Logo
Home=Current Comets | The German group | Tutorials | Archive: C/2012 K1 | Projects, publications | Contact

C/2012 K1 (PanSTARRS)


The PanSTARRS project discovered a 19.5 mag comet on May 19, 2012 near the border of the constellations Ophiuchus/Hercules. The coma was estimated as 2". On additional images comet C/2012 K1 (PanSTARRS) showed a round coma of diameter 10" and total magnitude 19.0. It will not pass perihelion until August 2014 and could - assuming an average evolution - reach magnitude 6.5 in November 2014 (CBET 3112 / MPEC 2012-L43). It should be brighter than 12.0 mag between February 2014 and February 2015. During this period it will move through the constellations Corona Borealis, Bootes, Canes Venatici, southern parts of Ursa Major, Leo Minor, Leo, Sextans, Hydra and Puppis, diving into the far southern sky thereafter. For mid-European observers it will not reappear until January 2015, then situated in Sculptor. It will be invisible for mid-European observers between mid-July and mid-September 2014, between mid-November 2014 and the start of January 2015 und after the start of February 2015. During the period of maximum brightness it will be visible in the morning sky at low altitudes above the southern horizon.

For the analysis 131 observations by 10 members of the German Comet Section and 515 international observations could be used. These indicate an average activity parameter of the comet, however, the absolute magnitude was 1 mag fainter after perihelion compared to the time prior to perihelion. The appropriate formulae are:

pre-perihelion: m = 5.1 mag + 5×log D + 9.4×log r

post-perihelion: m = 6.0 mag + 5×log D + 8.6×log r

Due to the fact that the comet was unobservable between the opening of July and the end of August the observed maximum brightness was magnitude 7.2 around Oct. 20, 2014.

Total Brightness and Coma Diameter

In 2013 the coma diameter increased only marginally from 0.3' to 0.8'. During the following months it increased more rapidly, reaching 9' in mid-May 2014, where it remained until the comet disappeared in the twilight. Post-perihelion the apparent coma diameter increased from 4.5' to 7.5' between the start of September and Oct. 20. The absolute coma diameter increased slowly in 2013 from 50.000 km to 120.000 km. At the start of 2014 it increased much faster, reaching 650.000 km at the end of May. The increase of the apparent coma diameter after perihelion is the result of the decreasing distance comet-Earth (until mid-October). Actually the coma decreased during this period from 375.000 km to 325.000 km, reaching 150.000 km by January 2015. Until Nov. 2014 the coma showed a noteworthy constant degree of condensation of DC 5, then decreasing to DC 3 until January. Within the central part of the coma a rather conspicuous central condensation could be observed.

Since mid-2013 the bright dust tail was discernible on images. Visual sightings have been reported between March and December 2014 with the tail showing a significant clock-wise curvature. Until the beginning of June its visually discernible length reached 0.3° (3 Mio. km). It was oriented towards SE at the beginning, rotating towards East until mid-May. Additionally, since mid-May a narrow, slightly structured gas tail was documented (mostly) photographically, which showed a length up to four-times that of the dust tail. At first, the orientation of the gas-tail differed by about 60° from that of the dust-tail, in mid-June the difference in orientation had decreased to 30°. At the start of October the tail reached its maximum length of 0.5° (3 Mio. km). Visually only the brighter dust tail was visible, which was oriented sunward at the start of September. At the start of October the orientation of the dust- and gas-tail still differed by about 90°. Post-perihelion the orientation of the dust tail changed from NE to ENE.

Andreas Kammerer

FGK observations


Back...