Proceedings Article | 11 September 2024
Lawrence Machia, Hank Corbett, Alan Vasquez Soto, Ramses Gonzalez, Nicholas Law, Thomas Procter, Nathan Galliher, Jonathan Carney, William Marshall, Shannon Fitton, Amy Glazier, Glenn Walters
KEYWORDS: Telescopes, Collimation, Optical alignment, Image quality, Climatology, Robotics, Equipment, Vibration, Turbulence, Sensors
The advent of inexpensive, low-noise CMOS sensors on the market along with advances in GPU computing are making possible a new class of wide-field astronomical surveys using large numbers of small-aperture, mass-produced telescopes, potentially lowering instrument costs by orders of magnitude. The Argus Array survey telescope will open new pathways into the study of optical transients via high-cadence, all-sky imaging. Each Argus image will cover 8000 square degrees of sky at 1.4 arcsec/pixel resolution, reaching mg = 16.1 in 1 second and mg = 19.5 in 30 seconds. The array itself consists of 900 20-cm-aperture telescopes on a single tracking mount secured within a climate-controlled enclosure. Aligning and maintaining this many telescopes manually is a complex and expensive requirement; therefore, Argus image quality optimization must be automated as much as possible. Each telescope is fitted with custom, low-cost robotic collimation and tilt-alignment systems capable of making down to 0.5μm adjustments and allowing for remote, hands-free alignment of each optical assembly. Yet these systems will not need to operate very frequently after initial alignment, as the optics will be maintained in their well-aligned state for long periods of time by the climate control system. The Argus Array enclosure will be kept filtered and isothermal to minimize the need for cleaning, realignment, and focusing of the optics. These systems require iterative prototyping and long-term testing. The robotic alignment systems must be made simple, precise, and reliable, and climate control must be shown not to interfere with image quality through induced ground-layer turbulence, dome-seeing, or vibration. To this end Pathfinder, a 1:3 linear scale Argus prototype, was deployed in December of 2022 to verify these and many other Argus technologies. Pathfinder is built within two insulated 20-foot shipping containers with the instrument occupying one container and the HVAC system, control server, and water-cooling systems housed separately in the other. This prototype currently operates with 12 telescopes, but can support up to 38, and observes a declination stripe of sky directly overhead. We present performance measurements of Pathfinder’s HVAC system along with the design and performance of the Argus automated alignment systems, showing that these systems meet the required specification for Argus science.
