1996A&A...310....8K

Query : 1996A&A...310....8K

1996A&A...310....8K - Astronomy and Astrophysics, volume 3108-30 (1996/6-1)

The ESO Nearby Abell Cluster Survey. I. Description of the dataset and definition of physical systems.

KATGERT P., MAZURE A., PEREA J., DEN HARTOG R., MOLES M., LE FEVRE O., DUBATH P., FOCARDI P., RHEE G., JONES B., ESCALERA E., BIVIANO A., GERBAL D. and GIURICIN G.

Abstract (from CDS):

We describe the results of the ESO Key-programme on "Structure and Dynamics of Rich Galaxy Clusters" (which we will henceforth refer to as the ESO Nearby Abell Cluster Survey - or ENACS). We discuss the sample of clusters for which data were obtained, and the observational programme of spectroscopy and photometry that we carried out. The final database contains a total of 5634 galaxies in the directions of 107 clusters from the catalogue by Abell, Corwin and Olowin 1989 (ACO hereafter) with richness R≥1 and mean redshifts z≤0.1. For 4465 galaxies the redshift is based solely on absorption lines, for 586 galaxies it is based on both absorption and emission lines, while for the remaining 583 galaxies the redshift is based exclusively on one or more emission lines. For 5615 galaxies an R25 magnitude was obtained. We discuss in some detail the methods of observation and analysis and determine the quality and reliability of the data from independent, repeated measurements. All absorption-line redshifts with a low S/N-ratio of the peak in the correlation function have been judged on plausibility by combined visual inspection of spectrum and correlation function. This has led to an empirically determined overall reliability of the 5634 accepted redshifts of 0.98. We discuss various methods for defining the compact, physically relevant systems in the 107 `pencil-beam' surveys. We have chosen to apply a fixed velocity gap to separate galaxies that do not form part of the same system. From the summed distribution of the velocity differences between galaxies adjacent in redshift we conclude that, for the average system in our survey, and for our sampling of the velocity distributions, a velocity gap of 1000km/s is the optimum one for defining the systems. With this gap size, systems are not broken up into sub-systems, and field galaxies are hardly linked to the systems. We present the mean redshifts of the 220 systems (with at least 4 members) identified in the 107 pencil beam surveys, using a fixed gap of 1000km/s. On average, about 75% of the 5634 galaxies are in the largest system found in the direction of the rich Abell cluster candidate. This shows that, within ≃1h–1Mpc of the cluster centre and down to R≃17, field contamination is not negligible for clusters with z≲0.1. However, about half of the 25% of galaxies outside the largest system belong to a secondary system along the same line of sight. At the same time, field contamination has produced only a small number of spurious rich clusters within the sample of R≥1, z≤0.1 clusters. For about 90% of the nearby rich Abell cluster candidates studied here we find a redshift system that either contains more than half of the total number of redshifts, or that has at least two times as many redshifts as the next largest system. Only in about 10% of the cases does an R≥1, z ≤0.1 entry in the ACO catalogue appear to be the result of a superposition of two almost equally rich (but relatively poorer) systems. Almost all of the rich and relatively nearby ACO cluster candidates that we studied thus appear to be real rich clusters that represent physical systems.

Abstract Copyright: ∼

Journal keyword(s): galaxies: clusters of - galaxies: redshifts - cosmology: observations - dark matter

VizieR on-line data: <Available at CDS (J/A+A/310/8): table6>

Simbad objects: 108

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Number of rows : 108
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 ACO 2717 ClG 00 03 12.9 -35 56 13           ~ 146 0
2 ACO 2715 ClG 00 03 20.67 -34 26 59.3           ~ 28 0
3 ACO 2734 ClG 00 11 21.60 -28 51 16.6           ~ 156 0
4 ACO 13 ClG 00 13 38.5 -19 30 19           ~ 107 1
5 ACO 2755 ClG 00 17 41.14 -35 12 01.0           ~ 42 1
6 ACO 2764 ClG 00 20 27 -49 13.3           ~ 32 0
7 ACO 2765 ClG 00 21 32.29 -20 45 25.3           ~ 13 0
8 ACO 2778 ClG 00 29 46.29 -30 15 24.2           ~ 21 0
9 ACO 2799 ClG 00 37 28.1 -39 08 59           ~ 40 0
10 ACO 2800 ClG 00 37 58 -25 05.5           ~ 41 0
11 ACO 87 ClG 00 43 01 -09 47.6           ~ 46 0
12 ACO 2819 ClG 00 45 51.1 -63 34 42           ~ 34 1
13 ACO 118 ClG 00 55 43.9 -26 24 46           ~ 44 0
14 ACO 119 ClG 00 56 08.57 -01 12 00.8           ~ 577 2
15 ACO 2854 ClG 01 00 46.20 -50 31 24.7           ~ 31 2
16 ACO 2871 ClG 01 08 04.1 -36 47 03           ~ 32 0
17 ACO 151 ClG 01 08 52.3 -15 25 01           ~ 199 1
18 ACO 168 ClG 01 15 07.58 +00 19 10.8           ~ 379 2
19 ACO 2911 ClG 01 26 12.9 -37 56 22           ~ 63 0
20 ACO 2915 ClG 01 28 57.00 -29 00 41.4           ~ 18 0
21 ACO 2923 ClG 01 31 50.60 -31 23 43.4           ~ 23 0
22 ACO 229 ClG 01 39 25 -03 37.8           ~ 25 0
23 ACO 2933 ClG 01 40 41.2 -54 33 26           ~ 28 0
24 ACO 2954 ClG 01 54 28.86 -71 28 02.3           ~ 11 0
25 ACO 295 ClG 02 02 27 -01 04.6           ~ 67 0
26 ACO 303 ClG 02 06 13 -03 18.7           ~ 16 0
27 ACO 3009 ClG 02 22 07 -48 34.4           ~ 18 0
28 ACO 367 ClG 02 36 36.0 -19 22 16           ~ 52 0
29 ACO 380 ClG 02 45 19.44 -26 24 58.1           ~ 24 0
30 ACO 420 ClG 03 09 17 -11 31.6           ~ 25 0
31 ACO 3093 ClG 03 10 52.0 -47 23 43           ~ 34 0
32 ACO 3094 ClG 03 11 25.00 -26 55 52.2           ~ 64 0
33 ACO 3108 ClG 03 15 14 -47 38.0           ~ 18 0
34 ACO 3111 ClG 03 17 49.3 -45 42 24           ~ 38 0
35 ACO 3112 ClG 03 17 52.9 -44 15 06           ~ 329 1
36 ACO 3122 ClG 03 22 10.9 -41 20 15           ~ 62 0
37 ACO 3128 ClG 03 29 50.6 -52 34 48           ~ 183 3
38 ACO 3142 ClG 03 36 42 -39 48.2           ~ 42 0
39 ACO 3141 ClG 03 36 49.4 -28 04 53           ~ 29 0
40 ACO 3144 ClG 03 37 23.1 -55 06 18           ~ 33 0
41 ACO 3151 ClG 03 40 27.2 -28 40 20           ~ 45 0
42 ACO 3158 ClG 03 43 07.5 -53 38 09           ~ 327 0
43 ACO 3194 ClG 03 59 12 -30 10.5           ~ 28 0
44 ACO 3202 ClG 04 00 14 -53 39.6           ~ 28 0
45 ACO 3223 ClG 04 08 34.5 -30 49 08           ~ 59 2
46 ACO 3264 ClG 04 31 19.3 -49 17 38           ~ 15 0
47 ACO 514 ClG 04 48 18 -20 28.7           ~ 149 0
48 ACO 524 ClG 04 57.8 -19 43           ~ 25 0
49 ACO 3301 ClG 05 01 05.8 -38 43 58           ~ 44 0
50 ACO 3341 ClG 05 25 31.859 -31 35 56.05           ~ 57 0
51 ACO 543 ClG 05 30 36.1584 -22 27 33.665           ~ 34 0
52 ACO 3354 ClG 05 34 39 -28 30.1           ~ 22 0
53 ACO 548 ClG 05 47 01.7 -25 36 59           B8 209 2
54 ACO 3365 ClG 05 48 12 -21 56.1           ~ 41 0
55 ACO 754 ClG 09 09 14.8 -09 40 35           ~ 695 1
56 ACO 957 ClG 10 14 02.35 -00 53 30.0           ~ 225 2
57 ACO 978 ClG 10 20 26.66 -06 31 37.5           ~ 126 1
58 ACO 1069 ClG 10 39 54.3 -08 36 40           ~ 116 1
59 ACO 3528 ClG 12 54 18.2 -29 01 16           ~ 166 1
60 ACO 3558 ClG 13 28 03.2 -31 31 35           ~ 476 2
61 ACO 3559 ClG 13 29 53.9 -29 31 29           ~ 74 0
62 ACO 3562 ClG 13 33 31.8 -31 40 23           ~ 337 1
63 ACO 1809 ClG 13 53 07.68 +05 08 32.7           ~ 179 0
64 ACO 2040 ClG 15 12 44.00 +07 27 34.5           ~ 144 1
65 ACO 2048 ClG 15 15 14.11 +04 23 10.4           ~ 109 0
66 ACO 2052 ClG 15 16 41.64 +07 01 45.5           ~ 756 1
67 ACO 3651 ClG 19 52 10.9 -55 05 16           ~ 74 0
68 ACO 3667 ClG 20 12 33.68 -56 50 26.3           ~ 676 1
69 ACO 3677 ClG 20 26 21 -33 21.1           ~ 28 0
70 ACO 3682 ClG 20 29 13.11 -36 57 45.1           ~ 16 0
71 ACO 3691 ClG 20 34 08.03 -38 01 45.5           ~ 20 0
72 ACO 3693 ClG 20 34 22.0 -34 29 40           ~ 46 0
73 ACO 3695 ClG 20 34 47.7 -35 49 39           ~ 96 2
74 ACO 3696 ClG 20 35 10 -34 54.6           ~ 17 1
75 ACO 3703 ClG 20 40 50.7 -61 12 49           ~ 22 0
76 ACO 3705 ClG 20 41 47.1 -35 10 30           ~ 47 0
77 ACO 3733 ClG 21 01 50.0 -28 06 54           ~ 64 3
78 ACO 3744 ClG 21 07 13.8 -25 28 54           ~ 80 1
79 ACO 3764 ClG 21 25 55.1 -34 43 28           ~ 28 0
80 ACO 2353 ClG 21 34 22.1 -01 34 33           ~ 27 0
81 ACO 3781 ClG 21 34 37 -66 50.6           ~ 14 0
82 ACO 2354 ClG 21 35 50 -14 54.6           ~ 17 0
83 ACO 3795 ClG 21 38 52.54 -32 04 19.2           ~ 12 0
84 ACO 2361 ClG 21 39 07 -14 19.4           ~ 35 0
85 ACO 2362 ClG 21 40 43 -14 16.3           ~ 37 0
86 ACO 3799 ClG 21 41 38 -72 43.3           ~ 10 0
87 ACO 3806 ClG 21 46 37.9 -57 17 07           ~ 59 0
88 ACO 3809 ClG 21 46 57.5 -43 54 06           ~ 99 0
89 ACO 2383 ClG 21 52 11 -21 11.9           ~ 12 0
90 ACO 3822 ClG 21 54 06.2 -57 50 49           ~ 98 0
91 ACO 3825 ClG 21 58 22.4 -60 23 39           ~ 66 0
92 ACO 2401 ClG 21 58 22.6 -20 06 13           ~ 71 0
93 ACO 3827 ClG 22 01 49.1 -59 57 15           ~ 178 0
94 ACO 2426 ClG 22 14 27.3 -10 22 05           ~ 91 0
95 ACO 3864 ClG 22 20 09.1 -52 28 01           ~ 38 0
96 ACO 2436 ClG 22 20 27.1 -02 47 34           ~ 17 0
97 ACO 3879 ClG 22 27.8 -69 02           ~ 29 0
98 2MASX J22274915-6901238 BiC 22 27 49.1188452360 -69 01 24.191317272   16.42       ~ 19 0
99 ACO 2462 ClG 22 39 17.3 -17 22 23           ~ 96 0
100 ACO 2480 ClG 22 46 04 -17 41.2           ~ 36 0
101 ACO 3921 ClG 22 49 59.0 -64 25 48           ~ 165 1
102 ACO 2500 ClG 22 53 46.37 -25 30 00.0           ~ 24 0
103 ACO 2502 ClG 22 55 03 -16 33.0           ~ 13 0
104 ACO 2569 ClG 23 17 54 -12 51.6           ~ 31 0
105 ACO 4008 ClG 23 30 17 -39 19.4           ~ 26 0
106 ACO 4010 ClG 23 31 10.3 -36 30 26           ~ 63 0
107 ACO 2644 ClG 23 41 05 +00 05.3           ~ 41 0
108 ACO 4053 ClG 23 54 45.43 -27 40 52.6           ~ 39 0

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