Description
This study presents findings from narrowband imaging of comet C/2006 P1 (McNaught) using the 3.6-meter New Technology Telescope (NTT) at La Silla, Chile. Observations commenced on January 27, 2007, 15 days after perihelion, and continued until February 4, with additional sessions from February 25 to 28. Imaging was conducted using the ESO Multi-Mode Instrument (EMMI) in both broadband (BV R) and six comet-specific narrowband filters (CN, C3, C2, NH2, blue, and red continuum). Various image processing techniques were employed to enhance structural features, including azimuthal mean/median profile subtraction, azimuthal renormalization, and division by a 1/ρ profile. These enhancements revealed dynamic coma structures, with jets transitioning from spiral patterns to linear or fan-like shapes over time. The consistency of morphological patterns across different processing methods confirmed their authenticity. The periodic recurrence of coma features in CN narrowband images allowed for the estimation of the comet’s nucleus rotation period. Time-series morphological analysis using two techniques, root mean square (RMS) and angular feature tracking in the coma were used to find temporal variations across two observing epochs, indicating a rotation period consistent with the observed morphological changes. The RMS analysis identifies minima suggesting a rotation period of the comet's nucleus of 11.3±0.5 hours, while time-resolved angular tracking of coma jets indicates a rotation period of about 5.65±0.3 hours, which is a factor of two.
