The SOLIS Vector Spectromagnetograph (VSM) is an f/6.6
Ritchey-Chretien telescope having a 50-cm aperture. VSM uses 256 by 1024 pixel
300 frames/s CCD cameras and ferroelectric polarization modulators. VSM measures
Stokes I, Q, U and V profiles in FeI 630.15 and 630.25 nm lines, Stokes I and V
profiles in the CaII 854.2 nm line and Stokes I profile in the HeI 1083.0 nm line.
Spatial resolution is 1.0 by 1.0 arcsec over a 2048 by 2048 arcsec field
(covering the solar disk). Scan rate is variable between 0.05 and 5.0 s/arcsec.
The VSM provides the following core science data products: (a) photospheric
full-disk vector-magnetograms using the FeI 630.15 and 630.25 nm lines
(field strength, azimuth, inclination, flux, Doppler velocity, continuum intensity);
(b) chromospheric full-disk magnetograms using the CaII 854.2 nm line (line-of-sight
magnetic flux, Doppler velocity, line core intensity); (c) full-disk HeI 1083.0 nm
line characteristics (equivalent width, continuum intensity, Doppler velocity, line
depth, line asymmetry, Doppler width, Si line width, Si line depth, Si Doppler
velocity); (d) photospheric full-disk longitudinal magnetograms using the FeI 630.15
and 630.25 nm lines (line-of-sight magnetic flux). Data products (a) to (c) are
produced three times a day while data product (d) were expected to be be produced
once a day.