C/2019 Q1 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	22 Jul 2020	18.7	5.001 AU	4.447 AU	23h20m	+20°27'	117.7°	10.4°	232°
Nearest approach	3 Sep 2020	18.6	5.012 AU	4.089 AU	22h19m	+17°54'	153.5°	5.1°	163°
Today	27 Oct 2025	25.7	13.758 AU	14.660 AU	15h46m	-12°53'	23.9°	1.7°	87°

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. (8.5 + 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 Q1 (Lemmon) are:

    e (Eccentricity)                : 1.0024990
    q (Perihelion distance)         : 5.0012360
    i (Inclination)                 : 155.71630
    Ω (Longitude of ascending node) : 42.47120
    ω (Argument of perihelion)      : 56.24920
    L (Longitude of perihelion)     : -11.28516
    B (Latitude of perihelion)      : 19.99529
    T (Time of perihelion passage)  : 2459052.89470

    Epoch                           : 2025 Oct 27
    Reference                       : MPEC 2024-EF7

    Classification(s):              : Nearly isotropic; New (a > 10000 AU)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-26 00:00 UT   15 46 17.7   -12 51 04    14.637   13.748   25.7    1.8    88   25.7 
2025-10-27 00:00 UT   15 46 28.9   -12 52 15    14.649   13.753   24.7    1.7    88   25.7 
2025-10-27 22:11 UT   15 46 39.3   -12 53 21    14.660   13.758   23.9    1.7    87   25.7 
2025-10-28 00:00 UT   15 46 40.1   -12 53 26    14.661   13.759   23.8    1.7    87   25.7 
2025-10-29 00:00 UT   15 46 51.5   -12 54 36    14.673   13.764   22.9    1.6    86   25.7 
2025-10-30 00:00 UT   15 47 03.0   -12 55 47    14.684   13.769   22.0    1.5    85   25.7 
2025-10-31 00:00 UT   15 47 14.5   -12 56 57    14.695   13.774   21.1    1.5    85   25.7 
2025-11-01 00:00 UT   15 47 26.1   -12 58 06    14.706   13.780   20.2    1.4    84   25.7 
2025-11-02 00:00 UT   15 47 37.9   -12 59 15    14.717   13.785   19.3    1.4    83   25.7 
2025-11-03 00:00 UT   15 47 49.7   -13 00 24    14.727   13.790   18.4    1.3    82   25.7 
2025-11-04 00:00 UT   15 48 01.5   -13 01 33    14.737   13.795   17.6    1.2    81   25.7 
2025-11-05 00:00 UT   15 48 13.5   -13 02 41    14.747   13.800   16.7    1.2    79   25.7 
2025-11-06 00:00 UT   15 48 25.5   -13 03 49    14.756   13.806   15.8    1.1    78   25.7 

    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.