C/2025 F2 (SWAN) - DISINTEGRATED
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Disintegration	16 Apr 2025	7.3	0.543 AU	1.196 AU	00h30m	+32°01'	26.8°	56.4°	322°
Perihelion	1 May 2025	8.4	0.334 AU	0.963 AU	03h33m	+28°15'	19.3°	88.0°	50°
Nearest approach	1 May 2025	8.4	0.334 AU	0.963 AU	03h38m	+27°36'	19.3°	88.0°	53°
Today	20 Mar 2026	-	4.878 AU	5.427 AU	00h27m	-51°44'	52.1°	9.3°	171°

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.)

Light curve

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations from COBS. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 9.6 + 5 log[∆] + 10.0 log[r]). An additional green curve is displayed when an increase in apparent brightness is expected due to forward scattering of sunlight, which occurs when a dust-rich comet is located between the Earth and the Sun. (See Marcus 2007)

Charts

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.

Orbital elements

The orbital elements of C/2025 F2 (SWAN) are:

    e (Eccentricity)                : 1.0001410
    q (Perihelion distance)         : 0.3336730
    i (Inclination)                 : 90.37170
    Ω (Longitude of ascending node) : 329.82630
    ω (Argument of perihelion)      : 153.84340
    L (Longitude of perihelion)     : 330.00885
    B (Latitude of perihelion)      : 26.15601
    T (Time of perihelion passage)  : 2460796.65030

    Epoch                           : 2026 Mar 19
    Reference                       : MPEC 2026-E44

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-03-19 00:00 UT   00 25 15.2   -51 52 23     5.413    4.857   51.5    9.2   170   20.1 
2026-03-20 00:00 UT   00 26 12.6   -51 48 12     5.420    4.867   51.8    9.3   171   20.1 
2026-03-20 23:55 UT   00 27 09.7   -51 44 09     5.427    4.878   52.1    9.3   171   20.2 
2026-03-21 00:00 UT   00 27 09.9   -51 44 08     5.427    4.878   52.1    9.3   171   20.2 
2026-03-22 00:00 UT   00 28 07.1   -51 40 13     5.433    4.889   52.3    9.3   172   20.2 
2026-03-23 00:00 UT   00 29 04.0   -51 36 25     5.440    4.899   52.6    9.3   173   20.2 
2026-03-24 00:00 UT   00 30 00.8   -51 32 44     5.446    4.910   52.9    9.3   174   20.2 
2026-03-25 00:00 UT   00 30 57.4   -51 29 12     5.453    4.921   53.2    9.3   175   20.2 
2026-03-26 00:00 UT   00 31 53.7   -51 25 47     5.459    4.931   53.5    9.4   176   20.2 
2026-03-27 00:00 UT   00 32 49.9   -51 22 30     5.465    4.942   53.8    9.4   177   20.2 
2026-03-28 00:00 UT   00 33 45.9   -51 19 21     5.471    4.952   54.1    9.4   177   20.2 
2026-03-29 00:00 UT   00 34 41.7   -51 16 19     5.476    4.963   54.4    9.4   178   20.2 
2026-03-30 00:00 UT   00 35 37.3   -51 13 25     5.482    4.973   54.8    9.4   179   20.3 

    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.