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C/2017 D2 (Barros)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion9 Jul 201715.52.511 AU1.646 AU 22h11m-32°34'140.0°15.1°274°
Nearest approach8 Aug 201715.42.532 AU1.535 AU 21h46m-27°14'166.3°5.4°322°
Today12 Sep 202630.722.378 AU22.561 AU 06h17m+51°02'78.2°2.5°278°
C/2017 D2 (Barros)- 2026-09-12
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)                : 0.9989990
    q (Perihelion distance)         : 2.5114770
    i (Inclination)                 : 31.19150
    Ω (Longitude of ascending node) : 331.28400
    ω (Argument of perihelion)      : 334.42670
    L (Longitude of perihelion)     : 309.02134
    B (Latitude of perihelion)      : -12.91819
    T (Time of perihelion passage)  : 2457944.34650
    P (Orbital period in years)     : 125673.21

    Epoch                           : 2026 May 29
    Reference                       : MPC194150

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-09-11 00:00 UT   06 17 22.8   +51 00 52    22.580   22.369   76.6    2.5   279   30.7 
2026-09-12 00:00 UT   06 17 28.4   +51 01 56    22.570   22.374   77.4    2.5   279   30.7 
2026-09-12 21:36 UT   06 17 33.2   +51 02 55    22.561   22.378   78.2    2.5   278   30.7 
2026-09-13 00:00 UT   06 17 33.7   +51 03 01    22.560   22.379   78.3    2.5   278   30.7 
2026-09-14 00:00 UT   06 17 38.8   +51 04 06    22.551   22.383   79.1    2.5   278   30.7 
2026-09-15 00:00 UT   06 17 43.6   +51 05 12    22.541   22.388   80.0    2.5   277   30.7 
2026-09-16 00:00 UT   06 17 48.1   +51 06 18    22.531   22.393   80.8    2.5   277   30.7 
2026-09-17 00:00 UT   06 17 52.3   +51 07 25    22.520   22.398   81.7    2.5   276   30.7 
2026-09-18 00:00 UT   06 17 56.3   +51 08 32    22.510   22.403   82.5    2.5   276   30.7 
2026-09-19 00:00 UT   06 17 60.0   +51 09 39    22.500   22.407   83.4    2.6   276   30.7 
2026-09-20 00:00 UT   06 18 03.4   +51 10 46    22.490   22.412   84.2    2.6   275   30.7 
2026-09-21 00:00 UT   06 18 06.5   +51 11 54    22.480   22.417   85.1    2.6   275   30.7 
2026-09-22 00:00 UT   06 18 09.4   +51 13 02    22.470   22.422   86.0    2.6   274   30.7 




    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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