The Fan Observatory Bench Optical Spectrograph (FOBOS)

The Fan Observatory Bench Optical Spectrograph (FOBOS) is intended for single-object optical spectroscopy at moderate resolution (R~1500-3000) using a fiber-fed, bench-mounted design to maintain stability. Whenever possible, the instrument uses off-the-shelf components to maintain a modest cost. FOBOS supports Galactic astronomy projects that require consistently well-measured (~5 km s^-1) radial velocities for large numbers of broadly distributed and relatively bright (V<~14) stars. The spectrograph provides wavelength coverage throughout the optical spectrum, although the instrument design was optimized for use in the range 4700 Å<λ<6700 Å. Test data indicate that the instrument is stable and capable of measuring radial velocities with precision better than 3 km s^-1 at a resolution of R~1500 with minimal calibration overhead.