scholarly journals The Texas Radio Astrometric Survey

1974 ◽  
Vol 61 ◽  
pp. 141-141
Author(s):  
James N. Douglas
Keyword(s):  
Radio Source ◽  
Radio Sources ◽  
Selection Effects ◽  
Sky Survey ◽  
Coordinate Measurements ◽  
Discrete Radio Sources

The 5-element Texas Interferometer is engaged in a 365 MHz survey of the sky with a primary goal of establishing positions of about 50000 discrete radio sources with an accuracy of about 1″ in each coordinate. Measurements are made relative to optical positions of identified sources, and the 2000 positions thus far obtained support our expectations of the accuracy of the survey. In a companion program, optical positions of objects near radio source positions are being measured to ±1/2″ accuracy on glass copies of the Palomar Sky Survey, yielding both improved overall calibration of the radio positions and identification of associated optical objects on the basis of position coincidence alone, without the selection effects usually introduced by auxiliary identification criteria.

scholarly journals A Comparison of the Structures of 3CR Quasars and Blank Field Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 435-436 ◽  
Author(s):  
F. N. Owen ◽  
J. J. Puschell ◽  
R. A. Laing
Keyword(s):  
Radio Source ◽  
Structural Properties ◽  
Low Frequency ◽  
Radio Sources ◽  
Blank Field ◽  
Sky Survey

The purpose of this communication is to update our knowledge of the radio structural properties of quasars and blank field radio sources (blank field ≡ any radio source without an identification on the Palomar Sky Survey prints). The quasar sample consists of all sources (25) with angular sizes greater than 10 arcsec in the list of Jodrell Bank quasars observed by Owen, Porcas and Neff (1978). The blank fields consist of 16 3CR sources also with structures >10 arcsec based on Cambridge 5 km telescope observations. The sources were selected in low-frequency surveys; their emission at ν < 1 GHz is dominated by extended components with steep spectra. Thus, both samples should be oriented randomly in space except for a slight bias to be in the plane of the sky.

scholarly journals Observations of Radio Emission from Normal Galaxies

1963 ◽  
Vol 16 (3) ◽  
pp. 360 ◽  
Author(s):  
DS Mathewson ◽  
JM Rome
Keyword(s):  
Radio Emission ◽  
Radio Source ◽  
Spiral Galaxies ◽  
Radio Sources ◽  
Early Type ◽  
General Belief ◽  
Normal Galaxies ◽  
Discrete Radio Sources

The results of observations of 37 normal galaxies using the 21O-ft steerable reflector of the A.N.R.A.O. at 1410 and 408 Mcls are presented. All southern galaxies brighter than tenth magnitude were studied. Twenty galaxies were detected, fourteen of which were new identifIcationis. Sc galaxies were found to have a mean radio index at 1410 Mcls of +3�3 with an r.m.s. deviation of 0�6. The ratio of optical to radio emission was signifIcantly higher for irregular and early type galaxies than for Sb and Sc galaxies_ Contrary to general belief, no constant relationship was found between the optical and radio sizes of spiral galaxies. Two discrete radio sources were detected in the Pegasus I cluster, one of which may be identified with the El galaxy, NGC 7626. The radio source found in Pegasus II coincided in position with the E3 galaxy, NGC 7501, in the cluster.

A Confusion Limited Radio Survey from the Molonglo Cross

1984 ◽  
Vol 5 (3) ◽  
pp. 290-340 ◽  
Author(s):  
Graeme L. White
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Radio Sources ◽  
Chronological Order ◽  
Extragalactic Radio Sources ◽  
Density Limit ◽  
Sky Survey ◽  
Radio Survey

Several catalogues of radio sources at 408 MHz have been prepared from observations made with the Molonglo cross telescope. These include (in chronological order) ‘The Molonglo Radio Source Catalogue 1’, the MC1, by Davies et al. (1973), the MC2 and MC3 by Sutton et al. (1974), MC4 by Clarke et al. (1976), ‘The Molonglo Deep Sky Survey of Radio Sources’ by Robertson (1977a,b,d) and ‘The Molonglo Reference Catalogue of Radio Sources’ (MRC) by Large et al. (1981). The catalogues MC1-4 cover selected areas of sky to a flux density limit of ~0.2 Jy to 0.3 Jy. The MRC includes extragalactic radio sources between δ = +18° and δ = −85° and is essentially complete at S408 = 1.00 Jy with raany sources to ˜0.7 Jy. The Wyllie (1969a,b) scale of flux density is used throughout.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A3 ◽  
Author(s):  
Andrew Butler ◽  
Minh Huynh ◽  
Jacinta Delhaize ◽  
Vernesa Smolčić ◽  
Anna Kapińska ◽  
...  
Keyword(s):  
Radio Source ◽  
Galactic Nuclei ◽  
Spectral Energy ◽  
Radio Sources ◽  
Density Level ◽  
Energy Distributions ◽  
Sky Survey ◽  
Multiple Component ◽  
Good Agreement ◽  
Compact Array

The 2.1 GHz radio source catalogue of the 25 deg2 ultimate XMM extragalactic survey south (XXL-S) field, observed with the Australia Telescope Compact Array (ATCA), is presented. The final radio mosaic achieved a resolution of ~ 4.8″ and a median rms noise of σ ≈ 41 μJy/beam. To date, this is the largest area radio survey to reach this flux density level. A total of 6350 radio components above 5σ are included in the component catalogue, 26.4% of which are resolved. Of these components, 111 were merged together to create 48 multiple-component radio sources, resulting in a total of 6287 radio sources in the source catalogue, 25.9% of which were resolved. A survival analysis revealed that the median spectral index of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz sources in the field is α = −0.75, consistent with the values of − 0.7 to − 0.8 commonly used to characterise radio spectral energy distributions of active galactic nuclei. The 2.1 GHz and 1.4 GHz differential radio source counts are presented and compared to other 1.4 GHz radio surveys. The XXL-S source counts show good agreement with the other surveys.

scholarly journals VLBA+GBT observations of the COSMOS field and radio source counts at 1.4 GHz

2018 ◽  
Vol 616 ◽  
pp. A128 ◽  
Author(s):  
N. Herrera Ruiz ◽  
E. Middelberg ◽  
A. Deller ◽  
V. Smolčić ◽  
R. P. Norris ◽  
...  
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Lower Limit ◽  
High Sensitivity ◽  
Host Galaxy ◽  
Radio Sources ◽  
Source Population ◽  
Star Forming ◽  
Brightness Temperatures ◽  
Long Baseline

We present very long baseline interferometry (VLBI) observations of 179 radio sources in the COSMOS field with extremely high sensitivity using the Green Bank Telescope (GBT) together with the Very Long Baseline Array (VLBA) (VLBA+GBT) at 1.4 GHz, to explore the faint radio population in the flux density regime of tens of μJy. Here, the identification of active galactic nuclei (AGN) is based on the VLBI detection of the source, meaning that it is independent of X-ray or infrared properties. The milli-arcsecond resolution provided by the VLBI technique implies that the detected sources must be compact and have large brightness temperatures, and therefore they are most likely AGN (when the host galaxy is located at z ≥ 0.1). On the other hand, this technique only allows us to positively identify when a radio-active AGN is present, in other words, we cannot affirm that there is no AGN when the source is not detected. For this reason, the number of identified AGN using VLBI should be always treated as a lower limit. We present a catalogue containing the 35 radio sources detected with the VLBA+GBT, ten of which were not previously detected using only the VLBA. We have constructed the radio source counts at 1.4 GHz using the samples of the VLBA and VLBA+GBT detected sources of the COSMOS field to determine a lower limit for the AGN contribution to the faint radio source population. We found an AGN contribution of >40−75% at flux density levels between 150 μJy and 1 mJy. This flux density range is characterised by the upturn of the Euclidean-normalised radio source counts, which implies a contribution of a new population. This result supports the idea that the sub-mJy radio population is composed of a significant fraction of radio-emitting AGN, rather than solely by star-forming galaxies, in agreement with previous studies.

scholarly journals High Frequency Peakers

2003 ◽  
Vol 20 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Daniele Dallacasa
Keyword(s):  
Radio Source ◽  
High Frequency ◽  
Peak Frequency ◽  
Source Size ◽  
Host Galaxy ◽  
Radio Sources ◽  
Inner Region

AbstractThere is quite a clear anticorrelation between the intrinsic peak frequency and the overall radio source size in compact steep spectrum (CSS) and gigahertz peaked spectrum (GPS) radio sources. This feature is interpreted in terms of synchrotron self-absorption (although free–free absorption may play a role as well) of the radiation emitted by a small radio source which is growing within the inner region of the host galaxy. This leads to the hypothesis that these objects are young and that the radio source is still developing/expanding within the host galaxy itself.Very young radio sources must have the peak in their radio spectra occurring above a few tens of gigahertz, and for this reason they are termed high frequency peakers (HFPs). These newly born radio sources must be very rare given that they spend very little time in this stage. Ho = 100 km s−1 Mpc−1 and qo = 0.5 are used throughout this paper.

scholarly journals Further Identifications For Strong Extragalactic Radio Sources In The Declination Zone 0° To ?20°

1966 ◽  
Vol 19 (5) ◽  
pp. 713 ◽  
Keyword(s):  
Radio Sources ◽  
Extragalactic Radio Sources ◽  
Sky Survey

We recently reported identifications for 71 extragalactic radio sources between declinations 0� and ?20� (Bolton and Ekers 1966). The identifications were based on a search of the 48 in. Sky Survey prints in positions etermined by Shimmins, Clarke, and Ek

The Limiting Magnitude of the ESO-B and SRC-J Sky Survey

1977 ◽  
Vol 3 (2) ◽  
pp. 128-129
Author(s):  
G. L. White
Keyword(s):  
Radio Sources ◽  
Wide Strip ◽  
Sky Survey ◽  
Southern Section

As part of an identification programme undertaken on the southern section of the Molonglo Deep Sky Survey of Radio Sources, the limiting magnitudes of some of the available ESO-B films and SRC-J films and plates in this area have been determined. The Molonglo Deep Sky Survey has been described by Robertson (1977). The southern section comprises a 45’ wide strip centred about declination -62° and stretching in an irregular fashion from 18h 25m to 00h 16m.

scholarly journals Observations of Galactic and Extragalactic Jets

1986 ◽  
Vol 89 ◽  
pp. 403-424
Author(s):  
R.A. Perley
Keyword(s):  
Radio Sources ◽  
Fourier Synthesis ◽  
Original Design ◽  
Quality Of Information ◽  
Very Large Array ◽  
Imaging Interferometer ◽  
Extragalactic Jets ◽  
Angular Extent ◽  
Discrete Radio Sources

Since nearly all discrete radio sources of astronomical interest are of insufficient angular extent for their detailed structural properties to be accessible to single-dish radio telescopes, radio interferometry must be employed to gain information on the morphologies of these objects. Recently constructed imaging interferometer arrays which employ the technique of Fourier synthesis, particularly MERLIN and the VLA (Very Large Array), and the more recent VLBI arrays, have given unprecedented imaging capabilities, with the result that our knowledge, and hence perceptions, of discrete radio sources have vastly changed over the last few years. An equally important parallel development has been image processing algorithms. These have vastly improved the quality of information produced by these arrays, so that an instrument such as the VLA can now produce images with speed and quality exceeding original design specifications by factors of 100 to 1000.

scholarly journals Advanced stream search for galaxy clusters with multifrequency microwave data

2018 ◽  
Vol 191 ◽  
pp. 01008
Author(s):  
Oleg Verkhodanov ◽  
Natalia Verkhodanova ◽  
Olesya Ulakhovich ◽  
Dmitrij Solovyov ◽  
Margarita Khabibullina
Keyword(s):  
Galaxy Clusters ◽  
A Priori ◽  
Radio Sources ◽  
Sky Survey ◽  
Microwave Data

Based on the data from the Westerbork Northern Sky Survey performed at a frequency of 325 MHz in the range of right ascensions 0h ≤ α < 2h and declinations 29o < δ < 78o and using multifrequency Planck maps, we selected candidate objects with the Sunyaev-Zeldovich effect. The list of the most probable candidates includes 381 sources. It is shown that the search for such objects can be accelerated by using a priori data on the negative level of fluctuations in the CMB map with remote low multipoles in the direction to radio sources.

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