Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.sao.ru/fetch/HL/leda/rawcat/a110.html
Дата изменения: Mon Dec 23 18:23:59 2013 Дата индексирования: Fri Feb 28 17:29:43 2014 Кодировка: Поисковые слова: md-11 |
![]() |
Compilation of cz (radial velocity) measurements |
| HyperLeda home | Documentation | Search by name | Search near a position | Define a sample | SQL Search | |
The catalog (table a110 in the database) presents the compilation of redshift of galaxies, z,
The observed shift in wavelength or frequency of light emitted by an object consists of relativistic Doppler effect, gravitational and cosmological redshifts. We can neglect the gravitational redshift in most of cases of extragalactic astronomy because the effect is very small. The cosmological redshift arises due to Hubble expansion of the Universe. The relativistic Doppler effect appears because of physical motion of the object and observer with respect to each other. See also the article on redshift from Wikipedia.
So called "optical" convention is
The "radio" convention is
Ref. number | Reference | Number of cz |
---|---|---|
27127 | SDSS - DR2 | 254507 |
24401 | 2DF | 236202 |
27139 | SDSS - DR4 | 136637 |
27128 | SDSS - DR3 | 114701 |
27124 | SDSS (Stoughton 2002) | 85221 |
The three main references from radio measurements are
23289 | Theureau et al. 1998 | 2143 |
4008 | de Vaucouleurs et al. RC3 | 1487 |
24372 | Haynes et al. 1999 | 1201 |
Below is a description of the fields of the table that can be accessed through the interfaces.
Heliocentric radial velocity (CZ) in km/s with its uncertainty and quality flag in parentheses (in html displays).
The quality flag has the following meaning:
description of quality flag | |
---|---|
value | signification |
0 | regular measurement |
1 | uncertain measurement, its weight is decreased by a factor 2 when computing the average value |
3 | preliminary measurement, probably superseeded in a more recent publication, it is ignored unless no other measurement is available |
4 | compilation, it is ignored unless no other measurement is available |
9 | rejected measurement |
Method of Measurement
code |
definition |
---|---|
0 | unspecified method |
1 | optical measurement |
2 | radio measurement |
3 | optical measurement from a particular region (knot. region HII) |
4 | radio CO |
5 | radio OH |
6 | average of measurements of members |
7 | RVSAO (cross correlation) |
8 | EMSAO (emission lines) |
Resolution in km/s when the velocity comes from radio measurement
Line Code: code of the spectral line used for making a measurement
code |
definition |
0 |
unspecified |
1 |
emission line (like 21-cm line
or H_alpha line) |
2 |
absorption line |
HyperLeda | Questions: leda@univ-lyon1.fr |