Ground-based observations of C/2025 K1 during 2025 December 1–13. Top: F-P diagrams for December 1, 7, and 13. Syndynes (loci of constant β) are red; synchrones (isochrones of constant dust-release epoch) are orange–yellow. The synchrone brackets indicate dust ages of order several tens of days, but are not interpreted as precise release dates. Insets mark the primary condensation and an O51-resolved feature consistent with C/2025 K1-C on December 7 and 13; the feature is projected close to the dust-tail direction. Bottom: Gaia-G-calibrated unfiltered magnitude, phase-corrected Afρ(0^∘) using a 10,000 km radius aperture centered on the primary condensation, and Tycho-reported apparent coma diameter. The aperture includes C/2025 K1-C on fragment-resolved dates. Vertical bands mark the November 2–4 activity increase and November 8–10 HST fragmentation interval.