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	16 Sep 2025	32.9	18.111 AU	18.982 AU	10h18m	+25°20'	29.2°	1.6°	318°

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
2025-09-16 00:00 UT   10 18 06.9   +25 20 39    18.982   18.111   29.1    1.5   318   32.9 
2025-09-16 02:33 UT   10 18 08.0   +25 20 35    18.982   18.111   29.2    1.6   318   32.9 
2025-09-17 00:00 UT   10 18 17.3   +25 20 03    18.979   18.115   29.9    1.6   317   32.9 
2025-09-18 00:00 UT   10 18 27.6   +25 19 28    18.976   18.120   30.7    1.6   316   32.9 
2025-09-19 00:00 UT   10 18 37.9   +25 18 54    18.972   18.124   31.6    1.7   315   32.9 
2025-09-20 00:00 UT   10 18 48.1   +25 18 22    18.968   18.129   32.4    1.7   314   32.9 
2025-09-21 00:00 UT   10 18 58.2   +25 17 50    18.964   18.133   33.3    1.7   314   32.9 
2025-09-22 00:00 UT   10 19 08.2   +25 17 20    18.959   18.138   34.1    1.8   313   32.9 
2025-09-23 00:00 UT   10 19 18.1   +25 16 50    18.955   18.142   35.0    1.8   312   32.9 
2025-09-24 00:00 UT   10 19 27.9   +25 16 22    18.950   18.146   35.8    1.9   312   32.9 
2025-09-25 00:00 UT   10 19 37.6   +25 15 56    18.945   18.151   36.7    1.9   311   32.9 
2025-09-26 00:00 UT   10 19 47.2   +25 15 30    18.939   18.155   37.6    1.9   310   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.