Analysis of currently observed comets

C/2008 J1 (Boattini)


On May 2, 2008 A. Boattini discovered a comet near the border of the constellations Equuleus and Delphinus, on images taken in the course of the Catalina Sky Survey. Comet C/2008 J1 (Boattini) presented a 50" coma of total magnitude 14.0 and a 2' long, fan-shaped tail in p.a. 235°. Visual observations during the following days showed the comet at magnitude 13.0. The comet will pass its perihelion in mid-July 2008, thereby moving northwards, reaching an expected maximum brightness of 12.5 mag. From mid-June until the end of the year the comet will be a circumpolar object, passing through the constellations Cepheus, Ursa Minor and back to Cepheus, closing in on the northern Pole to within 2° on Aug. 20 (getting even closer to the Pole and Polaris at the end of October/beginning of November, missing them by a few arcminutes). Estimates on the beginning of June 2008 show the comet already at 11.5 mag with a medium-condensed (DC 3), 2' coma. The current orbital elements result in a period of approximately 2100 years (IAUC 8940 / MPEC 2008-M02).

Until the beginning of February 2009 only 10 observations by 4 members of the German Comet Section were received. For the analysis 90 additional international observations were taken into account. These show clearly different brightness evolutions before and after perihelion, in both cases with great values of the activity parameter. The maximum brightness of 10.0 mag was reached in mid-July. The appropriate formulae are:

pre-perihelion: m = 2.1 mag + 5×log D + 32.5×log r
post-perihelion: m = 4.6 mag + 5×log D + 19.5×log r

The coma diameter increased from 1.0' (90.000 km) at the beginning of May to a maximum of 4.5' (300.000 km) in the first days of August. In a similar manner it decreased, reaching 1.5' (100.000 km) at the end of October. The degree of condensation remained constant at DC 3 until the early days of September, thereafter decreasing to DC 1-2 until the end of October. The coma showed an unusual morphology, comparable to a Galaxy.

Total Brightness and Coma Diameter

Andreas Kammerer

FGK observations


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