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Molonglo deep sky survey of radio sources.I. Dec Zone -20d.
Results of a deep survey made at 408 MHz with the Molonglo cross are given.
The catalogue lists positions and flux densities for a total of 373 radio
sources, most of which have not previously been catalogued, in a solid angle
of 0.0201 sr. This covers (with some excluded areas) right ascensions
01h00m - 06h44m and 13h45m-17h19m, with a range in declination of 41'.
Eighteen contour maps are given of sources that are extended or have very
close companions. A thorouth error analysis is given, as well as new
operational definitials of completeness and reliability. The lower limit
of flux density is 88 mJy, which is five times the r.m.s. error.
An upper limit of 1000 mJy has also been imposed. Typical errors in positions
are 15" and 6" at 250 mJy.
A short description of the Molonglo 1.6 km telescope and references
to more detailed accounts have been given by Devies et al. (1973).
The telescope is a meridian transit instrument, providing a comb of 11
simultaneous pencil beams along the meridian, separated by half the
beamwidth and spanning about 1/4^o of declination in all. For the present
survey, the beamwidth of the individual pencil beam was 2.66' in RA and
2.97' in dec, and the usual tapered aperture distribution was used.
The observations were made in Sep. 1973 over a period of 16 days, and
consist of drift scans with the telescope set to one declinatios number
during the transit of the RA range of the survey, and scanning a long
narrow strip of sky.
The flux densities in the present catalogue are given on the scale
due to Wyllie (1969MNRAS..142..229, 1969PAuSA...1..234). Hunstead
(1972MNRAS..157..367) has established a grid of subcalibtators on this
scale, and 16 of these were used as calibration sources for the observing
session. All were over 4Jy, so noise and confision errors were neglible
even for a single observation. The sources were
The flux densities were given by Hunstead (1972).
Molonglo deep sky survey of radio sources.II. Dec Zone -62d.
Results are given for the second zone of a deep survey made at 408 MHz Wdh the
Molonglo cross. The catalogue lists positions and flux densities for 95
sources, none of which has been previously catalogued, in a solid angle of
5.51 x 10^-3 sr. The right ascensions covered (with some excluded areas) are
18h26m to 00h06m, with a range in declination of 45'. The lower limit of flux
density is 84 mJy. An upper limit of looo mJy has also been imposed. The
position uncertainties are typically 12 at 100 mJy and 6 at 250 mJy.
The first instalment of the Molonglo deep sky survey, made at -20 deg, is
given in Part I (Robertson 1977a, present issue pp. 209-30), while the
number-flux density counts from both instalments are given in Part III
(Robertson 1977b, present issue pp. 241-9). The present paper gives the second
instalment of the deep sky survey, and contains the results from declination
zone -62 deg. The sensitivity of the Molonglo cross is greater at declinations
well south of the equator, due to the increased time taken for each source to
transit through the beams of the telescope. The improvement in sensitivity for
this survey relative to that at -20 deg was, however, not as great as expected