12P/Pons-Brooks
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	21 Apr 2024	3.7	0.781 AU	1.606 AU	03h28m	+09°49'	22.7°	29.7°	97°
Nearest approach	2 Jun 2024	5.5	1.099 AU	1.547 AU	05h52m	-19°31'	45.2°	40.9°	157°
Today	30 Dec 2025	18.9	6.898 AU	7.753 AU	16h46m	-36°24'	27.7°	3.8°	249°

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 estimated manually by the author. (4.0 + 5 log[∆] + 12.5 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 12P/Pons-Brooks are:

    e (Eccentricity)                : 0.9547150
    q (Perihelion distance)         : 0.7814260
    i (Inclination)                 : 74.18020
    Ω (Longitude of ascending node) : 255.85980
    ω (Argument of perihelion)      : 199.02050
    L (Longitude of perihelion)     : 261.22853
    B (Latitude of perihelion)      : -18.27405
    T (Time of perihelion passage)  : 2460421.66800
    P (Orbital period in years)     : 71.68

    Epoch                           : 2025 Dec 29
    Reference                       : MPEC 2025-XC7

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-29 00:00 UT   16 45 02.7   -36 23 34     7.751    6.884   26.4    3.6   247   18.9 
2025-12-30 00:00 UT   16 45 39.0   -36 24 03     7.752    6.891   27.1    3.7   248   18.9 
2025-12-30 19:41 UT   16 46 08.5   -36 24 27     7.753    6.898   27.7    3.8   249   18.9 
2025-12-31 00:00 UT   16 46 15.0   -36 24 33     7.753    6.899   27.9    3.8   249   18.9 
2026-01-01 00:00 UT   16 46 50.7   -36 25 03     7.753    6.907   28.7    3.9   250   18.9 
2026-01-02 00:00 UT   16 47 26.1   -36 25 35     7.754    6.915   29.4    4.0   251   18.9 
2026-01-03 00:00 UT   16 48 01.2   -36 26 06     7.754    6.922   30.2    4.1   252   19.0 
2026-01-04 00:00 UT   16 48 36.0   -36 26 39     7.754    6.930   31.0    4.2   253   19.0 
2026-01-05 00:00 UT   16 49 10.5   -36 27 12     7.754    6.938   31.8    4.3   254   19.0 
2026-01-06 00:00 UT   16 49 44.7   -36 27 46     7.753    6.945   32.6    4.4   254   19.0 
2026-01-07 00:00 UT   16 50 18.5   -36 28 20     7.752    6.953   33.4    4.5   255   19.0 
2026-01-08 00:00 UT   16 50 52.0   -36 28 55     7.751    6.961   34.2    4.6   256   19.0 
2026-01-09 00:00 UT   16 51 25.1   -36 29 30     7.750    6.968   35.0    4.6   256   19.0 

    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.