C/2012 S1 (ISON)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	1 Dec 2013	-9.3	0.013 AU	0.996 AU	16h32m	-22°08'	0.5°	39.8°	126°
Nearest approach	28 Dec 2013	7.6	0.986 AU	0.426 AU	16h59m	+51°55'	77.8°	77.2°	339°
Today	6 Nov 2025	31.8	30.892 AU	30.474 AU	07h34m	+37°04'	114.0°	1.7°	273°

This comet is a sungrazer. Although it may become very bright at perihelion, this will only be for a very short period very close to the sun.

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. (9.5 + 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/2012 S1 (ISON) are:

    e (Eccentricity)                : 1.0002330
    q (Perihelion distance)         : 0.0132770
    i (Inclination)                 : 63.89100
    Ω (Longitude of ascending node) : 295.10960
    ω (Argument of perihelion)      : 345.92900
    L (Longitude of perihelion)     : 288.81511
    B (Latitude of perihelion)      : -12.61010
    T (Time of perihelion passage)  : 2456628.07350

    Epoch                           : 2022 May 11
    Reference                       : MPEC 2022-H30

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-11-05 00:00 UT   07 34 19.5   +37 03 56    30.492   30.883  112.3    1.7   273   31.8 
2025-11-06 00:00 UT   07 34 15.9   +37 04 31    30.482   30.888  113.3    1.7   273   31.8 
2025-11-06 18:51 UT   07 34 12.8   +37 04 59    30.474   30.892  114.0    1.7   273   31.8 
2025-11-07 00:00 UT   07 34 12.0   +37 05 06    30.472   30.893  114.2    1.7   272   31.8 
2025-11-08 00:00 UT   07 34 08.0   +37 05 42    30.462   30.898  115.2    1.7   272   31.8 
2025-11-09 00:00 UT   07 34 03.8   +37 06 17    30.452   30.903  116.2    1.6   272   31.8 
2025-11-10 00:00 UT   07 33 59.5   +37 06 53    30.442   30.908  117.2    1.6   271   31.8 
2025-11-11 00:00 UT   07 33 55.0   +37 07 28    30.433   30.913  118.1    1.6   271   31.8 
2025-11-12 00:00 UT   07 33 50.4   +37 08 04    30.423   30.918  119.1    1.6   271   31.8 
2025-11-13 00:00 UT   07 33 45.6   +37 08 39    30.414   30.923  120.1    1.6   270   31.8 
2025-11-14 00:00 UT   07 33 40.7   +37 09 15    30.405   30.928  121.1    1.6   270   31.8 
2025-11-15 00:00 UT   07 33 35.6   +37 09 50    30.396   30.933  122.0    1.6   270   31.8 
2025-11-16 00:00 UT   07 33 30.4   +37 10 26    30.387   30.938  123.0    1.5   269   31.8 

    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.