Observations of Planetary Nebulae at a Frequency of 2,700 Megacycles per Second

Abstract

TWENTY-FOUR of the well-known planetary nebulae have recently been observed at a frequency of 2,700 Mc/s using the Jodrell Bank Mark II radio telescope, the 125 ft. × 85 ft. steerable paraboloid. A double-feed system was used, the receiver input being switched between two horns equally spaced (horizontally) from the focus of the telescope. The beamwidth for a single horn feed was ∼ 15′ arc and the angular separation of the two beams was 20′ arc. Amplification at the signal frequency was provided by a varactor diode parametric amplifier operating in a non-degenerate mode. The receiver bandwidth was 8 Mc/s and the output time constant was half a second.