C/2020 W5 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	1 Dec 2020	22.3	3.375 AU	2.521 AU	04h55m	+56°46'	144.7°	9.7°	190°
Nearest approach	1 Dec 2020	22.3	3.375 AU	2.521 AU	04h53m	+56°58'	144.7°	9.7°	188°
Today	20 May 2026	32.4	14.829 AU	14.019 AU	17h12m	+11°44'	141.9°	2.4°	214°

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)                : 1.0028750
    q (Perihelion distance)         : 3.3747460
    i (Inclination)                 : 88.60310
    Ω (Longitude of ascending node) : 75.46210
    ω (Argument of perihelion)      : 24.65880
    L (Longitude of perihelion)     : 76.10330
    B (Latitude of perihelion)      : 24.65098
    T (Time of perihelion passage)  : 2459184.64520

    Epoch                           : 2026 May 19
    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
2026-05-19 00:00 UT   17 13 10.1   +11 43 38    14.018   14.822  141.4    2.4   216   32.4 
2026-05-20 00:00 UT   17 12 53.9   +11 43 59    14.019   14.827  141.8    2.4   214   32.4 
2026-05-20 06:34 UT   17 12 49.5   +11 44 04    14.019   14.829  141.9    2.4   214   32.4 
2026-05-21 00:00 UT   17 12 37.7   +11 44 18    14.020   14.833  142.2    2.4   213   32.4 
2026-05-22 00:00 UT   17 12 21.3   +11 44 34    14.021   14.839  142.6    2.4   211   32.4 
2026-05-23 00:00 UT   17 12 04.9   +11 44 49    14.023   14.844  143.0    2.4   210   32.4 
2026-05-24 00:00 UT   17 11 48.3   +11 45 01    14.025   14.850  143.3    2.3   208   32.5 
2026-05-25 00:00 UT   17 11 31.7   +11 45 10    14.027   14.855  143.6    2.3   206   32.5 
2026-05-26 00:00 UT   17 11 15.1   +11 45 18    14.030   14.861  143.9    2.3   205   32.5 
2026-05-27 00:00 UT   17 10 58.3   +11 45 23    14.033   14.866  144.2    2.3   203   32.5 
2026-05-28 00:00 UT   17 10 41.5   +11 45 26    14.036   14.872  144.4    2.3   201   32.5 
2026-05-29 00:00 UT   17 10 24.7   +11 45 26    14.039   14.877  144.7    2.3   200   32.5 
2026-05-30 00:00 UT   17 10 07.8   +11 45 24    14.042   14.883  144.9    2.2   198   32.5 

    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.