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	3 Aug 2026	30.2	18.800 AU	18.734 AU	09h12m	-74°35'	92.1°	3.1°	175°

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
2026-08-02 00:00 UT   09 11 30.4   -74 36 17    18.717   18.791   92.6    3.1   174   30.2 
2026-08-03 00:00 UT   09 12 18.7   -74 35 47    18.728   18.796   92.3    3.1   175   30.2 
2026-08-03 16:04 UT   09 12 51.0   -74 35 28    18.734   18.800   92.1    3.1   175   30.2 
2026-08-04 00:00 UT   09 13 07.0   -74 35 19    18.738   18.802   92.0    3.1   176   30.2 
2026-08-05 00:00 UT   09 13 55.3   -74 34 54    18.748   18.807   91.7    3.1   176   30.2 
2026-08-06 00:00 UT   09 14 43.5   -74 34 31    18.759   18.812   91.4    3.1   177   30.2 
2026-08-07 00:00 UT   09 15 31.7   -74 34 11    18.769   18.817   91.2    3.1   178   30.2 
2026-08-08 00:00 UT   09 16 19.9   -74 33 53    18.779   18.823   90.9    3.1   179   30.2 
2026-08-09 00:00 UT   09 17 08.0   -74 33 38    18.790   18.828   90.6    3.1   179   30.2 
2026-08-10 00:00 UT   09 17 56.0   -74 33 25    18.800   18.833   90.3    3.1   180   30.2 
2026-08-11 00:00 UT   09 18 43.9   -74 33 15    18.811   18.838   90.0    3.1   181   30.2 
2026-08-12 00:00 UT   09 19 31.8   -74 33 07    18.821   18.844   89.7    3.1   181   30.2 
2026-08-13 00:00 UT   09 20 19.6   -74 33 02    18.832   18.849   89.4    3.1   182   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.