scholarly journals High Resolution Observations of the Orion Nebula at 408 MHz

1968 ◽  
Vol 21 (1) ◽  
pp. 95 ◽  
Author(s):  
BY Mills ◽  
PA Shaver
Keyword(s):  
High Resolution ◽  
Electron Temperature ◽  
Radio Telescope ◽  
Central Region ◽  
High Frequency ◽  
Orion Nebula ◽  
Radio Observatory

The Orion Nebula has been observed at 408 MHz with the 1 mile Cross radio telescope at the Molonglo Radio Observatory. NGC 1976 and NGC 1982 were observed separately and the former was well resolved.. Comparison with high frequency results shows that the central region is opti('ally thick; the electron temperature was measured directly at 7 6000K � 800 degK. Both nebulae are strongly concentrated towards their exciting stars..

The Electron Temperature of the Planetary Nebula IC 418

1969 ◽  
Vol 1 (5) ◽  
pp. 216-217
Author(s):  
A. E. Le Marne ◽  
P. A. Shaver
Keyword(s):  
High Resolution ◽  
Electron Temperature ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Pencil Beam ◽  
Radio Observatory ◽  
A Current

In a current programme at the Molonglo Radio Observatory using the high-resolution pencil beam of the instrument (∼3′ arc) an attempt is being made to extend the measured spectra of known planetary nebulae down to 408 MHz. Of 23 such planetaries already investigated, 14 have been detected. The main results will be given elsewhere; here it is proposed to discuss in detail only the well-known planetary nebula IC 418.

scholarly journals High-resolution spectral imaging of SNR W44 and IC443 at 22 GHz with the Sardinia Radio Telescope

2017 ◽  
Vol 12 (S331) ◽  
pp. 190-193
Author(s):  
S. Loru ◽  
A. Pellizzoni ◽  
E. Egron ◽  
N. Iacolina ◽  
S. Righini ◽  
...  
Keyword(s):  
High Resolution ◽  
Radio Telescope ◽  
High Frequency ◽  
Electron Distribution ◽  
Ad Hoc ◽  
Imaging Techniques ◽  
High Energy ◽  
Spatially Resolved ◽  
High Energy Tail ◽  
Science Activities

AbstractIn the framework of the Astronomical Validation and Early Science activities of the Sardinia Radio Telescope (SRT, www.srt.inaf.it), we performed 22 GHz imaging observations of SNR W44 and IC443. Thanks to the single-dish imaging performances of SRT and innovative ad hoc imaging techniques, we obtained maps that provide a detailed view of the structure of the remnants. We are planning to exploit the high-frequency radio data of SNRs to better characterize the spatially-resolved spectra and search for possible spectral steepening or breaks in selected SNR regions, assessing the high-energy tail of the region-dependent electron distribution.

scholarly journals Emission Nebulae as Radio Sources

1956 ◽  
Vol 9 (2) ◽  
pp. 218 ◽  
Author(s):  
BY Mills ◽  
AG Little ◽  
KV Sheridan
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Radio Telescope ◽  
Optical Data ◽  
Radio Sources ◽  
Pencil Beam ◽  
Orion Nebula ◽  
Average Electron Density ◽  
Average Electron ◽  
Bright Emission

Attempts have been made to detect 14 bright emission nebulae at a wavelength of 3?5 m using a pencil-beam radio telescope with a beamwidth of 50 min of arc. Of these nebulae, six were probably observed in emission, seven were undetectable, and one, NGC 6357, was observed in absorption; radio isophotes were obtained for NGC 2237 and NGC 3372. Radio and optical data have been combined to estimate electron densities, masses, and sometimes the electron temperature of many of the nebulae. Values range from an electron density of 3 cm?3 and a mass of 3�10. solar masses for the outer regions of the 30 Doradus complex to an average electron density of 500 cm?3 and a mass of 20 solar masses for the Orion Nebula. Temperatures generally appear to be in the neighbourhood of 10,000 �K, except in the case of NGC 6357, for which 6500 �K is estimated.

A Comparison of Radio and Optical Observations of the 30 Doradus Nebula

1968 ◽  
Vol 1 (3) ◽  
pp. 97-98 ◽  
Author(s):  
A. E. Le Marne
Keyword(s):  
High Resolution ◽  
Radio Telescope ◽  
Preliminary Report ◽  
Optical Observations ◽  
Balmer Line ◽  
Radio Observatory ◽  
Cross Type ◽  
30 Doradus

The Sydney University one mile cross-type radio telescope at the Molonglo Radio Observatory has been used to study the 30 Doradus nebula with high resolution (~3´ arc) at 408 MHz. This preliminary report compares these observations with Balmer line isophotes published by Faulkner. A description of the calibration procedures used in the present observations, an analysis of the various radio features in the 30 Doradus region, and a comparison with previous observations at other frequencies, will be described in a later paper.

Time Variation of the Radio Emission from Sco X-1

1969 ◽  
Vol 1 (5) ◽  
pp. 237-240 ◽  
Author(s):  
J. G. Ables
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Time Variation ◽  
Radio Observatory ◽  
Half Power

The radio object associated with Sco X—1 noted by Andrew and Purton has been observed at a wavelength of 6 cm with the 210 ft radio telescope at the Australian National Radio Observatory, Parkes. At this wavelength the half-power antenna beamwidth is 4′ arc.

scholarly journals PCDRN: Progressive Cascade Deep Residual Network for Pansharpening

2020 ◽  
Vol 12 (4) ◽  
pp. 676 ◽  
Author(s):  
Yong Yang ◽  
Wei Tu ◽  
Shuying Huang ◽  
Hangyuan Lu
Keyword(s):  
High Resolution ◽  
Loss Function ◽  
High Frequency ◽  
Experimental Results ◽  
Superior Performance ◽  
Residual Network ◽  
High Quality ◽  
Convolution Approach ◽  
Visual Assessments ◽  
Coarse To Fine

Pansharpening is the process of fusing a low-resolution multispectral (LRMS) image with a high-resolution panchromatic (PAN) image. In the process of pansharpening, the LRMS image is often directly upsampled by a scale of 4, which may result in the loss of high-frequency details in the fused high-resolution multispectral (HRMS) image. To solve this problem, we put forward a novel progressive cascade deep residual network (PCDRN) with two residual subnetworks for pansharpening. The network adjusts the size of an MS image to the size of a PAN image twice and gradually fuses the LRMS image with the PAN image in a coarse-to-fine manner. To prevent an overly-smooth phenomenon and achieve high-quality fusion results, a multitask loss function is defined to train our network. Furthermore, to eliminate checkerboard artifacts in the fusion results, we employ a resize-convolution approach instead of transposed convolution for upsampling LRMS images. Experimental results on the Pléiades and WorldView-3 datasets prove that PCDRN exhibits superior performance compared to other popular pansharpening methods in terms of quantitative and visual assessments.

scholarly journals Miniaturized high frequency phased array devices for high resolution neonatal and intraoperative imaging

1990 ◽  
Vol 15 (2) ◽  
pp. A10 ◽  
Author(s):  
David J. Sahn ◽  
Diana Tasker ◽  
Sandra Hagen-Ansert ◽  
Axel Brisken ◽  
Scott Corbett
Keyword(s):  
High Resolution ◽  
High Frequency ◽  
Phased Array ◽  
Intraoperative Imaging

Scattering of electromagnetic waves by hybrid waves in a two-electron-temperature plasma

1991 ◽  
Vol 46 (1) ◽  
pp. 99-106 ◽  
Author(s):  
S. K. Sharma ◽  
A. Sudarshan
Keyword(s):  
Growth Rate ◽  
Electron Temperature ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Lower Hybrid ◽  
Stimulated Scattering ◽  
Coupled Modes ◽  
Temperature Plasma ◽  
Electrostatic Perturbation

In this paper, we use the hydrodynamic approach to study the stimulated scattering of high-frequency electromagnetic waves by a low-frequency electrostatic perturbation that is either an upper- or lower-hybrid wave in a two-electron-temperature plasma. Considering the four-wave interaction between a strong high-frequency pump and the low-frequency electrostatic perturbation (LHW or UHW), we obtain the dispersion relation for the scattered wave, which is then solved to obtain an explicit expression for the growth rate of the coupled modes. For a typical Q-machine plasma, results show that in both cases the growth rate increases with noh/noc. This is in contrast with the results of Guha & Asthana (1989), who predicted that, for scattering by a UHW perturbation, the growth rate should decrease with increasing noh/noc.

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