New Comet C/2020 S3 (Erasmus)

September 21, 2020
CBET 4885 & MPEC 2020-S119, issued on 2020, September 20, announce the discovery of a comet (magnitude ~18.5) by Nicolas Erasmus (South African Astronomical Observatory), in four 30-s CCD images taken in 5" seeing on Sept. 17.6 UT with a 0.5-m f/2 Schmidt reflector at Mauna Loa, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program. The new comet has been designated C/2020 S3 (Erasmus).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 151 unfiltered exposures, 30 seconds each, obtained remotely on 2020, September 19.1 from L07 (Osservatorio Salvatore di Giacomo, Agerola) through a 0.5 m f/8 Ritchey Chretien + CCD FLI PL4240, shows that this object is a comet with a diffuse coma about 20" in diameter.

MPEC 2020-S119, assigns the following preliminary parabolic orbital elements to comet C/2020 S3 (Erasmus): T 2020 Dec. 13.24; e= 1.0; Peri. =  349.09; q = 0.4;  Incl.= 19.79

While the orbit is still very preliminary, there is a chance that this comet will pass through the SOHO C3 fov starting from about December 16, 2020 (the visibility on C3 will depend also on the magnitude this comet will reach around perihelion; a vmag at least +8 is required to be visible in C3). Below you can see a graph showing part of the possible C3 passage (from Dec. 16 to Dec. 21, 2020; click on it for a bigger version). At the following link is available the animation, just press the play button to see it.

by Ernesto Guido