On Nov. 6/7, 2013 Vitali Nevski discovered a comet on the border of the constellations Hydra/Cancer, using a 20cm-reflector at ISON-Kislovodsk Observatory. Additional observations of comet P/2013 V3 (Nevski) showed a moderately condensed 1.5' to 3' coma of magnitude 15.0, which was elongated towards p.a. 280°. Alan Hale observed the comet visually, reporting a 1.0' coma of magnitude 14.0. The comet passed perihelion on its orbit with a period of 45.4 years already in the last days of October. It was therefore assumed that the comet had reached maximum brightness around discovery date (CBET 3695 / MPEC 2014-C43).
Actually the comet was discovered during an outburst as is indicated by 11 observations from 4 observers of the German Comet Section and by 50 international observations. Only of magnitude 14 at discovery it brightened to 8.7 mag on Nov. 15. This was followed by a rapid eight-days fading to 10.5 mag. The following fading was considerably slower and and can be described by the formula
t > +25d: m = 8.6 mag + 5×log D + 12.5×log r This may indicate that a larger reservoir broke open shortly before discovery that ensured a prolonged activity.Total Brightness and Coma Diameter
In parallel to the brightening the coma expanded rapidly and linearly, reaching 8' (325.000 km) on Nov. 15. This was followed by a slower shrinkage, with the coma measuring 6.5' (250.000 km) at the end of November, 4.5' at the end of December (175.000 km), 2.5' (110.000 km) at the end of January and 0.6' (35.000 km) at the end of February. During the outburst the degree of condensation of the coma increased from DC 1-2 to DC 3-4, only to decrease immediately thereafter, reaching DC 2 during the first week of December. Until the end of the apparition the coma became extremely diffuse (DC 1). Visually a tail could not be observed.
Andreas Kammerer
