The Argus Optical Array: a 55GPix large telescope surveying 20% of the entire sky every second

The Argus Optical Array will be an all-sky, arcsecond-resolution, 5-m class telescope which builds a simultaneously high-cadence and deep survey by observing the entire sky all night. The 55 GPix array, currently being prototyped, will consist of 900 telescopes covering 20% of the entire sky, each with a very-low-noise CMOS detector enabling sub-second cadences. Argus will observe every part of the sky for 6-12 hours per night, achieving few-night depths of 23-24 magnitudes by trading off relatively small apertures for very long coadded exposure times. The Array is designed to provide the first deep and extremely-high-cadence imaging of the entire Northern sky, matching the sky coverage and timescales of the new wave of all-sky gravitational-wave, neutrino, radio and x-ray observatories. Over five years, the Array will build a two-color, many-million-epoch movie of the northern sky, enabling some of the most-sensitive-yet searches for high-speed transients, fast-radio-burst counterparts, gravitational-wave counterparts, exoplanet microlensing events, occultations by distant solar system bodies, and a host of other phenomena.

We are prototyping the Argus hardware and software pipelines in a series of instruments. The first, the Argus Technology Demonstrator, finished construction and on-sky testing in 2021. In Summer 2022 we will deploy the science-capable Argus Pathfinder, using 48 telescopes to cover the entire sky each night. The project is planned to culminate with the Argus Optical Array observing the entire Northern sky simultaneously with 900 telescopes. In the baseline design, each 55 GPix full-Argus exposure covers 20% of the entire sky to g=19.6, each minute, and reaches g=21.9 each hour. A high-speed mode will allow sub-second all-sky survey cadences for short times. Deep coadds will reach g=23.6 every five nights over 47% of the sky.

A 900-telescope array would, however, be one of the most complex astronomical instruments yet built. A conventional design, scaling up an array of individual telescopes, leads to thousands of moving parts and exposed optical components, and the associated maintenance costs would rapidly outweigh the mass-produced-hardware cost reductions compared to a single monolithic telescope. Argus is designed to dramatically reduce operations and maintenance costs by mounting the entire telescope array inside a lab-like environment, reducing the number of moving parts by orders of magnitude, and protecting all the optics within clean, stable, sealed enclosures.

In this talk we will describe the first results from the Argus Array prototyping program.