Analysis of Comet Apparitions

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C/2022 P1 (NEOWISE)

On Aug. 8, 2022 a comet of magnitude 19, showing a coma diameter of about 1', was discovered on images taken by the NEOWISE satellite in the southern part of Aries. Follow-up observations of comet C/2022 P1 (NEOWISE) showed a condensed coma of 0.5' diameter and total magnitude 16.5, but no tail. The comet will pass perihelion on Nov. 24, 2022 at a solar distance of 1.61 AU, expected to reach 16 mag (CBET 5158). It will approach Earth to within 0.86 AU on Sep. 25, 2022, when a brightness of 14.5 mag is predicted. The comet should be brighter than 16 mag between the end of August and mid-November 2022. During that time, it moves through the constellations Cetus, Sculptor, Grus, Microscopium and the southern parts of Sagittarius. From mid-European latitudes it can be followed only until around Sep. 20.

The comet showed a very high activity and became eventually 4.5 mag brighter than predicted! The rapid brightening during the first weeks was caused by a combination of high activity and the rapid approach of the comet to Earth. The maximum brightness of 10.1 mag was reached in mid-October 2022. Thereafter the comet continued to approach Sun, but receded from Earth. In addition the activity decreased much more slowly post-perihelion than it increased pre-perihelion. As a result the comet faded only slowly during the next five weeks. Based on 99 observations from 20 observers the following parameters can be used:

pre-perihelion: m0 = 1.3 mag / n = 15
post-perihelion: m0 = 5.5 mag / n = 7.5

Total Brightness and Coma Diameter

The coma diameter increased from 2' (100.000 km) at the start of the apparition to the maximum of 7' (350.000 km) by the opening of October. Thereafter it shrunk, measuring 1.5' (175.000 km) at the start of December. During the whole apparition the coma was medium-condensed with the degree of condensation constant at DC 3-4. After mid-December 2022 no estimates of the coma diameter and the degree of condensation have been reported. A tail was not observed.

Andreas Kammerer

FGK observations