C/2020 H4 (Leonard)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	8 Jul 2020	16.1	1.279 AU	1.145 AU	23h51m	+77°45'	72.3°	49.2°	246°
Perihelion	29 Aug 2020	15.8	0.927 AU	1.601 AU	10h40m	+41°50'	32.6°	35.9°	4°
Today	1 Jul 2025	30.2	14.647 AU	14.625 AU	06h45m	-66°06'	89.2°	4.0°	179°

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/2020 H4 (Leonard) are:

            e (Eccentricity)                : 0.9806160
            q (Perihelion distance)         : 0.9274540
            i (Inclination)                 : 84.49460
            Ω (Longitude of ascending node) : 307.45730
            ω (Argument of perihelion)      : 117.57640
            L (Longitude of perihelion)     : 297.04813
            B (Latitude of perihelion)      : 61.92174
            T (Time of perihelion passage)  : 2459090.73340
            P (Orbital period in years)     : 330.96

            Epoch                           : 2025 Jun 30
            Reference                       : MPEC 2020-L06

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (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. (15.00 + 5 log[∆] + 8.00 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
2025-07-01 00:00 UT   06 45 31.7   -66 06 07    14.625   14.647   89.2    4.0   179   30.2 
2025-07-01 01:19 UT   06 45 33.8   -66 06 08    14.625   14.647   89.2    4.0   179   30.2 
2025-07-02 00:00 UT   06 46 09.2   -66 06 28    14.632   14.653   89.2    4.0   179   30.2 
2025-07-03 00:00 UT   06 46 46.7   -66 06 53    14.639   14.658   89.1    4.0   180   30.2 
2025-07-04 00:00 UT   06 47 24.1   -66 07 22    14.645   14.664   89.0    4.0   181   30.2 
2025-07-05 00:00 UT   06 48 01.6   -66 07 53    14.652   14.670   89.0    4.0   182   30.2 
2025-07-06 00:00 UT   06 48 39.0   -66 08 29    14.659   14.675   88.9    4.0   183   30.2 
2025-07-07 00:00 UT   06 49 16.3   -66 09 07    14.666   14.681   88.8    4.0   183   30.2 
2025-07-08 00:00 UT   06 49 53.7   -66 09 49    14.673   14.686   88.7    4.0   184   30.2 
2025-07-09 00:00 UT   06 50 30.9   -66 10 35    14.680   14.692   88.7    4.0   185   30.2 
2025-07-10 00:00 UT   06 51 08.1   -66 11 24    14.687   14.698   88.6    4.0   186   30.2 
2025-07-11 00:00 UT   06 51 45.3   -66 12 16    14.694   14.703   88.5    4.0   187   30.2 

    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.