Bifrost: an ultra-low-cost cross-dispersed optical echelle spectrograph

Abstract

For on the order of a thousand dollars, we designed and built a high-resolution (R~19,000) optical spectrograph covering 400-950nm, designed to observe bright targets with small telescopes. Innovative 3D printing methods allow us to accurately and cheaply mount and house inexpensive commercial-off-the-shelf (COTS) optical components, including a DSLR camera lens. Bifrost is a fiber-fed spectrograph compatible with our existing and similarly inexpensive 3D-printed acquisition/guide system (compatible with a number of small telescopes, including the Meade LX200 series). A high resolution spectrograph with broadband coverage on a small telescope is optimal for cadence-sensitive spectroscopic variables; our targets of interest include high-mass X-ray binaries, ultra-magnetic stars, and the jets of the microquasar SS 433.