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We obtained broadband and narrowband images of the hyperactive comet 46P/Wirtanen on 33~nights during its 2018/2019 apparition, when the comet made an historic close approach to the Earth. With our extensive coverage, we investigated the temporal behavior of the comet on both seasonal and rotational timescales. CN observations were used to explore the coma morphology, revealing that there are two primary active areas that produce spiral structures. The direction of rotation of these structures changes from pre- to post-perihelion, indicating that the Earth crossed the comets equatorial plane sometime around perihelion. We also used the CN images to create photometric lightcurves that consistently show two peaks in the activity, confirming the two source regions. We measured the nucleus apparent rotation period at a number of epochs using both the morphology and the lightcurves. These results all show that the rotation period is continuously changing throughout our observation window, increasing from 8.98~hr in early November to 9.14~hr around perihelion and then decreasing again to 8.94~hr in February. Although the geometry changes rapidly around perihelion, the period changes cannot primarily be due to synodic effects. The repetition of structures in the coma, both within a night and from night-to-night, strongly suggests the nucleus is in a near-simple rotation state. We also detected two outbursts, one on December~12 and the other on January~28. Using apparent velocities of the ejecta in these events, 68$pm$5~m~s$^{-1}$ and 162$pm$15~m~s$^{-1}$, respectively, we derived start times of 2018~December~12 at 00:13~UT~$pm$7~min and 2019~January~27 at 20:01~UT~$pm$30~min.
Cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and
We measure the degree of linear polarization of comet 46P/Wirtanen during two months, embracing the perihelion passage in 2018 December with phase angles ranging from {alpha}=18.1 to 46.4 deg. The polarimetric response PQ obtained resembles what was
We report on photometry and high resolution spectroscopy of the chemically peculiar Jupiter-family Comet (hereafter JFC) 21P/Giacobini-Zinner. Comet 21P is a well known member of the carbon-chain depleted family but displays also a depletion of amine
We present the results of a molecular survey of comet 46P/Wirtanen undertaken with the IRAM 30-m and NOEMA radio telescopes in December 2018. Observations at IRAM 30-m during the 12-18 Dec. period comprise a 2 mm spectral survey covering 25 GHz and a
Far ultraviolet observations of comets yield information about the energetic processes that dissociate the sublimated gases from their primitive surfaces. Understanding which emission processes are dominant, their effects on the observed cometary spe