy of about 2" or better was achieved by underlaying a transparent precision grid and measuring positions with a Cuffey astrophotometer in the field mode using a reduction algorithm written by Archie Warnock III (PASP 93, 655, 1981). In 1984, the survey provided arguably the best Quasar surface densities in its class, and in 2000 it was one of the top three. A complete sample to within a small section of the Selected Area 28 field was studied by Kenneth J. Mitchell and three other Penn State graduate students (PASP 95, 45-47, 1983) over the 1981-2 end-of-year holidays using a Cassegrain spectroscope on the Department's 1.6m reflector. They found US 1329 to have a redshift about z = 0.249, which is the only quasar to be spectroscopically identified by a ground telescope from the state of Pennsylvania.