C/2019 J1 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	5 Apr 2019	17.8	2.476 AU	2.358 AU	19h25m	-16°29'	84.8°	23.7°	262°
Nearest approach	3 Jul 2019	17.4	2.652 AU	1.689 AU	20h30m	-30°44'	156.3°	8.9°	283°
Today	20 May 2026	30.9	17.949 AU	18.889 AU	03h23m	-00°28'	21.1°	1.2°	195°

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/2019 J1 (Lemmon) are:

    e (Eccentricity)                : 0.9622190
    q (Perihelion distance)         : 2.4757290
    i (Inclination)                 : 24.52490
    Ω (Longitude of ascending node) : 98.22860
    ω (Argument of perihelion)      : 167.50520
    L (Longitude of perihelion)     : 86.83016
    B (Latitude of perihelion)      : 5.15238
    T (Time of perihelion passage)  : 2458579.23420
    P (Orbital period in years)     : 530.45

    Epoch                           : 2026 May 19
    Reference                       : MPEC 2026-E44

    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
2026-05-19 00:00 UT   03 23 06.2   +00 28 52    18.886   17.944   20.6    1.1   192   30.9 
2026-05-20 00:00 UT   03 23 19.4   +00 28 02    18.889   17.949   21.0    1.2   195   30.9 
2026-05-20 00:32 UT   03 23 19.7   +00 28 01    18.889   17.949   21.1    1.2   195   30.9 
2026-05-21 00:00 UT   03 23 32.7   +00 27 13    18.891   17.954   21.5    1.2   197   30.9 
2026-05-22 00:00 UT   03 23 45.9   +00 26 25    18.893   17.958   22.0    1.2   199   30.9 
2026-05-23 00:00 UT   03 23 59.0   +00 25 38    18.894   17.963   22.5    1.2   201   30.9 
2026-05-24 00:00 UT   03 24 12.2   +00 24 52    18.896   17.968   23.0    1.3   203   30.9 
2026-05-25 00:00 UT   03 24 25.3   +00 24 08    18.897   17.973   23.5    1.3   205   30.9 
2026-05-26 00:00 UT   03 24 38.4   +00 23 24    18.897   17.978   24.1    1.3   207   30.9 
2026-05-27 00:00 UT   03 24 51.4   +00 22 42    18.898   17.983   24.7    1.3   208   30.9 
2026-05-28 00:00 UT   03 25 04.4   +00 22 01    18.898   17.988   25.3    1.4   210   30.9 
2026-05-29 00:00 UT   03 25 17.3   +00 21 21    18.899   17.993   25.9    1.4   211   30.9 
2026-05-30 00:00 UT   03 25 30.2   +00 20 42    18.898   17.998   26.5    1.4   213   30.9 

    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.