VERITAS Upgrade for Optical Monitoring of Astronomical Transients

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The Very Energetic Radiation Telescope Array System (VERITAS) is a specialized observatory located in southern Arizona, specifically designed for “gamma-ray astronomy”. VERITAS is comprised of four 12m optical reflectors designed to detect the faint flashes of blue light from very energetic photons (gamma-rays) interacting in the Earth’s atmosphere. Such gamma-ray photons come from violent processes in the universe such as exploding stars, super-massive black holes in the centers of galaxies, and very dense magnetized stars (called neutron stars). This project will modify the electronics of the VERITAS telescopes to allow continuous monitoring of optical variations in visible light from astrophysical objects while also capturing these gamma-ray events, to provide sensitivity to astronomical sources that are too faint, or vary too rapidly to be detected by conventional optical telescopes. There are two key scientific programs this instrumentation advancement will permit. Firstly, a search for optical counterparts of fast radio bursts (FRBs) – mysterious rapid outbursts of radio waves originating from very distant galaxies. Secondly, serendipitous observations of shadows cast by small outer-solar system bodies (typically beyond the orbit of Neptune) that transit nearby stars. The project plans to be active in informing the public of their work through an outreach program with St. Louis City Schools. This proposal is aimed at producing a new type of observatory sensitive to astrophysical phenomena with very rapid optical variability. Realizing this capability can be achieved by an improvement of the electronics on the VERITAS (Very Energetic Radiation Imaging Telescope Array) gamma-ray observatory. Improvements to the VERITAS waveform digitizer electronics would transform the VERITAS instrument into an optical observatory with unmatched sensitivity for observations on timescales less than 10 msec. The wide-field of view (3.5 deg) large aperture (12m diameter dishes) photon-counting detectors, and very high-speed readout (up to 500 MHz) would make this a uniquely capable instrument for studying the universe in a new temporal window. A novel approach is proposed whereby the programmable logic on the FADC boards would be changed in a way to provide high-speed streaming computation of the light intensity through a photon counting technique. The modified electronics would allow the system to continue to function as a gamma-ray telescope, while providing continuous monitoring of optical variability over the entire field-of-view. The project also plans interdisciplinary transfer of the technology developed to a cancer detection project at the same university.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.