WFI-2 reveals a polarimetric rainbow in the beautiful, ghostly zodiacal light surrounding the Sun, against a backdrop of familiar constellations, using raw images collected by the spacecraft.
This ethereal polarimetric rainbow reveals the direction and degree of polarization of the zodiacal light, in a preliminary data product from the WFI-2 spacecraft. On 18-April, WFI-2 executed its first polarimetric triplet imaging, collecting images through all three of its polarizers in succession. The polarimetric triplet image, expressed as RGB color channels, reveals the direction (via hue) and degree (via saturation) of polarization everywhere in the field of view all at once. WFI looks to one side of the Sun (marked with a star glyph). This image, made with Level 0 (uncalibrated) data direct from the WFI-2 camera, is consistent with existing results from ground observations (Leinert et al. 1998). Stars appear white because they are mostly unpolarized, compared to the 7% polarization of the zodiacal light. PUNCH uses a novel polarimetric formalism (“MZP”, DeForest et al. 2022), which allows direct display of polarization using color. Chromatic display of coronal polarization was demonstrated at the 2023 total solar eclipse (Patel et al. 2023), highlighting the long-term synergy between ground- and space-based observations of the corona.
References:
• Leinert et al. 1998: link to A&A Journal
• DeForest et al. 2022: link to Astrophysical Journal
• Patel et al. 2023: link to MNRAS
This is PUNCH Nugget #9. PUNCH nuggets are archived at the PUNCH mission website. You can sign up to receive PUNCH nuggets by email. NASA official releases about PUNCH are at the NASA PUNCH blog.
