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(Abreviated) Comet C/2017 K2 PANSTARRS drew attention to its activity already at a time of its discovery in May 2017 when it was about 16 au from the Sun. This Oort spike comet will approach its perihelion in December 2022, and the question about its dynamical past is one of the important issues to explore. To this aim it is necessary to obtain its precise osculating orbit, its original orbit, and propagate its motion backwards in time to the previous perihelion. We study a dynamical evolution of C/2017 K2 to the previous perihelion (backward calculations for about 3-4 Myr) as well as to the future (forward calculations for about 0.033 Myr). Outside the planetary system both Galactic and stellar perturbations were taken into account. We derived that C/2017 K2 is a dynamically old Oort spike comet (1/a$_{prev}$ = (48.7 $pm$ 7,9) x10$^{-6}$ au$^{-1}$) with the previous perihelion distance below 10 au for 97 per cent of VCs (nominal q$_{prev}$ = 3.77 au). It means that C/2017 K2 has already visited our planetary zone during its previous perihelion passage. Thus, it is almost certainly a dynamically old Oort spike comet.
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 additional d
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 $r_{mathrm{H
Optical observations of the Oort cloud comet C/2017 K2 (PANSTARRS) show that its activity began at large heliocentric distances (up to 35 au), which cannot be explained by either the sublimation or the crystallization of water ice. Supervolatile subl
Distant long-period comet C/2017 K2 has been outside the planetary region of the solar system for 3 Myr, negating the possibility that heat retained from the previous perihelion could be responsible for its activity. This inbound comet is also too co
We study the development of activity in the incoming long-period comet C/2017 K2 over the heliocentric distance range 9 < r_H < 16 AU. The comet continues to be characterized by a coma of sub-millimeter and larger particles ejected at low velocity. I