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Register a new userThe Evryscope: the first full-sky gigapixel-scale telescope
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Current time-domain wide-field sky surveys generally operate with few-degree-sized fields and take many individual images to cover large sky areas each night. We present the design and project status of the Evryscope (wide-seer), which takes a different approach: using an array of 7cm telescopes to form a single wide-field-of-view pointed at every part of the accessible sky simultaneously and continuously. The Evryscope is a gigapixel-scale imager with a 9060 sq. deg. field of view and has an etendue three times larger than the Pan-STARRS sky survey. The system will search for transiting exoplanets around bright stars, M-dwarfs and white dwarfs, as well as detecting microlensing events, nearby supernovae, and gamma-ray burst afterglows. We present the current project status, including an update on the Evryscope prototype telescopes we have been operating for the last three years in the Canadian High Arctic.
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We have conducted a survey of candidate hot subdwarf stars in the southern sky searching for fast transits, eclipses, and sinusoidal like variability in the Evryscope light curves. The survey aims to detect transit signals from Neptune size planets to gas-giants, and eclipses from M-dwarfs and brown dwarfs. The other variability signals are primarily expected to be from compact binaries and reflection effect binaries. Due to the small size of hot subdwarfs, transit and eclipse signals are expected to last only twenty minutes, but with large signal depths (up to completely eclipsing if the orientation is edge on). With its 2-minute cadence and continuous observing Evryscope is well placed to recover these fast transits and eclipses. The very large field of view (8150 sq. deg.) is critical to obtain enough hot subdwarf targets, despite their rarity. We identified 11,000 potential hot subdwarfs from the 9.3M Evryscope light curves for sources brighter than mg = 15. With our machine learning spectral classifier, we flagged high-confidence targets and estimate the total hot subdwarfs in the survey to be 1400. The light curve search detected three planet transit candidates, shown to have stellar companions from followup analysis. We discovered several new compact binaries (including two with unseen degenerate companions, and several others with potentially rare secondaries), two eclipsing binaries with M-dwarf companions, as well as new reflection effect binaries and others with sinusoidal like variability. The hot subdwarf discoveries identified here are spectroscopically confirmed and we verified the Evryscope discovery light curve with TESS light curves when available. Four of the discoveries are in the process of being published in separate followup papers, and we discuss the followup potential of several of the other discoveries.
New mass-produced, wide-field, small-aperture telescopes have the potential to revolutionize ground-based astronomy by greatly reducing the cost of collecting area. In this paper, we introduce a new class of large telescope based on these advances: an all-sky, arcsecond-resolution, 1000-telescope array which builds a simultaneously high-cadence and deep survey by observing the entire sky all night. As a concrete example, we describe the Argus Array, a 5m-class telescope with an all-sky field of view and the ability to reach extremely high cadences using low-noise CMOS detectors. Each 55 GPix Argus exposure covers 20% of the entire sky to g=19.6 each minute and g=21.9 each hour; a high-speed mode will allow sub-second survey cadences for short times. Deep coadds will reach g=23.6 every five nights over 47% of the sky; a larger-aperture array telescope, with an etendue close to the Rubin Observatory, could reach g=24.3 in five nights. These arrays can build two-color, million-epoch movies of the sky, enabling sensitive and rapid searches for high-speed transients, fast-radio-burst counterparts, gravitational-wave counterparts, exoplanet microlensing events, occultations by distant solar system bodies, and myriad other phenomena. An array of O(1,000) telescopes, however, would be one of the most complex astronomical instruments yet built. Standard arrays with hundreds of tracking mounts entail thousands of moving parts and exposed optics, and maintenance costs would rapidly outpace the mass-produced-hardware cost savings compared to a monolithic large telescope. We discuss how to greatly reduce operations costs by placing all optics in a thermally controlled, sealed dome with a single moving part. Coupled with careful software scope control and use of existing pipelines, we show that the Argus Array could become the deepest and fastest Northern sky survey, with total costs below $20M.
We outline the challenges faced by the planetary science community in the era of next-generation large-scale astronomical surveys, and highlight needs that must be addressed in order for the community to maximize the quality and quantity of scientific output from archival, existing, and future surveys, while satisfying NASAs and NSFs goals.
The Origins Space Telescope, one of four large Mission Concept studies sponsored by NASA for review in the 2020 US Astrophysics Decadal Survey, will open unprecedented discovery space in the infrared, unveiling our cosmic origins. We briefly describe in this article the key science themes and architecture for OST. With a sensitivity gain of up to a factor of 1,000 over any previous or planned mission, OST will open unprecedented discovery space, allow us to peer through an infrared window teeming with possibility. OST will fundamentally change our understanding of our cosmic origins - from the growth of galaxies and black holes, to uncovering the trail of water, to life signs in nearby Earth-size planets, and discoveries never imagined. Built to be highly adaptable, while addressing key science across many areas of astrophysics, OST will usher in a new era of infrared astronomy.
The Event Horizon Telescope (EHT) is a very long baseline interferometry (VLBI) array that comprises millimeter- and submillimeter-wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of ~1.3 mm, EHT angular resolution (lambda/D) is ~25 micro-as, which is sufficient to resolve nearby supermassive black hole candidates on spatial and temporal scales that correspond to their event horizons. With this capability, the EHT scientific goals are to probe general relativistic effects in the strong-field regime and to study accretion and relativistic jet formation near the black hole boundary. In this Letter we describe the system design of the EHT, detail the technology and instrumentation that enable observations, and provide measures of its performance. Meeting the EHT science objectives has required several key developments that have facilitated the robust extension of the VLBI technique to EHT observing wavelengths and the production of instrumentation that can be deployed on a heterogeneous array of existing telescopes and facilities. To meet sensitivity requirements, high-bandwidth digital systems were developed that process data at rates of 64 gigabit/s, exceeding those of currently operating cm-wavelength VLBI arrays by more than an order of magnitude. Associated improvements include the development of phasing systems at array facilities, new receiver installation at several sites, and the deployment of hydrogen maser frequency standards to ensure coherent data capture across the array. These efforts led to the coordination and execution of the first Global EHT observations in 2017 April, and to event-horizon-scale imaging of the supermassive black hole candidate in M87.
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