C/2019 K4 (Ye)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	15 Jun 2019	16.8	2.276 AU	2.719 AU	01h25m	+42°56'	54.0°	21.2°	271°
Nearest approach	17 Sep 2019	16.0	2.510 AU	1.525 AU	00h13m	+09°07'	165.1°	5.9°	219°
Today	11 Jan 2026	29.8	17.717 AU	17.932 AU	09h29m	-81°24'	75.8°	3.1°	332°

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)                : 0.9986250
    q (Perihelion distance)         : 2.2757280
    i (Inclination)                 : 105.28280
    Ω (Longitude of ascending node) : 180.33940
    ω (Argument of perihelion)      : 140.03270
    L (Longitude of perihelion)     : 192.79690
    B (Latitude of perihelion)      : 38.28946
    T (Time of perihelion passage)  : 2458649.87620
    P (Orbital period in years)     : 67332.77

    Epoch                           : 2025 Nov 12
    Reference                       : MPC119997

    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
2026-01-10 00:00 UT   09 31 41.5   -81 22 07    17.929   17.707   75.4    3.1   330   29.8 
2026-01-11 00:00 UT   09 30 34.2   -81 23 33    17.931   17.712   75.6    3.1   331   29.8 
2026-01-11 22:28 UT   09 29 30.3   -81 24 51    17.932   17.717   75.8    3.1   332   29.8 
2026-01-12 00:00 UT   09 29 25.9   -81 24 56    17.932   17.717   75.8    3.1   332   29.8 
2026-01-13 00:00 UT   09 28 16.5   -81 26 14    17.934   17.723   76.0    3.1   333   29.8 
2026-01-14 00:00 UT   09 27 06.1   -81 27 29    17.935   17.728   76.3    3.1   335   29.8 
2026-01-15 00:00 UT   09 25 54.7   -81 28 40    17.936   17.734   76.5    3.1   336   29.8 
2026-01-16 00:00 UT   09 24 42.4   -81 29 47    17.938   17.739   76.8    3.1   337   29.8 
2026-01-17 00:00 UT   09 23 29.2   -81 30 50    17.939   17.744   77.0    3.1   339   29.8 
2026-01-18 00:00 UT   09 22 15.1   -81 31 49    17.940   17.750   77.3    3.1   340   29.8 
2026-01-19 00:00 UT   09 21 00.2   -81 32 43    17.941   17.755   77.5    3.1   341   29.8 
2026-01-20 00:00 UT   09 19 44.6   -81 33 34    17.942   17.760   77.8    3.1   343   29.8 
2026-01-21 00:00 UT   09 18 28.2   -81 34 20    17.943   17.766   78.1    3.1   344   29.8 

    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.