C/2019 S4 (Lemmon)
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach24 Nov 201919.03.660 AU3.014 AU01h34m+72°38'124.1°12.9°138°
Perihelion8 Apr 202019.33.442 AU3.820 AU23h37m+65°55'60.7°14.7°334°
Today28 Mar 202426.811.525 AU10.983 AU16h17m-27°28'120.7°4.3°284°
C/2019 S4 (Lemmon)- 2024-03-28
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/2019 S4 (Lemmon) are:

            e (Eccentricity)                : 0.9856650
            q (Perihelion distance)         : 3.4417340
            i (Inclination)                 : 92.10500
            Ω (Longitude of ascending node) : 63.15800
            ω (Argument of perihelion)      : 71.37230
            L (Longitude of perihelion)     : 56.93905
            B (Latitude of perihelion)      : 71.25794
            T (Time of perihelion passage)  : 2458947.96480
            P (Orbital period in years)     : 3720.23

            Epoch                           : 2024 Mar 27
            Reference                       : MPEC 2021-S45

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (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 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. (11.00 + 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
2024-03-28 00:00 UT   16 17 19.3   -27 27 26    10.989   11.521  120.0    4.3   283   26.8 
2024-03-28 15:58 UT   16 17 10.0   -27 28 13    10.983   11.525  120.7    4.3   284   26.8 
2024-03-29 00:00 UT   16 17 05.3   -27 28 37    10.980   11.527  121.0    4.3   284   26.8 
2024-03-30 00:00 UT   16 16 50.9   -27 29 47    10.971   11.533  122.1    4.2   284   26.8 
2024-03-31 00:00 UT   16 16 36.2   -27 30 56    10.962   11.538  123.1    4.2   284   26.8 
2024-04-01 00:00 UT   16 16 21.1   -27 32 03    10.954   11.544  124.1    4.1   284   26.8 
2024-04-02 00:00 UT   16 16 05.6   -27 33 10    10.945   11.550  125.2    4.1   284   26.8 
2024-04-03 00:00 UT   16 15 49.8   -27 34 15    10.937   11.556  126.2    4.0   285   26.8 
2024-04-04 00:00 UT   16 15 33.6   -27 35 20    10.929   11.562  127.2    3.9   285   26.8 
2024-04-05 00:00 UT   16 15 17.0   -27 36 23    10.922   11.568  128.3    3.9   285   26.8 
2024-04-06 00:00 UT   16 15 00.1   -27 37 25    10.914   11.574  129.3    3.8   285   26.8 
2024-04-07 00:00 UT   16 14 42.9   -27 38 26    10.907   11.580  130.3    3.8   286   26.8 


    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.