A/2019 O4
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	5 Sep 2019	21.1	3.883 AU	3.042 AU	21h41m	+27°01'	141.6°	9.3°	149°
Perihelion	10 Feb 2020	21.8	3.646 AU	4.311 AU	20h29m	+25°04'	42.6°	10.6°	336°
Today	26 Apr 2024	25.8	11.283 AU	10.537 AU	11h35m	+05°01'	136.0°	3.6°	116°

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/2019 O4 are:

            e (Eccentricity)                : 0.8903820
            q (Perihelion distance)         : 3.6460620
            i (Inclination)                 : 115.06510
            Ω (Longitude of ascending node) : 354.92840
            ω (Argument of perihelion)      : 61.86740
            L (Longitude of perihelion)     : 316.53733
            B (Latitude of perihelion)      : 53.01675
            T (Time of perihelion passage)  : 2458890.47000
            P (Orbital period in years)     : 191.83

            Epoch                           : 2024 Apr 25
            Reference                       : MPEC 2021-P47

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (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 (15.50 + 5 log[∆] + 5.00 log[r]), whereas the red curve indicates the expected lightcurve for an asteroid (H=15.10; 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
2024-04-26 00:00 UT   11 35 17.9   +05 01 14    10.531   11.281  136.4    3.5   116   25.8 
2024-04-26 08:08 UT   11 35 11.6   +05 01 26    10.537   11.283  136.0    3.6   116   25.8 
2024-04-27 00:00 UT   11 34 59.2   +05 01 48    10.548   11.287  135.3    3.6   115   25.8 
2024-04-28 00:00 UT   11 34 40.8   +05 02 20    10.566   11.292  134.3    3.7   115   25.8 
2024-04-29 00:00 UT   11 34 22.7   +05 02 50    10.583   11.297  133.2    3.7   115   25.8 
2024-04-30 00:00 UT   11 34 04.8   +05 03 18    10.601   11.302  132.2    3.8   115   25.8 
2024-05-01 00:00 UT   11 33 47.3   +05 03 44    10.619   11.308  131.2    3.8   115   25.9 
2024-05-02 00:00 UT   11 33 30.1   +05 04 08    10.637   11.313  130.1    3.9   115   25.9 
2024-05-03 00:00 UT   11 33 13.3   +05 04 31    10.655   11.318  129.1    4.0   115   25.9 
2024-05-04 00:00 UT   11 32 56.7   +05 04 51    10.673   11.323  128.1    4.0   115   25.9 
2024-05-05 00:00 UT   11 32 40.5   +05 05 09    10.692   11.329  127.0    4.1   115   25.9 
2024-05-06 00:00 UT   11 32 24.6   +05 05 26    10.711   11.334  126.0    4.1   115   25.9 

    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.