accepted for publication in PASP The PRL Stabilized High Resolution Echelle Fiber-fed Spectrograph: Instrument Description & First Radial Velocity Results

We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mt Abu 1.2 m telescope, in India. Data obtained as part of the post-commissioning tests with PARAS show velocity precision better than 2 m s−1 over a period of several months on bright RV standard stars. For observations of σ Dra we report 1.7 m s−1 precision for a period of seven months and 2.1 m s−1 for HD 9407 over a period of 2 months. PARAS is capable of a single-shot spectral coverage of 3800- 9500A ̊ at a resolution of ∼67,000. The RV results were obtained between 3800A ̊ and 6900A ̊ using simultaneous wavelength calibration with a Thorium-Argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01- 0.02◦C (rms) at 25.55◦C, and enclosed in a vacuum vessel at pressure of 0.1 ±0.03 mbar. The blaze peak efficiency of the spectrograph between 5000A ̊ and 6500Å, including the detector, is ∼ 30%; and ∼ 25 % with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81 % reflectivity) is ∼7 % in the same wavelength region on a clear night with good seeing conditions. The stable point spread function (PSF), environmental control, existence of a simultaneous calibration fiber, and availability of observing time make PARAS attractive for a va-riety of exoplanetary and stellar astrophysics projects. Future plans include testing of octagonal fibers for further scrambling of light, and extensive calibration over the entir