Stromberg's original list [258] of optical radial velocities contained 41 galaxies. Some forty years later optical redshifts for 583 galaxies were published [146]. In the RC1 and RC2 ([7, 8] in Secondary Galaxy Catalogs) some 280 references to sources of optical velocity data are listed (Tables 12 and 13, respectively), with an additional 538 references to optical redshifts being found in RC3 ([9] in Secondary Galaxy Catalogs). Velocity data is no longer restricted to the optical measurements but includes derivations from 21-cm radio observations (see for instance [148, 262], Table V2 in RC2, and 209 references to radio wavelength redshifts in RC3, complete to 1987); corrections for errors in redshifts [232].

A major compilation [206] contains redshifts and original references for 8,250 galaxies, complete to 1980 and supersedes [121]; cross-correlation redshifts are discussed for 59 galaxies in [167]; redshifts for 115 galaxies [248]; a study of a complete sample of field galaxies [174]; data for 1093 galaxies with m_pg < 15.5 mag in a 6 degree strip across the North Galactic Cap [145]; the southern sky redshift survey [63]; radial velocities for 301 pairs of galaxies [158]; 44 galaxies in Perseus [106]; 359 galaxies in Abell clusters [280]; 285 galaxies observed for bulge-to-disk ratio estimates [241]; IRAS galaxies in the Bootes Void area [268]; a deep survey of 280 galaxies [175]; deep survey of IRAS galaxies towards the Bootes Void [89]; 5 suspected superclusters [53]; s-type Markarian galaxies [149]; multi-object spectroscopy of galaxies in Abell 400, 576, 1767 and 2124 [135]; 102 dwarf galaxies [96]; 75 galaxies in Abell 2256 [172]; 387 southern compact and bright-nuclei galaxies [102, 103]; 84 brightest Abell cluster galaxies [242]; 100 galaxies in 10 clusters [219]; 161 galaxies in 11 clusters [101]; 71 galaxies in the Indus region [62]; galaxies in Abell 496 and 2052 [220]; Tololo emission-line galaxies [28]; 298 late-type galaxies in the Virgo Cluster [137]; 155 galaxies in the winter Galactic Plane [196]; 135 galaxies in the Virgo region [97]; 472 galaxies in the Pisces-Perseus supercluster [120]; 100 galaxies in the Coma Cluster [263]; high-precision 21cm redshifts for 625 galaxies [264]; low surface brightness objects [244]; 150 galaxies in the Hercules supercluster [260]; 123 galaxies in the Cancer cluster [12]; 83 galaxies in poor cD clusters [18]; 21cm velocities for 440 galaxies betwen the Local supercluster and the Hydra-Centaurus supercluster [228]; 71 galaxies in the Hydra I (Abell 1060) cluster [229]; 469 elliptical galaxies [67]; 342 galaxies toward the Bootes Void [257]; 88 image-tube spectra of 79 galaxies [165]; flux-limited sample of 72 IRAS galaxies [249]; 21cm velocities for 342 out of 415 galaxies, and 383 galaxies observed in the Pisces-Perseus supercluster [118, 119, 127]; 228 southern galaxies [64]; Medium Sensitivity Survey X-ray sources [116]; several hundred spiral galaxies in 10 clusters [31]; 21cm redshifts for 324 isolated galaxies [126]; 26 galaxies in the direction of the Coma/Abell 1367 supercluster [123]; 92 galaxies in the direction of the Coma cluster [265]; flux-limited sample of IRAS galaxies [269]; 129 galaxies in groups and clusters [51]; approximately 40 galaxy redshifts in each of 14 rich clusters [55]; 1,268 radial velocities in 15 rich clusters [95]; 157 galaxies in 54 triplets [161]; galaxies in the Horologium region [52]; 559 Selected Area 94 objects [17]; 719 bright galaxies [235]; 21cm observations of 1787 nearby galaxies [105]; 21cm observations for 183 galaxies [262]; 164 field galaxies brighter than B ~ 15.5 mag [174]; 90 IRAS galaxies [133]; 172 central galaxies and companions [7]; 530 IRAS galaxies [184]; 70 peculiar objects [191]; redshifts in Klemola 27 [225]; 21cm observations for galaxies in the Pegasus I cluster [226]; 156 binary systems [275]; 145 blue Zwicky compact galaxies [179]; 160 galaxies in Abell 194 [50]; 289 galaxies in Abell 539 [201]; 107 southern galaxies [207]; 266 galaxies in the Hydra-Centaurus region [104]; the Fornax cluster [154, 227]; 300 galaxies in a strip crossing the Coma cluster [160]; galaxies with supernovae [13, 14, 15, 16]; compilation of double galaxy redshifts [215]; radial velocities of isolated galaxies [162]; 39 peculiar ESO galaxies [29]; redshifts for Karachensteva isolated galaxies [163], and for Karachentsev isolated triples [164]; radial velocities for 21 interacting double galaxies [159]; Zwicky compact galaxies [239].

Accidental and systematic errors in various sets of velocity measurements are discussed in [10, 86, 141, 185, 203, 230, 232]. A total of 2,713 velocities are reduced to a standard system in RC2; this was increased to 16,693 in RC3.

Corrections for the Solar Motion:

Radial velocities, V, when referred to the Galactic centre, must be corrected for the orbital motion of the Sun. Most researchers in the field (e.g., [236] or RC2) adopt the standard correction of

V = 300sinl x cosb km/s

where it is assumed that the Sun is moving at 300 km s^-1 toward l = 90 , b = 0, which is in good agreement with the estimate of V = (315 ± 15) km s^-1 toward l = 95, b = -8 for the Local Group velocity centroid [88].