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P/2021 A5 (PANSTARRS)
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach9 Sep 202520.52.715 AU1.715 AU 22h49m+01°39'171.2°3.2°142°
Today4 Nov 202520.92.667 AU2.088 AU 22h22m+02°24'115.3°19.6°74°
Perihelion11 Mar 202621.92.620 AU3.430 AU 00h48m+18°24'30.3°11.0°45°
P/2021 A5 (PANSTARRS)- 2025-11-04
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. (15.0 + 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 P/2021 A5 (PANSTARRS) are: 

    e (Eccentricity)                : 0.1396960
    q (Perihelion distance)         : 2.6204070
    i (Inclination)                 : 18.19030
    Ω (Longitude of ascending node) : 328.81030
    ω (Argument of perihelion)      : 61.57530
    L (Longitude of perihelion)     : 29.13895
    B (Latitude of perihelion)      : 15.93457
    T (Time of perihelion passage)  : 2461110.94530
    P (Orbital period in years)     : 5.32

    Epoch                           : 2025 Nov 03
    Reference                       : MPEC 2021-BE3

    Classification(s):              : Ecliptic; Active asteroid
    Tisserand (Jupiter)             : 3.148

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-11-03 00:00 UT   22 22 00.9   +02 20 16     2.066    2.669  117.1   19.3    74   20.8 
2025-11-04 00:00 UT   22 22 11.6   +02 22 29     2.077    2.668  116.2   19.5    74   20.8 
2025-11-04 21:59 UT   22 22 22.8   +02 24 35     2.088    2.667  115.3   19.6    74   20.9 
2025-11-05 00:00 UT   22 22 23.9   +02 24 47     2.089    2.667  115.3   19.6    74   20.9 
2025-11-06 00:00 UT   22 22 37.6   +02 27 11     2.100    2.666  114.4   19.8    74   20.9 
2025-11-07 00:00 UT   22 22 52.7   +02 29 41     2.111    2.666  113.4   19.9    73   20.9 
2025-11-08 00:00 UT   22 23 09.4   +02 32 15     2.123    2.665  112.5   20.1    73   20.9 
2025-11-09 00:00 UT   22 23 27.4   +02 34 56     2.135    2.664  111.7   20.2    73   20.9 
2025-11-10 00:00 UT   22 23 46.9   +02 37 42     2.146    2.664  110.8   20.3    73   20.9 
2025-11-11 00:00 UT   22 24 07.8   +02 40 34     2.158    2.663  109.9   20.5    73   20.9 
2025-11-12 00:00 UT   22 24 30.1   +02 43 32     2.170    2.662  109.0   20.6    72   20.9 
2025-11-13 00:00 UT   22 24 53.8   +02 46 35     2.182    2.662  108.1   20.7    72   20.9 
2025-11-14 00:00 UT   22 25 18.9   +02 49 44     2.194    2.661  107.3   20.8    72   21.0 




    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.

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