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C/2017 D2 (Barros)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion14 Jul 201715.42.500 AU1.595 AU 22h01m-33°53'145.6°13.3°281°
Nearest approach7 Aug 201715.32.514 AU1.520 AU 21h39m-29°21'165.3°5.9°330°
Today1 Dec 202530.120.985 AU20.172 AU 05h59m+52°54'144.7°1.6°217°
C/2017 D2 (Barros)- 2025-12-01
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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 10.4 + 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/2017 D2 (Barros) are: 

    e (Eccentricity)                : 0.9998490
    q (Perihelion distance)         : 2.5000880
    i (Inclination)                 : 31.25650
    Ω (Longitude of ascending node) : 330.95930
    ω (Argument of perihelion)      : 334.65390
    L (Longitude of perihelion)     : 308.91485
    B (Latitude of perihelion)      : -12.83362
    T (Time of perihelion passage)  : 2457948.99800

    Epoch                           : 2022 Jul 23
    Reference                       : MPC112391

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-11-30 00:00 UT   05 59 35.8   +52 54 01    20.173   20.976  143.7    1.6   220   30.1 
2025-12-01 00:00 UT   05 59 19.3   +52 54 26    20.172   20.981  144.3    1.6   218   30.1 
2025-12-01 19:47 UT   05 59 05.6   +52 54 46    20.172   20.985  144.7    1.6   217   30.1 
2025-12-02 00:00 UT   05 59 02.7   +52 54 50    20.172   20.986  144.8    1.6   217   30.1 
2025-12-03 00:00 UT   05 58 46.0   +52 55 13    20.172   20.991  145.4    1.5   215   30.1 
2025-12-04 00:00 UT   05 58 29.2   +52 55 34    20.172   20.996  145.9    1.5   213   30.1 
2025-12-05 00:00 UT   05 58 12.2   +52 55 53    20.173   21.001  146.4    1.5   212   30.1 
2025-12-06 00:00 UT   05 57 55.2   +52 56 11    20.174   21.006  146.8    1.5   210   30.1 
2025-12-07 00:00 UT   05 57 38.0   +52 56 27    20.175   21.011  147.3    1.5   208   30.1 
2025-12-08 00:00 UT   05 57 20.8   +52 56 42    20.176   21.016  147.7    1.4   206   30.1 
2025-12-09 00:00 UT   05 57 03.5   +52 56 54    20.178   21.021  148.1    1.4   204   30.2 
2025-12-10 00:00 UT   05 56 46.1   +52 57 06    20.180   21.026  148.5    1.4   202   30.2 
2025-12-11 00:00 UT   05 56 28.6   +52 57 15    20.182   21.031  148.8    1.4   200   30.2 




    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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