Measuring the gravitational astigmatism of a radio telescope.
Abstract
The gravitational astigmatism exhibited by a radio telescope when tilted is analyzed by measuring the focal length in two perpendicular planes. An elongated rotatable feed which illuminates only a central strip of the telescope may be employed for the measurements. The focal length differential, rim deviation and rms surface deviation are expressed as a function of elevation angle. Application of the analysis to a 140-ft radio telescope shows the gravitational deformation to be primarily a simple astigmatic shape.
- Publication:
-
IEEE Transactions on Antennas and Propagation
- Pub Date:
- March 1978
- DOI:
- 10.1109/TAP.1978.1141827
- Bibcode:
- 1978ITAP...26..315V
- Keywords:
-
- Astigmatism;
- Gravitational Effects;
- Optical Measurement;
- Radio Telescopes;
- Elevation Angle;
- Root-Mean-Square Errors;
- Astronomy;
- Radio Telescopes:Image Quality