Strong coma lobes from small gravitational deformations.
Abstract
Beam mapping at 1.3 cm wavelength is found to exhibit a considerable degradation at the 140 ft telescope which results from a large lateral defocusing, varying by 7.2 cm east-west and 2.8 cm north-south for pointing changes of 90 degrees. A structural analysis confirms that a gliding rotation of the best-fit paraboloid causes movement in the optical axis. The best-fit paraboloid glides along a slightly deformed surface while rotating about the center of the average surface curvature. A method to alleviate the degradation for this and other types of telescopes employs a variable lateral shift of the mount at the prime focus which is computer-controlled as a function of the pointing and follows the axial movements.
- Publication:
-
IEEE Transactions on Antennas and Propagation
- Pub Date:
- September 1980
- DOI:
- 10.1109/TAP.1980.1142393
- Bibcode:
- 1980ITAP...28..652V
- Keywords:
-
- Cassegrain Optics;
- Gravitational Effects;
- Radio Telescopes;
- Reflecting Telescopes;
- Sidelobes;
- Aberration;
- Beams (Radiation);
- Defocusing;
- Parabolic Bodies;
- Structural Analysis;
- Wave Degradation;
- Astronomy;
- Radio Telescopes;
- Radio Equipment