C/2019 K4 (Ye)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	15 Jun 2019	16.8	2.275 AU	2.718 AU	01h26m	+42°58'	54.0°	21.2°	270°
Nearest approach	17 Sep 2019	16.0	2.509 AU	1.524 AU	00h13m	+09°09'	165.1°	5.9°	219°
Today	4 Apr 2026	29.9	18.159 AU	17.976 AU	08h08m	-79°33'	98.9°	3.1°	72°

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)                : 0.9986700
    q (Perihelion distance)         : 2.2749820
    i (Inclination)                 : 105.27860
    Ω (Longitude of ascending node) : 180.37220
    ω (Argument of perihelion)      : 140.03520
    L (Longitude of perihelion)     : 192.82539
    B (Latitude of perihelion)      : 38.28801
    T (Time of perihelion passage)  : 2458649.99260
    P (Orbital period in years)     : 70743.98

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    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
2026-04-03 00:00 UT   08 09 16.1   -79 37 32    17.974   18.152   98.6    3.1    71   29.9 
2026-04-04 00:00 UT   08 09 02.9   -79 34 16    17.976   18.157   98.9    3.1    72   29.9 
2026-04-04 08:58 UT   08 08 58.3   -79 33 02    17.976   18.159   98.9    3.1    72   29.9 
2026-04-05 00:00 UT   08 08 51.0   -79 30 58    17.977   18.162   99.1    3.1    73   29.9 
2026-04-06 00:00 UT   08 08 40.4   -79 27 40    17.979   18.168   99.3    3.1    74   29.9 
2026-04-07 00:00 UT   08 08 31.0   -79 24 21    17.980   18.173   99.5    3.1    75   29.9 
2026-04-08 00:00 UT   08 08 23.0   -79 21 00    17.982   18.178   99.7    3.1    76   29.9 
2026-04-09 00:00 UT   08 08 16.1   -79 17 39    17.983   18.184   99.9    3.1    77   29.9 
2026-04-10 00:00 UT   08 08 10.5   -79 14 18    17.985   18.189  100.2    3.1    78   29.9 
2026-04-11 00:00 UT   08 08 06.1   -79 10 55    17.987   18.194  100.4    3.1    79   29.9 
2026-04-12 00:00 UT   08 08 02.9   -79 07 32    17.989   18.200  100.6    3.1    80   29.9 
2026-04-13 00:00 UT   08 08 00.9   -79 04 09    17.991   18.205  100.7    3.1    81   29.9 
2026-04-14 00:00 UT   08 08 00.1   -79 00 44    17.993   18.210  100.9    3.1    82   29.9 

    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.