UGC - Uppsala General Catalog of Galaxies

Overview

The Uppsala General Catalogue of Galaxies (UGC) is an essentially complete catalog of galaxies to a limiting diameter of 1.0 arcminute and/or to a limiting apparent magnitude of 14.5 on the blue prints of the Palomar Observatory Sky Survey (POSS). Coverage is limited to the sky north of declination -02.5 degrees. Galaxies smaller than 1.0 arcminute in diameter but brighter than 14.5 mag may be included from the Catalogue of Galaxies and of Clusters of Galaxies (CGCG, Zwicky et al. 1961-1968); all such galaxies in the CGCG are included in the UGC. The galaxies are numbered in order of their 1950.0 right ascension values.

The catalog contains descriptions of the galaxies and their surrounding areas, plus conventional system classifications and position angles for flattened galaxies. Galaxy diameters on both the blue and red POSS prints are included and the classifications and descriptions are given in such a way as to provide as accurate an account as possible of the appearance of the galaxies on the prints. Only the data portion of the published UGC is included in the machine-readable version, notice. For additional details regarding the classifications, measurement of apparent magnitudes, and data content, the source reference should be consulted.

Catalog Bibcode

1973UGC...C...0000N

References

The Uppsala General Catalogue of Galaxies (UGC), Nilson P. 1973, Uppsala Astron. Obs. Ann. 6.

Provenance

This database table was first ingested by the HEASARC in September 2000 based on a machine-readable version of the UGC obtained from the ADC (ADC Catalog VII/26D). This latter version was a corrected and modified version of the original magnetic tape version of the UGC. A list of the types of changes and modifications made by the ADC is available at https://cdsarc.u-strasbg.fr/ftp/cats/VII/26D/ReadMe, while the list of the affected entries is available at https://cdsarc.u-strasbg.fr/ftp/cats/VII/26D/errors.dat.gz.

The HEASARC last updated this database table in November 2021 upon reflection that the original catalog's coordinates were B1950 (instead of J1950, as originally assumed by the HEASARC). Due to the precision of the coordinates in this catalog, the difference is negligible.

Parameters

UGC_Number
The catalog number of the object in the UGC.

Name
The UGC galaxy designation based on the catalog number. The galaxies are numbered in order of their 1950.0 right ascension values.

RA
The Right Ascension of the galaxy in the selected equinox. Notice that the RAs in the original catalog were given in "epoch 1950.0" coordinates to a precision of 0.1 minutes of time. Based on the language in the original catalog and other documentation, the HEASARC has interpreted the positions to be in the B1950 equatorial coordinate system.

Dec
The Declination of the galaxy in the selected equinox. Notice that the Declinations in the original catalog were given in "epoch 1950.0" coordinates to a precision of 1 arcminute. Based on the language in the original catalog and other documentation, the HEASARC has interpreted the positions to be in the B1950 equatorial coordinate system.

LII
The Galactic Longitude of the galaxy. This parameter was added by the HEASARC and calculated from the given 1950.0 position.

BII
The Galactic Latitude of the galaxy. This parameter was added by the HEASARC and calculated from the given 1950.0 position.

MCG
The Morphological Catalogue of Galaxies (MCG: CDS/ADC Catalog VII/62A, Vorontsov-Velyaminov et al. 1962, 1963, 1964, 1968) designation of the galaxy, if available, or a pseudo-MCG designation (explained below), if not. The first number of the designation is the Palomar Observatory Sky Survey (POSS) 6 deg zone, from the equator +00 to the north celestial pole +15; the second number is the POSS field along the zone, while the third number is the galaxy in this field in the MCG. Non-MCG galaxies are assigned the number 000 in the third position, but the first and second values are given correctly.

POSS_Field
The number of the Palomar Observatory Sky Survey (POSS) field in which the galaxy is best visible.

Blue_Major_Axis
The major axis of the galaxy as measured on the POSS blue print, in arcminutes. The precision of this number is typically 0.1 arcminutes, although in some cases it was only given to the nearest arcminute in the originating catalog.

Blue_Minor_Axis
The minor axis of the galaxy as measured on the POSS blue print, in arcminutes. The precision of this number is typically 0.01 or 0.1 arcminutes, although in some cases it was only given to the nearest arcminute in the originating catalog.

Position_Angle
The position angle of the galaxy's major axis, in degrees, measured in the conventional manner from North through East. This field is left blank if this datum is not available. The original catalog's coordinates were in the B1950 equatorial coordinates system. The position angles are therefore relative to that Equatorial North Pole, with a positive angle tilting toward the East. Since the HEASARC catalogs all use J2000, the original RA and Dec columns were converted from B1950 to J2000 for consistency with the rest of the HEASARC database. However, the HEASARC did not transform the position angle, which remains relative to North in the "epoch 1950.0" equatorial coordinates system.

Hubble_Type
The classification in the Hubble system or a less specific description of the galaxy type. Notice that this is an abbreviated version of the information available in the printed version of this catalog, which latter should be consulted, if required. Some abbreviations are used:

    Abbreviation       Meaning

    COMP               Companion
    DBL SYS            Double System
    DWF                Dwarf
    DWRF EL            Dwarf Elliptical
    DWF PEC            Dwarf Peculiar
    DWRF SP            Dwarf Spiral
    DWF SYS            Dwarf System
    DISTRBD            Disturbed
    ERUPTVE            Eruptive
    EX CMPT            Extremely Compact
    PECULR             Peculiar
    TRP SYS            Triple System

Phot_Mag
The photographic magnitude of the galaxy, usually given to a precision of 0.1 magnitudes, sometimes to only the nearest magnitude, in the originating version of the catalog.

Radial_Velocity
The radial velocity of the galaxy in km/s relative to the Local Group of galaxies and corrected for the solar motion according to the relation V0 = +300 cos A, where A is the distance to the conventional Solar apex at lI = 55 deg, bI = 0 deg, or lII = 87 deg, bII = +1 deg. If the uncertainties in the measurements were considered too large to make corrections meaningful, usually only the uncorrected value is given.

Red_Major_Axis
The major axis of the galaxy as measured on the POSS red print, in arcminutes. The precision of this number is typically 0.1 arcminutes, although in some cases it was only given to the nearest arcminute in the originating catalog.

Red_Minor_Axis
The minor axis of the galaxy as measured on the POSS red print, in arcminutes. The precision of this number is typically 0.01 or 0.1 arcminutes, although in some cases it was only given to the nearest arcminute in the originating catalog.

Inclination_Code
A code describing the inclination of the galaxy, measured on a scale from 1 (face-on) to 7 (edge-on). For galaxies of high inclination, a value is calculated from the Hubble formula n = 10(a-b)/a, where a is the major axis and b the minor axis. The value of 7 denotes objects that are inclined not more than a few degrees to the line of sight.

Class
The HEASARC Browse classification is derived from the hubble_type parameter for this database table.

Contact Person

Questions regarding the UGC database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:35:54 EDT