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Comet 67P/Churyumov-Gerasimenko was selected in 2003 as the new target of the Rosetta mission. It has since been the subject of a detailed campaign of observations to characterise its nucleus and activity. Here we present previously…

We present observations of comet 67P/Churyumov-Gerasimenko acquired in support of the $Rosetta$ mission. We obtained usable data on 68 nights from 2014 September until 2016 May, with data acquired regularly whenever the comet was…

The binary asteroid 288P/(300163) is unusual both for its combination of wide-separation and high mass ratio and for its comet-like activity. It is not currently known whether there is a causal connection between the activity and the…

Comet 67P/Churyumov-Gerasimenko (67P) become observable for the first time in 2021 since the Rosetta rendezvous in 2014--16. Here, we present pre-perihelion polarimetric measurements of 67P from 2021 performed with the Very Large Telescope…

Dormant or near-dormant short-period comets can unexpectedly regain ability to eject dust. In many known cases, the resurrection is short-lived and lasts less than one orbit. However, it is possible that some resurrected comets can remain…

We present observations of comet 67P/Churyumov-Gerasimenko during its 2021/22 apparition, aiming to investigate its dust and gas environment and compare the results with those obtained in 2015/16 using the same telescope. Quasi-simultaneous…

On 2018 November 18, coronagraphs onboard the Solar and Heliospheric Observatory (SOHO) captured an unrecognized comet crossing its fields of view. We identified this comet to be the minor planet (139359) 2001 ME1 whose previously unnoticed…

Comet Hale--Bopp (C/1995 O1) has been the single most significant comet encountered by modern astronomy, still having displayed significant activity at 25.7 AU solar distance in late 2007. It is a puzzling question when and where this…

Jupiter-family Comet D/1770 L1 (Lexell) was the first discovered Near-Earth Object (NEO), and passed the Earth on 1770 Jul 1 at a recorded distance of 0.015 au. The comet was subsequently lost due to unfavorable observing circumstances…

Comet 67P/Churyumov-Gerasimenko (67P) was imaged with the 2m telescope at Mt. Wendelstein Observatory in the Alps. Coma and tail monitoring was performed during 51 nights between 22 August 2015 and 9 May 2016. The images through r and i…

We monitor the inner coma of comet 41P/Tuttle-Giacobini-Kres\'{a}k searching for variations of its colour. Fast changes in colour of the comet 41P/Tuttle-Giacobini-Kres\'{a}k provide important clues for better understanding of the…

Comet 21P/Giacobini-Zinner is a peculiar comet from the viewpoints of the chemical and physical properties of its dust grains. We conduct optical high-resolution spectroscopic observations of the comet. The intensity ratios of forbidden…

Long-period comet C/2018 F4 (PANSTARRS) was observed to show duplicity of its inner region in 2020 September, suggestive of a splitting event. We here present analyses of our observations of the comet taken from the LOOK project and the…

The encounter of the meteoric material from 73P/Schmassmann--Wachmann~3 produced during the comet's 1995 outburst in May 2022 provides a rare and valuable opportunity to understand a fragmenting comet. Here we explore various ejection…

We present the history of investigation of the dynamical properties of pairs and groups of genetically related long-period comets (other than the Kreutz sungrazing system). Members of a comet pair or group move in nearly identical orbits…

On 2007 October 29 the outbursting comet 17P/Holmes passed within 0.79 arcsec of a background star. We recorded the event using optical, narrowband photometry and detect a 3% to 4% dip in stellar brightness bracketing the time of closest…

Comet C/2025 K1 (ATLAS) reached perihelion at 0.33 au on 2025 October 8. Daily monitoring by the LCO Outbursting Objects Key Project revealed a major activity increase between November 2 and 4, accompanied by rapid changes in coma…

We present results from our observing campaign of Comet 209P/LINEAR during its exceptionally close approach to Earth during May of 2014, the third smallest perigee of any comet in two centuries. These circumstances permitted us to pursue…

The quasi-Hilda object, 212P/2000YN30 with a cometary-like orbit, was found to display a dust tail structure between January and March, 2009. From orbital calculations, it is shown that this object could have been an active comet in its…

This comprehensive study of comet C/1995 O1 focuses first on investigating its orbital motion over a period of 17.6 yr (1993-2010). The comet is suggested to have approached Jupiter to 0.005 AU on -2251 November 7, in general conformity…