C/2018 K1 (Weiland)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	8 Apr 2018	18.4	1.880 AU	2.218 AU	21h43m	-21°41'	57.5°	26.7°	246°
Nearest approach	9 Jun 2018	17.0	2.025 AU	1.017 AU	17h51m	-25°09'	170.0°	5.0°	281°
Today	9 Oct 2025	32.9	18.213 AU	18.850 AU	10h21m	+25°11'	49.2°	2.4°	304°

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.)

The orbital elements of C/2018 K1 (Weiland) are:

            e (Eccentricity)                : 0.9378170
            q (Perihelion distance)         : 1.8796280
            i (Inclination)                 : 164.18610
            Ω (Longitude of ascending node) : 260.20330
            ω (Argument of perihelion)      : 325.25290
            L (Longitude of perihelion)     : 293.92230
            B (Latitude of perihelion)      : -8.93539
            T (Time of perihelion passage)  : 2458216.66380
            P (Orbital period in years)     : 166.19

            Epoch                           : 2023 Apr 14
            Reference                       : MPC114602

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (P < 200 years)
        

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. The gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (14.90 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 13.92 + 5 log[∆] + 10.00 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-09 00:00 UT   10 21 41.4   +25 11 51    18.850   18.213   49.1    2.4   304   32.9 
2025-10-09 00:31 UT   10 21 41.6   +25 11 51    18.850   18.213   49.2    2.4   304   32.9 
2025-10-10 00:00 UT   10 21 49.3   +25 11 44    18.842   18.217   50.1    2.4   304   32.9 
2025-10-11 00:00 UT   10 21 57.0   +25 11 38    18.833   18.221   51.0    2.4   304   32.9 
2025-10-12 00:00 UT   10 22 04.6   +25 11 33    18.824   18.226   51.9    2.5   303   32.9 
2025-10-13 00:00 UT   10 22 12.0   +25 11 29    18.816   18.230   52.8    2.5   303   32.9 
2025-10-14 00:00 UT   10 22 19.3   +25 11 27    18.807   18.235   53.7    2.5   302   32.9 
2025-10-15 00:00 UT   10 22 26.4   +25 11 26    18.797   18.239   54.6    2.6   302   32.9 
2025-10-16 00:00 UT   10 22 33.3   +25 11 27    18.788   18.243   55.6    2.6   302   32.9 
2025-10-17 00:00 UT   10 22 40.1   +25 11 28    18.779   18.248   56.5    2.6   301   32.9 
2025-10-18 00:00 UT   10 22 46.8   +25 11 32    18.769   18.252   57.4    2.6   301   32.9 
2025-10-19 00:00 UT   10 22 53.2   +25 11 37    18.759   18.257   58.4    2.7   301   32.9 

    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.