C/2020 R4 (ATLAS)


Type: Periodic Perihelion date: 1 March 2021 Perihelion distance (q): 1.0 Aphelion distance (Q) : 194 Period (years): 961 Eccentricity (e): 0.99 Inclination (i): 164.5 JPL orbit diagram COBS lightcurve The ATLAS (Asteroid Terrestrial-impact Last Alert System) team discovered a 19th magnitude comet in images taken with the 0.5m Schmidt at Mauna Loa on 12 September 2020. It was posted on the PCCP as A10qhkr and subsequently confirmed as cometary by several astrometrists. There were pre-discovery images of the comet in Catalina Sky Survey data from August and PanSTARRS from August and September. It was subsequently re-reported by ATLAS as A10wNNY and Catalina as C23NY71 in April 2021. The comet was at perihelion at 1.0 au in March 2021, but it was not an optimum return. The comet reached 9th magnitude post perihelion when it approached us to 0.5 au. It has a rather faint absolute magnitude, but these comets often appear brighter to visual observers. Imaging by Taras Prystavski on 12 December suggested that it was at least three magnitudes brighter than expected. JJ Gonzalez observed it at 9th magnitude in January. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 20-Mar-21 13.47 0.02 8.9 6.4 10-Apr-21 7.8 8.8 14-Apr-21 8.5 10.2 21-Apr-21 9.3 7.0