C/2021 A1 (Leonard) - DISINTEGRATED
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach12 Dec 20212.50.773 AU0.232 AU17h08m-01°46'21.5°152.2°354°
Perihelion3 Jan 20225.50.616 AU0.919 AU21h38m-35°43'37.6°76.8°99°
Disintegration1 Mar 202210.91.288 AU1.999 AU21h23m-34°54'33.1°24.9°220°
Today29 Mar 2024-9.035 AU8.538 AU16h45m-10°45'116.9°5.7°271°
C/2021 A1 (Leonard)- 2024-03-29
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 A1 (Leonard) are:

            e (Eccentricity)                : 1.0001100
            q (Perihelion distance)         : 0.6161510
            i (Inclination)                 : 132.74540
            Ω (Longitude of ascending node) : 255.90840
            ω (Argument of perihelion)      : 225.14030
            L (Longitude of perihelion)     : 221.61152
            B (Latitude of perihelion)      : -31.36935
            T (Time of perihelion passage)  : 2459582.87450

            Epoch                           : 2024 Mar 28
            Reference                       : MPEC 2023-CD7

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

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 (8.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 8.12 + 5 log[∆] + 11.50 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.10. (See Marcus 2007)


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
2024-03-29 00:00 UT   16 46 02.9   -10 47 05     8.542    9.031  116.4    5.7   272   23.8 
2024-03-29 12:08 UT   16 45 55.3   -10 45 55     8.538    9.035  116.9    5.7   271   23.8 
2024-03-30 00:00 UT   16 45 47.8   -10 44 46     8.534    9.039  117.4    5.6   271   23.8 
2024-03-31 00:00 UT   16 45 32.2   -10 42 25     8.527    9.046  118.5    5.6   271   23.8 
2024-04-01 00:00 UT   16 45 16.2   -10 40 05     8.520    9.054  119.5    5.5   271   23.8 
2024-04-02 00:00 UT   16 44 59.8   -10 37 44     8.513    9.062  120.5    5.5   271   23.8 
2024-04-03 00:00 UT   16 44 42.9   -10 35 23     8.506    9.070  121.5    5.4   270   23.8 
2024-04-04 00:00 UT   16 44 25.5   -10 33 01     8.500    9.078  122.6    5.3   270   23.8 
2024-04-05 00:00 UT   16 44 07.7   -10 30 39     8.493    9.085  123.6    5.3   270   23.8 
2024-04-06 00:00 UT   16 43 49.5   -10 28 17     8.487    9.093  124.6    5.2   269   23.8 
2024-04-07 00:00 UT   16 43 30.9   -10 25 55     8.481    9.101  125.7    5.1   269   23.8 
2024-04-08 00:00 UT   16 43 11.8   -10 23 32     8.475    9.109  126.7    5.1   269   23.8 


    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.