next up previous contents
Next: Test of polarimeter Up: IRAM 0.8 mm Previous: Receiver test

Receiver operation at the 30m radiotelescope

This receiver has been used for observations at the 30m telescope on February 1--15, 1994. The 30m telescope is equipped with a multiplexing quasi optical system for parallel observation in 3 frequency bands. It was possible to operate in parallel in the 0.8 mm, 1.3 mm and in 3 mm bands. The telescope system noise temperature in the 0.8 mm band is strongly dependent on frequency, weather and the telescope orientation. The best SSB system noise temperature during the observation period was 500 K at 330 GHz when the opacity was about 0.17. When the automatic calibration loads are used for the measurements of the receiver noise the losses between the receiver and the standard reference plane have to be taken into account. The noise temperature measured in the reference plane of automatic calibration () may be 30--40 K higher than the receiver noise temperature due to the loss in the multiplexing system. Fig. {8 gives a sample result: the CO(3-2) transition spectrum in IC 342, measured with the new receiver at the telescope.

Figure 5: Receiver DSB noise temperature. The frequencies in the black part of the curve are available with the present LO remote control. Noise temperature is measured immediately in front of receiver.

Figure 6: Receiver sensitivity in photons.

Figure 7: Receiver DSB noise temperature in the 500 MHz IF band, measured with the autocorrelator

Figure 8: The CO(3-2) transition spectrum of the galaxy IC 342 measured with the new receiver at the telescope (by courtesy of Andreas Schulz et al.)

Acknowledgements. The construction and installation of the new G2 mixer and of the 345 GHz receiver benefited from valuable support from several members of IRAM's technical staff, among whom : M.Voss and D.Billon for the fabrication of the junctions, J.L.Orecchia and J.Sendra for the machining, J.Blondel, C.Boucher, and J.Y.Chenu for the cryogenics and support of laboratory tests, and H.Hein for the on-site installation and tests.

Alexandre KARPOV

next up previous contents
Next: Test of polarimeter Up: IRAM 0.8 mm Previous: Receiver test

Robert Lucas
Thu Mar 9 14:41:52 MET 1995