C/2020 J1 (SONEAR)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	17 Apr 2021	12.9	3.344 AU	2.591 AU	16h43m	-36°51'	131.7°	12.9°	291°
Nearest approach	16 May 2021	12.8	3.355 AU	2.355 AU	15h24m	-29°17'	169.7°	3.1°	13°
Today	14 Dec 2025	23.6	13.144 AU	12.564 AU	09h39m	+55°35'	124.3°	3.5°	261°

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 4.5 + 5 log[∆] + 12.2 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 J1 (SONEAR) are:

    e (Eccentricity)                : 0.9993700
    q (Perihelion distance)         : 3.3439770
    i (Inclination)                 : 142.30910
    Ω (Longitude of ascending node) : 226.56880
    ω (Argument of perihelion)      : 341.54030
    L (Longitude of perihelion)     : 241.36570
    B (Latitude of perihelion)      : -11.16252
    T (Time of perihelion passage)  : 2459322.23880
    P (Orbital period in years)     : 386708.84

    Epoch                           : 2025 Dec 14
    Reference                       : MPEC 2023-KD6

    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
2025-12-13 00:00 UT   09 40 38.6   +55 28 07    12.572   13.133  122.9    3.6   263   23.6 
2025-12-14 00:00 UT   09 40 16.3   +55 31 44    12.567   13.138  123.6    3.6   262   23.6 
2025-12-14 23:23 UT   09 39 54.0   +55 35 16    12.564   13.144  124.3    3.5   261   23.6 
2025-12-15 00:00 UT   09 39 53.4   +55 35 21    12.564   13.144  124.3    3.5   261   23.6 
2025-12-16 00:00 UT   09 39 29.9   +55 38 57    12.560   13.150  125.0    3.5   260   23.6 
2025-12-17 00:00 UT   09 39 05.9   +55 42 33    12.557   13.156  125.7    3.5   259   23.6 
2025-12-18 00:00 UT   09 38 41.3   +55 46 07    12.553   13.161  126.4    3.5   258   23.6 
2025-12-19 00:00 UT   09 38 16.2   +55 49 40    12.550   13.167  127.1    3.4   257   23.6 
2025-12-20 00:00 UT   09 37 50.5   +55 53 12    12.548   13.173  127.7    3.4   256   23.6 
2025-12-21 00:00 UT   09 37 24.3   +55 56 43    12.545   13.179  128.4    3.4   255   23.6 
2025-12-22 00:00 UT   09 36 57.5   +56 00 13    12.543   13.185  129.0    3.3   253   23.6 
2025-12-23 00:00 UT   09 36 30.1   +56 03 41    12.540   13.190  129.7    3.3   252   23.6 
2025-12-24 00:00 UT   09 36 02.3   +56 07 08    12.538   13.196  130.3    3.3   251   23.6 

    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.