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C/2025 B2 (Borisov)
ephemeris date magn radius delta ra dec elong phase PA
Today16 Oct 202520.18.472 AU8.265 AU07h48m+85°16'98.6°6.7°276°
Nearest approach14 Dec 202520.08.398 AU8.000 AU21h06m+85°37'110.7°6.3°53°
Perihelion11 Sep 202620.08.240 AU8.294 AU16h37m+78°13'83.4°7.0°81°
C/2025 B2 (Borisov)- 2025-10-16
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. (6.2 + 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/2025 B2 (Borisov) are: 

    e (Eccentricity)                : 1.0012170
    q (Perihelion distance)         : 8.2401010
    i (Inclination)                 : 91.74470
    Ω (Longitude of ascending node) : 84.86660
    ω (Argument of perihelion)      : 78.82330
    L (Longitude of perihelion)     : 76.10664
    B (Latitude of perihelion)      : 78.68966
    T (Time of perihelion passage)  : 2461294.75030

    Epoch                           : 2025 Oct 15
    Reference                       : MPEC 2025-R69

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-15 00:00 UT   07 45 40.1   +84 58 27     8.282    8.475   97.8    6.7   277   20.1 
2025-10-16 00:00 UT   07 47 12.4   +85 07 49     8.273    8.474   98.2    6.7   277   20.1 
2025-10-16 22:48 UT   07 48 40.4   +85 16 44     8.265    8.472   98.6    6.7   276   20.1 
2025-10-17 00:00 UT   07 48 45.0   +85 17 12     8.265    8.472   98.7    6.7   276   20.1 
2025-10-18 00:00 UT   07 50 18.0   +85 26 37     8.256    8.471   99.1    6.7   276   20.1 
2025-10-19 00:00 UT   07 51 51.5   +85 36 03     8.248    8.469   99.5    6.7   275   20.1 
2025-10-20 00:00 UT   07 53 25.5   +85 45 29     8.240    8.468   99.9    6.7   275   20.1 
2025-10-21 00:00 UT   07 55 00.0   +85 54 57     8.232    8.467  100.3    6.6   274   20.1 
2025-10-22 00:00 UT   07 56 35.1   +86 04 26     8.223    8.465  100.7    6.6   273   20.1 
2025-10-23 00:00 UT   07 58 10.9   +86 13 55     8.216    8.464  101.1    6.6   273   20.0 
2025-10-24 00:00 UT   07 59 47.5   +86 23 26     8.208    8.463  101.5    6.6   272   20.0 
2025-10-25 00:00 UT   08 01 25.0   +86 32 57     8.200    8.461  101.9    6.6   272   20.0 
2025-10-26 00:00 UT   08 03 03.5   +86 42 28     8.193    8.460  102.3    6.6   271   20.0 




    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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