323P/SOHO
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	16 Feb 2025	15.9	0.879 AU	0.222 AU	18h14m	-29°00'	54.9°	113.2°	265°
Perihelion	14 Mar 2025	6.1	0.040 AU	1.027 AU	23h31m	-03°07'	1.4°	35.9°	246°
Today	15 Sep 2025	27.4	2.892 AU	3.680 AU	09h29m	+15°56'	33.3°	11.0°	290°

This comet is a sunskirter. Although it may become very bright at perihelion, this will only be for a very short period very close to the sun.

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 323P/SOHO are:

            e (Eccentricity)                : 0.9834750
            q (Perihelion distance)         : 0.0403260
            i (Inclination)                 : 5.21700
            Ω (Longitude of ascending node) : 323.92850
            ω (Argument of perihelion)      : 353.33740
            L (Longitude of perihelion)     : 317.29325
            B (Latitude of perihelion)      : -0.60446
            T (Time of perihelion passage)  : 2460748.74000
            P (Orbital period in years)     : 3.81

            Epoch                           : 2025 Sep 15
            Reference                       : MPC182891

            Classification(s):              : Ecliptic; Jupiter family; Sunskirter
            Tisserand (Jupiter)             : 2.379
        

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. (20.00 + 5 log[∆] + 10.00 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.30. (See Marcus 2007)

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
2025-09-15 00:00 UT   09 29 02.5   +15 59 54     3.681    2.885   32.6   10.8   290   27.4 
2025-09-15 21:30 UT   09 29 49.4   +15 56 14     3.680    2.892   33.3   11.0   290   27.4 
2025-09-16 00:00 UT   09 29 54.8   +15 55 48     3.680    2.893   33.3   11.0   290   27.4 
2025-09-17 00:00 UT   09 30 46.7   +15 51 45     3.678    2.901   34.1   11.2   290   27.5 
2025-09-18 00:00 UT   09 31 37.9   +15 47 44     3.676    2.908   34.9   11.4   290   27.5 
2025-09-19 00:00 UT   09 32 28.6   +15 43 44     3.673    2.916   35.6   11.6   290   27.5 
2025-09-20 00:00 UT   09 33 18.7   +15 39 47     3.671    2.924   36.4   11.8   290   27.5 
2025-09-21 00:00 UT   09 34 08.2   +15 35 52     3.668    2.931   37.2   11.9   290   27.5 
2025-09-22 00:00 UT   09 34 57.2   +15 31 60     3.665    2.939   37.9   12.1   290   27.5 
2025-09-23 00:00 UT   09 35 45.6   +15 28 10     3.661    2.946   38.7   12.3   290   27.5 
2025-09-24 00:00 UT   09 36 33.3   +15 24 22     3.658    2.953   39.5   12.5   290   27.5 
2025-09-25 00:00 UT   09 37 20.5   +15 20 36     3.654    2.961   40.3   12.6   290   27.5 

    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.