We present here the optical design of an efficient Fiber-fed, Prism Cross-dispersed, Echelle Spectrograph (Resolution
~70,000 @seeing limited ~2arcsecs conditions) which will operate in the wavelength region of 3700A to 8100A. It will
be used for extra-solar planets searches down to the precision of 3m/s and as well as for follow-up observations for new
transit discoveries. The spectrograph design is such that with a beam size of 100mm (4inch) it should suit the existing 1
to 2m class of telescopes available in India. The fiber-fed spectrograph will be installed with a 1.2m telescope, which is
situated at Mt. Abu (5800feet), Rajasthan, India. We estimate the spectrograph to be >30% efficient from the slit to the
CCD detector, and up to 15% efficient including sky, telescope, fiber-fed optics etc. We expect to reach the S/N ratio of
70 on a 10mag star for an integration time of 40mins. We aim to achieve 5m/s to 3m/s Radial Velocity accuracies on
such a star using the simultaneous ThAr referencing method. Since thermal stability is absolutely necessary to achieve
<5m/s RV accuracies, the whole spectrograph is planned to be kept inside a vibration free isolated tank under low
vacuum (0.001 mbar) in a thermally isolated room at 28C +/- 0.01C. It should see the first light by the summer of 2009.
We are guaranteed at least 120 nights per year for the planet search program, more nights are possible.
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