(POSS, Palomar Observatory Sky Survey I, POSS-I, National Geographic Society-Palomar Observatory Sky Survey, NGS-POSS)
(1950s photographic plates from Palomar 48 inch telescope)
The Palomar Observatory Sky Survey
(POSS) was a 1950s survey using the Palomar 48 Inch Telescope at Palomar Observatory,
that produced a set of photographic plates (the POSS plates) covering the 60%
of the sky
visible from the observatory. A printed version was available to
astronomers to assist in observation, and a number of astronomers
produced catalogs by inspecting them for
object types of specific interest.
The Second Palomar Observatory Sky Survey (aka
Palomar Observer Sky Survey II or POSS-II)
is a repeat done in the 1980s and 1990s with the same telescope
but with technological upgrades. The
Palomar Digital Sky Survey (DPOSS) is a digitization
of the POSS-II photographic plates.