Home=Current Comets
| The German Group
| Tutorials
| Archive: C/2020 F8
| Projects, publications
| Images
| Contact
Michael Mattiazzo discovered a comet on public website UV-images of the SWAN camera aboard the satellite SOHO between Mar. 26 and Apr. 7 in the constellation Grus. After publication of his discovery several observers tried to confirm the comet visually or photographically. M. Masek succeeded on Apr. 10 by recording the comet with a CCD camera and 300mm telephoto lens at the Pierre Auger Observatory in Argentina. Comet C/2020 F8 (SWAN) showed a 5' coma of total magnitude 8.5. Additional observations showed a coma diameter up to 8' and a 25' tail. The comet will reach its perihelion at a solar distance of only 0.43 AU on May 27, 2020, when it could be as bright as 3.5 mag (CBET 4750/52)! Pre-perihelion the comet moves constantly northward, while the elongation decreases. Thus the comet will be observable at mid-European locations only between May 15 and June 10 scantly above the northern horizon. During that short period it moves through the constellations Pisces, Triangulum, Perseus and Auriga. Not until mid-August will it become well observable in the morning sky. The magnitude at this time should be only 10.5, with the comet fading to 14 mag until the end of year. Until then the comet will move through the constellations Gemini, Monoceros, Orion and Eridanus. On June 10 Earth will cross the comet's orbital plane.
The comet showed an erratic development during its short apparition. Based on 254 observations from 45 observers three or even four phases can be differentiated. Following a slow increase during the first days from 8.2 mag (Apr. 12) to 7.0 mag (Apr. 25), the brightness increased rapidly between Apr. 25 and May 1. On May 2, 2020 the comet peaked at magnitude 5.0. Thereafter the heliocentric brightness decreased at increasing rate even though the comet still approached the Sun. On June 2 the comet had faded to 9.0 mag. In the brightness variation diagram the plotted magnitude refers to the "average" development according to the parameters m0=6.8 mag / n=-0.4. The reason for the unusual behavior was soon realized: the comet had begun to break apart. On the last pictures it shows as a narrow, very elongated strip of dust without any condensation.
Total Brightness and Coma DiameterThe apparent coma diameter showed a very symmetric development on both sides of the maximum of 10' on May 5. At the beginning and the end of the apparition it measured 3.5'. The absolute coma diameter showed a very different development. Measuring 200.000 km at the start of the apparition it had increased to 320.000 km by May 1, only to shrunk to 125.000 at the end of the apparition. Until May 1 the degree of condensation increased from DC 4 to the maximum value of DC 6. On May 10 the coma showed a degree of condensation of DC 5-6, thereafter decreasing rapidly to DC 1 at the end of May.
Brightness / Activity variationsA tail was observed between the end of April and the end of May. Around May 5 it reached its maximum length of almost 2° (3 Mio. km). During that period it changed its orientation from SW to N.