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Typical astronomical spectrographs have a resolution ranging between a fewhundred to 200.000. Deconvolution and correlation techniques are being employedwith a significance down to 1/1000 th of a pixel. HeAr and ThAr lamps areusually used for calibration in low and high resolution spectroscopy,respectively. Unfortunately, the emitted lines typically cover only a smallfraction of the spectrometer's spectral range. Furthermore, their exactposition depends strongly on environmental conditions. A problem is the strongintensity variation between different (intensity ratios {>300). In addition,the brightness of the lamps is insufficient to illuminate a spectrograph via anintegrating sphere, which in turn is important to calibrate a long-slitspectrograph, as this is the only way to assure a uniform illumination of thespectrograph pupil.  Laboratory precision laser spectroscopy has experienced a major advance withthe development of optical frequency combs generated by pulsed femto-secondlasers. These lasers emit a broad spectrum (several hundred nanometers in thevisible and near infra-red) of equally-spaced "comb" lines with almost uniformintensity (intensity ratios typically <10). Self-referencing of the laserestablishes a precise ruler in frequency space that can be stabilized to the10e-18 uncertainty level, reaching absolute frequency inaccuracies at the10e-12 level per day when using the Global Positioning System's (GPS) timesignal as the reference. The exploration of the merits of this new technologyholds the promise for broad-band, highly accurate and reproducible calibrationrequired for reliable operation of current and next generation astronomicspectrometers.

A new Generation of Spectrometer Calibration Techniques based on Optical Frequency Combs