scholarly journals Wild, Woolley and Savage ? or how John Bolton and I went hunting for Quasars and QSOs

1994 ◽  
Vol 47 (5) ◽  
pp. 589
Author(s):  
Ann Savage
Keyword(s):  
Radio Sources ◽  
Stellar Objects ◽  
Quasi Stellar Objects

This paper is about how I met John Bolton and includes some highlights of the four years I took compiling my Ph.D. at the Parkes Observatory. It is strongly linked to the discovery of quasars (quasi-stellar radio sources) and QSOs (quasi-stellar objects, not necessarily radio sources)-John being dedicated to discovering quasars and I to discovering QSOs. I hope my perception of John Bolton as a person comes through as it seems I was fortunate in meeting him at a time when, according to some, he had mellowed!

scholarly journals Radio Emission from Compact Objects

1972 ◽  
Vol 44 ◽  
pp. 190-213
Author(s):  
K. I. Kellermann
Keyword(s):  
Angular Size ◽  
Brightness Distribution ◽  
Compact Objects ◽  
Radio Sources ◽  
Stellar Objects ◽  
Large Intensity ◽  
Quasi Stellar Objects ◽  
One Year ◽  
Ngc 1275 ◽  
Compact Sources

Compact radio stars are associated with both galaxies and quasi-stellar objects; and there appears to be no way to distinguish between the radio galaxies and the quasi-stellar radio sources from their radio properties alone.The compact radio sources are opaque at the longer radio wavelengths and have spectra that are either peaked or complex. They have a complex brightness distribution and often contain components less than 0.001 arc sec in size.Many of the compact sources show large intensity variations and in NGC 1275 there is evidence for a change in the angular size during one year.

scholarly journals The Parkes 2700 MHz Survey (Tenth Part). Supplementary Catalogue for the Declination Zone +4° to +25°

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

A catalogue of lSI radio sources is presented covering the declination zone +4� to +25� and all right ascensions, omitting two regions within approximately 10� of the galactic plane (R.A. 05h30'" to 07ho()m and R.A. lShOO'" to 2Oh30"'). The catalogue was compiled from a 'fast' finding survey at 2700 MHz aimed at detecting sources stronger than o� 5 Jy. Subsequently, measurements of accurate flux density and position were made on all the sources which were not in the Parkes 40S MHz catalogue and on a few sources in the 40S MHz catalogue for which only data of low accuracy were available. The' positions of sources were determined to an accuracy of 10" arc r.m.s. in both coordinates. Flux densities for most of the sources were also measured at 5009 MHz. Identifications are suggested for 17 galaxies and 62 quasi-stellar objects.

scholarly journals Further Identifications Of Radio Sources Between Declinations 0° And 20°

1966 ◽  
Vol 19 (3) ◽  
pp. 471 ◽  
Keyword(s):  
Radio Sources ◽  
Stellar Objects ◽  
Sky Survey ◽  
Position Data ◽  
Quasi Stellar Objects

Clarke, Bolton, and Shimmins (1966) have recently suggested identifications for 138 of the radio sources listed in the Parkes catalogue for declinations 0� to +20� (Day, Shimmins, Ekers, and Cole 1966). The identifications were made from inspection of the Palomar Sky Survey plates in areas 2' arc square centred on the catalogue positions. In general, identifications were suggested only for galaxies or possible quasi-stellar objects brighter than 17m . 5, in order to avoid the possibility of chance coincidences. Where objects fainter than 17m . 5 were suggested, position data of higher accuracy were available, due principally to unpublished measurements by Shimmins, Clarke, and Ekers with the 210 ft telescope.

scholarly journals Accurate Positions and Some Optical Identifications for 255 Radio Sources Between Declinations +20° and ?33°

1969 ◽  
Vol 22 (2) ◽  
pp. 237 ◽  
Author(s):  
Jeannette K Merkelijn
Keyword(s):  
Radio Sources ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Optical Identifications

Accurate positions have been measured at 2700 MHz for 255 sources from the Parkes catalogue between declinations +20� and -33�. The estimated accuracy in both coordinates is approximately 15N arc. For 103 of the sources, identifications are suggested using the accurate positions. Sixty-two of the sources are identified with galaxies and 41 with quasi-stellar objects.

scholarly journals New Optical Identifications from the Parkes 2700 MHz Resurvey of the ± 4° Declination Zone

1982 ◽  
Vol 35 (2) ◽  
pp. 207 ◽  
Author(s):  
Ann Savage ◽  
JG Bolton ◽  
Jenny Trett
Keyword(s):  
Radio Sources ◽  
Stellar Objects ◽  
Sky Survey ◽  
Quasi Stellar Objects ◽  
Optical Identifications

Identifications are suggested for 59 radio sources from the resurvey of declination zone �4�, 27 with galaxies and 32 with stellar objects; 19 of the latter are confirmed as quasi-stellar objects (QSOs). The identifications were made from the Palomar Sky Survey prints plus supplementary plates taken with the Palomar and U.K. Schmidt telescopes and the Anglo-Australian 3�9 m telescope.

scholarly journals Observations of the Linear Polarization of Radio Sources at 6 cm Wavelength

1968 ◽  
Vol 21 (4) ◽  
pp. 493 ◽  
Author(s):  
D Morris ◽  
JB Whiteoak
Keyword(s):  
Linear Polarization ◽  
High Frequency ◽  
Wavelength Dependence ◽  
Radio Galaxies ◽  
Short Wave ◽  
Radio Sources ◽  
Polarization Data ◽  
Stellar Objects ◽  
Quasi Stellar Objects

The polarizations of 45 sources have been measured at 6 cm wavelength and have been compared with values obtained at longer wavelengths. The resulting wavelength dependence has been studied in relation to the spectra of the sources. For the quasi. stellar objects in particular, polarization features at short wave� lengths are associated with the young components of the source which radiate at high frequency. However, it is not possible to distinguish between radio galaxies and quasi-stellar objects solely on the basis of polarization data.

scholarly journals Australian Journal of Physics Astrophysical Supplements

1973 ◽  
Vol 26 (5) ◽  
pp. 689
Author(s):  
JG Bolton ◽  
AJ Shimmins
Keyword(s):  
Australian Journal ◽  
Radio Sources ◽  
Stellar Objects ◽  
Quasi Stellar Objects

A catalogue of 885 radio sources is presented, covering right ascensions lOb to 15b and 19b to 07b between declinations -35� and -45�. The catalogue is believed to be complete to 0�22 f.u. at 2700 MHz (940 sources per steradian) and the positions are accurate to �15N arc in both coordinates for sources stronger than 0�3 f.u. Flux densities at 5009 MHz have been measured for 350 of the strong sources. Eighty-eight of the sources have been identified with galaxies and 39 have been identified and confirmed as quasi-stellar objects.

scholarly journals Populations of Extragalactic Radio Sources

1994 ◽  
Vol 47 (5) ◽  
pp. 625 ◽  
Author(s):  
JV Wall
Keyword(s):  
Big Bang ◽  
Current View ◽  
Radio Sources ◽  
Large Area ◽  
Microwave Background ◽  
Stellar Objects ◽  
Sky Surveys ◽  
Extragalactic Radio Sources ◽  
The Face ◽  
Quasi Stellar Objects

In the late 1950s and early 1960s, radio sky surveys were the centre of an intense and public debate-Big-Bang versus Steady-State cosmology-the arguments revolving about source counts and statistical interpretations in the face of instrumental complications. The 1965 discovery of the microwave background took the fire from the debate, but left the momentum in place for large-area radio surveys at different frequencies, and for extensive identification/redshift-measurement programs. By the 1970s the data enabled us to start disentangling the different populations of extragalactic radio sources. We could refine our taxonomy, and we could view the possibility of delineating individual cosmic histories and evolutions. We could at least describe a goal to elucidate the birth-life-death cycles of the objects involved [quasi-stellar objects (QSOs) and radio galaxies: together the 'active galactic nuclei' (AGNs)] whose unaccountably prodigious energies somehow produce the beautifully aligned radio structures with which we are now familiar. One part of John Bolton's vision to see how distorted a view of the AGN universe the original long-wavelength surveys provided. One legacy is thus the 'short-wavelength survey' for extragalactic radio sources, which has done so much to balance our picture of the radio sky. And indeed the legacy continues in the form of the immense sky surveys at present under way, complete with their sub-industries of radio-positioning and identification. From these, yet further results are emerging on spatial distribution and the skeleton structure of the universe. It is the purpose of this paper to outline something of this current view of the populations, their differences, similarities and unifying concepts.

scholarly journals QSO photometric redshifts from SDSS, WISE, and GALEX colours

2020 ◽  
Vol 493 (1) ◽  
pp. L70-L75
Author(s):  
S J Curran
Keyword(s):  
Near Infrared ◽  
Empirical Method ◽  
Machine Learning Techniques ◽  
Radio Sources ◽  
Photometric Redshifts ◽  
Stellar Objects ◽  
Vast Number ◽  
Quasi Stellar Objects ◽  
Continuum Radio ◽  
Non Gaussian

ABSTRACT Machine learning techniques, specifically the k-nearest neighbour algorithm applied to optical band colours, have had some success in predicting photometric redshifts of quasi-stellar objects (QSOs): Although the mean of differences between the spectroscopic and photometric redshifts, Δ$z$, is close to zero, the distribution of these differences remains wide and distinctly non-Gaussian. As per our previous empirical estimate of photometric redshifts, we find that the predictions can be significantly improved by adding colours from other wavebands, namely the near-infrared and ultraviolet. Self-testing this, by using half of the 33 643 strong QSO sample to train the algorithm, results in a significantly narrower spread in Δ$z$ for the remaining half of the sample. Using the whole QSO sample to train the algorithm, the same set of magnitudes return a similar spread in Δ$z$ for a sample of radio sources (quasars). Although the matching coincidence is relatively low (739 of the 3663 sources having photometry in the relevant bands), this is still significantly larger than from the empirical method (2 per cent) and thus may provide a method with which to obtain redshifts for the vast number of continuum radio sources expected to be detected with the next generation of large radio telescopes.

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