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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 AU22h01m-33°53'145.6°13.3°281°
Nearest approach7 Aug 201715.32.514 AU1.520 AU21h39m-29°21'165.3°5.9°330°
Today17 Oct 202530.120.761 AU20.398 AU06h08m+52°15'110.0°2.6°259°
C/2017 D2 (Barros)- 2025-10-17
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
2025-10-16 00:00 UT   06 08 13.9   +52 13 19    20.415   20.751  108.4    2.6   260   30.1 
2025-10-17 00:00 UT   06 08 08.5   +52 14 32    20.406   20.756  109.2    2.6   260   30.1 
2025-10-17 20:31 UT   06 08 03.6   +52 15 34    20.398   20.761  110.0    2.6   259   30.1 
2025-10-18 00:00 UT   06 08 02.8   +52 15 45    20.397   20.761  110.1    2.6   259   30.1 
2025-10-19 00:00 UT   06 07 56.7   +52 16 57    20.389   20.766  111.0    2.6   259   30.1 
2025-10-20 00:00 UT   06 07 50.4   +52 18 08    20.380   20.771  111.8    2.6   258   30.1 
2025-10-21 00:00 UT   06 07 43.7   +52 19 19    20.371   20.776  112.7    2.5   258   30.1 
2025-10-22 00:00 UT   06 07 36.7   +52 20 30    20.363   20.781  113.6    2.5   257   30.1 
2025-10-23 00:00 UT   06 07 29.4   +52 21 40    20.355   20.786  114.4    2.5   256   30.1 
2025-10-24 00:00 UT   06 07 21.8   +52 22 49    20.347   20.791  115.3    2.5   256   30.1 
2025-10-25 00:00 UT   06 07 13.9   +52 23 58    20.339   20.796  116.1    2.5   255   30.1 
2025-10-26 00:00 UT   06 07 05.7   +52 25 06    20.331   20.801  117.0    2.4   254   30.1 
2025-10-27 00:00 UT   06 06 57.2   +52 26 13    20.323   20.806  117.8    2.4   254   30.1 




    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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