C/2020 Y2 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	19 Mar 2022	14.6	3.265 AU	2.939 AU	07h48m	-67°03'	100.1°	17.5°	63°
Perihelion	17 Jun 2022	14.8	3.147 AU	3.436 AU	06h33m	-40°42'	65.1°	17.0°	167°
Today	21 Oct 2025	20.2	10.320 AU	9.389 AU	00h46m	+27°58'	158.1°	2.1°	139°

The interactive orbit chart above shows the comet's path through the solar system and its position at the given date. Green and blue lines are shown perpendicular to the ecliptic plane: Green if the path is above the ecliptic plane, blue if it is below. (Left-click and drag to rotate the view; Right-click and drag to move the view; Use scroll wheel to zoom in our out.)

Light curve

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations from COBS. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 9.0 + 5 log[∆] + 6.3 log[r]). An additional green curve is displayed when an increase in apparent brightness is expected due to forward scattering of sunlight, which occurs when a dust-rich comet is located between the Earth and the Sun. (See Marcus 2007)

Charts

The all-sky chart below shows the path of the comet over the same period as the light curve. The comet's current position is marked yellow.

The following chart shows the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Orbital elements

The orbital elements of C/2020 Y2 (ATLAS) are:

    e (Eccentricity)                : 0.9974330
    q (Perihelion distance)         : 3.1466900
    i (Inclination)                 : 101.22720
    Ω (Longitude of ascending node) : 26.54410
    ω (Argument of perihelion)      : 266.41700
    L (Longitude of perihelion)     : -45.62777
    B (Latitude of perihelion)      : -78.22192
    T (Time of perihelion passage)  : 2459748.16460
    P (Orbital period in years)     : 42918.26

    Epoch                           : 2025 Oct 20
    Reference                       : MPEC 2024-YC7

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-20 00:00 UT   00 47 05.5   +28 00 55     9.378   10.311  158.5    2.0   143   20.2 
2025-10-21 00:00 UT   00 46 36.1   +27 59 14     9.386   10.318  158.3    2.0   140   20.2 
2025-10-21 10:31 UT   00 46 23.3   +27 58 30     9.389   10.320  158.1    2.1   139   20.2 
2025-10-22 00:00 UT   00 46 06.8   +27 57 32     9.394   10.324  158.0    2.1   138   20.2 
2025-10-23 00:00 UT   00 45 37.8   +27 55 47     9.403   10.330  157.6    2.1   135   20.2 
2025-10-24 00:00 UT   00 45 09.0   +27 54 00     9.412   10.336  157.2    2.1   132   20.2 
2025-10-25 00:00 UT   00 44 40.3   +27 52 12     9.421   10.343  156.7    2.2   129   20.2 
2025-10-26 00:00 UT   00 44 11.9   +27 50 22     9.431   10.349  156.3    2.2   127   20.2 
2025-10-27 00:00 UT   00 43 43.8   +27 48 30     9.441   10.355  155.7    2.3   125   20.2 
2025-10-28 00:00 UT   00 43 15.9   +27 46 36     9.451   10.362  155.2    2.3   122   20.2 
2025-10-29 00:00 UT   00 42 48.2   +27 44 41     9.462   10.368  154.6    2.4   120   20.2 
2025-10-30 00:00 UT   00 42 20.8   +27 42 44     9.472   10.374  154.0    2.4   118   20.2 
2025-10-31 00:00 UT   00 41 53.7   +27 40 46     9.483   10.380  153.3    2.5   116   20.3 

    Terminology:
            
    delta:  distance between comet and earth in AU
    radius: distance between comet and sun in AU
    magn:   magnitude (brightness) estimate    
    ra:     right ascension in hours (24h = 360deg)
    dec:    declination in degrees
    elong:  elongation in degrees (angle sun-earth-comet)    
    phase:  phase angle in degrees (angle sun-comet-earth)        
    AU:     Astronomical Unit (mean distance between earth and sun: 149597870.7 km      
    

Orbital elements usually provided by the MPC (Minor Planet Center).
Observations contributed by observers worldwide, via COBS (Comet Observation Database) or the MPC (Minor Planet Center)
Calculations by a modified version of AAPlus, a C# implementation of the AA+ project by PJ Naughter from the algorithms presented in the book "Astronomical Algorithms" by Jean Meeus.
NGC2000 dso catalog and star labels from VizieR as provided by the Strasbourg astronomical Data Center.
Tycho2 catalog from the ESO archive.