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High-Precision Calibration of Astronomical Spectrographs with Laser Frequency Combs

Dr Michael Murphy

Centre for Astrophysics and Supercomputing, Swinburne University of Technology

Friday, 9 November 2007, 3.30pm, EN101, (Ground Floor, EN Building), Hawthorn.

Femtosecond frequency combs have recently revolutionised the standards and metrology fields. As the name suggests, they provide a "picket fence" of laser modes spaced equally in frequency space and cover a wide frequency range. In astronomy, there are many applications where we need precisely calibrated spectrographs and/or where we require long-term stability (over decades) of relative frequency measurements. By recording a frequency comb spectrum simultaneously with our astronomical object spectrum, we might be able to obtain an absolute frequency scale which will enable spectra from different times and different instruments to be compared reliably. I will outline some practical problems involved with building a astronomical comb system, outline current efforts to overcome these and discuss some of the scientific goals which would become feasible or benefit enormously by having a spectrograph calibrated with a frequency comb.

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