P/2025 C1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	6 Feb 2025	19.2	2.746 AU	2.378 AU	14h15m	-14°38'	101.2°	20.6°	290°
Nearest approach	22 Apr 2025	18.7	2.783 AU	1.782 AU	14h06m	-18°07'	173.9°	2.2°	346°
Today	5 Jan 2026	21.4	3.348 AU	4.295 AU	18h09m	-29°10'	13.7°	4.0°	245°

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 13.0 + 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 P/2025 C1 (ATLAS) are:

    e (Eccentricity)                : 0.3456780
    q (Perihelion distance)         : 2.7460260
    i (Inclination)                 : 7.51660
    Ω (Longitude of ascending node) : 9.09580
    ω (Argument of perihelion)      : 186.81430
    L (Longitude of perihelion)     : 15.85209
    B (Latitude of perihelion)      : -0.88934
    T (Time of perihelion passage)  : 2460713.11220
    P (Orbital period in years)     : 8.60

    Epoch                           : 2026 Jan 04
    Reference                       : MPC188413

    Classification(s):              : Ecliptic; Jupiter family
    Tisserand (Jupiter)             : 2.911

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-01-04 00:00 UT   18 07 13.8   -29 10 10     4.295    3.344   13.0    3.8   243   21.4 
2026-01-05 00:00 UT   18 08 52.0   -29 10 23     4.295    3.347   13.6    4.0   244   21.4 
2026-01-05 02:29 UT   18 09 02.2   -29 10 24     4.295    3.348   13.7    4.0   245   21.4 
2026-01-06 00:00 UT   18 10 30.0   -29 10 32     4.295    3.350   14.2    4.1   245   21.4 
2026-01-07 00:00 UT   18 12 07.8   -29 10 38     4.294    3.353   14.8    4.3   246   21.4 
2026-01-08 00:00 UT   18 13 45.4   -29 10 42     4.294    3.356   15.4    4.5   247   21.4 
2026-01-09 00:00 UT   18 15 22.7   -29 10 42     4.293    3.359   16.0    4.6   248   21.4 
2026-01-10 00:00 UT   18 16 59.8   -29 10 39     4.292    3.362   16.7    4.8   248   21.4 
2026-01-11 00:00 UT   18 18 36.7   -29 10 34     4.291    3.365   17.3    5.0   249   21.4 
2026-01-12 00:00 UT   18 20 13.3   -29 10 26     4.290    3.368   17.9    5.2   250   21.4 
2026-01-13 00:00 UT   18 21 49.6   -29 10 15     4.289    3.371   18.6    5.3   250   21.4 
2026-01-14 00:00 UT   18 23 25.7   -29 10 01     4.287    3.374   19.2    5.5   251   21.4 
2026-01-15 00:00 UT   18 25 01.5   -29 09 45     4.286    3.377   19.8    5.7   251   21.4 

    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.