Third Reference Catalogue of Bright Galaxies


This subdirectory contains the Third Reference Catalogue of Bright Galaxies (RC3). This file has details about this distribution of RC3.

The file rc3.10.0.dat contains the entire catalogue of 23,001 galaxies. Two previous versions of RC3 are also available here: rc39b.dat (no plus/minus symbols; also omitted in "rc3.10.0.dat") and rc39c.dat (with a few miscellaneous corrections, and with "±" (plus/minus) symbols as in the printed version; these "±" symbols may display in your browser, database manager, or other application with different characters depending on the file type).

These files are ASCII files containing only 7-bit ASCII characters (except the plus/minus symbols in "rc39c.dat"). bintro.tex, with LaTeX commands, is an earlier version of this file, and applies to "rc39[b|c].dat".

Finally, there is a comma-separated-variable version rc39b.csv for those who wish to import RC3 into a spreadsheet or DBMS. The contents of the CSV file are the same as "rc39b.dat"; the file is briefly described in rc3colscsv.txt. I'll be happy to prepare a CSV version of "rc3.10.0.dat" if I have requests for it.

1. Introduction

This is a brief description of the data entries in the Third Reference Catalogue of Bright Galaxies (RC3) by G. and A. de Vaucouleurs, H.G. Corwin, R.J. Buta, G. Paturel, and P. Fouque. It accompanies an ASCII version of RC3.10.0 (dated 1 June 2020) distributed on the World Wide Web. Any problems relating to this particular distribution should be addressed directly to me at

hcorwin1153@sbcglobal.net

Files included in this distribution are:

Please note that there are only 23,001 entries in RC3.10.0. Several Galactic objects, plate defects, and duplicate entries have been removed. Details are in the "rc3[new]bugs.txt" files (links above), and in Corwin et al., AJ 108, 2128, 1994.

Details of the reduction procedures, and Notes, References, and Appendices are in Volume 1 of the printed version of RC3, available from Springer-Verlag New York. References here to page numbers are to this first volume of RC3. Volumes 2 and 3 (included in the current distribution) are also available from Springer-Verlag should you wish to have a printed and bound version of the complete catalogue.

2. Revisions and Additions

This version of RC3 was inspired by my work on a forthcoming all-sky galaxy catalogue for amateur astronomers who might want a more compact and up-to-date list than the original RC3. (For preliminary examples of where that all-sky catalogue might be headed, see the SGC and SEGC sections of this web site.) I needed to use RC3 for its photometric systems of diameters and magnitudes, but -- with the two different precisions given for the positions, and with RC3's non-standard name formats -- I found the older versions of RC3 difficult to use. This new version addresses both of those shortcomings, and adds some significant new data as well.

3. Use and Distribution

You may use any of the data in the electronic versions of RC3 in any way you wish. We do ask that you acknowledge RC3 and its authors in any publication that results from your use of the Catalogue. You may also freely distribute unaltered electromagnetic copies of RC3 to friends and colleagues as long as a copy of this documentation -- including this notice -- accompanies the Catalogue.

The printed version of RC3 is protected by copyright, and may not be reproduced in any manner without the written permission of the copyright holder, Springer-Verlag New York, Inc.

4. The Catalogue

The data for each galaxy are found on four successive lines. The entries are as follows:

  • Column 1 -- Positions
  • Line 1 -- RA and DEC = right ascension and declination for the equinox J2000.0, given to 0.1 second of time and 1 arcsec (Section 3.1.a, page 11). For "rc39[b|c].dat", the J2000 position is precessed from the B1950 position. For "rc3.10.0.dat", the J2000 position is the "base" position for RC3 and is precessed to B1950.
  • Line 2 -- l and b = Galactic longitude and latitude in the IAU 1958 system (Blaauw et al. 1960); both to 0.01 degrees.
  • Line 3 -- SGL and SGB = supergalactic longitude and latitude in the RC2 system (Section 3.1.b), both to 0.01 degrees.
  • Line 4 -- RA and DEC = right ascension and declination for the equinox B1950.0, precessed from the J2000.0 position in Column 1, Line 1 (Section 3.1.a, page 11). For "rc39[b|c].dat", the B1950 position is the "base" position for RC3, and is precessed to J2000.
  • Column 2 -- Names = commonly used designations for the galaxies (Section 3.2, page 12).
  • Line 1 -- Names (e.g. LMC, SMC) or NGC and IC designations.
  • Line 2 -- UGC (Nilson 1973), ESO (Lauberts 1982), MCG, Volumes 1-4 and MCG, Volume 5 (Vorontsov-Velyaminov et al. 1962-1974), UGCA (Nilson 1974), and CGCG (Zwicky et al. 1961-1968) designations, given in that order of preference. MCG designations not listed here are given in UGC, UGCA, and ESO.
  • Line 3 -- Other common designations (see Table 1, page 14, for a complete list).
  • Line 4 -- PGC (Paturel et al. 1989) designation. For cross identifications of various catalogues with PGC, see Appendix 10, page 561.
  • Column 3 -- Types and Luminosity Classes
  • Line 1 -- Type = mean revised morphological type in the RC2 system, coded as in RC2 (Section 3.3.a, page 13).
  • Line 2 -- ST and nL = sources of revised type estimates and number of luminosity class estimates. To those sources listed in Table 3, page 16, I have added "HC" meaning classifications by me, not otherwise published. I have arbitrarily assigned an error of 1.5 to these types.
  • Line 3 -- T = mean numerical index of stage along the Hubble sequence in the RC2 system (coded as explained in Section 3.3.c, page 16), and its mean error.
  • Line 4 -- L = mean numerical luminosity class in the RC2 system (coded as explained in Section 3.3.d, page 18), and its mean error. As with the types in Column 3, Line 1, my new luminosity classes carry an arbitrary error of 1.5.
  • Column 4 -- Optical Diameters and Axis Ratios
  • Line 1 -- logD25 = mean decimal logarithm of the apparent major isophotal diameter measured at or reduced to surface brightness level μB = 25.0 B-mag/arcsec2, and its mean error, as explained in Section 3.4.a, page 21. The unit of D is 0.1 arcminute to avoid negative entries. A few very uncertain diameters are flagged with question marks.
  • Line 2 -- logR25 = mean decimal logarithm of the ratio of the major isophotal diameter, D25, to the minor isophotal diameter, d25, measured at or reduced to the surface brightness level μB = 25.0 B-mag/arcsec2, and its mean error, as explained in Section 3.4.b, page 26. A few very uncertain axis ratios are flagged with question marks.
  • Line 3 -- logAe = decimal logarithm of the apparent diameter (in 0.1 arcmin) of the "effective aperture," the circle centered on the nucleus within which one-half of the total B-band flux is emitted, and its mean error, both derived as explained in Section 3.4.c, page 28.
  • Line 4 -- logD0 = decimal logarithm of the isophotal major diameter corrected to "face-on" (inclination = 0 degrees), and corrected for Galactic extinction to Ag = 0, but not for redshift, as explained in Section 3.4.d, page 29.
  • Column 5 -- Major Axis Position Angle, Galactic and Internal Extinctions
  • Line 1 -- p.a. = position angle, measured in degrees from north through east (all p.a. < 180 degrees), taken when available from UGC, ESO, and the Kiso Atlas (and in a few cases from HI data) (Section 3.5.a, page 30).
  • Line 2 -- Ag = Galactic extinction in B-band magnitudes, calculated following Burstein and Heiles (1978a), (1978b), (1982), and (1984), as explained in Section 3.5.b, page 30.
  • Line 3 -- Ai = internal extinction in B-band magnitudes (for correction to face-on), calculated from logR and T, as explained in Section 3.5.c, page 31.
  • Line 4 -- A21 = HI line self-absorption in magnitudes (for correction to face-on), calculated from logR and T >= 1, as explained in section 3.5.d, page 32.
  • Column 6 -- Optical and Infrared Magnitudes
  • Line 1 -- BT = total (asymptotic) magnitude in the B system, and its mean error, derived by extrapolation from photoelectric aperture-magnitude data, BTA, and from surface photometry with photoelectric zero point, BTS, as explained in Section 3.6.a, page 32. The magnitude is followed by an "M" when it is the weighted mean of BTA and BTS, by a "V" when it is a V-band magnitude rather than a B-band magnitude, and by a "v" when the nucleus of the galaxy is variable. The magnitude is replaced by an asterisk (*) when deriving BTA would have required an extrapolation in excess of 0.75 mag.
  • Line 2 -- mB = photographic magnitude and its mean error from Ames (1930), Shapley and Ames (1932), CGCG, Buta and Corwin (1986), and/or Lauberts and Valentijn (1989) reduced to the BT system, as explained in Section 3.6.b, page 37.
  • Line 3 -- mFIR = far-infrared magnitude calculated from mFIR = -20.0 - 2.5logFIR, where FIR is the far infrared continuum flux measured at 60 and 100 microns as listed in the IRAS Point Source Catalog (1987). For galaxies larger than 8 arcmin in RC2 and for the Virgo cluster area, resolved by the IRAS beam, integrated fluxes are taken from Rice et al. (1988) or Helou et al. (1988). See Section 3.6.c, page 43, for details.
  • Line 4 -- BT0 = total "face-on" magnitude corrected for Galactic and internal extinction, and for redshift, as explained in Section 3.6.d, page 44.
  • Column 7 -- Total Color Indices
  • Line 1 -- (B-V)T = total (asymptotic) color index in the Johnson B-V system, and its mean error, derived by extrapolation from photoelectric color-aperture data, and/or from surface photometry with photoelectric zero point, as explained in Section 3.7.a, page 45.
  • Line 2 -- (U-B)T = total (asymptotic) color index in the Johnson U-B system, and its mean error, derived by extrapolation from photoelectric color-aperture data, and/or from surface photometry with photoelectric zero point, as explained in Section 3.7.a, page 45.
  • Line 3 -- (B-V)T0 = total B-V color index corrected for Galactic and internal extinction, and for redshift, as explained in Section 3.7.b, page 47.
  • Line 4 -- (U-B)T0 = total U-B color index corrected for Galactic and internal extinction, and for redshift, as explained in Section 3.7.b, page 47.
  • Column 8 -- Effective Color Indices and B-band Surface Brightness
  • Line 1 -- (B-V)e = mean B-V color index, and its mean error, within the effective aperture Ae, derived by interpolation from photoelectric color-aperture data, as explained in Section 3.7.a, page 45.
  • Line 2 -- (U-B)e = mean U-B color index, and its mean error, within the effective aperture Ae, derived by interpolation from photoelectric color-aperture data, as explained in Section 3.7.a, page 45.
  • Line 3 -- m'e = mean B-band surface brightness in magnitudes per square arcmin (B-mag/arcmin2) within the effective aperture Ae, and its mean error, as given by the relation m'e = BT + 0.75 + 5logAe - 5.26. m'e is statistically related to the effective mean surface brightness, μ'e (RC2, p. 31; Olson and de Vaucouleurs 1981), with which it coincides when log R = 0 (i = 0 degrees) (Section 3.8.a, page 49).
  • Line 4 -- m'25 = the mean surface brightness in magnitudes per square arcmin (B-mag/arcmin2) within the μB = 25.0 B-mag/arcsec2 elliptical isophote of major axis D25 and axis ratio R25, defined as in RC2 (Equation 21) by: m'25= BT + Delta m25 + 5logD25 - 2.5logR25 - 5.26, where Delta m25 = 2.5log(LT/LD25) = B25 - BT is the magnitude increment contributed by the outer regions of a galaxy fainter than μB = 25.0 B-mag/arcsec2. For details, see Section 3.8.b, page 50.
  • Column 9 -- 21-cm Magnitude and Linewidths, Hydrogen Index
  • Line 1 -- m21 = 21-cm emission line magnitude, and its mean error, defined by m21 = 21.6 - 2.5log(SH), where SH is the measured neutral hydrogen flux density in units of 10-24 W/m2. For details, see Section 3.9.a, page 51.
  • Line 2 -- W20 = neutral hydrogen line full width (in km/s) measured at the 20% level (I20/Imax), and its mean error, as explained in Section 3.9.b, page 51.
  • Line 3 -- W50 = neutral hydrogen line full width (in km/s) measured at the 50% level (I50/Imax), and its mean error, as explained in Section 3.9.b, page 51.
  • Line 4 -- HI = corrected neutral hydrogen index, which is the difference m210 - BT0 between the corrected (face-on) 21-cm emission line magnitude and the similarly corrected magnitude in the BT system. Details are given in Section 3.9.c, page 52. Since m21 and BT are listed separately in columns 6 and 9, line 1, there is no need to list the uncorrected index.
  • Column 10 -- Radial Velocities
  • Line 1 -- V21 = cz is the mean heliocentric radial velocity, and its mean error, in km/s derived from neutral hydrogen observations, as explained in Section 3.10.a, page 52.
  • Line 2 -- Vopt = cz is the mean heliocentric radial velocity, and its mean error, in km/s derived from optical observations, as explained in Section 3.10.b, page 53.
  • Line 3 -- VGSR = the weighted mean of the neutral hydrogen and optical velocities, corrected to the "Galactic standard of rest," as explained in Section 3.10.c, page 54.
  • Line 4 -- V3K = the weighted mean velocity corrected to the reference frame defined by the 3 K microwave background radiation, as explained in Section 3.10.d, page 55.
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    hcorwin1153@sbcglobal.net

    Latest revision of this file: 14 June 2020