C/2020 W5 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	1 Dec 2020	22.3	3.372 AU	2.519 AU	04h55m	+56°44'	144.7°	9.7°	191°
Nearest approach	1 Dec 2020	22.3	3.372 AU	2.518 AU	04h53m	+56°57'	144.8°	9.7°	188°
Today	24 Oct 2025	32.1	13.651 AU	14.261 AU	16h56m	+10°58'	50.5°	3.2°	65°

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. The light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (15.0 + 5 log[∆] + 10.0 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 W5 (Lemmon) are:

    e (Eccentricity)                : 1.0023230
    q (Perihelion distance)         : 3.3719750
    i (Inclination)                 : 88.61150
    Ω (Longitude of ascending node) : 75.47010
    ω (Argument of perihelion)      : 24.62530
    L (Longitude of perihelion)     : 76.10646
    B (Latitude of perihelion)      : 24.61759
    T (Time of perihelion passage)  : 2459184.57210

    Epoch                           : 2025 Oct 23
    Reference                       : MPEC 2021-BE3

    Classification(s):              : Nearly isotropic; New (a > 10000 AU)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-23 00:00 UT   16 56 02.9   +11 01 52    14.241   13.643   51.4    3.3    66   32.1 
2025-10-24 00:00 UT   16 56 15.1   +10 59 13    14.256   13.649   50.7    3.2    65   32.1 
2025-10-24 07:44 UT   16 56 19.0   +10 58 22    14.261   13.651   50.5    3.2    65   32.1 
2025-10-25 00:00 UT   16 56 27.4   +10 56 36    14.271   13.654   50.0    3.2    64   32.1 
2025-10-26 00:00 UT   16 56 39.9   +10 54 01    14.286   13.660   49.4    3.2    63   32.1 
2025-10-27 00:00 UT   16 56 52.6   +10 51 28    14.301   13.666   48.7    3.1    62   32.1 
2025-10-28 00:00 UT   16 57 05.4   +10 48 56    14.315   13.672   48.1    3.1    61   32.1 
2025-10-29 00:00 UT   16 57 18.4   +10 46 26    14.329   13.677   47.4    3.1    60   32.1 
2025-10-30 00:00 UT   16 57 31.5   +10 43 58    14.343   13.683   46.8    3.0    59   32.1 
2025-10-31 00:00 UT   16 57 44.8   +10 41 32    14.357   13.689   46.2    3.0    58   32.1 
2025-11-01 00:00 UT   16 57 58.3   +10 39 08    14.371   13.694   45.5    3.0    57   32.2 
2025-11-02 00:00 UT   16 58 11.9   +10 36 46    14.384   13.700   44.9    2.9    56   32.2 
2025-11-03 00:00 UT   16 58 25.6   +10 34 25    14.398   13.706   44.3    2.9    55   32.2 

    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.