C/2020 S3 Erasmus
Closest to Earth on 2020 Nov 19 at 1.03AU.
Closest to Sun on 2020 Dec 12 at 0.40AU.
Maximum magnitude 4 in Dec 2020.
Orbital period: +5000 years


Comet C/2020 S3 Erasmus and NGC 4050 on 2020 November 14 at 17:30UT

There were quite a few comets discovered in 2020 with small perihelion distances. Only C/2020 F3 and C/2020 F8 managed to put on a show.
Although the orbit of S3 Erasmus looked promising, with perihelion of 0.40AU on 2020 Dec 12, the comet was too close to the Sun at, and beyond, perihelion.
However, it did put on a reasonable showing leading up to perihelion, when visible in the pre-dawn skies.

My visual observation on the morning of October 19 using a 20cm reflector estimated a magnitude of 10.9.

By October 21, it had brightened to magnitude 10.4.


November 2020
Moonlight interfered with observing until November 12, when the magnitude 8.0 comet was situated low in Corvus.
On November 11.73UT, I estimated a magnitude of 8.2 with a moderately condensed coma 4'


It was 50’ East of Gamma Corvi on the morning of Nov 17 as shown in the above image. Magnitude 7.4

It was 45’ NE of planetary nebula NGC 4361 on Nov 18. NGC 4361 is at top right in the below image

On the morning of November 24, the now magnitude 7.0 comet lied 1 degree East of galaxy pair NGC5068 and NGC5084 in Virgo,
at about 10 degrees altitude at start of astronomical twilight.

Image of the comet on 2020 November 26 at 17:30UT.
Moonlight interfered from the morning of November 28 as the comet sank deeper into morning twilight.

December 2020
By early December, the now magnitude 6.0 comet was a very difficult target low in twilight.

My final view of the comet came on the morning of December 3, when I estimated it at magnitude 6.2

All was not lost however as the comet became viewable from the SOHO LASCO C3 camera
between December 18 (entering the field at 2o’clock position) and January 2 (departing at the 11o’clock position).
https://soho.nascom.nasa.gov/data/Theater/

Also, the comet was photographed during the total solar eclipse of 2020 Dec 14 in Chile/Argentina!

My personal observations in ICQ format:

2020S3 2020 12 02.75 M 6.2 TT 10.0B 25 3 7/ ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria; start of nautical twilight, altitude 8 degrees
2020S3 2020 11 26.73 M 7.1 TT 10.0B 25 3 7 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria; altitude 8 degrees, twilight.
2020S3 2020 11 24.73 M 7.2 TT 7.0B 15 3 7 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria; brightening has stalled
2020S3 2020 11 19.73 M 7.2 TT 7.0B 15 4 7 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria
2020S3 2020 11 16.73 M 7.4 TT 7.0B 15 4 7 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria
2020S3 2020 11 14.73 M 7.6 TT 7.0B 15 5 7 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria
2020S3 2020 11 12.73 M 8.0 TT 7.0B 15 4 6 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria
2020S3 2020 11 11.73 M 8.2 TT 7.0B 15 4 D6 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria
2020S3 2020 10 21.76 C 10.4 TT 7.0A 2a300 3 4 ICQ XX MAT08 C dCDS CMC A4A 0 U d Michael Mattiazzo, Swan Hill, Victoria
2020S3 2020 10 18.75 S 10.9 TT 20.0L 6 70 3 4 ICQ XX MAT08 Michael Mattiazzo, Swan Hill, Victoria