Chromosphere and Prominence Magnetometer

The Chromospheric and Prominence Magnetometer (ChroMag) will measure and monitor the magnetic and thermodynamic conditions of the chromosphere at the true base of the heliospheric system. ChroMag measurements will permit the study of the dynamic evolution of the heliosphere’s thermo-magnetic interface on an ongoing (synoptic) basis as well as during the onset of the large-scale eruptions that episodically impact the near-Earth environment.

The baseline design consists of a refractive telescope with an aperture of 20 cm that feeds a narrow-band Lyot filter imaging polarimeter. The chromospheric magnetic field can be inferred from the spectro-polarimetric measurements made by ChroMag through the application of so-called inversion codes. At left, ChroMag is shown set up in the lab at HAO.

A prototype instrument is currently deployed at the NCAR Mesa Spar facility in Boulder (shown here). This instrument has been planned primarily to demonstrate and verify the instrument concept and reduce risk in the instrument design. Production of science quality observations is a secondary objective. The prototype has a smaller aperture than ChroMag proper, and hence will not meet the spatial resolution requirement. It is also a single-beam polarimeter, which means that it will be sensitive to atmospheric seeing conditions that induce crosstalk between intensity and polarization. Since it is not deployed to a high-quality site where good seeing conditions cannot be expected, the polarimetric accuracy is expected to suffer as a result.

Shown here is the first light 854.2nm Ca II line image of the chromosphere.