Analysis of past comet apparitions

C/2005 N1 (Juels-Holvorcem)


On July 2, 2005 the amateur team C.W. Juels (USA) and P.R. Holvorcem (Brasilia) discovered their second comet with an automated 7 cm refractor. The 14.5 mag comet C/2005 N1 (Juels-Holvorcem), located in the constellation of Perseus, presented a bright 30" inner coma and an outer one of 70" diameter. In addition, it showed a 120" long fanned tail (IAUC 8557). Moving through the constellations of Auriga, Lynx, Ursa Major into Coma Berenice it was located in the morning sky during the following weeks with an expected maximum brightness of 13.0 mag at perihelion. Actually it even reached 11.5 mag!

No observation by a member of the German Comet Section has been received, likely due to its position in the morning sky. The 48 observations by international observers used for the analysis indicate quite different brightness evolutions pre- and post-perihelion:

pre-perihelion: m = 9.6m + 5×log D + 13.8×log r

post-perihelion: m = 10.0m + 5×log D + 7.5×log r (approximate values)

yielding a maximum brightness of 11.4 mag in mid-August. Post-perihelion the brightness evolution is not well documented. Taking into account CCD-observations during fall/winter 2005/06 a significant fading becomes apparent, which can be described approximately by the brightness parameters shown above. The apparent coma diameter increased from 0.8' (60.000 km) at the beginning of the apparition to almost 2.0' (150.000 km) in mid-September (with the hint of a possible decrease around the start of October). The degree of condensation was constant at DC 3.

Total Brightness and Coma diameter

Andreas Kammerer


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