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C/2021 G3 (PANSTARRS)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion18 Oct 202121.45.187 AU5.747 AU 10h36m+18°51'51.6°8.7°300°
Nearest approach5 Feb 202220.95.253 AU4.367 AU 10h28m+39°48'151.3°5.2°219°
Today14 May 202626.912.362 AU12.636 AU 21h40m+57°42'72.1°4.5°263°
C/2021 G3 (PANSTARRS)- 2026-05-14
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. (10.5 + 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 G3 (PANSTARRS) are: 

    e (Eccentricity)                : 0.9996920
    q (Perihelion distance)         : 5.1866860
    i (Inclination)                 : 102.87990
    Ω (Longitude of ascending node) : 147.32040
    ω (Argument of perihelion)      : 10.64250
    L (Longitude of perihelion)     : 144.92184
    B (Latitude of perihelion)      : 10.37173
    T (Time of perihelion passage)  : 2459505.54640

    Epoch                           : 2026 May 13
    Reference                       : MPEC 2026-E44

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-05-13 00:00 UT   21 40 57.8   +57 37 41    12.636   12.355   71.6    4.5   265   26.9 
2026-05-14 00:00 UT   21 40 58.7   +57 40 52    12.636   12.360   71.9    4.5   264   26.9 
2026-05-14 09:20 UT   21 40 58.9   +57 42 06    12.636   12.362   72.1    4.5   263   26.9 
2026-05-15 00:00 UT   21 40 59.0   +57 44 02    12.636   12.366   72.2    4.5   263   26.9 
2026-05-16 00:00 UT   21 40 58.7   +57 47 12    12.636   12.371   72.6    4.5   262   26.9 
2026-05-17 00:00 UT   21 40 57.9   +57 50 21    12.636   12.376   72.9    4.5   261   26.9 
2026-05-18 00:00 UT   21 40 56.5   +57 53 29    12.635   12.382   73.2    4.5   260   26.9 
2026-05-19 00:00 UT   21 40 54.6   +57 56 37    12.635   12.387   73.5    4.5   259   26.9 
2026-05-20 00:00 UT   21 40 52.1   +57 59 44    12.634   12.392   73.9    4.5   258   26.9 
2026-05-21 00:00 UT   21 40 49.0   +58 02 50    12.634   12.397   74.2    4.5   257   26.9 
2026-05-22 00:00 UT   21 40 45.3   +58 05 55    12.633   12.403   74.6    4.5   256   26.9 
2026-05-23 00:00 UT   21 40 41.1   +58 08 58    12.633   12.408   74.9    4.5   255   26.9 
2026-05-24 00:00 UT   21 40 36.3   +58 12 01    12.632   12.413   75.3    4.5   254   26.9 




    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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