C/2025 Q3 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	30 Oct 2025	17.3	2.522 AU	1.614 AU	03h53m	+34°53'	149.8°	11.4°	232°
Nearest approach	25 Nov 2025	16.7	2.372 AU	1.410 AU	02h54m	+17°02'	163.2°	6.9°	74°
Perihelion	25 Feb 2026	17.4	2.113 AU	2.493 AU	02h23m	-19°34'	56.4°	23.0°	92°

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 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. (12.2 + 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 Q3 (ATLAS) are:

    e (Eccentricity)                : 0.9971460
    q (Perihelion distance)         : 2.1125780
    i (Inclination)                 : 90.18600
    Ω (Longitude of ascending node) : 233.14410
    ω (Argument of perihelion)      : 218.45240
    L (Longitude of perihelion)     : 232.99640
    B (Latitude of perihelion)      : -38.45216
    T (Time of perihelion passage)  : 2461097.13960
    P (Orbital period in years)     : 20139.01

    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   03 55 37.2   +35 28 56     1.632    2.529  148.0   12.0   233   17.3 
2025-10-30 00:00 UT   03 53 33.1   +34 58 42     1.617    2.523  149.5   11.5   232   17.3 
2025-10-30 04:27 UT   03 53 09.9   +34 53 00     1.614    2.522  149.8   11.4   232   17.3 
2025-10-31 00:00 UT   03 51 27.1   +34 27 36     1.602    2.517  151.0   11.0   231   17.2 
2025-11-01 00:00 UT   03 49 19.4   +33 55 36     1.588    2.511  152.5   10.5   230   17.2 
2025-11-02 00:00 UT   03 47 10.1   +33 22 43     1.574    2.505  154.1   10.0   228   17.2 
2025-11-03 00:00 UT   03 44 59.2   +32 48 56     1.561    2.499  155.7    9.4   227   17.1 
2025-11-04 00:00 UT   03 42 47.0   +32 14 17     1.548    2.493  157.3    8.9   226   17.1 
2025-11-05 00:00 UT   03 40 33.5   +31 38 45     1.536    2.487  158.8    8.3   224   17.1 
2025-11-06 00:00 UT   03 38 19.0   +31 02 20     1.524    2.481  160.4    7.7   222   17.1 
2025-11-07 00:00 UT   03 36 03.5   +30 25 05     1.513    2.475  162.0    7.1   220   17.0 
2025-11-08 00:00 UT   03 33 47.1   +29 46 58     1.502    2.469  163.6    6.5   218   17.0 
2025-11-09 00:00 UT   03 31 30.1   +29 08 02     1.492    2.463  165.2    5.9   215   17.0 

    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.