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Abstract The broadband solar K-corona is linearly polarized due to Thomson scattering. Various strategies have been used to represent coronal polarization. Here, we present a new way to visualize the polarized corona, using observations from the 2023 April 20 total solar eclipse in Australia in support of the Citizen CATE 2024 project. We convert observations in the common four-polarizer orthogonal basis (0°, 45°, 90°, & 135°) to −60°, 0°, and +60° (MZP) polarization, which is homologous toR, G, Bcolor channels. The unique image generated provides some sense of how humans might visualize polarization if we could perceive it in the same way we perceive color. 

The “Heliophysics Big Year” was an extended “year” when major solar events engaged the public. NASA and the National Science Foundation (NSF) funded several projects to educate the public on the science of the heliosphere and safe observing practices. In response to this initiative, we worked with other teams to create and disseminate accurate yet engaging information. We expanded our eclipse website (https://space.rice.edu/eclipse/) with activities, citizen science projects, resources, training videos, suggested equipment, and links to other compendia. We directed the Citizen CATE 2024 project, and trained state coordinators and their teams to use the specialized equipment and procedures. We trained teachers at local, regional, national, and international workshops, providing eclipse viewing cards, lenses for making “solar cup projectors,” a pattern for a safe viewing screen, and additional materials. With other teams, we gave presentations to the media at SciLine in San Antonio and hosted public events to demonstrate safe eclipse viewing techniques. The most lasting and impactful product was our planetarium show “Totality,” which was distributed free of license fees. More than 180,000 views of the show and its animations have been documented. We improved our space weather forecasting site (https://mms.rice.edu) and used our email lists (14,000+) to send out real-time warnings about the major solar storm of 10–11 May 2024. In total, we provided nearly two million people with heliophysics information. In summary, the federal/private/business partnerships meant that the events of this “year” were a fun, safe, learning experience for tens of millions of Americans. 

We present the design of a portable coronagraph, CATEcor (where CATE stands for Continental-America Telescope Eclipse), that incorporates a novel “shaded-truss” style of external occultation and serves as a proof-of-concept for that family of coronagraphs. The shaded-truss design style has the potential for broad application in various scientific settings. We conceived CATEcor itself as a simple instrument to observe the corona during the darker skies available during a partial solar eclipse, or for students or interested amateurs to detect the corona under ideal noneclipsed conditions. CATEcor is therefore optimized for simplicity and accessibility to the public. It is implemented using an existing dioptric telescope and an adapter rig that mounts in front of the objective lens, restricting the telescope aperture and providing external occultation. The adapter rig, including occulter, is fabricated using fusion deposition modeling (FDM; colloquially “3D printing”), greatly reducing cost. The structure is designed to be integrated with moderate care and may be replicated in a university or amateur setting. While CATEcor is a simple demonstration unit, the design concept, process, and trades are useful for other more sophisticated coronagraphs in the same general family, which might operate under normal daytime skies outside the annular-eclipse conditions used for CATEcor. 

We present results of a dual eclipse expedition to observe the solar corona from two sites during the annular solar eclipse of 14 October 2023 using a novel coronagraph designed to be accessible for amateurs and students to build and deploy. The coronagraph (CATEcor) builds on the standardized eclipse observing equipment developed for the Citizen CATE 2024 experiment. The observing sites were selected for likelihood of clear observations, for historic relevance (near the Climax site in the Colorado Rocky Mountains), and for centrality to the annular eclipse path (atop Sandia Peak above Albuquerque, New Mexico). The novel portion of CATEcor is an external occulter assembly that slips over the front of a conventional dioptric telescope, forming ashaded-trussexternally occulted coronagraph. CATEcor is specifically designed to be easily constructed in a garage or “makerspace” environment. We successfully observed some bright features in the solar corona to an altitude of approximately 2.25 R_⊙during the annular phases of the eclipse. Future improvements to the design, in progress now, will reduce both stray light and image artifacts; our objective is to develop a design that can be operated successfully by amateur astronomers at sufficient altitude even without the darkened skies of a partial or annular eclipse.