C/2020 J1 (SONEAR)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	17 Apr 2021	12.9	3.344 AU	2.589 AU	16h42m	-36°51'	132.0°	12.9°	291°
Nearest approach	16 May 2021	12.8	3.355 AU	2.356 AU	15h24m	-29°18'	169.7°	3.1°	13°
Today	18 Sep 2025	23.5	12.632 AU	13.169 AU	09h40m	+51°38'	55.8°	3.8°	322°

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 J1 (SONEAR) are:

            e (Eccentricity)                : 0.9995280
            q (Perihelion distance)         : 3.3444400
            i (Inclination)                 : 142.30790
            Ω (Longitude of ascending node) : 226.57950
            ω (Argument of perihelion)      : 341.56110
            L (Longitude of perihelion)     : 241.35907
            B (Latitude of perihelion)      : -11.15053
            T (Time of perihelion passage)  : 2459322.41850
            P (Orbital period in years)     : 596447.35

            Epoch                           : 2025 Sep 17
            Reference                       : MPEC 2023-KD6

            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 (8.50 + 5 log[∆] + 8.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 4.50 + 5 log[∆] + 12.16 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
2025-09-18 00:00 UT   09 40 23.9   +51 38 13    13.169   12.631   55.8    3.8   322   23.5 
2025-09-18 02:42 UT   09 40 25.8   +51 38 19    13.169   12.632   55.8    3.8   322   23.5 
2025-09-19 00:00 UT   09 40 40.6   +51 39 08    13.164   12.637   56.4    3.8   322   23.5 
2025-09-20 00:00 UT   09 40 57.0   +51 40 06    13.160   12.643   57.1    3.8   321   23.5 
2025-09-21 00:00 UT   09 41 13.2   +51 41 08    13.155   12.649   57.8    3.9   320   23.5 
2025-09-22 00:00 UT   09 41 29.2   +51 42 12    13.149   12.655   58.5    3.9   320   23.5 
2025-09-23 00:00 UT   09 41 44.9   +51 43 19    13.144   12.661   59.2    3.9   319   23.5 
2025-09-24 00:00 UT   09 42 00.4   +51 44 29    13.139   12.666   59.9    3.9   318   23.5 
2025-09-25 00:00 UT   09 42 15.6   +51 45 42    13.133   12.672   60.7    4.0   317   23.5 
2025-09-26 00:00 UT   09 42 30.5   +51 46 58    13.127   12.678   61.4    4.0   317   23.5 
2025-09-27 00:00 UT   09 42 45.2   +51 48 17    13.122   12.684   62.1    4.0   316   23.5 
2025-09-28 00:00 UT   09 42 59.6   +51 49 39    13.116   12.690   62.8    4.0   315   23.5 

    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.