scholarly journals Australian Journal of Physics Astrophysical Supplement

1976 ◽  
Vol 29 (5) ◽  
pp. 471
Author(s):  
JN Clarke ◽  
AG Little ◽  
BY Mills
Keyword(s):  
Flux Density ◽  
High Frequency ◽  
Magellanic Clouds ◽  
Australian Journal ◽  
The Other ◽  
Optical Data ◽  
Radio Sources ◽  
Angular Extent

The fourth catalogue of radio sources observed at 408 MHz with the Molonglo radiotelescope is presented. A total of 1349 sources is listed to a limiting flux density of 0�2 Jy, the catalogue being largely complete above 0� 25 Jy. The area of sky surveyed includes the Magellanic Clouds as well as a comparison region of similar angular extent. Detailed notes are provided on some of the Cloud sources, and maps are given for complex sources in the region of the Clouds. Those sources for which high-frequency or optical data are available are classified into two lists, one of Cloud members and the other of 'unidentified nonthermal sources', presumably not Cloud members.

scholarly journals Connection Between Optical and High Frequency Radio Variability in AGN

1994 ◽  
Vol 159 ◽  
pp. 411-411
Author(s):  
M. Tornikoski ◽  
E. Valtaoja ◽  
A.G. Smith ◽  
A.D. Nair
Keyword(s):  
High Frequency ◽  
Optical Data ◽  
Research Station ◽  
Radio Sources ◽  
Data Sets ◽  
Temporal Data ◽  
Extragalactic Radio Sources ◽  
Radio Data

We have been searching for correlated optical and radio variability in large temporal data sets of 22 extragalactic radio sources. The optical data were obtained with the 76-cm reflector at the Rosemary Hill Observatory in Florida, USA. The radio data were obtained at two different sites: 22, 37 and some of the 90 GHz data at the Metsähovi Radio Research Station, Finland, and 90 and 230 GHz data at the Swedish-ESO Submillimetre Telescope (SEST) on La Silla, Chile. Because the SEST data unfortunately reaches only back to 1988, the 90 and 230 GHz data were complemented by the IRAM data from Steppe et al. (A&AS 75, 1988 and A&AS 96, 1992).

scholarly journals Unveiling the high-frequency radio source population with the AT20G survey

2013 ◽  
Vol 9 (S304) ◽  
pp. 205-208
Author(s):  
Elizabeth K. Mahony
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
High Frequency ◽  
Gamma Ray ◽  
Low Frequency ◽  
Radio Sources ◽  
Source Population ◽  
Frequency Source ◽  
Galaxy Population ◽  
5 Ghz

AbstractUntil recently, the radio sky above 5 GHz was relatively unexplored. This has changed with the completion of the Australia Telescope 20 GHz survey (AT20G; Murphy et al., 2010); a blind survey of the southern sky down to a limiting flux density of 40 mJy. The AT20G survey provides by far the largest and most complete sample of high-frequency radio sources yet obtained, offering new insights into the nature of the high-frequency active galaxy population. Whilst the radio data provides a unique sample of objects, these data alone are insufficient to completely constrain models of radio source properties and the evolution of radio galaxies. Complementary multiwavelength data is vital in understanding the physical properties of the central black hole.In this talk I will provide a brief overview of the AT20G survey, followed by a discussion of the multiwavelength properties of the high-frequency source population. In particular, I will focus on the optical properties of AT20G sources, which are very different to those of a low-frequency selected sample, along with the gamma-ray properties where we find a correlation between high-frequency radio flux density and gamma-ray flux density. By studying the multiwavelength properties of a large sample of high-frequency radio sources we gain a unique perspective on the inner dynamics of some of the most active AGN.

scholarly journals CSS versus Large Size Sources

1996 ◽  
Vol 175 ◽  
pp. 63-66 ◽  
Author(s):  
R. Fanti ◽  
R. E. Spencer
Keyword(s):  
Flux Density ◽  
High Power ◽  
High Frequency ◽  
Large Fraction ◽  
Radio Sources ◽  
Frequency Spectra ◽  
Large Size ◽  
Spectrum Radio

A large fraction of the sources in flux density limited radio samples have angular sizes < 2 arcsec (and hence projected linear sizes ≤ 10–15 kpc for H0 = 100 Km/(sec Mpc), and steep (α > 0.5, S∝ v–α) high frequency spectra (Kapahi, 1981; Peacock and Wall 1982). The proportion of these Compact Steep–spectrum Sources (CSSs) is high (15–30% depending on the selection frequency) amongst distant (z > 0.2) radio sources of high power, both galaxies and quasars. We include in this class the GHz Peaked Spectrum Radio Sources (GPS), sub–kpc objects whose radio spectra are peaked at GHz frequencies (see, e.g., O'Dea et al, 1991).

scholarly journals High resolution VLBI observations of the nuclei of bright galaxies and quasars at 327 MHz

1986 ◽  
Vol 119 ◽  
pp. 169-170
Author(s):  
S. Ananthakrishnan ◽  
V.K. Kulkarni
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
The Other ◽  
Radio Sources ◽  
Interplanetary Scintillation ◽  
Ss 433 ◽  
Vlbi Observations ◽  
Nearby Galaxies ◽  
Compact Sources ◽  
3C 120

An intercontinental VLBI experiment at 327 MHz involving the Ooty Radio Telescope and telescopes at Jodrell Bank, Westerbork, Torun and Crimea was carried out during December 8–12, 1983. The purpose of the experiment was to (i) establish the feasibility of performing MKII VLBI observations from India and (ii) to study the low frequency structure of nearby galaxies, quasars and some other well known radio sources at metre wavelengths. The sources observed were NGC 262, 315, 1052, 1068, 1265, 1275, 4151, 4486, 7674 and 3C 120; PKS 1055+018, 1148−001 and CTA 102; 3C 237 and SS 433. The bright NGC galaxies chosen were selected from an Interplanetary Scintillation survey of 150 nearby galaxies (Bagri and Ananthakrishnan 1983); they were found to have a flux density greater than about 0.2 Jy in subarcsec components at 327 MHz and have high frequency VLBI observations. The quasars chosen are amongst the most compact sources known at metrewavelengths. The other objects were the well known sources which have been studied extensively at higher frequencies.

scholarly journals Australian Journal of Physics Astrophysical Supplements

1973 ◽  
Vol 26 (5) ◽  
pp. 689
Author(s):  
M Davies ◽  
AG Little ◽  
BY Mills
Keyword(s):  
Flux Density ◽  
Australian Journal ◽  
Radio Sources

A catalogue of radio sources observed at a frequency of 408 MHz with the Molonglo radiotelescope is presented. The catalogue includes an area of 0�21 sr between declinations -19�.3 and - 22� �4. A total of 1545 sources is listed down to a limiting flux density of O� 1 f.u., the catalogue being largely complete above 0�25 f.u. Errors in position vary from ~ 5N arc for sources stronger than 1 f.u. to ~ 30N arc for the weakest sources.

scholarly journals The relation between radio flux density and ionizing ultra-violet flux for HII regions and supernova remnants in the Large Magellanic cloud

2003 ◽  
pp. 31-37 ◽  
Author(s):  
M.D. Filipovic ◽  
P.A. Jones ◽  
G.L. Vhite
Keyword(s):  
Flux Density ◽  
Supernova Remnants ◽  
Ultra Violet ◽  
Hii Regions ◽  
Large Magellanic Cloud ◽  
Magellanic Clouds ◽  
Radio Sources ◽  
Radio Flux ◽  
Stellar Associations ◽  
Vacuum Ultra Violet

We present a comparison between the Parkes radio surveys (Filipovic et al 1995) and Vacuum Ultra-Violet (VUV) surveys (Smith et al. 1987) of the Large Magellanic Clouds (LMC). We have found 72 sources in common in the LMC which are known HII regions (52) and supernova remnants (SNRs) (19). Some of these radio sources are associated with two or more UV stellar associations. A comparison of the radio flux densities and ionizing UV flux for HII regions shows a very good correlation, as expected from theory. Many of the Magellanic Clouds (MCs) SNRs are embedded in HII regions, so there is also a relation between radio and UV which we attribute to the surrounding HII regions.

scholarly journals Australian Journal of Physics Astrophysical Supplement

1975 ◽  
Vol 28 (6) ◽  
pp. 755
Author(s):  
Beverley J Wills
Keyword(s):  
Flux Density ◽  
Australian Journal ◽  
Radio Sources

Accurate measurements of relative flux density have been made between frequencies of 468 and 5009 MHz for 300 radio sources selected from the Parkes catalogue. The observations, their analysis and accuracy are described, and the flux densities presented together with their errors. Excluding the uncertainties in scaling these flux densities to an absolute system, r.m.s. errors vary from 0�24 Jy and 2�4 % at 635 MHz to 1�8 % at 2700 MHz; uncertainties in 'absolute' scaling are thought to be about 5 %. The present flux densities are compared with accurate values published elsewhere. The data have been combined with other published flux densities between 10 and 10000 MHz to derive spectra, which are presented graphically. Some sources whose spectra may be useful for flux density calibration are noted.

scholarly journals Australian Journal of Physics Astrophysical Supplement

1973 ◽  
Vol 26 (1) ◽  
pp. 115
Author(s):  
OB Slee ◽  
CS Higgins
Keyword(s):  
Radio Source ◽  
Flux Density ◽  
Australian Journal ◽  
Radio Sources ◽  
Success Rates ◽  
Low Resolution ◽  
Upper Limits

The Culgoora radioheliograph operating at 80 MHz has been used to observe 999 radio sources selected from published catalogues and distributed over the declination range -48� to +35�. The Culgoora-l list contains measurements with 3' . 7 arc resolution of positions, flux densities, and angular sizes of 777 sources, while upper limits to the flux densities of 222 undetected sources are given in a separate list. Success rates for the detection of various classes of radio source at 80 MHz are listed and discussed. Comparisons are made between the Culgoora flux densities and those given in other catalogues, and it is shown that unresolved sources in the earlier low-resolution measurements near 80 MHz cause the flux density to be systematically overestimated.

scholarly journals Australian Journal of Physics Astrophysical Supplement

1975 ◽  
Vol 28 (2) ◽  
pp. 239
Author(s):  
JG Bolton ◽  
AJ Shimmins ◽  
JV Wall
Keyword(s):  
Flux Density ◽  
Galactic Plane ◽  
Australian Journal ◽  
Radio Sources

A catalogue of 34S radio sources is presented, covering right ascensions O&h 00'" to 17hOO'" and 19h30'" to 06h30'" between declinations _4� and -30�. The regions omitted re within - 10� of the galactic plane. The catalogue was compiled from a 'fast' finding survey at 2700 MHz aimed at detecting sources stronger than o� 5 Jy. Subsequent measurements of flux density and position were made on all the sources which were not in the Parkes 40S MHz catalogue, and on some sources in the Parkes 40S MHz catalogue for which only data of low accuracy were available.

scholarly journals Chance or Necessity—The Fungi Co−Occurring with Formica polyctena Ants

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 204
Author(s):  
Igor Siedlecki ◽  
Michał Gorczak ◽  
Alicja Okrasińska ◽  
Marta Wrzosek
Keyword(s):  
Molecular Identification ◽  
High Frequency ◽  
Its Rdna ◽  
The Other ◽  
Formica Polyctena ◽  
Ant Nests ◽  
Mutualistic Fungi ◽  
The Tropics ◽  
High Diversity ◽  
Better Than

Studies on carton nesting ants and domatia−dwelling ants have shown that ant–fungi interactions may be much more common and widespread than previously thought. Until now, studies focused predominantly on parasitic and mutualistic fungi–ant interactions occurring mostly in the tropics, neglecting less−obvious interactions involving the fungi common in ants’ surroundings in temperate climates. In our study, we characterized the mycobiota of the surroundings of Formica polyctena ants by identifying nearly 600 fungal colonies that were isolated externally from the bodies of F. polyctena workers. The ants were collected from mounds found in northern and central Poland. Isolated fungi were assigned to 20 genera via molecular identification (ITS rDNA barcoding). Among these, Penicillium strains were the most frequent, belonging to eight different taxonomic sections. Other common and widespread members of Eurotiales, such as Aspergillus spp., were isolated very rarely. In our study, we managed to characterize the genera of fungi commonly present on F. polyctena workers. Our results suggest that Penicillium, Trichoderma, Mucor, Schwanniomyces and Entomortierella are commonly present in F. polyctena surroundings. Additionally, the high diversity and high frequency of Penicillium colonies isolated from ants in this study suggest that representatives of this genus may be adapted to survive in ant nests environment better than the other fungal groups, or that they are preferentially sustained by the insects in nests.

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