C/2020 W5 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	1 Dec 2020	22.3	3.374 AU	2.521 AU	04h55m	+56°45'	144.7°	9.7°	191°
Nearest approach	1 Dec 2020	22.3	3.374 AU	2.521 AU	04h53m	+56°58'	144.7°	9.7°	188°
Today	9 Mar 2026	32.4	14.427 AU	14.403 AU	17h23m	+10°17'	89.4°	3.9°	275°

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)                : 1.0027950
    q (Perihelion distance)         : 3.3741340
    i (Inclination)                 : 88.61050
    Ω (Longitude of ascending node) : 75.45730
    ω (Argument of perihelion)      : 24.64910
    L (Longitude of perihelion)     : 76.09481
    B (Latitude of perihelion)      : 24.64137
    T (Time of perihelion passage)  : 2459184.56530

    Epoch                           : 2026 Mar 08
    Reference                       : MPEC 2026-E44

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-03-08 00:00 UT   17 23 36.8   +10 15 04    14.416   14.419   88.2    3.9   276   32.4 
2026-03-09 00:00 UT   17 23 37.6   +10 16 36    14.407   14.424   89.0    3.9   275   32.4 
2026-03-09 11:02 UT   17 23 37.9   +10 17 18    14.403   14.427   89.4    3.9   275   32.4 
2026-03-10 00:00 UT   17 23 38.1   +10 18 08    14.398   14.430   89.8    3.9   274   32.4 
2026-03-11 00:00 UT   17 23 38.3   +10 19 40    14.389   14.435   90.7    3.9   274   32.4 
2026-03-12 00:00 UT   17 23 38.3   +10 21 13    14.380   14.441   91.5    3.9   273   32.4 
2026-03-13 00:00 UT   17 23 37.9   +10 22 46    14.372   14.447   92.3    3.9   273   32.4 
2026-03-14 00:00 UT   17 23 37.3   +10 24 19    14.363   14.452   93.2    3.9   272   32.4 
2026-03-15 00:00 UT   17 23 36.3   +10 25 53    14.354   14.458   94.0    3.9   272   32.4 
2026-03-16 00:00 UT   17 23 35.1   +10 27 27    14.345   14.464   94.8    3.9   271   32.4 
2026-03-17 00:00 UT   17 23 33.5   +10 29 01    14.336   14.469   95.7    3.9   271   32.4 
2026-03-18 00:00 UT   17 23 31.7   +10 30 35    14.328   14.475   96.5    3.9   270   32.4 
2026-03-19 00:00 UT   17 23 29.6   +10 32 09    14.319   14.480   97.3    3.9   269   32.4 

    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.