C/2021 T1 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	5 Oct 2021	19.1	3.062 AU	2.241 AU	23h40m	+43°48'	138.5°	12.5°	155°
Perihelion	14 Oct 2021	19.1	3.061 AU	2.266 AU	23h05m	+41°10'	135.8°	13.1°	129°
Today	22 Dec 2024	27.7	10.000 AU	10.906 AU	16h42m	-13°08'	21.8°	2.1°	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.)

The orbital elements of C/2021 T1 (Lemmon) are:

            e (Eccentricity)                : 0.9987410
            q (Perihelion distance)         : 3.0610970
            i (Inclination)                 : 140.36020
            Ω (Longitude of ascending node) : 56.84500
            ω (Argument of perihelion)      : 51.58060
            L (Longitude of perihelion)     : 12.69057
            B (Latitude of perihelion)      : 29.98876
            T (Time of perihelion passage)  : 2459502.13930
            P (Orbital period in years)     : 119888.37

            Epoch                           : 2024 Dec 21
            Reference                       : MPEC 2022-OB6

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (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 light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (12.50 + 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
2024-12-22 00:00 UT   16 42 17.4   -13 07 50    10.906    9.996   21.3    2.1   302   27.7 
2024-12-22 13:21 UT   16 42 26.5   -13 08 25    10.906   10.000   21.8    2.1   301   27.7 
2024-12-23 00:00 UT   16 42 33.7   -13 08 53    10.906   10.003   22.2    2.1   301   27.7 
2024-12-24 00:00 UT   16 42 49.8   -13 09 54    10.906   10.009   23.1    2.2   299   27.7 
2024-12-25 00:00 UT   16 43 05.8   -13 10 55    10.906   10.016   23.9    2.3   299   27.7 
2024-12-26 00:00 UT   16 43 21.6   -13 11 54    10.906   10.022   24.8    2.4   298   27.7 
2024-12-27 00:00 UT   16 43 37.3   -13 12 51    10.905   10.028   25.7    2.4   297   27.7 
2024-12-28 00:00 UT   16 43 52.9   -13 13 48    10.904   10.035   26.6    2.5   296   27.7 
2024-12-29 00:00 UT   16 44 08.2   -13 14 44    10.903   10.041   27.5    2.6   295   27.7 
2024-12-30 00:00 UT   16 44 23.5   -13 15 38    10.901   10.048   28.4    2.7   294   27.7 
2024-12-31 00:00 UT   16 44 38.6   -13 16 31    10.900   10.054   29.3    2.7   294   27.7 
2025-01-01 00:00 UT   16 44 53.5   -13 17 23    10.898   10.060   30.2    2.8   293   27.7 

    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.