Rotation Period of C/2006 P1 (McNaught) Through Morphological Analysis with Narrowband Imaging

Vincent Okoth; Cyrielle Opitom; Colin Snodgrass; Brian Murphy; James E. Robinson

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arXiv · 2603.00389

Rotation Period of C/2006 P1 (McNaught) Through Morphological Analysis with Narrowband Imaging

Vincent Okoth·Cyrielle Opitom·Colin Snodgrass·Brian Murphy·James E. Robinson

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Abstract

This study presents findings from narrowband imaging of comet C/2006 P1 (McNaught) using the 3.6-metre 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 (B, V, 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 division and subtraction, azimuthal renormalisation, and division by inverse profile, as well as the Larson-Sekanina technique. 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 validated their authenticity. The periodic recurrence and temporal evolution of CN coma features in narrowband images indicate a nucleus rotation period of 11.8 h, consistent with stable active regions and rotationally modulated outgassing near perihelion.

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Vincent Okoth, Cyrielle Opitom, Colin Snodgrass, Brian Murphy, James E. Robinson. 2026-02-28. Rotation Period of C/2006 P1 (McNaught) Through Morphological Analysis with Narrowband Imaging. https://arxiv.org/abs/2603.00389

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