VII/42A GMP catalogue: galaxies in the Coma cluster (Godwin+ 1983)
The Coma Cluster - I. A catalogue of magnitudes, colours, ellipticities and position angles for 6724 galaxies in the field of the Coma cluster Godwin J.G., Metcalfe N., Peach J.V. <Mon. Not. R. Astron. Soc. 202, 113 (1983)> =1983MNRAS.202..113G
ADC_Keywords: Clusters, galaxy Description: The catalogue contains isophotal magnitudes, radii, intensity profiles, ellipticities and (b-r) colours for 6724 galaxies with b26.5 < 21.0 mag in a 26.3 degree square area centered on the Coma cluster. The sample is essentially complete to b26.5 = 20.0, with rms deviations in b26.5, r24.75 and (b-r) all about 0.15mag. The plates used in this investigation were all taken with the Palomar 48-inch Schmidt telescope during good conditions in 1976 May. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file catalog.dat 104 6724 The catalogue of galaxies, published as Appendix Microfiche MN202/1 and 2
Byte-by-byte Description of file: catalog.dat
Bytes Format Units Label Explanations
1- 4 I4 --- GMP [1/6724]+ Identification number 5 A1 --- n_GMP [?] "?" indicates a probable galaxy (1) 6- 11 I6 arcsec Xpos [-4900/4900]+= increasing westwards (2) 12- 17 I6 arcsec Ypos [-4900/4900] increasing northwards (2) 19 A1 --- n_b26.5 [*] indicates an overlapped image in b-band 20- 24 F5.2 mag b26.5 b-band integrated magnitude (3) 26- 30 F5.1 arcsec r(b26.5) Isophotal radius in b; rms is 0.5arcsec (4) 32 A1 --- n_r24.75 [*] indicates an overlapped image in r-band 33- 37 F5.2 mag r24.75 ?=99.99 r-band integrated magnitude (5) 39- 43 F5.1 arcsec r(r24.75) ?=999.9 Isophotal radius in r; rms is 0.7arcsec. (4) 46- 49 F4.2 mag (b-r) ?=9.99 (b-r) color index (6) 51- =4 F0. arcsec r(b-r) ?=99.9 Isophotal radius in (b-r) (4) 56- 58 F3.1 --- eps ?=9.9 Ellipticity (7) 60- 62 I3 deg PosAngle ?=999 Position angle of the major axis (8) 64- 68 F5.2 mag/arcsec alpha(b) ?=9.99 Slope parameter in b-band (9) 70- 73 F4.1 mag gamma(b) ?=9.9 Profile indicator (10) 75- 76 I2 --- N(points) ?=99 Number of points used to form alpha(b) and gamma(b) 78- 80 I3 --- GP [1/923]? Number in Godwin and Peach (1977) 82- 84 I3 --- [RB67] [1/271]? Number in Rood and Baum (1967,1968) 86-104 A19 --- Com Comments (11)
Note (1): Metcalfe and Peach subjectively discriminated between galaxies and stars by examination of 14270 images brighter than b26.5 = 21.0. The final list of objects includes 6205 galaxies, 146 double galaxies, and 2 triple galaxies together with 350 probable galaxies and 21 probable double galaxies for a total of 6724 objects. An extensive discussion of the completeness and purity of the search is given in Section 5 of the paper Note (2): X and Y positions in arc seconds relative to the approximate center of the cluster, increasing westwards and northwards respectively. The origin of these coordinates is at RA=12h57.3 Dec=+28d14.4'(1950.0). The galaxies are ordered by increasing Xpos. Note (3): The b-band magnitude integrated within the 26.5b mag/arsec2 isophote. This limiting isophote, about 3 percent over the background sky brightness, was chosen for optimum signal-to-noise ratio. The rms deviation in b26.5, based on the repeatability of measurements using different scans of the same plates, is 0.13 mag for images brighter than b26.5 = 20, rising to 0.2 mag in the range 20 ≤ b26.5 < 21. The external errors are likely to be of order 0.15 mag for images brighter than b26.5 = 20. Note (4): The isophotal radius is defined by r = sqrt(A/pi) where A is the area enclosed within the isophote. Note (5): The r-band magnitude integrated within the 24.75r mag/arcsec2 isophote. This limiting isophote, about 3 percent over the background sky brightness, was chosen for optimum signal-to-noise ratio. The limiting isophotes for the r-band and b-band magnitudes are separated by roughly the mean galaxy color, so that they refer to roughly equal metric areas in a given galaxy. The rms deviation in r24.75 is 0.2 mag for images brighter than r24.75 = 18. The external errors are likely to be of order 0.15 mag for images brighter than b26.5 = 20. A value of 99.99 indicates the r-band magnitude was omitted because of the limited range of surface brightness measurement. Note (6): The external error in the (b-r) color is likely to be of order 0.15 mag for images brighter than b26.5 = 20. A value of 9.99 indicates that the color was not determined. Note (7): The ellipticity is defined by eps = (1-b/a) , where b/a is the axial ratio of the ellipse best approximating the 24r mag/arcsec2 isophote, or, in the event of an overlap, the lowest undisturbed isophote. The typical accuracy is ±0.1 for images with isophotal diameter r(r24) ≥ 5 arcsec. A value of 9.9 indicates the ellipticity was not determined. Note (8): The position angle, theta, of the major axis of the ellipse is measured counter-clockwise on the sky from north. This angle is measured to within a few degrees for most images. A value of 999 indicates that the position angle was not determined. Note (9): The slope parameter is defined as the slope of the logarithmic brightness residuals of each image against a polynomial representing the standard stellar profile. Its rms dispersion, based on measurements from overlapping scan areas, is about 0.05mag/arcsec. A value of 9.99 indicates the slope parameter was not determined. Note (10): this parameter specifies the amount by which the central surface brightness of the b-band image fell short of that which would have been expected for a stellar image with the same number of points measured. A value of 9.9 indicates that this quantity was not determined. Note (11): in cases where the object is marked as "double" or "triple" the photometric data refer to the combined image of its components.
References: Godwin, J. G., Peach, J. V. 1977, MNRAS 181, 711 =1977MNRAS.181..323G Rood, H. J., Baum, W. A. 1967, AJ 72, 398. =1967AJ.....72..398R Rood, H. J., Baum, W. A. 1968, AJ 73, 442. =1968AJ.....73..442R See also: J/A+AS/111/265 : More redshifts by Biviano et al. Historical Notes: * A tape version of the catalogue was provided by J.G. Godwin to CDS (Centre de Donnees de Strasbourg) in June 1983 * Modifications made by Lee E. Brotzman and Robert S. Hill at the Astronomical Data Center (ADC), Goddard Space Flight Center, in January 1984: to strip off the CDS number in the first eight bytes, strip off the last four bytes (which were always blank), and to insert default values (all nines) into numerical fields without data. A printed document describing the catalogue was generated. * 18-Aug-1995 at CDS: this standardized documentation was done from Lee E. Brotzman and Robert S. Hill's document.
(End) Francois Ochsenbein [CDS] 18-Aug-1995
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