C/2017 E2 (Tsuchinshan)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	22 Oct 2015	18.3	3.156 AU	2.319 AU	23h33m	+35°47'	141.0°	11.4°	121°
Perihelion	16 May 2016	17.3	2.326 AU	2.666 AU	01h51m	+77°34'	59.7°	22.0°	331°
Today	4 Nov 2026	31.4	21.135 AU	21.641 AU	11h21m	-62°33'	58.1°	2.3°	238°

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. (11.5 + 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 E2 (Tsuchinshan) are:

    e (Eccentricity)                : 0.8920280
    q (Perihelion distance)         : 2.3257550
    i (Inclination)                 : 78.99950
    Ω (Longitude of ascending node) : 11.45460
    ω (Argument of perihelion)      : 89.19900
    L (Longitude of perihelion)     : 97.26409
    B (Latitude of perihelion)      : 78.97073
    T (Time of perihelion passage)  : 2457525.34250
    P (Orbital period in years)     : 99.97

    Epoch                           : 2026 May 29
    Reference                       : MPC194150

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-11-03 00:00 UT   11 21 35.1   -62 30 43    21.640   21.131   58.0    2.3   237   31.4 
2026-11-04 00:00 UT   11 21 47.6   -62 33 14    21.641   21.135   58.1    2.3   238   31.4 
2026-11-04 01:21 UT   11 21 48.3   -62 33 23    21.641   21.135   58.1    2.3   238   31.4 
2026-11-05 00:00 UT   11 21 59.7   -62 35 46    21.643   21.138   58.2    2.3   239   31.4 
2026-11-06 00:00 UT   11 22 11.6   -62 38 20    21.644   21.141   58.3    2.3   240   31.4 
2026-11-07 00:00 UT   11 22 23.2   -62 40 54    21.646   21.145   58.5    2.3   241   31.4 
2026-11-08 00:00 UT   11 22 34.6   -62 43 30    21.647   21.148   58.6    2.3   242   31.4 
2026-11-09 00:00 UT   11 22 45.6   -62 46 06    21.648   21.151   58.8    2.3   244   31.4 
2026-11-10 00:00 UT   11 22 56.4   -62 48 44    21.649   21.155   58.9    2.3   245   31.4 
2026-11-11 00:00 UT   11 23 06.9   -62 51 22    21.650   21.158   59.1    2.3   246   31.4 
2026-11-12 00:00 UT   11 23 17.0   -62 54 02    21.650   21.161   59.3    2.3   247   31.4 
2026-11-13 00:00 UT   11 23 26.9   -62 56 42    21.651   21.165   59.4    2.3   248   31.4 
2026-11-14 00:00 UT   11 23 36.5   -62 59 24    21.651   21.168   59.6    2.3   249   31.4 

    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.