VII. Explanation of Designations and Symbols Used

1. Positions of all objects are given for the epoch of 1950.0 and with an accuracy of about one minute of arc.
2. Most of the objects in this catalogue were originally published in seven lists which were distributed between 1963 and 1969 to various interested observers. They have been widely referred to in the literature by numbers N Zw n. Thus II Zw 36 for instance is the designation for the object 36 in Zwicky's original list II. For convenience of reference and identification these Zw numbers are also listed in the present catalogue.
3. The structural features of all objects are briefly described and it is indicated of whether they are single or members of groups and clusters.
4. Photographic apparent magnitudes m_p were estimated from the inspection of copy-negatives of the original Palomar 48-inch Schmidt survey plates. The values of m_p are subject to considerable errors since the original plates themselves were not available for our study. Estimated colors may also be afflicted by the same uncertainties, but they should nevertheless be of help in enabling observers to identify all objects listed.

   For compact and post-eruptive galaxies that are listed in the six volume catalogue of galaxies and of clusters of galaxies, by Zwicky et al. (referred to by CAT), the values of m_p are given as m_p = ....[CAT]. The designation Cl .... also refers to clusters of galaxies listed in the CAT.

   In a few cases indicative absolute magnitudes M_p are also given. These are calculated on the assumption that the symbolic velocities of recession <V_s> are strictly proportional to the distances of the respective objects and that the Lundmark-Hubble redshift constant is equal to 100 km/sec per million parsecs.

5. Some of the post-eruptive galaxies and galaxies with compact parts can also be found in the NGC, IC and MCG (Vorontsov-Velyaminov morphological catalogue), as well as in the various radio-, variable star and blue star catalogues. The respective designations are therefore also added, whenever identification appeared certain.
6. Compact means that the object in question has an apparent photographic, visual, red or bolometric surface brightness greater than that corresponding to the 20th magnitude per square second of arc.

   Eruptive means that the output of radiation of the object in some range or ranges of wave length is variable.

   Post-Eruptive means that jets, flares and plumes are associated with the object in question which suggest past eruptive activity by their structures as well as by their colors and spectra.

7. Symbols used

   d = angular diameter of an object

   = angular distance between two objects

   l = angular length of jets, plumes and chains of objects, etc.

   mp, m_v = apparent photographic and photovisual magnitude

   M_p = indicative absolute photographic magnitude

   For the definition of indicative absolute quantities, such as indicative length, luminosity and mass see F. Zwicky and M. L. Humason, Ap. J. 132, 638, 1960.

   M = indicative mass

   M = mass of the sun

   L = indicative absolute luminosity

   = (M / M) / (L / L) = relative mass-luminosity ratio

   <V_s> = c < / > = average symbolic velocity of recession

   <V_s> followed by (Zwicky, year) means that the respective redshift / has been measured by Zwicky on a plate obtained with the nebular spectrograph of the 200-inch Hale telescope in the year indicated but has not been previously published

   abs. = absorption

   cont = continuum

   H,K = absorption lines of Ca II at 3968.5 and 3933.7

   G-band = blend of absorption lines at 4304.4, mainly due to CH

   [X] = forbidden line
   X without bracket = permitted line

   Off and on the usual designations for the structural types of ordinary galaxies are used, such as E = elliptical, S = normal spirals, SB = barred spirals, Irr. = irregulars.

   Letters N, S, E, W mean north, south, east, west; it is assumed that the letters S and E will not be confused with the same designations for spiral and elliptical galaxies.

   For references given in the tables, see bibliography which follows.