Fr.: relevé sur tout le ciel
Palomar Observatory Sky Survey (POSS)
bardid-e âsmân-e nepâhešgâh-e Palomar
Fr.: Palomar Observatory Sky Survey
A photographic atlas of the northern hemisphere and a portion of the southern hemisphere created at Mount → Palomar Observatory in southern California. The original survey was completed in 1954 using the 48-in Schmidt (Oschin) Telescope. The square photographic plates were 35.5 cm (14-inch) on a side, each encompassing roughly 6 × 6 degrees of the sky. The survey was originally intended to cover the entire sky from +90 degrees declination down to -24 degrees (plate centers) in 879 regions, using both red and blue sensitive emulsions, and including stars to magnitude +22. Ultimately the survey was extended to -30 degrees (both red and blue), an additional 57 regions. Finally, the Whiteoak Southern Extension was added in 1962 (red plates only), with another 100 plates which extended the set down to a declination of -42 degrees plate center.
Fr.: relevé du ciel
The observation and recording of large extents of the sky with a particular instrument using one or more wavelengths in the same spectral domain. → survey.
Sloan Digital Sky Survey (SDSS)
bardid-e adadi-ye âsmân-e Sloan
Fr.: relevé numérique du ciel Sloan
A major → redshift survey using a dedicated 2.5-m wide angle telescope with different modes in → imaging and → spectroscopy. The telescope, a modified → Ritchey-Chretien→ altitude-azimuth type is located at Apache Point Observatory, south east New Mexico, United States. A large consortium of universities and institutions all over the world participate in the project. The telescope started its observations in 2000, taking spectra and images of about 35% of the night sky, with 3 million spectra and 500 million images coming together to form the most comprehensive astrophysical catalog in the world. This catalog contains millions of galaxies up to z = 1, bright → quasars up to z = 6, with images in five major filter bands (u, g, r, i and z). SDSS was divided into multiple surveys/projects: SDSS I (2000-2005); SDSS II (2005-2008), including the Sloan Supernova Survey; SDSS III (2008-2014), including the APO Galactic Evolution Experiment (APOGEE), Baryon Oscillation Spectroscopic Survey (BOSS); SDSS IV (2014-2020), including the Mapping Nearby Galaxies at APO (MaNGA).
Two Micron All Sky Survey (2MASS)
An astronomical → survey conducted from 1997 to 2001 of the entire sky in near-infrared J, H, and K bands (wavelengths 1.25, 1.65, and 2.17 microns respectively). The aim was to detect and characterize point sources brighter than about 1 → mJy in each band, with → signal-to-noise ratio greater than 10, using a pixel size of 2".0. Two automated 1.3-m telescopes were used, one at Mt. Hopkins, AZ, and one at CTIO, Chile. 2MASS is currently producing the following data products: 1) A digital atlas of the sky comprising approximately 4 million 8' × 16' images, having about 4" spatial resolution in each of the wavelength bands. 2) A point source catalog containing accurate positions and fluxes for 300 million stars and other unresolved objects. 3) An extended source catalog containing positions and total magnitudes for more than 1,000,000 galaxies and nebulae.