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°33'	165.7°	5.0°	327°
Today	15 Sep 2025	29.5	15.748 AU	16.309 AU	10h12m	+54°46'	54.5°	3.0°	335°

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 A/2020 H9 are:

            e (Eccentricity)                : 0.9924300
            q (Perihelion distance)         : 2.5610610
            i (Inclination)                 : 137.87300
            Ω (Longitude of ascending node) : 213.10640
            ω (Argument of perihelion)      : 312.59630
            L (Longitude of perihelion)     : 251.99791
            B (Latitude of perihelion)      : -29.58971
            T (Time of perihelion passage)  : 2458839.22280
            P (Orbital period in years)     : 6222.80

            Epoch                           : 2025 Sep 15
            Reference                       : MPEC 2022-ED3

            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 gray curve indicates the expected brightness if this object is a comet (18.00 + 5 log[∆] + 5.00 log[r]), whereas the red curve indicates the expected lightcurve for an asteroid (H=17.10; G=.15).

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
2025-09-15 00:00 UT   10 12 03.3   +54 46 33    16.312   15.743   54.0    3.0   335   29.5 
2025-09-15 20:28 UT   10 12 19.0   +54 46 56    16.309   15.748   54.5    3.0   335   29.5 
2025-09-16 00:00 UT   10 12 21.7   +54 46 60    16.309   15.749   54.6    3.0   335   29.5 
2025-09-17 00:00 UT   10 12 40.0   +54 47 29    16.305   15.754   55.2    3.0   334   29.5 
2025-09-18 00:00 UT   10 12 58.2   +54 48 00    16.302   15.760   55.8    3.0   333   29.5 
2025-09-19 00:00 UT   10 13 16.2   +54 48 34    16.298   15.765   56.4    3.0   332   29.5 
2025-09-20 00:00 UT   10 13 34.1   +54 49 11    16.294   15.771   57.0    3.1   331   29.5 
2025-09-21 00:00 UT   10 13 51.8   +54 49 50    16.291   15.776   57.6    3.1   330   29.5 
2025-09-22 00:00 UT   10 14 09.4   +54 50 32    16.286   15.782   58.3    3.1   330   29.5 
2025-09-23 00:00 UT   10 14 26.8   +54 51 16    16.282   15.787   58.9    3.1   329   29.5 
2025-09-24 00:00 UT   10 14 44.0   +54 52 03    16.278   15.793   59.5    3.1   328   29.5 
2025-09-25 00:00 UT   10 15 01.0   +54 52 53    16.273   15.798   60.1    3.2   327   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.