C/2018 R5 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	28 Sep 2018	19.5	3.739 AU	2.838 AU	22h49m	+23°02'	150.0°	7.7°	132°
Perihelion	10 Jan 2019	20.2	3.638 AU	4.194 AU	22h43m	-06°33'	49.8°	11.9°	67°
Today	20 May 2025	28.9	14.559 AU	14.183 AU	10h21m	-47°01'	109.9°	3.7°	98°

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)                : 0.8416950
            q (Perihelion distance)         : 3.6379200
            i (Inclination)                 : 103.68470
            Ω (Longitude of ascending node) : 171.26690
            ω (Argument of perihelion)      : 178.27200
            L (Longitude of perihelion)     : 171.67583
            B (Latitude of perihelion)      : 1.67893
            T (Time of perihelion passage)  : 2458494.27230
            P (Orbital period in years)     : 110.16

            Epoch                           : 2025 May 19
            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
2025-05-20 00:00 UT   10 21 39.0   -47 05 11    14.173   14.555  110.3    3.7    98   28.9 
2025-05-20 19:09 UT   10 21 38.8   -47 01 49    14.183   14.559  109.9    3.7    98   28.9 
2025-05-21 00:00 UT   10 21 38.8   -47 00 58    14.186   14.559  109.7    3.8    99   28.9 
2025-05-22 00:00 UT   10 21 39.1   -46 56 46    14.199   14.564  109.2    3.8   100   28.9 
2025-05-23 00:00 UT   10 21 39.7   -46 52 35    14.212   14.568  108.7    3.8   100   28.9 
2025-05-24 00:00 UT   10 21 40.7   -46 48 25    14.226   14.572  108.1    3.8   101   28.9 
2025-05-25 00:00 UT   10 21 42.1   -46 44 17    14.239   14.577  107.5    3.8   102   28.9 
2025-05-26 00:00 UT   10 21 43.8   -46 40 09    14.253   14.581  107.0    3.8   103   28.9 
2025-05-27 00:00 UT   10 21 45.9   -46 36 04    14.266   14.585  106.4    3.8   104   28.9 
2025-05-28 00:00 UT   10 21 48.4   -46 31 59    14.280   14.590  105.8    3.8   105   28.9 
2025-05-29 00:00 UT   10 21 51.3   -46 27 56    14.294   14.594  105.3    3.8   105   28.9 
2025-05-30 00:00 UT   10 21 54.5   -46 23 55    14.308   14.598  104.7    3.9   106   28.9 

    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.