C/2020 S8 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	10 Apr 2021	15.7	2.356 AU	1.468 AU	15h04m	+15°11'	144.4°	14.3°	231°
Nearest approach	23 Apr 2021	15.7	2.360 AU	1.411 AU	14h10m	+12°37'	154.8°	10.4°	185°
Today	9 May 2025	27.6	12.330 AU	12.786 AU	04h55m	-37°53'	61.1°	4.1°	149°

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 S8 (Lemmon) are:

            e (Eccentricity)                : 0.9901910
            q (Perihelion distance)         : 2.3558700
            i (Inclination)                 : 108.54120
            Ω (Longitude of ascending node) : 24.01530
            ω (Argument of perihelion)      : 160.13660
            L (Longitude of perihelion)     : 30.56870
            B (Latitude of perihelion)      : 18.79256
            T (Time of perihelion passage)  : 2459314.90590
            P (Orbital period in years)     : 3722.12

            Epoch                           : 2025 May 08
            Reference                       : MPEC 2021-P47

            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 (12.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 11.19 + 5 log[∆] + 10.00 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
2025-05-09 00:00 UT   04 55 23.9   -37 54 19    12.783   12.328   61.1    4.1   149   27.6 
2025-05-09 06:35 UT   04 55 28.7   -37 53 39    12.786   12.330   61.1    4.1   149   27.6 
2025-05-10 00:00 UT   04 55 41.4   -37 51 56    12.792   12.334   61.0    4.1   150   27.6 
2025-05-11 00:00 UT   04 55 58.9   -37 49 36    12.801   12.340   60.8    4.1   151   27.6 
2025-05-12 00:00 UT   04 56 16.5   -37 47 20    12.809   12.347   60.7    4.1   152   27.6 
2025-05-13 00:00 UT   04 56 34.3   -37 45 07    12.817   12.353   60.6    4.1   153   27.6 
2025-05-14 00:00 UT   04 56 52.2   -37 42 58    12.825   12.359   60.5    4.1   154   27.6 
2025-05-15 00:00 UT   04 57 10.2   -37 40 53    12.834   12.365   60.3    4.1   155   27.7 
2025-05-16 00:00 UT   04 57 28.3   -37 38 51    12.841   12.371   60.2    4.1   156   27.7 
2025-05-17 00:00 UT   04 57 46.5   -37 36 53    12.849   12.377   60.1    4.1   157   27.7 
2025-05-18 00:00 UT   04 58 04.8   -37 34 59    12.857   12.383   60.0    4.1   158   27.7 
2025-05-19 00:00 UT   04 58 23.2   -37 33 08    12.865   12.389   60.0    4.1   159   27.7 

    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.