C/2020 Y3 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	3 Dec 2020	17.5	1.990 AU	2.584 AU	13h28m	-24°06'	43.6°	20.0°	277°
Nearest approach	10 Mar 2021	17.1	2.306 AU	1.592 AU	14h58m	+23°08'	124.6°	20.8°	258°
Today	2 Jul 2025	29.5	13.599 AU	13.539 AU	21h51m	+56°27'	91.2°	4.3°	222°

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.)

The orbital elements of C/2020 Y3 (ATLAS) are:

            e (Eccentricity)                : 0.9855260
            q (Perihelion distance)         : 1.9903230
            i (Inclination)                 : 83.14340
            Ω (Longitude of ascending node) : 191.34540
            ω (Argument of perihelion)      : 341.85070
            L (Longitude of perihelion)     : 189.10429
            B (Latitude of perihelion)      : -18.01503
            T (Time of perihelion passage)  : 2459186.72770
            P (Orbital period in years)     : 1612.51

            Epoch                           : 2025 Jun 30
            Reference                       : MPEC 2021-R75

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. The gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (13.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 12.46 + 5 log[∆] + 10.00 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-07-02 00:00 UT   21 51 47.0   +56 27 15    13.539   13.598   91.2    4.3   222   29.5 
2025-07-02 01:53 UT   21 51 45.7   +56 27 25    13.539   13.599   91.2    4.3   222   29.5 
2025-07-03 00:00 UT   21 51 29.5   +56 29 16    13.537   13.604   91.6    4.3   221   29.5 
2025-07-04 00:00 UT   21 51 11.5   +56 31 14    13.535   13.610   92.1    4.3   221   29.5 
2025-07-05 00:00 UT   21 50 53.2   +56 33 08    13.533   13.616   92.5    4.3   220   29.5 
2025-07-06 00:00 UT   21 50 34.5   +56 34 59    13.531   13.622   93.0    4.3   219   29.5 
2025-07-07 00:00 UT   21 50 15.5   +56 36 46    13.529   13.628   93.4    4.3   218   29.5 
2025-07-08 00:00 UT   21 49 56.1   +56 38 30    13.527   13.634   93.9    4.3   217   29.5 
2025-07-09 00:00 UT   21 49 36.3   +56 40 10    13.525   13.640   94.3    4.3   216   29.5 
2025-07-10 00:00 UT   21 49 16.3   +56 41 46    13.523   13.646   94.7    4.3   215   29.5 
2025-07-11 00:00 UT   21 48 55.8   +56 43 18    13.522   13.652   95.2    4.3   214   29.5 
2025-07-12 00:00 UT   21 48 35.1   +56 44 47    13.520   13.657   95.6    4.2   213   29.5 

    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.