JPL Horizons barycentric solution for epoch 1950 (before entering planetary region)
Goto JPL Horizons
Ephemeris Type: Orbital Elements
Center: @0 (Solar System Barycenter)
Time Span: 1950-01-01 to 2050-01-01 and Step Size: 100 years
1950-Jan-01 is "PR= 1.76E+06 / 365.25 days" = 4818 years
Green, Daniel W. E. (January 11, 2020). "COMET C/2019 Y4 (ATLAS)". Liste de distribution des circulaires de l'Union Astronomique Internationale et du Minor Planet Center (Mailing list). Archived from the original on March 25, 2020. Retrieved March 25, 2020.
Green, Daniel W. E. (January 11, 2020). "COMET C/2019 Y4 (ATLAS)". Liste de distribution des circulaires de l'Union Astronomique Internationale et du Minor Planet Center (Mailing list). Archived from the original on March 25, 2020. Retrieved March 25, 2020.