Australia’s first ‘astrocomb’

Australia’s first ‘astrocomb’

We’ve demonstrated an ‘astrocomb’ on an Australian telescope for the first time!

An ‘astrocomb’ is a femtosecond laser frequency comb fired into an astronomical spectrograph. Frequency combs earned their inventors – Ted Hänsch and John Hall – the 2005 Nobel Prize in Physics. The “teeth” of the comb form a regularly-spaced set of sharp lines in the spectrum, all with known, highly-precise frequencies, thereby providing a kind of ‘frequency ruler’ with which to calibrate the spectrograph. Simple, right? Well, maybe in theory, but in practice it’s quite a challenge.

With a team of frequency comb experts from the University of Western Australia (Andre Luiten, Clayton Locke, Philip Light) and an astronomical instrument specialist from the Australian Astronomical Observatory (Jon Lawrence), we built, transported, installed and tested an ‘astrocomb’ at the 3.9-metre Anglo-Australian Telescope at Siding Spring Observatory. The test was so successful that we’ve managed to use the data to measure/limit the sensitivity variations within individual pixels of the CCD detector.

The paper details are as follows:
Murphy M.T., Locke C.R., Light P.S., Luiten A.N., Lawrence J.S.,
Laser frequency comb techniques for precise astronomical spectroscopy,
2012, Mon. Not. Roy. Astron. Soc., 422, 761, arXiv:1202.0819.