18-09-2014, 02:48 PM
RADIO ASTRONOMY
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INTRODUCTION
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena.
Radio astronomy comes under the observational astronomy.
Radio astronomy studies radiation with wavelengths greater than approximately one millimetre. Radio astronomy is different from most other forms of observational astronomy in that the observed radio waves can be treated as waves rather than as discrete photons.
LOCATING RADIO OBJECTS IN THE SKY
To share information with others, a reference system must be adopted. The system used by astronomers is the celestial coordinate system.
Azimuth is the angle around the horizontal from due north and running clockwise. Altitude is the height of the object.
The longitude lines on a celestial sphere are called Right Ascension. Right Ascension is measured on the celestial equator in an easterly direction. Declination corresponds to latitude and is measured in degrees
RADIO TELESCOPE
Radio telescopes are used to study naturally occurring radio emission from stars, galaxies, quasars, and other astronomical objects between wavelengths of about 10 meters (30 [MHz]) and 1 millimetre (300 GHz)
Radio telescopes vary widely, but they all have two basic components: (1) a large radio antenna and (2) a sensitive radiometer or radio receiver.
The most familiar type of radio telescope is the radio reflector consisting of a parabolic antenna--the so-called dish or filled-aperture telescope.
ADVANTAGES OF RADIO ASTRONOMY
Can observe day and night
Can penetrate clouds
Only stopped by strong winds, thunderstorms and snow!
Radio interferometry can produce better resolution than optical astronomy
DISADVANTAGES OF RADIO ASTRONOMY
Powers received are very low, since each photon has a small h
need big collectors (dishes)
Angular resolution is poor
but can’t do much better optical interferometry
Radio: to get ~0.5 arc sec, =5cm
d~50 km
Thus, radio astronomers need interferometers
CONCLUSION
When Karl Jan sky discovered a source of radio waves near the centre our Own galaxy, this proved that in astronomy there literally is more than meet The eye. This acted like a wake-up call for astronomy as awhile, and made Astronomers realize that the limited information stream they are provided With requires crafty and ingenious approaches to extract all possible details From. This has led to astronomy across multiple spectra, including IR, x-ray And gamma, to help complete our picture of the cosmos.
[attachment=68121]
INTRODUCTION
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena.
Radio astronomy comes under the observational astronomy.
Radio astronomy studies radiation with wavelengths greater than approximately one millimetre. Radio astronomy is different from most other forms of observational astronomy in that the observed radio waves can be treated as waves rather than as discrete photons.
LOCATING RADIO OBJECTS IN THE SKY
To share information with others, a reference system must be adopted. The system used by astronomers is the celestial coordinate system.
Azimuth is the angle around the horizontal from due north and running clockwise. Altitude is the height of the object.
The longitude lines on a celestial sphere are called Right Ascension. Right Ascension is measured on the celestial equator in an easterly direction. Declination corresponds to latitude and is measured in degrees
RADIO TELESCOPE
Radio telescopes are used to study naturally occurring radio emission from stars, galaxies, quasars, and other astronomical objects between wavelengths of about 10 meters (30 [MHz]) and 1 millimetre (300 GHz)
Radio telescopes vary widely, but they all have two basic components: (1) a large radio antenna and (2) a sensitive radiometer or radio receiver.
The most familiar type of radio telescope is the radio reflector consisting of a parabolic antenna--the so-called dish or filled-aperture telescope.
ADVANTAGES OF RADIO ASTRONOMY
Can observe day and night
Can penetrate clouds
Only stopped by strong winds, thunderstorms and snow!
Radio interferometry can produce better resolution than optical astronomy
DISADVANTAGES OF RADIO ASTRONOMY
Powers received are very low, since each photon has a small h
need big collectors (dishes)
Angular resolution is poor
but can’t do much better optical interferometry
Radio: to get ~0.5 arc sec, =5cm
d~50 km
Thus, radio astronomers need interferometers
CONCLUSION
When Karl Jan sky discovered a source of radio waves near the centre our Own galaxy, this proved that in astronomy there literally is more than meet The eye. This acted like a wake-up call for astronomy as awhile, and made Astronomers realize that the limited information stream they are provided With requires crafty and ingenious approaches to extract all possible details From. This has led to astronomy across multiple spectra, including IR, x-ray And gamma, to help complete our picture of the cosmos.