## Radio Telescopes in the world: photo gallery

Several photos of different single parabolic antennas used as radio telescopes are presented.

## Angular Resolution of a (Radio) Telescope

La hability of a radio telescope to observe details from an object in the sky is called, in the astronomical vocabulary, angular resolution. The angular resolution of a single (parabolic in shape) radio telescope is defined as proportional to the ratio between the wavelength (of the incoming radiation) over the diameter de la aperture of the parabola. Thus, if wavelentgh is "lambda" and diameter is "D", the angular resolution (angle theta) is theta=lambda/D multiplied by a constant, say k. Theta is given in radians (1 radian is 57.2958 degrees). For example: if lambda is 2.7mm [characteristic wavelength of the molecule carbon monoxide, CO, in its transition between its rotational levels from level J=1 to J=0] observed with a (single) radio telescope of 10.4m (de OVRO), the angular is (if k=1.22) theta=0.000316 radians equivalent to theta=65 seconds of arc.

## Angular Resolution of a (Radio) Interferometer

The angular resolution of an interferometer to observe detail from an object in the sky is defined as proportional to the ratio between wavelength over distance from one antenna to the other. Thus if the separation distance between two antennas is "d", the angular resolution (angle theta) es theta=k lambda/d. For example: if lambda is 2.7mm observed with the radio interferometer at OVRO with a maximum separation of 200m the angular resolution is (if k=1.22) theta=0.0000165 radians equivalent to theta=3.4 seconds of arc.
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J. Antonio García-Barreto / tony@astroscu.unam.mx
(Created: August 14, 1998| Last Update: July 15, 2003)