scholarly journals Radio Emission from Cassiopeia 23N5A on 130-cm. Wave-length

Nature ◽  
1962 ◽  
Vol 193 (4812) ◽  
pp. 261-261 ◽  
Author(s):  
A. TLAMICHA
Keyword(s):  
Radio Emission ◽  
Wave Length

scholarly journals 79. Radio emission from the moon and the nature of its surface

1957 ◽  
Vol 4 ◽  
pp. 406-407 ◽  
Author(s):  
V. S. Troitzky ◽  
S. E. Khaikin
Keyword(s):  
Radio Emission ◽  
Attenuation Coefficient ◽  
Wave Length ◽  
Degree Of Polarization ◽  
Lunar Phase ◽  
Radio Waves ◽  
The Moon ◽  
Subsolar Point ◽  
Image Position ◽  
Academy Of Sciences

A theoretical study of the integral radio emission of the moon, measured at the wave-length of 3·2 cm. (Zelinskaja and Troitzky[1]; Kajdanovsky, Turusbekov and Khaikin[2]), was carried out at the Gorky radio astronomical station ‘Zimenky’ and at the Physical Institute of the Academy of Sciences of the U.S.S.R. The following expression for the average radio temperature of the entire lunar disk, as a function of the lunar phase, Ωt, was obtained (Troitzky, 1954) [3]: Here tan ξ = δ/(1 + δ) and δ = β/κ, where β is the attenuation coefficient of the thermal wave, κ the power attenuation coefficient of the radio wave. Further, Tm = 374°K. is the temperature of the subsolar point, Tn is the temperature at the lunar midnight, Θ = Tm – Tn and k0 is the reflexion coefficient of radio waves for vertical incidence (k0 ≈ 0–1). The numerical coefficients in equation (1) were obtained as a result of averaging the Fresnel reflexion coefficients over the whole disk. The degree of polarization of the total radio emission was calculated and was found to be about 4 %.

scholarly journals 41. The spherical component of the galactic radio emission

1957 ◽  
Vol 4 ◽  
pp. 233-237
Author(s):  
J. E. Baldwin
Keyword(s):  
Radio Emission ◽  
Brightness Temperature ◽  
Radio Telescope ◽  
Galactic Plane ◽  
Wave Length ◽  
Spherical Component ◽  
Long Wave ◽  
Half Power ◽  
Right Ascension ◽  
Galactic Radio

As part of the programme of observations with the large Cambridge radio telescope, a survey of the integrated radio emission has been made using one of the four elements of the interferometer. At a wave-length of 3·7 metres this aerial has beam-widths to half-power points of 2° in right ascension and 15° in declination. The use of a long wave-length makes it possible to obtain accurate measurements of the brightness temperature of the sky in regions away from the galactic plane. It is with the radiation from these regions that this paper is primarily concerned.

scholarly journals 37. Galactic radio emission and the distribution of discrete sources: Introductory Lecture

1957 ◽  
Vol 4 ◽  
pp. 211-217
Author(s):  
R. Hanbury Brown
Keyword(s):  
Radio Emission ◽  
Thermal Emission ◽  
Wave Length ◽  
Black Body ◽  
Interstellar Gas ◽  
Ionized Gas ◽  
Introductory Lecture ◽  
The Galaxy ◽  
Image Position ◽  
Galactic Radio

At wave-lengths greater than about 1 metre the majority of the radio emission which is observed from the Galaxy cannot be explained in terms of thermal emission from ionized interstellar gas. This conclusion is widely accepted and is based on observations of the equivalent temperature of the sky and the spectrum of the radiation. The spectrum at metre wave-lengths is of the general form: where TA is the equivalent black-body temperature of a region of sky and λ is the wave-length. The exponent n varies with direction but lies between about 2·5 and 2·8, and is thus significantly greater than the value of 2·0 which is the maximum to be expected for thermal emission from an ionized gas. Furthermore, the value of TA is about 1050K. at 15 metres and thus greatly exceeds the electron temperature expected in H 11 regions.At centimetre wave-lengths it is likely that the majority of the radiation observed originates in thermal emission from ionized gas; however, the present discussion is limited to a range of wave-lengths from about 1 to 10 metres where the ionized gas in the Galaxy is believed to be substantially transparent and where the origin of most of the radiation is believed to be non-thermal.

Thermal Radio Emission of the Moon at a Wave Length of 10 cm

1962 ◽  
Vol 14 ◽  
pp. 497-499
Author(s):  
V. N. Koshchenko ◽  
A. D. Kuzmin ◽  
A. E. Salomonovich
Keyword(s):  
Surface Layer ◽  
Radio Emission ◽  
Thermal Radiation ◽  
Wave Length ◽  
The Moon ◽  
Phase Dependence ◽  
Radio Range ◽  
Thermal Radio ◽  
Thermal Radio Emission

The investigations of intensity and phase dependence of the thermal radiation of the Moon at various wave lengths of the radio-range are very important for clarifying the properties and structure of the Moon's surface layer.

scholarly journals 57. A survey of Soviet observations of the radio emission from the sun during solar eclipses

1957 ◽  
Vol 4 ◽  
pp. 311-312 ◽  
Author(s):  
B. M. Tchikhatchev
Keyword(s):  
Radio Emission ◽  
Solar Eclipse ◽  
Radio Astronomy ◽  
Wave Length ◽  
Central Path ◽  
The Sun ◽  
Maximum Phase ◽  
The Caucasus ◽  
The Crimea ◽  
Solar Eclipses

Soviet scientists working in the domain of radio astronomy carried out a number of observations of the radio emission from the sun during solar eclipses. The first observation was obtained by Prof. S. E. Khaikin and the author during the eclipse of 20 May 1947 at a wave-length of 1·5 metres. The solar eclipse of 25 February 1952 was observed in Archman, Turkmenian S.S.R., on wave-lengths of 3·2 and 10 cm. by V. S. Troitzky, and on 1, 1·5, 2 and 2·6 metres by the author and by V. V. Vitkevitch. The eclipse of 30 June 1954 was observed in Novomoskovsk, Ukrainian S.S.R., on 3·2 and 10 cm. by V. S. Troitzky, and on 10 and 23 cm. by V. V. Vitkevitch. It was also observed in the Caucasus on a wave-length of 3·2 cm. by A. P. Moltchanov. All the above observations were carried out in places located in the vicinity of the central path of the totality. The eclipse of 30 June 1954 was observed also outside the path of totality on the southern shore of the Crimea by a group of Dr Vitkevitch's colleagues on wave-lengths of 1, 1·5 and 3·5 metres. The maximum phase in this place was 92 %.

Probe size and 5th-order aberration

1987 ◽  
Vol 45 ◽  
pp. 134-135 ◽  
Author(s):  
Zhifeng Shao
Keyword(s):  
Electron Probe ◽  
Spherical Aberration ◽  
Wave Length ◽  
Cylindrical Symmetry ◽  
Electron Wave ◽  
Third Order ◽  
The Third ◽  
Probe Radius ◽  
Small Probe ◽  
Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

New Feasible Concepts of Aberration Correction for Realizing High-Resolution Electron Microscopes

1990 ◽  
Vol 48 (1) ◽  
pp. 202-203
Author(s):  
H. Rose
Keyword(s):  
Spherical Aberration ◽  
Wave Length ◽  
Electron Wave ◽  
Optical Lens ◽  
Resolution Electron ◽  
Rotationally Symmetric ◽  
Electron Microscopes ◽  
The Cost ◽  
Imaging Performance ◽  
Acceleration Voltage

The imaging performance of the light optical lens systems has reached such a degree of perfection that nowadays numerical apertures of about 1 can be utilized. Compared to this state of development the objective lenses of electron microscopes are rather poor allowing at most usable apertures somewhat smaller than 10-2 . This severe shortcoming is due to the unavoidable axial chromatic and spherical aberration of rotationally symmetric electron lenses employed so far in all electron microscopes.The resolution of such electron microscopes can only be improved by increasing the accelerating voltage which shortens the electron wave length. Unfortunately, this procedure is rather ineffective because the achievable gain in resolution is only proportional to λ1/4 for a fixed magnetic field strength determined by the magnetic saturation of the pole pieces. Moreover, increasing the acceleration voltage results in deleterious knock-on processes and in extreme difficulties to stabilize the high voltage. Last not least the cost increase exponentially with voltage.

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