7C(G) Source List Description

The entries in the source list are as follows:

• Right ascension and declination of the beam fitted position of the source at epoch B1950.0; the rms accuracies are 5 and 7 arcsec respectively.
• Right ascension and declination of the centroid position of the source at epoch B1950.0. Multiple peaks integrated together have the same centroid positions.
• The Galactic longitude and latitude of the beam fitted position of the source.
• The beam-fitted and integrated flux densities, in Jy. The beam-fitted flux is the preferred flux density unless the source is clearly extended, in which case the integrated flux density should be used.
• The signal-to-noise ratio, i.e. the interpolated peak height of the source on the map (after subtraction of the local zero level), divided by the local noise.
• The extent of the source size in units of the local beam area. This estimate is influenced by residual ionospheric smearing of the synthesised beam. Another measure of whether a source is resolved or not, is the ratio of integrated/beam-fitted flux densities. The flux density calibration is performed in such a way as to ensure that the median value of this ratio for unresolved sources is unity. Thus, any source with this ratio >>1 is resolved, and for this survey a ratio of integrated/beam-fitted flux densities greater than about 1.2 is a good indication that the source is resolved.
• The number of individual peaks that were included in the flux integration is given, together with a single character flag indicating whether the source is the main (`M') or a component (`C') peak in the integration. Usually no number and flag are given, indicating the source has a single peak only. For multiple sources each peak has a separate entry in the source list, with its own beam fitted flux density and position, although the integrated flux and the centroid position are the same for each. Some multiple peaked sources appear with different numbers of components in overlapping fields. These entries have not been averaged together, and care should be taken with such entries.

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