The online 3CRR catalogue: field information
This page gives information on each of the different fields in the
online catalogue.
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).
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.
This is usually the spectral index between 178 and 750 MHz.
This was originally made on the basis of low-resolution, low-frequency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.
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:
- 0 -- Low-excitation radio galaxy, redshift from low-excitation or
absorption lines.
- 1 -- Narrow-line radio galaxy.
- 2 -- Broad-line radio galaxy.
- 3 -- Quasar.
(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).)
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).