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ABELL: Catalogue of rich clusters of galaxies

Contents

Table name:     abell
Records:        5524
Version:        1988
Spectral Band:  Uband,Vband,OPT
Kind of Object: Cluster of Galaxies
Mode:           Redshift
Preview:	No
Coordinates:    J2000

Reference

Description

The contents of the Abell Catalogue data files is identical to the tables. The four files were included:

Note that the northern Abell catalogue does not list xcen, ycen, Abell type, m1, m3, m10, previous listings, or number of plates and observers. The northern catalogue has also had all known errors corrected (Struble and Rood 1987a, Leir 1976 as reported by Struble and Rood 1987a, and Corwin 1972 unpublished).

Fields

Name	Type	Meaning

number	C	Running number ("Abell" number) in order of right 
		ascension for 1855 as listed by Abell (1958) for the 
		northern clusters (1 to 2712) and in order of right 
		ascension for 1950 for the southern clusters (2713 
		to 4076). The supplementary southern clusters are 
		numbered from S1 to S1174.
field	C	The Southern Sky Survey Field number in which the 
		cluster is located.  For clusters found in two or more 
		fields, the field given is the one in which the 
		cluster is closest to the plate center.
r_a	I	Right Ascension for 1950 of the apparent cluster center.
dec	I	Declination for 1950 of the apparent cluster center.
atype	C	Cluster classification in Abell's system: 
		I = irregular, R = regular, IR and RI = intermediate.
                ":" indicates a mean type with differences between 
		estimates of two steps, or an uncertain type estimate; 
		"?" indicates a mean type with differences between 
		estimates of three steps, or a questionable type 
		estimate.
bmtype	C	Classification in the Bautz-Morgan system 
		(Bautz and Morgan 1970). ":" indicates a mean type
		with differences between estimates of two steps, 
		or an uncertain type estimate; "?" indicates a mean 
		type with differences between estimates of three or 
		more steps, or a questionable type estimate.  For the 
		northern Abell catalogue, these types are primarily 
		from Leir and van den Bergh (1977).  Other sources for 
		the northern catalogue are Bautz and Morgan (1970), 
		Bautz(1972), Corwin (1974), Kristian et al (1978), 
		Sandage et al (1976), and White (1978).
xcen	I	Rectangular coordinates in millimeters of the apparent 
		cluster center, refered to the CENTER of the Southern 
		Sky Survey Field given in the previous column.
ycen	I	Rectangular coordinates in millimeters of the apparent 
		cluster
lists	C	Sources of previous listings (see lists) Even though 
		all questionable cases of cross identification were 
		checked on the Southern Sky Survey, there remain a few 
		uncertain cases. These are given in the Notes to the 
		Catalogue.
obs	C	Number of fields in which the cluster was found, 
		and the observer's initial (A = Abell, C = Corwin,
		O=Olowin).
z	I	Cluster redshift
z_c	C	Flag for uncertainties on z
m1	I	Weighted mean total V magnitude estimate for the 
		first-ranked cluster member. No galactic extinction 
		correction has been applied.
m1_c	C	Flag for uncertainties on m1: ":" indicates a mean 
		magnitude with a standard deviation of more than 
		+-0.5 mag, or an uncertain magnitude estimate. 
		"?" indicates a mean magnitude with a standard 
		deviation of more than +-1.0 mag, or a questionable 
		magnitude estimate.  *"*" indicates that the 
		magnitude estimate is for a known or probable 
		foreground object.
m3	I	Weighted mean total V magnitude estimate for the 
		third-ranked cluster member, again uncorrected for 
		galactic extinction.
m3_c	C	Flag for uncertainties on m3 (see m1_c)
m10	I	Weighted mean total V magnitude estimate for the 
		tenth-ranked cluster member, again uncorrected for 
		galactic extinction.
m10_c	C	Flag for uncertainties on m10 (see_m1_c)
m10a	I	Magnitude for the tenth-ranked cluster member in 
		Abell's (1958) system, corrected for galactic extinction
		following Abell's formula.  For the northern Abell 
		catalogue, this is Abell's original magnitude. For the 
		southern catalogue, these were transformed from the 
		m10 on the first line (see text).
m10a_c	C	Flag for uncertainties on m10a (see_m1_c)
xll	I	Rectangular coordinates of the apparent cluster 
		center, refered to the south-east (lower left) edge of 
		the Southern Sky Survey Field given in the first line. 
		The field edges are defined by the crosses near the 
		edges of the plates; thus, it is possible for these 
		coordinates to be negative.  For the northern Abell 
		catalogue, these coordinates are from Rood and 
		Sastry (1971).  Olowin's data were transformed 
		assuming that the plate center is 164 millimeters from 
		the crosses.
yll	I	Rectangular coordinates of the apparent cluster center.
members	I	Number of cluster members between m3 and m3+2, 
		corrected for background contamination using the 
		"universal" luminosity function from Rainey (1976). 
		The southern counts are corrected to the system of the 
		northern catalogue (see text).
members C	Flag for uncertainties on members
dist	I	Distance class corresponding to Abell's (1958) 
		criteria. For the northern Abell catalogue, this is 
		Abell's original distance class from his m10. 
		For the southern catalogue, these are from the m10A's 
		listed in the next column.
rich	I	Richness class as defined by Abell (1958).  For the 
		northern Abell catalogue, this is Abell's original 
		richness_class.

Derived_Quantities

r_a        F   J2000 Right Ascension
d_e        F   J2000 Declination
l_ii       F   Galactic Longitude
b_ii       F   Galactic Latitude
L          F   SuperGalactic Longitude
B          F   SuperGalactic Latitude

Redshift

Redshift listed in the table are from the lists by Struble and Rood (1987b, northern Abell clusters), Huchra's 1986 collection of published redshifts (Huchra, private communication), Fairall (1985), Corwin (1981; see also Corwin and Emerson 1982), Couch and Newell (1981 and private communication), Noonan (1981), and Spinrad (private communication). The redshift is in parentheses if it is more than 0.3 dex from the expected redshift for the cluster's m10. Redshifts from Huchra's list and from Fairall (1985) were determined by selecting all galaxies with known redshifts within one Abell radius of the cluster center, rejecting discordant redshifts, and averaging the remainder.

Center

When the cluster was found in more than one field, a mean position is listed. Abell and Corwin used overlays positioned with respect to SAO stars to estimate the position, while Olowin calculated positions from his measured rectangular coordinates. Thus, Olowin's positions were given double weight when means were taken.

The field centers are defined by the crosses near the edges of the plates. The positive x direction is to the east (left) and the positive y direction is to the north (top). These are in the same sense as the rectangular coordinates given by Lauberts (1983) in the ESO/Uppsala Catalogue, and are listed to facilitate location of the cluster on the 5 x 5 degree ESO 1.0-m Schmidt portion of the Southern Sky Survey. Abell and Corwin measured rectangular coordinates from the left and bottom edges of the plates, so the xcen and ycen from their data are calculated assuming that the plate center is 164 millimeters from the left and bottom crosses on the plates (they also measured the crosses). Olowin refered his rectangular coordinates directly to the plate center as defined by the crosses, so no transformation is necessary for his data.

Distance

Distance classes:

richness

Richness classes :
        0 : counts 30- 49
        1 : counts 50- 79
        2 : counts 80-129
        3 : counts 130-199
        4 : counts 200-299
        5 : counts 300 or over

lists

Abbreviations are as follows:
	  B  Braid and MacGillivray (1978)
	  D  Duus and Newell (1977)      
	  d  Dressler (1980)            
	  K  Klemola (1969)            
	  O  Olowin (1987)            
	  Q  Quintana and White (1980 and private communication)
	  R  Rose (1976)   
	  S  Sersic (1974)
	  s  Snow (1970)