A/2019 O4
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach5 Sep 201921.13.877 AU3.035 AU 21h41m+26°57'141.7°9.3°149°
Perihelion11 Feb 202021.73.638 AU4.303 AU 20h29m+25°07'42.6°10.6°336°
Today30 Mar 202626.814.769 AU13.836 AU 11h09m-03°42'158.4°1.4°91°
A/2019 O4- 2026-03-30
astro.vanbuitenen.nl


 
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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=15.10; 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/2019 O4 are:

    e (Eccentricity)                : 0.8906660
    q (Perihelion distance)         : 3.6384570
    i (Inclination)                 : 114.95870
    Ω (Longitude of ascending node) : 354.90560
    ω (Argument of perihelion)      : 61.82100
    L (Longitude of perihelion)     : 316.67971
    B (Latitude of perihelion)      : 53.04972
    T (Time of perihelion passage)  : 2458890.74430
    P (Orbital period in years)     : 191.97

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (P < 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-03-29 00:00 UT   11 10 11.6   -03 45 29    13.816   14.760  160.3    1.3    89   26.8 
2026-03-30 00:00 UT   11 09 54.7   -03 44 12    13.826   14.765  159.3    1.4    90   26.8 
2026-03-30 23:15 UT   11 09 38.4   -03 42 58    13.836   14.769  158.4    1.4    91   26.8 
2026-03-31 00:00 UT   11 09 37.9   -03 42 56    13.836   14.769  158.3    1.4    91   26.8 
2026-04-01 00:00 UT   11 09 21.2   -03 41 40    13.847   14.774  157.4    1.5    92   26.9 
2026-04-02 00:00 UT   11 09 04.7   -03 40 24    13.857   14.779  156.4    1.6    93   26.9 
2026-04-03 00:00 UT   11 08 48.3   -03 39 08    13.868   14.783  155.4    1.6    94   26.9 
2026-04-04 00:00 UT   11 08 32.1   -03 37 52    13.880   14.788  154.4    1.7    95   26.9 
2026-04-05 00:00 UT   11 08 16.0   -03 36 37    13.891   14.793  153.4    1.7    96   26.9 
2026-04-06 00:00 UT   11 08 00.0   -03 35 22    13.903   14.797  152.4    1.8    97   26.9 
2026-04-07 00:00 UT   11 07 44.3   -03 34 08    13.915   14.802  151.4    1.9    97   26.9 
2026-04-08 00:00 UT   11 07 28.7   -03 32 53    13.928   14.807  150.4    1.9    98   26.9 
2026-04-09 00:00 UT   11 07 13.2   -03 31 40    13.941   14.811  149.4    2.0    98   26.9 



    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.