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C/2021 K3 (Catalina)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion2 Feb 202221.15.219 AU6.155 AU 19h54m-22°02'16.8°3.1°255°
Nearest approach28 Jun 202220.55.334 AU4.355 AU 19h00m-39°01'162.7°3.3°333°
Today4 Sep 202626.512.404 AU13.067 AU 11h03m-39°47'47.2°3.4°176°
C/2021 K3 (Catalina)- 2026-09-04
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)                : 1.0026940
    q (Perihelion distance)         : 5.2194240
    i (Inclination)                 : 134.79470
    Ω (Longitude of ascending node) : 114.51710
    ω (Argument of perihelion)      : 181.94240
    L (Longitude of perihelion)     : 113.14828
    B (Latitude of perihelion)      : -1.37827
    T (Time of perihelion passage)  : 2459612.74660

    Epoch                           : 2026 Sep 03
    Reference                       : MPC194174

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-09-03 00:00 UT   11 03 28.6   -39 46 56    13.054   12.397   47.7    3.5   174   26.5 
2026-09-04 00:00 UT   11 03 45.7   -39 47 13    13.064   12.403   47.3    3.4   175   26.5 
2026-09-04 05:43 UT   11 03 49.8   -39 47 18    13.067   12.404   47.2    3.4   176   26.5 
2026-09-05 00:00 UT   11 04 02.9   -39 47 34    13.075   12.408   46.9    3.4   177   26.5 
2026-09-06 00:00 UT   11 04 20.0   -39 47 57    13.086   12.413   46.5    3.4   178   26.5 
2026-09-07 00:00 UT   11 04 37.1   -39 48 24    13.096   12.419   46.1    3.4   179   26.5 
2026-09-08 00:00 UT   11 04 54.2   -39 48 54    13.106   12.424   45.7    3.3   180   26.5 
2026-09-09 00:00 UT   11 05 11.2   -39 49 27    13.116   12.429   45.4    3.3   181   26.5 
2026-09-10 00:00 UT   11 05 28.3   -39 50 04    13.126   12.434   45.0    3.3   182   26.5 
2026-09-11 00:00 UT   11 05 45.3   -39 50 43    13.135   12.440   44.7    3.3   183   26.5 
2026-09-12 00:00 UT   11 06 02.3   -39 51 25    13.144   12.445   44.4    3.2   185   26.5 
2026-09-13 00:00 UT   11 06 19.2   -39 52 10    13.153   12.450   44.0    3.2   186   26.5 
2026-09-14 00:00 UT   11 06 36.1   -39 52 59    13.162   12.455   43.7    3.2   187   26.6 




    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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