Home=Current Comets: 24P (2025/26)
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During the winter months 2025/26 comet 24P/Schaumasse (P=8.18a) should become an object that should be easily visible through a telescope and probably even in binoculars. It will pass perihelion at a solar distance of 1.18 AU on Jan. 8, 2026. On Jan. 4, 2026 it will come to within 0.59 AU to Earth. There are different approaches concerning the brightness parameters. While a high activity parameter of n = 12 is generally assumed, values between m0 = 7.5 mag and m0 = 9.5 mag are discussed for the absolute magnitude. Accordingly, the brightness should increase from 13 mag (11 mag) in mid-November 2025 to 10.5 mag (8.5 mag) in early January 2026, thereafter fading to 11.5 mag (9.5 mag) by mid-February. During the winter months of 2025/26 the comet can be observed in the morning sky. It will move from the constellation Cancer to the border of of the constellations Bootes/Virgo, where it will reach its maximum brightness of 10.5 mag (possibly 8.5 mag). The Earth will cross the comet's orbital plane on Dec. 10.
The comet showed rather high activity parameters both pre- and post-perihelion, with the activity increasing more rapidly pre-perihelion than decreasing post-perihelion. At the end of October 2025 the brightness was only 15.0 mag, while at the beginning of May 2026 the comet was still 13.5 mag bright. Based on 547 observations by 62 observers (until the start of May 2026), the brightness parameters are as follows:
pre-perihelion: m0 = 7.5 mag / n = 17The comet thus reached a maximum brightness of 9.2 mag around Jan. 10, 2026. It should get fainter than 16 mag by mid-June.
Total Brightness and Coma Diameter
While the coma measured only 1.5' (60,000 km) at the end of October 2025, it grew to a maximum of 10' (260,000 km) by mid-January 2026. Thereafter it shrunk rather rapidly to 3' (100,000 km) until end of March, then more slowly, reaching 2' (75,000 km) by the start of May. The coma was always rather diffuse, with a faint central condensation discernible. The degree of condensation remained constant at DC 3-4 until mid-March 2026, decreasing to DC 1-2 until the start of May. Tail reports, even via CCD, were rare. They started at the beginning of 2026, reporting a maximum length of 10' (350,000 km) on CCD images immediately after perihelion. The tail was constantly oriented towards p.a. 290°.Andreas Kammerer
