Related papers: Cometary activity at 25.7 AU: Hale--Bopp 11 years …

We present a high-resolution observation of distant comet C/2014 UN$_{271}$ (Bernardinelli-Bernstein) using the {\it Hubble Space Telescope} on 2022 January 8. The signal of the nucleus was successfully isolated by means of the nucleus…

The outburst and subsequent brightness evolution of Comet 17P/Holmes has been observed using the MMT Observatory's All-Sky Camera (Pickering 2006) on Mt. Hopkins near Tucson, Arizona, USA. The comet was picked up at the limiting visual…

Context. A comprehensive study of comets over a wide heliocentric distance range helps us understand the physical processes driving their activity and reveals compositional differences across dynamical groups. C/2017 K2 (PANSTARRS) is a…

We present two-colour CCD imaging of 2060 Chiron obtained between 1996 and 1998 with the 2.15 m telescope at CASLEO (San Juan, Argentina). These post-perihelion observations show that Chiron was then near its historical brightness minima,…

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…

The results of the photometric observations of comet C/2009 P1 (Garradd) performed at the 60-cm Zeiss-600 telescope of the Terskol observatory have been analyzed. During the observations, the comet was at the heliocentric and geocentric…

The spectra and images obtained through broadband BVR filters for Jupiter famaly comet P/2011 P1 were analyzed. We observed the comet on November 24, 2011, when its heliocentric distance was 5.43 AU. Two dimensional long slit spectra and…

We discuss the composition and size distribution of the dust in the coma of comet Hale-Bopp. We do this by fitting simultaneously the infrared emission spectrum measured by the infrared space observatory (ISO) and the measured degree of…

We imaged Comet 252P/2000 G1 (LINEAR) (hereafter 252P) with the Hubble Space Telescope and both 252P and P/2016 BA$_{14}$ (PanSTARRS) (hereafter BA$_{14}$) with the Discovery Channel Telescope in March and April 2016, surrounding its close…

We combine ground- and space-based observations of long-period comet C/2021 O3 (Panstarrs) (perihelion distance 0.287 au) in order to investigate its reported near-perihelion destruction. Pre-perihelion photometric observations show a…

(1) We find that comet 107P/WH was active in 1949, 1979, 1992, 2005, and 2009. (2) Its age can be measured. We find T-AGE=4700 comet years, WB-AGE=7800 cy. (3) This is a methuselah comet very near to its dormancy phase, being temporarily…

We present optical observations of Halley type comet 12P/Pons-Brooks on its approach to perihelion. The comet was active even in the first observations at about 8 au. Starting at 4 au, 12P exhibited an extraordinary series of outbursts, in…

Intrinsically faint comets in nearly-parabolic orbits with perihelion distances much smaller than 1 AU exhibit strong propensity for suddenly disintegrating at a time not long before perihelion, as shown by Bortle (1991). Evidence from…

We report results based on mid-infrared photometry of comet 103P/Hartley 2 taken during May 4-13, 2010 (when the comet was at a heliocentric distance of 2.3 AU, and an observer distance of 2.0 AU) by the Wide-field Infrared Survey Explorer…

We study the activity evolution of the main-belt comet 324P/La Sagra over time and the properties of its emitted dust. We performed aperture photometry on images taken by a wide range of telescopes at optical and thermal infrared…

The Deep Impact spacecraft fly-by of comet 103P/Hartley 2 occurred on 2010 November 4, one week after perihelion with a closest approach (CA) distance of about 700 km. We used narrowband images obtained by the Medium Resolution Imager (MRI)…

We present a study of comet C/2017 K2 (PANSTARRS) using prediscovery archival data taken from 2013 to 2017. Our measurements show that the comet has been marginally increasing in activity since at least 2013 May (heliocentric distance of…

As the ESA Rosetta mission approached, orbited, and sent a lander to comet 67P/Churyumov-Gerasimenko in 2014, a large campaign of ground-based observations also followed the comet. We constrain the total activity level of the comet by…

In support of the EPOXI mission, we have compiled the secular light curve (SLC) of comet 103P/Hartley 2, the next target of EPOXI. a) Of the order of 30 photometric parameters are measured, over 20 of them new. The turn on point of activity…

To gain a greater insight into the impending evolution of the physical behavior of comet C/2012 S1, its light curve and orbital properties are compared with those for C/1962 C1 (Seki-Lines) and C/2002 O4 (Hoenig). All three are likely Oort…