Skip Navigation Links

C/2018 U1 (Lemmon)
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach18 Jun 202115.25.090 AU4.128 AU 17h19m-03°36'159.0°4.1°162°
Perihelion1 Nov 202115.94.981 AU5.808 AU 16h31m-22°05'30.7°5.8°99°
Today9 Sep 202621.112.948 AU13.287 AU 07h40m-44°23'68.3°4.1°238°
C/2018 U1 (Lemmon)- 2026-09-09
astro.vanbuitenen.nl


 
-1 month
-1 week
-1 day
Now
+1 day
+1 week
+1 month

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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 6.3 + 5 log[∆] + 8.3 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/2018 U1 (Lemmon) are: 

    e (Eccentricity)                : 0.9991970
    q (Perihelion distance)         : 4.9812230
    i (Inclination)                 : 108.33000
    Ω (Longitude of ascending node) : 75.48880
    ω (Argument of perihelion)      : 180.26610
    L (Longitude of perihelion)     : 75.40511
    B (Latitude of perihelion)      : -0.25260
    T (Time of perihelion passage)  : 2459519.84170
    P (Orbital period in years)     : 488574.35

    Epoch                           : 2026 Sep 08
    Reference                       : MPC194157

    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
2026-09-08 00:00 UT   07 40 39.2   -44 20 13    13.285   12.941   67.9    4.1   237   21.1 
2026-09-09 00:00 UT   07 40 49.7   -44 22 48    13.286   12.946   68.2    4.1   238   21.1 
2026-09-09 10:24 UT   07 40 54.2   -44 23 56    13.287   12.948   68.3    4.1   238   21.1 
2026-09-10 00:00 UT   07 40 59.9   -44 25 26    13.287   12.951   68.4    4.1   238   21.1 
2026-09-11 00:00 UT   07 41 09.8   -44 28 06    13.288   12.957   68.7    4.2   239   21.1 
2026-09-12 00:00 UT   07 41 19.4   -44 30 48    13.289   12.962   68.9    4.2   240   21.1 
2026-09-13 00:00 UT   07 41 28.6   -44 33 32    13.290   12.967   69.2    4.2   241   21.1 
2026-09-14 00:00 UT   07 41 37.4   -44 36 19    13.291   12.972   69.5    4.2   242   21.1 
2026-09-15 00:00 UT   07 41 46.0   -44 39 07    13.292   12.978   69.7    4.2   243   21.1 
2026-09-16 00:00 UT   07 41 54.2   -44 41 56    13.292   12.983   70.0    4.2   244   21.1 
2026-09-17 00:00 UT   07 42 02.0   -44 44 48    13.293   12.988   70.3    4.2   245   21.1 
2026-09-18 00:00 UT   07 42 09.5   -44 47 42    13.293   12.994   70.6    4.2   246   21.1 
2026-09-19 00:00 UT   07 42 16.6   -44 50 37    13.293   12.999   70.8    4.2   247   21.1 




    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.

Privacy policy