Fast Transients and Furious Spectroscopy: Revealing the High-Speed Sky with Argus Pathfinder

New sensor technologies and mass-produced optical systems will allow the Argus Pathfinder project to push to far faster survey speeds than any telescope before, which will enable new discoveries. For example, superflares are very fast bursts of radiation from stars. Understanding superflare behavior is crucial to the search for life beyond Earth, and it requires high-speed observations and the ability to point multiple telescopes very rapidly to events as they occur. Other mysterious fast events have been seen at other wavelengths, and they have visible-light counterparts that can shed light on what they are. These and other “transients” occur at random times and places in the sky. The best way to catch them is to survey as much of the sky as possible, as quickly as possible. Argus Pathfinder will make a “movie” of a very large patch of sky. It will observe thousands of transients as they evolve, and rapidly alert other ground- and space-based telescopes. The investigators will contribute to developing and upgrading the Morehead Planetarium’s major time-domain astronomy exhibit to improve the engagement and astronomical inspiration of the approximately 150,000 schoolchildren who interact with the exhibit each year. The 2.3GPix Argus Pathfinder array covers a stripe of the sky 92 degrees in declination and 3.7 degrees in right ascension, with 1.4”/pixel sampling almost reaching the atmospheric-seeing limit. The system tracks each stripe of the sky for 15 minutes, and thus covers almost the entire Northern sky each night. Pathfinder’s CMOS detectors are capable of reading out entire frames with only millisecond-level overheads and have 1-electron-level readnoise, which comes close to single-photon detection capabilities. Pathfinder’s large high-speed detector array, wide passband, and very wide field of view combine to make the system capable of reaching orders of magnitude beyond the closest comparable searches for 1-second duration transients. In the 30s-cadence base survey, Pathfinder will push eight magnitudes deeper than the best previous probes capable of covering the entire sky, and it will cover a survey area at least 5,000 times larger than the deep, narrow minute-timescale probes attempted on larger telescopes. These capabilities will enable a comprehensive characterization of the high-speed sky – and detailed astrophysical measurements of individual populations such as fast radio bursts and stellar superflares. For the latter, Pathfinder will obtain time-resolved light curves and spectra to model the flares’ all-important energetic particle releases and constrain their habitability impacts. For the largest flares, the system will use the new rapid-slew capabilities of the Swift satellite to obtain minute-timescale direct EUV and X-ray flux measurements, and thus a direct measurement of potential planetary habitability impacts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.