OPASpec: a dual-channel spectrograph for the original polyOculus array

Abstract

We present the design, calibration, and on-sky deployment of OPASpec, a dual-channel spectrograph designed for use with the Original PolyOculus Array (OPA) intended for full operation at Mount Laguna Observatory (MLO) but initially commissioned at Robinson Observatory in Orlando, Florida. Covering a total wavelength range of 360 to 880 nm (3600 to 8800 Å) with resolution of R∼3000, OPASpec utilizes a dichroic optic to separate incoming light into blue (360 to 560 nm) and red (570 to 880 nm) channels, each consisting of dedicated volume phase holographic (VPH) diffraction gratings and custom fabricated camera lens assemblies. We precisely align both optical paths, terminating at a shared focal plane on an ATIK APX-60 CMOS detector. OPASpec’s flexible, compact, and cost-effective design facilitates a broad range of astronomical applications from characterizing stellar flares, in search of coronal mass ejections, resolving common stellar chromospheric lines, and time-domain astrophysics observations.