C/2021 K1 (ATLAS)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion2 May 202116.12.502 AU2.897 AU23h05m-06°55'57.4°19.8°247°
Nearest approach12 Sep 202115.62.811 AU1.887 AU01h16m-10°36'151.2°9.9°281°
Today1 Apr 202524.910.173 AU10.246 AU06h18m+12°41'83.0°5.6°93°
C/2021 K1 (ATLAS)- 2025-04-01
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.)

The orbital elements of C/2021 K1 (ATLAS) are:

            e (Eccentricity)                : 0.8016280
            q (Perihelion distance)         : 2.5019350
            i (Inclination)                 : 16.27130
            Ω (Longitude of ascending node) : 140.92350
            ω (Argument of perihelion)      : 184.23320
            L (Longitude of perihelion)     : 144.98772
            B (Latitude of perihelion)      : -1.18509
            T (Time of perihelion passage)  : 2459337.15550
            P (Orbital period in years)     : 44.79

            Epoch                           : 2025 Mar 31
            Reference                       : MPEC 2022-O08

            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 is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (11.00 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 9.78 + 5 log[∆] + 10.00 log[r]).


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
2025-04-01 00:00 UT   06 18 33.6   +12 40 29    10.233   10.170   83.6    5.6    93   24.9 
2025-04-01 14:15 UT   06 18 38.4   +12 41 12    10.246   10.173   83.0    5.6    93   24.9 
2025-04-02 00:00 UT   06 18 41.8   +12 41 42    10.255   10.175   82.6    5.6    93   24.9 
2025-04-03 00:00 UT   06 18 50.3   +12 42 56    10.276   10.179   81.7    5.6    93   24.9 
2025-04-04 00:00 UT   06 18 59.1   +12 44 08    10.297   10.184   80.7    5.6    94   24.9 
2025-04-05 00:00 UT   06 19 08.4   +12 45 20    10.318   10.189   79.8    5.5    94   24.9 
2025-04-06 00:00 UT   06 19 18.0   +12 46 31    10.339   10.193   78.9    5.5    94   24.9 
2025-04-07 00:00 UT   06 19 27.9   +12 47 41    10.360   10.198   78.0    5.5    94   24.9 
2025-04-08 00:00 UT   06 19 38.2   +12 48 51    10.380   10.203   77.0    5.5    94   25.0 
2025-04-09 00:00 UT   06 19 48.9   +12 49 60    10.401   10.207   76.1    5.5    95   25.0 
2025-04-10 00:00 UT   06 19 59.9   +12 51 08    10.422   10.212   75.2    5.4    95   25.0 
2025-04-11 00:00 UT   06 20 11.2   +12 52 15    10.443   10.217   74.3    5.4    95   25.0 

































































    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.