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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 report Spitzer Space Telescope observations of comet 67P/Churyumov-Gerasimenko at 5.5 and 4.3 AU from the Sun, post-aphelion. Comet 67P is the primary target of the European Space Agency's Rosetta mission. The Rosetta spacecraft will…

Hyperactive comets have high water production rates, with inferred sublimation areas of order the surface area of the nucleus. Comets 46P/Wirtanen and 103P/Hartley 2 are two examples of this cometary class. Based on observations of comet…

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…

We present a dynamical study of 39 active Centaurs and 17 high-perihelion (q$>$4.5 au) JFCs with a focus on investigating recent orbital changes as potential triggers for comet-like activity. We have identified a common feature in the…

Comets are made of volatile and refractory material and naturally experience various degrees of sublimation as they orbit around the Sun. This gas release, accompanied by dust, represents what is traditionally described as activity.…

We report the discovery of activity emanating from (18916) 2000 OG44 (alternately designated 1977 SD), a minor planet previously reported to be both an extinct comet or an asteroid on a cometary orbit. We observed 2000 OG44 with a thin tail…

Comet 12P/Pons-Brooks is a periodic comet with an orbital period of approximately 71 years. Because of the period duration, aphelion of 35.3 au, and highly inclined orbit (74.2 deg), it is classified as a Halley-type comet. In this work, we…

Comet 133P/Elst-Pizarro is the first-known and currently best-characterised member of the main-belt comets, a recently-identified class of objects that exhibit cometary activity but which are dynamically indistinguishable from main-belt…

We report on our extensive photometry and imaging of Comet 46P/Wirtanen during its 2018/19 apparition and use these data to constrain modeling of Wirtanen's activity. Narrowband photometry was obtained on nine epochs from 2018 October…

We report the detection of water vapor associated with main-belt comet 358P/PANSTARRS on UT 2024 January 8-9 using the NIRSPEC instrument aboard JWST. We derive a water production rate of Q(H2O)=(5.0+/-0.2)x10^25 molecules/s, marking only…

176P/LINEAR is a member of the new cometary class known as main-belt comets (MBCs). It displayed cometary activity shortly during its 2005 perihelion passage that may be driven by the sublimation of sub-surface ices. We have therefore…

We present observations showing in-bound long-period comet C/2017 K2 (PANSTARRS) to be active at record heliocentric distance. Nucleus temperatures are too low (60 K to 70 K) either for water ice to sublimate or for amorphous ice to…

We observed comet 96P/Machholz 1 on a total of 9 nights before and after perihelion during its 2017/2018 apparition. Both its unusually small perihelion distance and the observed fragmentation during multiple apparitions make 96P an object…

We present initial observations of the newly-discovered active asteroid 313P/Gibbs (formerly P/2014 S4), taken to characterize its nucleus and comet-like activity. The central object has a radius $\sim$0.5 km (geometric albedo 0.05…

Comet C/2017 K2 (PANSTARRS) was discovered by the Pan-STARRS1 (PS1) Survey on 2017 May 21 at a distance 16.09 au from the Sun, the second most distant discovery of an active comet. Pre-discovery images in the PS1 archive back to 2014 and…

We present an analysis of the photometric data of comets 47P/Ashbrook -Jackson, 65P/Gunn, 362P/2008 GO98, and P/2017 S5 (ATLAS) observed at Kyiv Comet Station (MPC code - 585) in 2017. The upper limits of radii for cometary nuclei, Afrho…

Previous studies have suggested that Comet 209P/LINEAR may produce strong me- teor activity on Earth on 2014 May 24; however, exact timing and activity level is difficult to estimate due to the limited physical observations of the comet.…

We quantified ten parent volatiles in comet C/2009 P1 (Garradd) before perihelion, through high-dispersion infrared spectra acquired with CRIRES at ESO's VLT on UT 2011 August 07 (Rh = 2.4 AU) and September 17-21 (Rh = 2.0 AU). On August…

Photometric and spectroscopic observations of five nearly parabolic comets with eccentricity larger than 0.99 at heliocentric distances greater than 4 AU were performed. No molecular emission was observed for any studied comet and the…