C/2017 D2 (Barros)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	14 Jul 2017	15.4	2.500 AU	1.595 AU	22h01m	-33°53'	145.6°	13.3°	281°
Nearest approach	7 Aug 2017	15.3	2.514 AU	1.520 AU	21h39m	-29°21'	165.3°	5.9°	330°
Today	13 Jan 2026	30.2	21.199 AU	20.415 AU	05h46m	+52°46'	141.9°	1.6°	134°

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
2026-01-12 00:00 UT   05 47 18.0   +52 47 37    20.396   21.190  143.0    1.6   137   30.2 
2026-01-13 00:00 UT   05 47 02.4   +52 46 53    20.407   21.195  142.4    1.6   135   30.2 
2026-01-13 17:04 UT   05 46 51.4   +52 46 20    20.415   21.199  141.9    1.6   134   30.2 
2026-01-14 00:00 UT   05 46 47.0   +52 46 07    20.418   21.200  141.7    1.6   134   30.2 
2026-01-15 00:00 UT   05 46 31.7   +52 45 20    20.430   21.205  141.1    1.7   133   30.2 
2026-01-16 00:00 UT   05 46 16.6   +52 44 31    20.442   21.210  140.4    1.7   131   30.2 
2026-01-17 00:00 UT   05 46 01.7   +52 43 42    20.454   21.215  139.7    1.7   130   30.2 
2026-01-18 00:00 UT   05 45 47.0   +52 42 50    20.466   21.220  139.0    1.7   129   30.2 
2026-01-19 00:00 UT   05 45 32.5   +52 41 58    20.479   21.225  138.3    1.8   127   30.2 
2026-01-20 00:00 UT   05 45 18.2   +52 41 04    20.492   21.230  137.6    1.8   126   30.2 
2026-01-21 00:00 UT   05 45 04.1   +52 40 09    20.505   21.235  136.9    1.8   125   30.2 
2026-01-22 00:00 UT   05 44 50.3   +52 39 13    20.518   21.240  136.2    1.8   124   30.2 
2026-01-23 00:00 UT   05 44 36.6   +52 38 16    20.532   21.245  135.4    1.9   123   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.