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Hydrogen Maser arrives 2003/11/09


The new EFOS-C 28 hydrogen maser frequency standard arrived at HartRAO from Switzerland on 2003 November 9. Designed and built at the Observatoire Cantonal de Neuchatel, the maser was accompanied by Alain Jornod, who commissioned it and carried out training of the HartRAO staff. The new maser replaces the EFOS 6 maser that has been in service for 18 years.

The maser provides standard outputs of 5 MHz, 10 MHz and 1 PPS. These are phase-locked to the microwave emission frequency of the hydrogen gas in the maser cavity of 1420 405 751.689 Hz. The frequency stability is 1 part in 1015 over 1000 seconds, and the frequency drift is less than 1 part in 1014 per day. The stability is about a factor of three better than the older maser.

The maser is essential for the operation of the telescope in the international networks of radio telescopes using the Very Long Baseline Interferometry (VLBI) technique for astronomy and geodesy. The maser provides the clock signal that is recorded with the radio signal from the telescope, and allows the signals from each pair of telescopes in the network to be aligned to obtain interference fringes between the two signals.

at the door
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Pieter Stronkhorst is seen above in the unenviable job of using the forklift to manoever the R1.5m atomic clock through the door of the observatory.

emerging from crate
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The shipping crate is partly open. Jonathan Quick surveys the maser, while Japie Greef works.

removing from base
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Alain Jornod, on the left, with Keith Jones, Jonathan Quick and Roland Huang move the maser off the base of the crate.

checking out the maser
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A computer has been connected to the maser, which stands in the foreground with a side panel removed. Alain checks the readings while Keith and Jonathan watch.

removing from base
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Alain explains the details of the computer readouts.

removing from base
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Don't try this at home, it needs a trained professional. Jonathan demonstrates the correct technique for turning on the maser. Keith notes that the green LEDs have come on, indicating that all is well.