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	15 Oct 2026	33.4	19.805 AU	20.328 AU	10h13m	+25°46'	57.1°	2.4°	301°

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
2026-10-14 00:00 UT   10 13 46.1   +25 46 49    20.346   19.798   55.4    2.4   301   33.4 
2026-10-15 00:00 UT   10 13 52.5   +25 46 50    20.336   19.802   56.4    2.4   301   33.4 
2026-10-15 19:39 UT   10 13 57.7   +25 46 52    20.328   19.805   57.1    2.4   301   33.4 
2026-10-16 00:00 UT   10 13 58.8   +25 46 53    20.326   19.806   57.3    2.4   301   33.4 
2026-10-17 00:00 UT   10 14 04.9   +25 46 57    20.316   19.810   58.2    2.5   300   33.4 
2026-10-18 00:00 UT   10 14 10.9   +25 47 02    20.306   19.814   59.2    2.5   300   33.4 
2026-10-19 00:00 UT   10 14 16.6   +25 47 08    20.296   19.818   60.1    2.5   300   33.4 
2026-10-20 00:00 UT   10 14 22.3   +25 47 16    20.285   19.823   61.0    2.5   299   33.4 
2026-10-21 00:00 UT   10 14 27.7   +25 47 25    20.275   19.827   62.0    2.5   299   33.4 
2026-10-22 00:00 UT   10 14 33.0   +25 47 35    20.264   19.831   62.9    2.6   299   33.4 
2026-10-23 00:00 UT   10 14 38.2   +25 47 47    20.253   19.835   63.9    2.6   299   33.4 
2026-10-24 00:00 UT   10 14 43.1   +25 47 59    20.242   19.839   64.8    2.6   298   33.4 
2026-10-25 00:00 UT   10 14 47.9   +25 48 14    20.231   19.843   65.7    2.6   298   33.4 

    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.