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The radio telescope, image courtesy of Sze Ern Foo     William P. Coldrick at the telescope
The Astrophysics Group benefits from the Coldrick Observatory established on the roof of the Physics Department. The observatory was funded through through the generosity of Mr. William P. Coldrick (above right), a graduate of the University, who also endowed the Chair in Astrophysics and Cosmology presently held by Mark Birkinshaw . The major instrument of the observatory is a 6 metre radio telescope (above left), built by Weston Antennas. Its Cassegrain geometry has been designed to operate between 4.5 GHz and 25 GHz, making it very suitable for studying water masers at 22.235 GHz. The main research aims include a survey searching for new maser sources in the Galaxy and monitoring the variability of known sources.
The 22 GHz front-end receiver is a copy of a MERLIN K-band receiver which is about to be (re-) installed on the telescope. The receiver operates in both circular polarisations and the polariser and the first amplifiers are cooled to 10 K by a closed-cycle helium refrigeration system. This apparatus was funded by a JREI grant to M.D. Gray.
The front-end converts the signals to an intermediate frequency (IF) near 4.2 GHz. These will be further converted to a second IF at 150 MHz in a mixer stage on the telescope using a local oscillator whose frequency can be adjusted by the supervising computer to allow for the Doppler effect of the Earth's velocity. This part of the receiver has been developed and built in-house.
The back end is a digital Fourier spectrometer specially developed under a JREI grant to M.R.W. Masheder in partnership with AlphaData Parallel Systems Ltd. (Edinburgh) and Beam Ltd. (Bristol). Fourier transforms are taken in real time by FFT code written for field programmable gate arrays (FPGA). The data are therefore integrated in the frequency domain. This very flexible arrangement will be used to provide a pair of power spectra with 4096 channels over 25 MHz. Further details of this apparatus are available here .
The observatory also has the use of a 25-cm Meade optical telescope with CCD camera, which is mounted in a dome on the roof of the Physics Building.
William P. Coldrick and Mark Birkinshaw at radio telescope
6-m telescope on place on roof