The online 3CRR catalogue: field information

This page gives information on each of the different fields in the online catalogue.

3CRR name

This is the name by which the radio source is most commonly known. The 3CRR catalogue includes several sources which were missed in the original 3C surveys, either because of low surface brightness or due to their proximity to other bright objects. These objects are listed with their names from other catalogues, typically either radio names from the 4C catalogue (e.g. 4C14.11) or the NGC name for the host galaxy (e.g. NGC6251).


178-MHz flux

The flux densities have been corrected to the flux scale used by Roger, Costain & Bridle (1973), following Laing & Peacock (1980). They are therefore different by a factor 1.09 from the fluxes in the original 3CRR paper.

Spectral index

This is usually the spectral index between 178 and 750 MHz.

Fanaroff-Riley classification

This was originally made on the basis of low-resolution, low-frequency images; the catalogue has references to the images used to make the current classification, which are sometimes, but not always, the same as the `best' radio image. A C denotes a compact, core-dominated source.


B1950.0 co-ordinates for the optical identification.

5-GHz core flux

Where possible we have tabulated the flux density of the core at 5 GHz on arcsecond scales (i.e. as measured at high resolution with the VLA or 5-km telescope) though we have tried to avoid listing the flux of known steep-spectrum cores which are resolved on 0.1-arcsec scales. In a few cases, particularly for compact steep-spectrum sources, a flux density derived from MERLIN or VLBI observations is quoted. Many of the flux densities come from the compilation of Giovannini et al. (1988). In some cases 5-GHz data were not available, and we have used other frequencies, most often 8 GHz. Some sources are known to be variable and the single values tabulated here must be used with caution. Notes to this field specify if either of these is true of a particular source.

Please let us know (see the index page for contact details) if you have a core detection for one of the sources with an upper limit, or a better upper limit, or a 5-GHz core value where we have one measured at another frequency.


Source type. Numerical values are as follows: (In the final version of the catalogue this will probably be replaced with a textual indicator of the source type which will be easier to interpret. Classifications come from LRL, supplemented where available by more recent spectroscopic observations by Robert Laing (private communication).)

'Best' radio map

This field gives references to radio maps of the object. The listing is not exhaustive. We have tried to pick out maps in the literature which show both the large- and small-scale structure of the source, preferably at a frequency between 1.4 and 8 GHz. For the sources with redshift < 0.5 an image of the `best' map in this sense can usually be found in Paddy Leahy's Atlas. The Atlas page for such an object can be viewed from the object page. For literature references we have relied heavily on compilations of recent VLA maps, such as Leahy & Perley (1991), Bridle et al. (1994), Leahy et al. (1997), Hardcastle et al. (1997) and Best et al. (1997), which between them cover a large fraction of the objects with z < 1, though we have tried to refer to detailed studies of individual objects where available.

We are particularly interested in receiving updates to the listings in this field. If you have made a better map than those listed here, please let us know.


B magnitude is Johnson B. V magnitude is Johnson V. R magnitude is Kron-Cousins R. r magnitude is Gunn r.

R magnitudes originally measured on the Johnson system have been converted to the Kron-Cousins system.

Galaxy magnitudes are given for a standard metric aperture of diameter 86 kpc (H_0 = 50, q_0 = 0).