A/2020 H9
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	21 Dec 2019	22.4	2.561 AU	3.422 AU	16h53m	-44°23'	24.6°	9.2°	217°
Nearest approach	22 Apr 2020	21.2	2.872 AU	1.887 AU	14h32m	-24°32'	165.7°	5.0°	327°
Today	16 Oct 2025	29.5	15.917 AU	16.147 AU	10h20m	+55°21'	74.9°	3.5°	312°

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 displayed light curve is calculated under the assumption that the object remains inactive. (H=17.10; G=.15).

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 A/2020 H9 are:

    e (Eccentricity)                : 0.9923990
    q (Perihelion distance)         : 2.5607660
    i (Inclination)                 : 137.87270
    Ω (Longitude of ascending node) : 213.09970
    ω (Argument of perihelion)      : 312.58630
    L (Longitude of perihelion)     : 252.00088
    B (Latitude of perihelion)      : -29.59512
    T (Time of perihelion passage)  : 2458839.17890
    P (Orbital period in years)     : 6183.70

    Epoch                           : 2025 Oct 15
    Reference                       : MPEC 2022-ED3

    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
2025-10-16 00:00 UT   10 20 09.2   +55 20 14    16.151   15.914   74.5    3.5   313   29.5 
2025-10-16 10:51 UT   10 20 14.6   +55 21 01    16.147   15.917   74.9    3.5   312   29.5 
2025-10-17 00:00 UT   10 20 21.1   +55 21 60    16.144   15.920   75.3    3.5   312   29.5 
2025-10-18 00:00 UT   10 20 32.7   +55 23 49    16.137   15.925   76.0    3.5   311   29.5 
2025-10-19 00:00 UT   10 20 44.0   +55 25 40    16.130   15.931   76.7    3.5   311   29.5 
2025-10-20 00:00 UT   10 20 55.0   +55 27 34    16.123   15.936   77.4    3.5   310   29.5 
2025-10-21 00:00 UT   10 21 05.6   +55 29 30    16.115   15.942   78.2    3.5   309   29.5 
2025-10-22 00:00 UT   10 21 16.0   +55 31 28    16.108   15.947   78.9    3.5   309   29.5 
2025-10-23 00:00 UT   10 21 26.1   +55 33 29    16.101   15.953   79.7    3.5   308   29.5 
2025-10-24 00:00 UT   10 21 35.8   +55 35 33    16.094   15.958   80.4    3.5   308   29.5 
2025-10-25 00:00 UT   10 21 45.2   +55 37 38    16.086   15.964   81.1    3.5   307   29.5 
2025-10-26 00:00 UT   10 21 54.3   +55 39 47    16.079   15.969   81.9    3.5   306   29.5 

    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.