C/2018 K1 (Weiland)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	9 Apr 2018	18.3	1.861 AU	2.185 AU	21h46m	-21°31'	58.1°	27.2°	246°
Nearest approach	9 Jun 2018	16.9	2.004 AU	0.996 AU	17h53m	-25°17'	170.0°	5.0°	281°
Today	15 Apr 2026	33.1	19.033 AU	18.581 AU	09h57m	+28°04'	115.4°	2.7°	118°

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 13.9 + 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/2018 K1 (Weiland) are:

    e (Eccentricity)                : 0.9380940
    q (Perihelion distance)         : 1.8605750
    i (Inclination)                 : 164.18110
    Ω (Longitude of ascending node) : 260.26170
    ω (Argument of perihelion)      : 325.08790
    L (Longitude of perihelion)     : 294.14274
    B (Latitude of perihelion)      : -8.97554
    T (Time of perihelion passage)  : 2458217.98820
    P (Orbital period in years)     : 164.77

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    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
2026-04-14 00:00 UT   09 57 60.0   +28 04 46    18.547   19.026  117.1    2.7   118   33.1 
2026-04-15 00:00 UT   09 57 51.2   +28 04 42    18.566   19.030  116.1    2.7   118   33.1 
2026-04-15 18:27 UT   09 57 44.5   +28 04 38    18.581   19.033  115.4    2.7   118   33.1 
2026-04-16 00:00 UT   09 57 42.5   +28 04 37    18.585   19.034  115.2    2.7   118   33.1 
2026-04-17 00:00 UT   09 57 34.1   +28 04 30    18.604   19.038  114.2    2.8   117   33.1 
2026-04-18 00:00 UT   09 57 26.0   +28 04 21    18.624   19.043  113.2    2.8   117   33.1 
2026-04-19 00:00 UT   09 57 18.0   +28 04 11    18.643   19.047  112.3    2.8   117   33.1 
2026-04-20 00:00 UT   09 57 10.2   +28 04 00    18.663   19.051  111.3    2.8   117   33.1 
2026-04-21 00:00 UT   09 57 02.7   +28 03 48    18.682   19.055  110.4    2.8   116   33.1 
2026-04-22 00:00 UT   09 56 55.4   +28 03 34    18.702   19.060  109.4    2.9   116   33.1 
2026-04-23 00:00 UT   09 56 48.3   +28 03 19    18.722   19.064  108.4    2.9   116   33.1 
2026-04-24 00:00 UT   09 56 41.5   +28 03 03    18.742   19.068  107.5    2.9   115   33.1 
2026-04-25 00:00 UT   09 56 34.9   +28 02 45    18.762   19.073  106.5    2.9   115   33.1 

    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.