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Comet 73P/Schwassmann-Wachmann (P=5.44a) is not expected to be an easy object in the apparition 2022. It will pass perihelion on Aug. 25, 2022 in the solar distance of 0.97 AU, expected to reach magnitude 12. However the comet showed several outbursts during the last perihelion passages, making reliable predictions impossible. Between June and November the comet should be brighter than 16 mag, thereby moving along the ecliptic from Leo to the region near the border of Capricornus/Microscopium. From mid-European locations the comet will be an evening object; however between end of June and mid-November it will be situated too low above the horizon.
Until start of February 2023 comparatively few observations have been published from this comet. For the analysis 98 observations from 20 observers could be used. These show a rather large scatter of the estimates (at least pre-perihelion) and a sudden rise of activity between end of September and start of October 2022. The brightness development can be represented quite well with the following formulae t < +35d: m = 11.7 mag + 5×log D + 15×log r t > +45d: m = 9.8 mag + 5×log D + 4.2×log rPre-perihelion the brightness development is much worse documented than post-perihelion. Pre-perihelion the comet showed an high level of activity with the apparent brightness peaking at magnitude 11.5 at the time of perihelion. Thereafter it slowly faded until the end of September. Within the next ten days it experienced a sudden rise in the level of activity, resulting in the maximum brightness of 10.1 mag on Oct. 9, 2022. During the following weeks it faded rather slowly, reaching 13.0 mag in mid-January 2023.
Total Brightness and Coma DiameterBetween May and August 2022 the coma diameter increased from 0.5' (30.000 km) to 1.5' (60.000 km) and reached a maximum of 3.5' around Nov. 20 and of 240.000 km around Dec. 20. Thereafter it decreased, measuring 1.5' (100.000 km) by year's end. Until end of October 2022 the degree of condensation was estimated as DC 4-5, then it decreased to DC 2-3 by year's end. A tail was reported throughout the apparition, with maximum length of 15' (1.5 mio. km) in October/November 2022. Its orientation slowly changed from WSW to WNW.
End of July 2022 Michael Jäger discovered two fragments of magnitude 19.5, which were designated BU and BV. Three additional fragments of magnitude 19 (designations BW, BX and BY) were discovered by Michael Jäger and Gerald Rhemann in August.
Andreas Kammerer