C/2018 R5 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	28 Sep 2018	19.5	3.739 AU	2.837 AU	22h49m	+23°03'	150.0°	7.7°	132°
Perihelion	10 Jan 2019	20.2	3.637 AU	4.194 AU	22h43m	-06°32'	49.8°	11.9°	67°
Today	18 Sep 2025	29.3	15.070 AU	15.739 AU	10h50m	-43°26'	46.8°	2.8°	198°

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/2018 R5 (Lemmon) are:

            e (Eccentricity)                : 0.8417060
            q (Perihelion distance)         : 3.6373890
            i (Inclination)                 : 103.67090
            Ω (Longitude of ascending node) : 171.28450
            ω (Argument of perihelion)      : 178.27110
            L (Longitude of perihelion)     : 171.69323
            B (Latitude of perihelion)      : 1.67990
            T (Time of perihelion passage)  : 2458494.31720
            P (Orbital period in years)     : 110.15

            Epoch                           : 2025 Sep 17
            Reference                       : MPC114603

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (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 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. (11.50 + 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
2025-09-18 00:00 UT   10 50 26.5   -43 26 44    15.738   15.069   46.9    2.8   198   29.3 
2025-09-18 03:14 UT   10 50 29.1   -43 26 52    15.739   15.070   46.8    2.8   198   29.3 
2025-09-19 00:00 UT   10 50 45.6   -43 27 46    15.744   15.073   46.7    2.8   199   29.3 
2025-09-20 00:00 UT   10 51 04.6   -43 28 51    15.751   15.078   46.5    2.8   200   29.3 
2025-09-21 00:00 UT   10 51 23.6   -43 29 58    15.757   15.082   46.4    2.8   201   29.3 
2025-09-22 00:00 UT   10 51 42.4   -43 31 07    15.762   15.086   46.2    2.8   203   29.3 
2025-09-23 00:00 UT   10 52 01.2   -43 32 19    15.768   15.090   46.1    2.7   204   29.3 
2025-09-24 00:00 UT   10 52 19.8   -43 33 33    15.773   15.094   46.0    2.7   205   29.3 
2025-09-25 00:00 UT   10 52 38.3   -43 34 50    15.779   15.099   45.9    2.7   206   29.3 
2025-09-26 00:00 UT   10 52 56.8   -43 36 08    15.784   15.103   45.8    2.7   207   29.3 
2025-09-27 00:00 UT   10 53 15.1   -43 37 29    15.789   15.107   45.8    2.7   209   29.3 
2025-09-28 00:00 UT   10 53 33.2   -43 38 52    15.793   15.111   45.7    2.7   210   29.3 

    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.