Principal Galaxies Catalogue
Encyclopedia
The Catalogue of Principal Galaxies (PGC) is an astronomical catalogue published in 1989 that lists B1950 and J2000 equatorial coordinates and cross-identifications for 73,197 galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

. 40,932 coordinates (56%) have standard deviation
Standard deviation
Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...

s smaller than 10″
Minute of arc
A minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....

. A total of 131,601 names from the 38 most common sources are listed. Available mean
Mean
In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....

 data for each object are given:
  • 49,102 morphological descriptions,
  • 52,954 apparent major and minor axis,
  • 67,116 apparent magnitude
    Apparent magnitude
    The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

    s,
  • 20,046 radial velocities
    Radial velocity
    Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...

     and
  • 24,361 position angle
    Position angle
    Position angle, usually abbreviated PA, is a measurement derived from observing visual binary stars. It is defined as the angular offset in degrees of the secondary star to the primary, relative to the north celestial pole....

    s.

External links

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