PUNCH News

PUNCH mission's “first light” released on June 3rd. The PUNCH Outreach team has contributed to cultural astronomy research in Chaco Canyon, NM by determining the two dates (before and after summer solstice) when the “first light” of sunrise occurs with a dramatic “double diamond ring” effect atop a horizon feature called Triangle Rock. On these dates, the apex of Triangle Rock's shadow passes through the center of a large spiral petroglyph on the eastern face of an Ancestral Puebloan solar observation site called Rock of the Sun. The spiral center defines the viewpoint for the sunrise “horizon calendar” that features the double diamond spectacle and other visually prominent interactions useful for tracking time near the summer solstice.

Each PUNCH instrument uses three polarizers, aligned 60° apart, to measure how much, and in which direction, light from the sky is polarized. We can then display the images using color to represent the polarization of the light.

PUNCH is doing something very ambitious: merging together images from four separate instruments mounted on four separate spacecraft. Doing so requires very, very precise determination of the conversion between each pixel’s value and brightness on the night sky. That’s because, in one 90-minute orbit, the same feature on the sky is imaged by at least eight different pixels across different regions of at least three different cameras. Combining those data requires us to know exactly how to convert the value of each pixel to brightness on the sky.

During this meeting, we will track a CME through PUNCH's field of view and connect it to other mission observations.

We invite the community to attend the seventh PUNCH (Polarimeter to UNify the Corona and Heliosphere) Science Meeting from May 12th through the 14th, 2026 in Boulder, Colorado. As of May 2025, PUNCH has been taking observations, and everyone is invited to share their early results from these data. Topical science sessions will be organized around the themes of the origin and evolution of the ambient solar wind and turbulence within it and the physics, tracking, and predictability of transient events including CMEs, CIRs, and shocks.

PUNCH compresses its images on-orbit with “square-root coding”, to avoid downlinking photo-counting noise (Nugget #13 “Don’t Downlink Quantum Noise”). Removing the photon noise affects the statistics of remaining noise in the data, in a way that depends on the original data value. That, in turn, affects measurements of stray light in the instruments, putting a faint pattern of stripes in PUNCH photometric data (visible as the “stairstep” pattern in the blue trace in the top plot).

Last week, astronomers announced a new comet, designated C/2025 R2 (SWAN), that was discovered in Lyman-α images from the SOHO spacecraft. Since mid-August, PUNCH has been observing this comet, along with every other object within 45° of the Sun. PUNCH collects data at a 4-minute cadence in polarized light and at an 8-minute cadence in unpolarized light.