C/2021 C6 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	11 Nov 2021	19.8	3.292 AU	3.274 AU	09h46m	+06°47'	82.4°	17.3°	289°
Nearest approach	12 Jan 2022	19.1	3.344 AU	2.382 AU	07h44m	+07°44'	165.8°	4.1°	350°
Today	20 Jul 2026	28.8	13.223 AU	12.910 AU	00h56m	-03°53'	105.8°	4.2°	250°

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. (12.0 + 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/2021 C6 (Lemmon) are:

    e (Eccentricity)                : 0.9988350
    q (Perihelion distance)         : 3.2923450
    i (Inclination)                 : 164.61010
    Ω (Longitude of ascending node) : 332.32290
    ω (Argument of perihelion)      : 203.94260
    L (Longitude of perihelion)     : 309.14680
    B (Latitude of perihelion)      : -6.18271
    T (Time of perihelion passage)  : 2459529.88860
    P (Orbital period in years)     : 150234.31

    Epoch                           : 2026 May 29
    Reference                       : MPC194173

    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
2026-07-19 00:00 UT   00 56 45.9   -03 51 30    12.926   13.214  104.3    4.3   249   28.8 
2026-07-20 00:00 UT   00 56 38.8   -03 52 49    12.915   13.219  105.2    4.3   250   28.8 
2026-07-20 13:14 UT   00 56 34.7   -03 53 33    12.910   13.223  105.8    4.2   250   28.8 
2026-07-21 00:00 UT   00 56 31.3   -03 54 09    12.905   13.225  106.2    4.2   250   28.8 
2026-07-22 00:00 UT   00 56 23.5   -03 55 31    12.894   13.231  107.2    4.2   250   28.8 
2026-07-23 00:00 UT   00 56 15.5   -03 56 54    12.884   13.237  108.2    4.2   250   28.8 
2026-07-24 00:00 UT   00 56 07.1   -03 58 19    12.874   13.242  109.2    4.2   250   28.8 
2026-07-25 00:00 UT   00 55 58.5   -03 59 46    12.864   13.248  110.1    4.1   250   28.8 
2026-07-26 00:00 UT   00 55 49.6   -04 01 14    12.854   13.254  111.1    4.1   251   28.8 
2026-07-27 00:00 UT   00 55 40.4   -04 02 44    12.844   13.260  112.1    4.1   251   28.8 
2026-07-28 00:00 UT   00 55 30.9   -04 04 15    12.834   13.266  113.1    4.0   251   28.8 
2026-07-29 00:00 UT   00 55 21.1   -04 05 48    12.824   13.271  114.1    4.0   251   28.8 
2026-07-30 00:00 UT   00 55 11.1   -04 07 22    12.815   13.277  115.1    4.0   251   28.8 

    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.