The Coronal Solar Magnetism Observatory: Overview and Recent Progress

Magnetism is the dominant force in the solar corona. It plays a key role in structuring the corona on all spatial scales, in heating the corona, and accelerating the solar wind. The storage and release of magnetic free energy in the corona powers solar eruptions that are responsible for space weather with serious consequences for our technological society. Daily synoptic measurements of the magnetic structure of the global solar corona are needed to advance our understanding of these critical physical processes and to enable a predictive capability of solar eruptive events. The lack of synoptic measurements of global coronal magnetism is due to a technology gap in our current capabilities. One pathway to bridge this gap is to observe the Zeeman and saturated Hanle effects of forbidden emission lines in the visible and IR portions of the coronal spectrum with a ground-based coronagraph. The IR has the advantage that the Zeeman splitting scales as the wavelength squared. A dedicated, high-throughput coronagraph/polarimeter that combines a large aperture with a large field of view is needed to observe the weak circular polarization signals and monitor the evolution of coronal magnetism. The Coronal Solar Magnetism Observatory (COSMO) 1.5-m aperture Large Coronagraph represents a proposed instrument able to meet this technological challenge, complementing the recently built Daniel K. Inouye Solar Telescope that has a large aperture and high spatial resolution, but is limited in FOV and is not a dedicated coronal facility. Other COSMO instruments include the COSMO K-Coronagraph (K-Cor) and the Chromospheric and prominence Magnetometer (ChroMag). In this talk, we will describe the COSMO project and its suite of instrumentation and highlight recent progress, including ongoing efforts to conduct a site survey and design the large coronagraph.