scholarly journals 18 cm High Resolution Observations of 15 Extragalactic Radio Sources

1988 ◽  
Vol 129 ◽  
pp. 141-142
Author(s):  
J. A. Waak ◽  
J. H. Spencer ◽  
R. S. Simon ◽  
K. J. Johnston
Keyword(s):  
High Resolution ◽  
Dynamic Range ◽  
Radio Sources ◽  
Owens Valley ◽  
Extragalactic Radio Sources ◽  
Self Calibration

On 8–12 October 1981 a 5-station MkII VLBI experiment at 1660 MHz was performed using antennas at Westford, Maryland Point, Green Bank, Fort Davis, and Owens Valley. Fifteen extragalactic sources (Table 1) were observed with an average synthesized beam of roughly 10 mas. The data were processed using the NRAO correlator, globally fringe-fit, and mapped with the AIPS package. In addition to the usual self-calibration techiques, corrections were made to eliminate baseline-dependent calibration errors. Some of the sources, for example 1641+399 (3C345), display extended components not before observed at the dynamic range of the maps, which on the average is roughly 200:1.

scholarly journals High-resolution VLA low radio frequency observations of the Perseus cluster: radio lobes, mini-halo, and bent-jet radio galaxies

2020 ◽  
Vol 499 (4) ◽  
pp. 5791-5805
Author(s):  
M Gendron-Marsolais ◽  
J Hlavacek-Larrondo ◽  
R J van Weeren ◽  
L Rudnick ◽  
T E Clarke ◽  
...  
Keyword(s):  
High Resolution ◽  
Dynamic Range ◽  
Galaxy Cluster ◽  
High Dynamic Range ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Nearby Galaxy ◽  
Cluster Galaxy ◽  
Ngc 1275 ◽  
Perseus Cluster

ABSTRACT We present the first high-resolution 230–470 MHz map of the Perseus cluster obtained with the Karl G. Jansky Very Large Array. The high dynamic range and resolution achieved have allowed the identification of previously unknown structures in this nearby galaxy cluster. New hints of sub-structures appear in the inner radio lobes of the brightest cluster galaxy NGC 1275. The spurs of radio emission extending into the outer X-ray cavities, inflated by past nuclear outbursts, are seen for the first time at these frequencies, consistent with spectral aging. Beyond NGC 1275, we also analyse complex radio sources harboured in the cluster. Two new distinct, narrowly collimated jets are visible in IC 310, consistent with a highly projected narrow-angle tail radio galaxy infalling into the cluster. We show how this is in agreement with its blazar-like behaviour, implying that blazars and bent-jet radio galaxies are not mutually exclusive. We report the presence of filamentary structures across the entire tail of NGC 1265, including two new pairs of long filaments in the faintest bent extension of the tail. Such filaments have been seen in other cluster radio sources such as relics and radio lobes, indicating that there may be a fundamental connection between all these radio structures. We resolve the very narrow and straight tail of CR 15 without indication of double jets, so that the interpretation of such head–tail sources is yet unclear. Finally, we note that only the brightest western parts of the mini-halo remain, near NGC 1272 and its bent double jets.

scholarly journals An Atlas of Extragalactic Radio Sources

1996 ◽  
Vol 175 ◽  
pp. 157-158 ◽  
Author(s):  
J.P. Leahy ◽  
A.H. Bridle ◽  
R.G. Strom
Keyword(s):  
High Resolution ◽  
Line Emission ◽  
Radio Sources ◽  
X Rays ◽  
Complete Sample ◽  
High Quality ◽  
Extragalactic Radio Sources ◽  
Optical Line

Our Atlas of Extragalactic Radio Sources will present high-quality images of the nearer half of “3CRR”, the sample defined by Laing, Riley & Longair (1983). This is the best-studied complete sample of extragalactic radio sources. All 173 members have secure redshifts and most have been imaged in the radio at high resolution. There is also copious information on their optical line emission, and many have been detected in the sub-mm, FIR, and in X-rays. 3CRR is widely used as a baseline against which fainter, higher-redshift samples can be compared to define the evolution of the population (e.g. Neeser et al. 1995; Law-Green, this conference).

scholarly journals Multi-Frequency Polarization Studies of Radio Galaxies

1982 ◽  
Vol 97 ◽  
pp. 53-54
Author(s):  
G. G. Pooley
Keyword(s):  
High Resolution ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Frequency Range ◽  
Extragalactic Radio Sources ◽  
High Resolution Mapping ◽  
New Instrument ◽  
Resolution Mapping ◽  
Polarization Studies ◽  
The One

This is a brief report on some of the work in progress at Cambridge, with emphasis on studies of extragalactic radio sources using the One-mile and 5-km telescopes; together with the 6C survey and a new instrument now being commisioned at 151 MHz, we have a frequency range of 100:1 available for high-resolution mapping. The 6C survey has resulted in the discovery of a number of giant radio galaxies, most notably NGC 6251. At 151 MHz, the beautiful jet is not prominent; we have mapped it with the One-mile and 5-km instruments and a paper (by Saunders et al.) will shortly appear in Monthly Notices. Dr Willis will speak later on the structure of this source.

scholarly journals John Bolton's Variable-baseline Interferometer and the Structure of Radio Galaxies

1994 ◽  
Vol 47 (5) ◽  
pp. 569
Author(s):  
RD Ekers
Keyword(s):  
Radio Galaxies ◽  
Radio Sources ◽  
California Institute ◽  
Owens Valley ◽  
Extragalactic Radio Sources ◽  
Flexible Cable

John Bolton was a pioneer in the study of extragalactic radio sources, first at the CSIRO Radiophysics Laboratory and then at the California Institute of Technology's Owens Valley interferometer. I became his Ph.D. student after he returned to the Parkes Observatory from California, and I helped in the construction of the Parkes interferometer. This consisted of a 60-ft dish connected to the existing 210-ft dish by a flexible cable trailing from the 60-footer. The interferometer was used to observe continuously at 467 and 1401 MHz while the 60-ft dish was pulled along a track. The wisdom of the design is illustrated by comparing observations of Pictor A made at Parkes and at Owens Valley.

scholarly journals Astrophysical Results from Geodetic VLBI Campaigns

1994 ◽  
Vol 159 ◽  
pp. 423-423 ◽  
Author(s):  
S. Britzen ◽  
A. Witzel ◽  
A.-M. Gontier ◽  
C.J. Schalinski ◽  
J. Campbell
Keyword(s):  
Structural Changes ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Time Base ◽  
Radio Sources ◽  
Extragalactic Radio Sources ◽  
Geodetic Vlbi ◽  
Earth Rotation Parameters ◽  
High Dynamic ◽  
Source Structure

Geodetic VLBI observations of extragalactic radio sources –designed to measure earth orientation parameters– are performed regularly since more than 10 years now. In different campaigns about 20 Quasars and BL Lacs are being monitored at 2.3 and 8.4 GHz. The high duty-cycle of these observations (every month for IRIS-S) and the resulting enormous data base allow to study the milliarcsecond structures and their variations simultaneously at two frequencies on short timescales. Since the accuracy of baseline determination and measurement of earth rotation parameters has reached a limit where source structure contributions become significant, there is substantial interest to monitor and correct for the source structure “effects”. Therefore we perform a regular analysis of sources selected from IRIS-S (high north-south resolution and almost circular beam for low declination sources) and EUROPE (high sensitivity due to large telescopes) campaigns covering a maximum time base of 10 years (1983–1993). The (undesired) structure of the sources leads to an occasional updating of the source catalogue in order to have “pointlike” sources which are observed 10–15 times for three to seven minutes during 24 hours. Meanwhile about 50 sources have been observed in geodetic campaigns. The comparatively poor data quality requires careful calibration with a source whose structure is well–known from high dynamic range observations (e.g. the blazar 1803+784). The dynamic range of these maps is limited to 1:50. The merit of this database lies obviously in the monthly persecution of structural changes in extragalactic radio sources over at best 10 years time and the filling of the gaps between high dynamic range observations. Sources which are presently of particular interest to us, include 1803+784, 4C39.25, 0528+134, 3C454.3 and OJ287.

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

The Heights of Solar Radio Sources at 1424 MHz and 696 MHz

1969 ◽  
Vol 1 (5) ◽  
pp. 192-194 ◽  
Author(s):  
D. G. Cole ◽  
R. F. Mullaly
Keyword(s):  
Solar Activity ◽  
High Resolution ◽  
Solar Disk ◽  
Previous Investigation ◽  
Solar Radio ◽  
Radio Sources ◽  
Grating Interferometer ◽  
Maximum Solar Activity

The heights of solar radio sources at 1424 MHz and 696 MHz have been measured during the years 1965 and 1966. Solar activity at this time was near minimum. The number of radio sources appearing on the solar disk rarely exceeded three at any time and it thus was possible to resolve the majority of these with a high resolution grating interferometer. Many of the previous height measurements at these frequencies have been made near times of maximum solar activity and the confusion of sources within the beam has limited their accuracy. The number of sources studied here is quite considerably higher than in any previous investigation at these frequencies, and the period of observation has been continuous.

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