C/2018 K1 (Weiland)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	9 Apr 2018	18.3	1.860 AU	2.187 AU	21h46m	-21°31'	57.9°	27.1°	246°
Nearest approach	9 Jun 2018	16.9	2.004 AU	0.996 AU	17h52m	-25°15'	170.0°	5.0°	281°
Today	19 Jun 2026	33.3	19.311 AU	19.881 AU	09h56m	+27°19'	54.6°	2.5°	100°

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)                : 0.9380720
    q (Perihelion distance)         : 1.8597350
    i (Inclination)                 : 164.18280
    Ω (Longitude of ascending node) : 260.24880
    ω (Argument of perihelion)      : 325.06250
    L (Longitude of perihelion)     : 294.15512
    B (Latitude of perihelion)      : -8.98034
    T (Time of perihelion passage)  : 2458217.80370
    P (Orbital period in years)     : 164.57

    Epoch                           : 2026 May 29
    Reference                       : MPC194156

    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
2026-06-18 00:00 UT   09 56 06.0   +27 21 56    19.846   19.302   56.4    2.5   101   33.3 
2026-06-19 00:00 UT   09 56 11.1   +27 20 52    19.863   19.306   55.5    2.5   101   33.3 
2026-06-19 23:13 UT   09 56 16.1   +27 19 50    19.881   19.311   54.6    2.5   100   33.3 
2026-06-20 00:00 UT   09 56 16.3   +27 19 48    19.881   19.311   54.6    2.5   100   33.3 
2026-06-21 00:00 UT   09 56 21.6   +27 18 43    19.899   19.315   53.7    2.4   100   33.3 
2026-06-22 00:00 UT   09 56 27.2   +27 17 38    19.916   19.319   52.8    2.4   100   33.3 
2026-06-23 00:00 UT   09 56 32.9   +27 16 32    19.933   19.323   51.9    2.4    99   33.3 
2026-06-24 00:00 UT   09 56 38.7   +27 15 26    19.950   19.328   51.1    2.3    99   33.3 
2026-06-25 00:00 UT   09 56 44.8   +27 14 20    19.967   19.332   50.2    2.3    99   33.3 
2026-06-26 00:00 UT   09 56 50.9   +27 13 14    19.983   19.336   49.3    2.3    98   33.3 
2026-06-27 00:00 UT   09 56 57.3   +27 12 07    20.000   19.340   48.4    2.3    98   33.3 
2026-06-28 00:00 UT   09 57 03.7   +27 11 01    20.016   19.345   47.5    2.2    98   33.3 
2026-06-29 00:00 UT   09 57 10.4   +27 09 54    20.032   19.349   46.7    2.2    97   33.3 

    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.