Synoptic Optical Long-term Investigations of the Sun

Synoptic Optical Long-term Investigations of the Sun (SOLIS) is a synoptic facility for solar observations over a long time frame that is funded by the National Science Foundation (NSF) and designed and built by the National Solar Observatory (NSO)[1] .[2] It is operated by the NSO Integrated Synoptic Program (NISP). SOLIS is a single set of three instruments mounted on a common observing platform. The instruments are a Vector Spectromagnetograph (VSM), an Integrated Sunlight Spectrometer (ISS), and a Full-Disk Patrol (FDP). The VSM provides full-disk vector (strength and direction) maps of the solar magnetic field both in the photosphere and in the chromosphere on a daily basis, continuing the 40-year record of NSO magnetic field observations. The ISS obtains spectra of the Sun integrated over the solar disk, so the Sun appears as it would as a much more distant star. The combination of data from the ISS and the VSM is useful for studies of exoplanet systems as it allows the modeling of the influence of a star's magnetic field on its spectrum giving clues to the activity level that the exoplanets may be subject to. The FDP provides full-disk images of the Sun in a variety of spectral lines with a cadence as high as 10 seconds.

SOLIS was located on top of the Vacuum Telescope building[3] at Kitt Peak National Observatory until July 2014, then temporarily moved to the University of Arizona Agricultural Farm in Tucson until October 2017, and is now being permanently relocated to Big Bear Solar Observatory in California.[4][5] Once back to operations, SOLIS will provide unique observations of the Sun on a continuing basis for several decades to understand the solar activity cycle, sudden energy releases in the solar atmosphere, and solar irradiance changes and their relationship to global change.