C/2021 K3 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	2 Feb 2022	21.1	5.219 AU	6.155 AU	19h54m	-22°02'	16.7°	3.1°	255°
Nearest approach	28 Jun 2022	20.5	5.333 AU	4.354 AU	19h00m	-39°01'	162.7°	3.3°	333°
Today	30 Oct 2026	26.7	12.701 AU	13.346 AU	11h17m	-41°15'	47.8°	3.3°	248°

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)                : 1.0025890
    q (Perihelion distance)         : 5.2187260
    i (Inclination)                 : 134.79460
    Ω (Longitude of ascending node) : 114.51720
    ω (Argument of perihelion)      : 181.93250
    L (Longitude of perihelion)     : 113.15536
    B (Latitude of perihelion)      : -1.37124
    T (Time of perihelion passage)  : 2459612.65420

    Epoch                           : 2026 Oct 29
    Reference                       : MPC194174

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-10-29 00:00 UT   11 17 11.9   -41 11 36    13.348   12.692   47.1    3.3   247   26.7 
2026-10-30 00:00 UT   11 17 21.6   -41 14 05    13.347   12.697   47.5    3.3   248   26.7 
2026-10-30 15:49 UT   11 17 27.9   -41 15 43    13.346   12.701   47.8    3.3   248   26.7 
2026-10-31 00:00 UT   11 17 31.0   -41 16 34    13.346   12.703   47.9    3.3   249   26.7 
2026-11-01 00:00 UT   11 17 40.2   -41 19 05    13.345   12.708   48.4    3.3   250   26.7 
2026-11-02 00:00 UT   11 17 49.0   -41 21 38    13.344   12.713   48.8    3.4   251   26.7 
2026-11-03 00:00 UT   11 17 57.6   -41 24 11    13.343   12.718   49.3    3.4   252   26.7 
2026-11-04 00:00 UT   11 18 05.9   -41 26 46    13.341   12.724   49.8    3.4   253   26.7 
2026-11-05 00:00 UT   11 18 14.0   -41 29 21    13.339   12.729   50.3    3.4   254   26.7 
2026-11-06 00:00 UT   11 18 21.7   -41 31 58    13.337   12.734   50.8    3.5   255   26.7 
2026-11-07 00:00 UT   11 18 29.1   -41 34 35    13.335   12.739   51.3    3.5   256   26.7 
2026-11-08 00:00 UT   11 18 36.2   -41 37 13    13.333   12.745   51.8    3.5   257   26.7 
2026-11-09 00:00 UT   11 18 43.0   -41 39 53    13.330   12.750   52.4    3.5   258   26.7 

    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.