C/2024 A1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	28 Jan 2025	16.4	4.051 AU	3.273 AU	07h03m	-16°58'	137.2°	9.5°	36°
Perihelion	13 Jun 2025	17.0	3.874 AU	4.771 AU	07h08m	+16°58'	25.0°	6.4°	109°
Today	31 Dec 2025	16.7	4.249 AU	3.426 AU	08h21m	+55°43'	142.5°	8.1°	220°

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 7.8 + 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/2024 A1 (ATLAS) are:

    e (Eccentricity)                : 1.0007210
    q (Perihelion distance)         : 3.8744330
    i (Inclination)                 : 94.50550
    Ω (Longitude of ascending node) : 112.14040
    ω (Argument of perihelion)      : 353.21630
    L (Longitude of perihelion)     : 112.67578
    B (Latitude of perihelion)      : -6.76264
    T (Time of perihelion passage)  : 2460839.63390

    Epoch                           : 2025 Dec 30
    Reference                       : MPEC 2025-YF1

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-30 00:00 UT   08 22 51.2   +55 23 07     3.425    4.245  142.2    8.2   223   16.7 
2025-12-31 00:00 UT   08 21 16.9   +55 40 56     3.426    4.248  142.5    8.1   220   16.7 
2025-12-31 04:04 UT   08 21 00.8   +55 43 56     3.426    4.249  142.5    8.1   220   16.7 
2026-01-01 00:00 UT   08 19 40.5   +55 58 32     3.427    4.252  142.7    8.1   218   16.7 
2026-01-02 00:00 UT   08 18 01.9   +56 15 54     3.429    4.255  142.9    8.0   215   16.7 
2026-01-03 00:00 UT   08 16 21.2   +56 32 60     3.431    4.259  143.0    8.0   213   16.7 
2026-01-04 00:00 UT   08 14 38.4   +56 49 50     3.434    4.262  143.2    8.0   210   16.7 
2026-01-05 00:00 UT   08 12 53.5   +57 06 24     3.437    4.266  143.2    7.9   208   16.7 
2026-01-06 00:00 UT   08 11 06.7   +57 22 41     3.441    4.269  143.2    7.9   205   16.7 
2026-01-07 00:00 UT   08 09 17.9   +57 38 41     3.444    4.273  143.2    7.9   203   16.7 
2026-01-08 00:00 UT   08 07 27.2   +57 54 23     3.448    4.276  143.2    7.9   200   16.7 
2026-01-09 00:00 UT   08 05 34.7   +58 09 46     3.453    4.280  143.1    7.9   198   16.8 
2026-01-10 00:00 UT   08 03 40.5   +58 24 50     3.458    4.284  142.9    8.0   195   16.8 

    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.