PhotometricGlowSubtraction for PixInsight

This is PhotometricGlowSubtraction

PhotometricGlowSubtraction removes the glow that bright stars spread across an astronomical image. It measures your telescope’s own point spread function (PSF) from the stars in the image, out to several arcminutes. Then, using each star’s position and brightness from the Gaia DR3 catalog, it subtracts every bright star’s glow, including stars just outside the frame whose light still reaches in. The cores of the stars are left untouched, and nothing in the image is smoothed or filtered. What comes off is a physical model of the stray light, and it can be saved as an image of its own and inspected.

Why it matters: the glow around bright stars is often brighter than the faintest things a deep image is after, such as galactic cirrus, the tidal streams and outer halos of galaxies, and the faint edges of a nebula. Gradient and background tools can’t remove it, because it isn’t a gradient. It is centered on each star, a different size around each one, and it overlaps from star to star. PhotometricGlowSubtraction takes it off star by star, using the same method used in low surface brightness astronomy. It works on linear, plate-solved images, early in processing, and leaves the background for your usual gradient tool.

What about halos? PhotometricGlowSubtraction does not subtract star halos because halos are highly unpredictable optical reflections, not measurable physical characteristics of the stars themselves. Because PhotometricGlowSubtraction is built entirely around exact measurement and physical modeling rather than destructive image “filtering” (morphological transformations, AI-driven healing, etc.), halo removal falls outside PhotometricGlowSubtraction’s scope: precise mathematical subtraction based on measured physical reality. A mouthful, but accurate.