ArgusSpec: rapid, autonomous spectroscopic follow-up of bright transients

Abstract

ArgusSpec will be a fast-response, low-resolution spectroscopic follow-up system. Built almost entirely from off-the-shelf components, including a medium-aperture (16-in.) Ritchey-Chretien telescope, a very-low-noise CMOS detector, a low-resolution (R~100) spectrograph, and a fast-slew (50 deg/s) mount, ArgusSpec will begin observations of bright transient events (mV ≤ 13) within tens of seconds of detection. ArgusSpec will use all-sky transient alerts from the Evryscope, the Argus Pathfinder, and the planned full Argus Array; the latter two systems giving the fastest alerts for optical transients to date. Until now, the high-cadence sky has been largely inaccessible for spectroscopy. For example, large flares from active stars have dramatic impacts on orbiting exoplanets, but are difficult targets for spectroscopic follow-up due to their short-timescale evolution. Planets in the active stars’ habitable zones will be impacted by flares and superflares (energies ≥ 10³³ erg), and associated high-energy particle emissions, which could strip the planet of its atmosphere and impart massive amounts of ultraviolet flux; this could be devastating to any life on the planet’s surface. There has not been a systematic spectroscopic survey of energetic flaring events across a wide range of stellar masses; almost all large flares observed spectroscopically have been from a small sample of active mid-M stars through staring campaigns. For the first time, ArgusSpec will build a library of superflare spectra from across the night sky, allowing for statistical constraints to be placed on their blackbody evolution and morphology. Here we present the design, project status, and science drivers of ArgusSpec.