|Description:|| This past weekend the volunteers of CAMRAS, who are restoring the venerable Dwingeloo radio telescope back to working order, organised a weekend of observations. Our goal was to measure the performance of the telescope after all the work that has been carried out in the past year.|
Escaping the oppressing heat and humidity outside, we pointed the telescope in a fixed direction, and watched a number of bright astronomical objects drift by. These driftscans were carried out with a bandwidth of 48kHz at a frequency 1296 MHz, which corresponds to a wavelength of 23 cm. The rotation of the Earth causes the objects to "move" by a maximum of 0.25 degrees per minute, depending on the source declination. (The Pole Star, at a declination of almost 90 degrees, stays approximately at the same position, and only rotates).
The top graph shows some multi-minute driftscans, with an integration time of 4 seconds. Using the known declinations of these sources we converted the time-data to angular offsets from the main beam, and by normalizing the power measurements we were able to determine the shape of the radiation pattern of the dish: a HPBW of 0.64 degrees (see bottom graph).