C/2019 K4 (Ye)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	15 Jun 2019	16.8	2.274 AU	2.716 AU	01h26m	+43°00'	54.1°	21.2°	270°
Nearest approach	17 Sep 2019	16.0	2.508 AU	1.523 AU	00h13m	+09°10'	165.1°	5.9°	219°
Today	4 Oct 2026	30.3	19.122 AU	19.360 AU	09h57m	-75°24'	74.7°	2.9°	222°

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 11.1 + 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/2019 K4 (Ye) are:

    e (Eccentricity)                : 0.9986660
    q (Perihelion distance)         : 2.2741790
    i (Inclination)                 : 105.27560
    Ω (Longitude of ascending node) : 180.39240
    ω (Argument of perihelion)      : 140.03260
    L (Longitude of perihelion)     : 192.84439
    B (Latitude of perihelion)      : 38.29110
    T (Time of perihelion passage)  : 2458650.08980
    P (Orbital period in years)     : 70388.75

    Epoch                           : 2026 May 29
    Reference                       : MPC194161

    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
2026-10-03 00:00 UT   09 56 48.2   -75 21 33    19.348   19.115   75.1    2.9   221   30.3 
2026-10-04 00:00 UT   09 57 23.4   -75 23 26    19.357   19.120   74.8    2.9   222   30.3 
2026-10-04 08:34 UT   09 57 35.8   -75 24 07    19.360   19.122   74.7    2.9   222   30.3 
2026-10-05 00:00 UT   09 57 58.2   -75 25 21    19.366   19.126   74.6    2.9   223   30.3 
2026-10-06 00:00 UT   09 58 32.5   -75 27 18    19.375   19.131   74.4    2.9   224   30.3 
2026-10-07 00:00 UT   09 59 06.4   -75 29 17    19.384   19.136   74.2    2.9   224   30.3 
2026-10-08 00:00 UT   09 59 39.9   -75 31 17    19.393   19.141   73.9    2.9   225   30.3 
2026-10-09 00:00 UT   10 00 12.9   -75 33 19    19.402   19.146   73.7    2.9   226   30.3 
2026-10-10 00:00 UT   10 00 45.4   -75 35 23    19.410   19.152   73.5    2.9   227   30.3 
2026-10-11 00:00 UT   10 01 17.5   -75 37 29    19.419   19.157   73.3    2.9   228   30.3 
2026-10-12 00:00 UT   10 01 49.1   -75 39 36    19.427   19.162   73.1    2.9   229   30.3 
2026-10-13 00:00 UT   10 02 20.2   -75 41 45    19.436   19.167   72.9    2.9   230   30.3 
2026-10-14 00:00 UT   10 02 50.8   -75 43 56    19.444   19.172   72.7    2.8   230   30.3 

    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.