A new solar system object first observed on December 28, 2020, at magnitude 18.30 o by the ATLAS Survey station T08 ATLAS-MLO, Mauna Loa was found to exhibit a coma by follow-up observations. The new comet is designated C/2020 Y2 and named for the parent survey ATLAS.
At discovery, C/2020 Y2 was near 5.8 au from the sun and 6.2 au from Earth. This object is currently in the morning sky constellation of Virgo at 525 days before perihelion.
The initial orbit from MPEC 2021-A83 calculated by Rudenko specifies a perihelion date in June 2022 at a solar distance of 3.133 au brightening to near 14th magnitude. Furthermore, Rudenko specifies a value of 1/a (original) of +0.001566 AU**-1, indicative of a dynamically old comet returning to the inner solar system after some 16,000 years.
Minor Planet Center one-line elements (MPC 1-line) specify H=6.5 and n=4.0 indicating a moderately active comet. There are several comets with similar brightness parameters. Among them include C/2015 O1 (PANSTARRS) with a perihelion distance of 3.7 au which also peaked in brightness near 14th magnitude and developed a growing coma exhibiting gas emission and a dust tail in early 2018. While comet behavior is difficult to predict, comet C/2015 O1 can give us an idea of what we may see when comet C/2020 Y2 gets closer to perihelion in 2022.
The light curves for both comets show dips and variations as Earth distance or delta approaches and recedes from the comet.An orbit viewer currently shows the comet below the ecliptic plane on a highly inclined 101 degree near parabolic orbit.
The Asteroid Terrestrial-impact Last Alert System or ATLAS is an asteroid impact early warning system funded by NASA operating twin 0.5 m aperture telescopes on the high mountains of Hawaii, ATLAS 1 on Haleakala and ATLAS 2 on Maunaloa. The dome and sub-building for a new ATLAS facility at the South African Astronomical Observatory – Sutherland Observing station was completed in December 2020.ATLAS reports photometry extra precision, magnitudes to 0.01 mag, usually in either “cyan” (c) band from 420–650 nm or “orange” (o) band from 560–820 nm.
MPEC 2021-A83 : COMET C/2020 Y2 (ATLAS) (2021 January 8)
JPL Small Body database
Minor Planet Center orbit and observation database
J. L. Tonry, L. Denneau, A. N. Heinze, B. Stalder, K. W. Smith, S. J. Smartt, C. W. Stubbs, H. J. Weiland, A. Rest, ATLAS: A High-Cadence All-Sky Survey System, Publications of the Astronomical Society of the Pacific, Volume 130, Issue 988, pp. 064505 (2018).
South African Astronomical Observatory – Sutherland Observing station – How to build a Telescope Dome and Sub-Building YouTube video (Dec 10, 2020)
Seiichi Yoshida, C/2020 Y2 (ATLAS) (Updated on January 9, 2021)