C/2024 B1 (Lemmon)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	7 Oct 2024	14.5	1.634 AU	1.996 AU	12h19m	+48°16'	54.5°	29.9°	350°
Nearest approach	15 Oct 2024	14.5	1.637 AU	1.988 AU	13h00m	+46°24'	55.1°	30.0°	354°
Today	2 Jul 2025	18.0	3.635 AU	2.820 AU	16h20m	+01°00'	137.5°	10.9°	127°

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/2024 B1 (Lemmon) are:

            e (Eccentricity)                : 1.0010200
            q (Perihelion distance)         : 1.6338080
            i (Inclination)                 : 70.90300
            Ω (Longitude of ascending node) : 79.18820
            ω (Argument of perihelion)      : 66.21750
            L (Longitude of perihelion)     : 115.77855
            B (Latitude of perihelion)      : 59.85100
            T (Time of perihelion passage)  : 2460591.22050

            Epoch                           : 2025 Jun 30
            Reference                       : MPEC 2025-MC0

            Classification(s):              : Nearly isotropic; New (a > 10000 AU)
        

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 (13.00 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 11.30 + 5 log[∆] + 7.97 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
2025-07-02 00:00 UT   16 20 19.7   +01 02 15     2.817    3.634  137.6   10.9   127   18.0 
2025-07-02 03:08 UT   16 20 12.9   +01 00 33     2.820    3.635  137.5   10.9   127   18.0 
2025-07-03 00:00 UT   16 19 28.1   +00 49 13     2.835    3.643  136.8   11.0   126   18.0 
2025-07-04 00:00 UT   16 18 37.9   +00 36 13     2.853    3.653  135.9   11.2   125   18.1 
2025-07-05 00:00 UT   16 17 49.1   +00 23 15     2.871    3.662  135.1   11.3   124   18.1 
2025-07-06 00:00 UT   16 17 01.7   +00 10 19     2.889    3.672  134.2   11.4   123   18.1 
2025-07-07 00:00 UT   16 16 15.8   +00 02 35     2.908    3.681  133.3   11.6   122   18.1 
2025-07-08 00:00 UT   16 15 31.2   +00 15 26     2.927    3.690  132.5   11.7   121   18.1 
2025-07-09 00:00 UT   16 14 48.0   +00 28 15     2.946    3.700  131.6   11.9   120   18.2 
2025-07-10 00:00 UT   16 14 06.2   +00 41 01     2.966    3.709  130.7   12.0   119   18.2 
2025-07-11 00:00 UT   16 13 25.8   +00 53 44     2.985    3.719  129.8   12.1   119   18.2 
2025-07-12 00:00 UT   16 12 46.8   -01 06 25     3.005    3.728  128.9   12.3   118   18.2 

    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.