Astrophysics (Index)About

plate

(photographic plate)
(product of astronomical photography)

A plate (i.e., photographic plate) is a pane of glass coated with the photographic chemicals necessary for taking a photograph, an alternative to the use of photographic film. Such plates have been used in astronomy since the late 1800s, but such photography has been replaced by the use of electronic sensors such as CCDs, introduced in the latter part of the 20th century. Film has been used as well, but plates have the advantage of stability of their size: no stretching or shrinking. An astrometry technique has been literally measuring physical distances between imaged objects on a plate, so this stability is relevant.

Surveys have produced collections of plates, often with more than one plate for each field, taken with various filters. (Note that such collections may include film as well, which may sometimes be referred to as plates.) Some such collections have been used for years to create catalogs of various specific kinds of objects. Example collections include the POSS plates from the Palomar Observatory Sky Survey (POSS), and the ESO plates from the UK Schmidt Survey. More recent surveys like the Sloan Digital Sky Survey (SDSS), that use electronic sensors rather than photographic methods, produce data sets used similarly. Plates as old as a century retain value by offering data regarding peculiar velocity, visual binaries, variable stars, supernovae and other transient phenomena, and earlier positions of solar system objects.


The term plate has other uses: in some situations a lens is referred to as a plate, such as a Schmidt corrector plate. The word is also used in the terms, waveplate, phase plate, and microchannel plate.


(equipment)
Further reading:
https://en.wikipedia.org/wiki/Photographic_plate#Astronomy
http://astronomyonline.org/astrophotography/ccdversusplates.asp
https://www.plate-archive.org/
https://obs.carnegiescience.edu/plate-archives
https://library.cfa.harvard.edu/plate-stacks

Referenced by pages:
Abell Catalog
APM Galaxy Survey (APMUKS)
Arp-Madore Catalog of Southern Peculiar Galaxies (AM)
Astrographic Catalog (AC)
Atlas of Galactic Nebulae (GN)
Berkeley Open Cluster Catalogue (Be)
Bologna Catalog of Globular Clusters (Bol)
Catalog of Galaxies and Clusters of Galaxies (CGCG)
comparator
Czernik Catalog (Cz)
DASCH
Digitized Sky Survey (DSS)
Duus-Newell catalog (DN)
ESO Schmidt Telescope
ESO/Uppsala Survey of the ESO (B) Atlas
exposure time
field curvature
Hamburg Schmidt Survey (HS)
Hamburg/ESO Survey (HE)
Large Bright QSO Survey (LBQS)
Lowell Proper Motion Survey (G)
Luyten Half-second Catalog (LHS)
Luyten Palomar Survey (LP)
Luyten Two-Tenths Arcsecond Catalog (LTT)
Lynds Catalog of Dark Nebulae (LDN)
Lynds Catalogue of Bright Nebulae (LBN)
Magellanic Catalogue of Stars (MACS)
Morphological Catalogue of Galaxies (MCG)
multi-object spectrograph
Palomar 48 Inch Telescope (P48)
Palomar Globular Clusters (Pal)
Palomar Observatory Sky Survey (POSS)
Parsamian Nebula Catalog
passband
photomultiplier tube (PMT)
plate measuring machine (APM)
plate scale
rare designator prefixes
Second Byurakan Survey (SBS)
Sharpless Catalog (Sh2)
spectral line
stray light
SuperCOSMOS Sky Survey (SSS)
UK Schmidt Survey
UK Schmidt Telescope (UKST)
USNO Twin Astrograph
van den Bergh galaxy classification
Van Den Bergh Reflection Nebula Catalog (vdB)

Index