A/2025 S3
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	30 Oct 2025	19.8	3.432 AU	2.439 AU	02h21m	+12°24'	178.3°	0.5°	324°
Perihelion	25 Jun 2026	19.9	2.244 AU	2.458 AU	00h39m	+70°07'	65.9°	24.4°	267°
Nearest approach	29 Jul 2026	19.8	2.278 AU	2.268 AU	16h53m	+79°08'	77.6°	25.8°	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.)

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. The displayed light curve is calculated under the assumption that the object remains inactive. (H=15.10; G=.15).

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 A/2025 S3 are:

    e (Eccentricity)                : 0.9895600
    q (Perihelion distance)         : 2.2444800
    i (Inclination)                 : 103.56270
    Ω (Longitude of ascending node) : 36.72990
    ω (Argument of perihelion)      : 71.12590
    L (Longitude of perihelion)     : 2.28144
    B (Latitude of perihelion)      : 66.90343
    T (Time of perihelion passage)  : 2461216.58960
    P (Orbital period in years)     : 3152.27

    Epoch                           : 2025 Oct 29
    Reference                       : MPEC 2025-UQ3

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-29 00:00 UT   02 23 49.0   +12 18 36     2.449    3.441  177.1    0.8   291   19.9 
2025-10-30 00:00 UT   02 21 42.4   +12 23 12     2.441    3.433  178.2    0.5   316   19.8 
2025-10-30 04:26 UT   02 21 18.9   +12 24 03     2.439    3.432  178.3    0.5   324   19.8 
2025-10-31 00:00 UT   02 19 34.9   +12 27 48     2.433    3.426  178.4    0.4     8   19.8 
2025-11-01 00:00 UT   02 17 26.6   +12 32 22     2.426    3.418  177.5    0.7    43   19.8 
2025-11-02 00:00 UT   02 15 17.6   +12 36 54     2.420    3.410  176.3    1.1    57   19.8 
2025-11-03 00:00 UT   02 13 07.9   +12 41 25     2.414    3.403  174.8    1.5    63   19.9 
2025-11-04 00:00 UT   02 10 57.7   +12 45 54     2.408    3.395  173.4    1.9    67   19.9 
2025-11-05 00:00 UT   02 08 47.0   +12 50 22     2.403    3.387  171.9    2.4    69   19.9 
2025-11-06 00:00 UT   02 06 35.9   +12 54 48     2.398    3.380  170.5    2.8    71   19.9 
2025-11-07 00:00 UT   02 04 24.5   +12 59 12     2.394    3.372  169.0    3.2    72   20.0 
2025-11-08 00:00 UT   02 02 12.9   +13 03 34     2.391    3.365  167.5    3.7    73   20.0 
2025-11-09 00:00 UT   02 00 01.2   +13 07 55     2.387    3.357  166.0    4.1    73   20.0 

    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.