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	18 Aug 2025	31.8	30.493 AU	31.267 AU	07h31m	+36°35'	39.4°	1.2°	298°

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.)

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
        

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. 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. (9.50 + 5 log[∆] + 10.00 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.30. (See Marcus 2007)

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-08-18 00:00 UT   07 31 02.3   +36 35 49    31.271   30.488   38.7    1.2   298   31.8 
2025-08-18 20:04 UT   07 31 08.6   +36 35 52    31.267   30.493   39.4    1.2   298   31.8 
2025-08-19 00:00 UT   07 31 09.8   +36 35 52    31.266   30.493   39.6    1.2   298   31.8 
2025-08-20 00:00 UT   07 31 17.2   +36 35 55    31.261   30.498   40.4    1.2   297   31.8 
2025-08-21 00:00 UT   07 31 24.5   +36 35 59    31.255   30.503   41.3    1.3   296   31.8 
2025-08-22 00:00 UT   07 31 31.8   +36 36 03    31.250   30.509   42.2    1.3   296   31.8 
2025-08-23 00:00 UT   07 31 38.9   +36 36 07    31.244   30.514   43.0    1.3   295   31.8 
2025-08-24 00:00 UT   07 31 45.9   +36 36 13    31.238   30.519   43.9    1.3   295   31.8 
2025-08-25 00:00 UT   07 31 52.9   +36 36 18    31.232   30.524   44.8    1.3   295   31.8 
2025-08-26 00:00 UT   07 31 59.7   +36 36 25    31.225   30.529   45.7    1.4   294   31.8 
2025-08-27 00:00 UT   07 32 06.5   +36 36 31    31.219   30.534   46.6    1.4   294   31.8 
2025-08-28 00:00 UT   07 32 13.1   +36 36 39    31.212   30.539   47.4    1.4   293   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.