The Evryscope has the potential to open a new parameter space for optical astronomy by trading instantaneous depth and sky sampling for simultaneous coverage of the entire accessible sky. This large dataset will enable extremely-wide-field transiting exoplanet searches, realtime searches for transient and variable phenomena, and it offers the capability to effectively pre-image unexpected events detected by other surveys. Our current designs offer limiting magnitudes that will allow both galactic and extragalactic events to be recorded, and the extremely wide field of view opens the possibility of monitoring large samples of rare objects that up to now have required individual targeting.
In the following paragraphs we summarize our plans for our prototype Evryscope system. However, with a continuous movie of 1/4 of the entire sky every two minutes, the projects described below only scratch the surface of the system’s capabilities.
Current exoplanet transit surveys are limited to fields of view of 100-1000 square degrees and so cannot effectively search for transits around large samples of stars that occur rarely in the sky. The Evryscope will have an order-of-magnitude larger field of view than the next-largest current exoplanet surveys, which will enable four transiting planet key projects:
1. Searching for exoplanets around nearby, bright stars which can be easily followed-up for precision spectrophotometric and mapping techniques.
2. A habitable-zone survey for rocky transiting planets around bright, nearby M-dwarfs.
3. A white-dwarf survey for transiting planets; the Evryscope will be the first extremely-wide-field survey with the time resolution and sensitivity to be able to cover a sample of relatively bright, nearby white-dwarfs by searching for very deep eclipses.
4. TESS precursor observations. The Evryscope will provide long-term monitoring of TESStargets, measuring stellar activity and vetting for variable stars. The system will also increase the TESS giant planet yield by recovering multiple transits from objects seen as single eclipses in the relatively short TESS search period.
The Evryscope prototype will also search for transit and eclipse timing variations to detect non-transiting bodies in transiting exoplanet and eclipsing binary systems. With few-minute cadences over large section of the sky, the Evryscope can also search for and characterize rare gravitational microlensing events involving nearby stars.
The Evryscope prototype will monitor the brightness of millions of stars across the sky each night, building up a multi-year, two-minute-cadence database of stellar activity for every star brighter than V=16.5 in its 110-degree declination range. This will enable the detection and characterization of unprecedented numbers of young and active stars, long-period eclipsing binaries which can be used to constrain the mass/radius relation, as well as the detection of a wide variety of other types of stellar variability.
Pre-explosion imaging of gamma-ray-bursts and nearby supernovae
The Evryscope’s short-cadence limit of V=16.5 will enable it to measure the lightcurves of the brightest rapid transients such as gamma-ray-bursts. Co-adding will push the depth to up to V=19 on hour timescales, sufficient to monitor nearby supernovae as they occur. Because all data is recorded, the Evryscope will uniquely be able to provide pre-explosion imaging for minutes, weeks or even months before each event. This unique capability will potentially enable the detection of outbursts or the monitoring of rise times from the very beginning of transient events.