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C/2021 K3 (Catalina)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion2 Feb 202221.15.220 AU6.155 AU 19h54m-22°02'16.9°3.1°255°
Nearest approach28 Jun 202220.55.334 AU4.355 AU 19h00m-39°01'162.7°3.3°333°
Today31 Jul 202626.412.219 AU12.589 AU 10h54m-40°10'66.4°4.4°145°
C/2021 K3 (Catalina)- 2026-07-31
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 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. (10.0 + 5 log[∆] + 10.0 log[r]). An additional green curve is displayed when an increase in apparent brightness is expected due to forward scattering of sunlight, which occurs when a dust-rich comet is located between the Earth and the Sun. (See Marcus 2007)



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 C/2021 K3 (Catalina) are: 

    e (Eccentricity)                : 1.0027590
    q (Perihelion distance)         : 5.2197950
    i (Inclination)                 : 134.79460
    Ω (Longitude of ascending node) : 114.51750
    ω (Argument of perihelion)      : 181.94840
    L (Longitude of perihelion)     : 113.14445
    B (Latitude of perihelion)      : -1.38252
    T (Time of perihelion passage)  : 2459612.80460

    Epoch                           : 2026 Jul 30
    Reference                       : MPC194174

    Classification(s):              : Nearly isotropic; New (a > 10000 AU)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-07-30 00:00 UT   10 54 05.2   -40 12 29    12.572   12.213   67.1    4.4   144   26.4 
2026-07-31 00:00 UT   10 54 19.4   -40 10 45    12.588   12.218   66.5    4.4   145   26.4 
2026-07-31 02:15 UT   10 54 20.7   -40 10 35    12.589   12.219   66.4    4.4   145   26.4 
2026-08-01 00:00 UT   10 54 33.7   -40 09 04    12.604   12.223   65.8    4.3   146   26.4 
2026-08-02 00:00 UT   10 54 48.2   -40 07 27    12.620   12.229   65.2    4.3   146   26.4 
2026-08-03 00:00 UT   10 55 02.8   -40 05 53    12.635   12.234   64.6    4.3   147   26.4 
2026-08-04 00:00 UT   10 55 17.6   -40 04 23    12.651   12.239   63.9    4.3   148   26.4 
2026-08-05 00:00 UT   10 55 32.6   -40 02 57    12.666   12.245   63.3    4.2   149   26.4 
2026-08-06 00:00 UT   10 55 47.7   -40 01 34    12.682   12.250   62.7    4.2   149   26.4 
2026-08-07 00:00 UT   10 56 02.9   -40 00 15    12.697   12.255   62.1    4.2   150   26.4 
2026-08-08 00:00 UT   10 56 18.3   -39 58 60    12.712   12.260   61.5    4.2   151   26.4 
2026-08-09 00:00 UT   10 56 33.8   -39 57 48    12.727   12.266   60.8    4.1   152   26.4 
2026-08-10 00:00 UT   10 56 49.4   -39 56 40    12.742   12.271   60.2    4.1   152   26.4 




    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.

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