C/2012 S1 (ISON)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	27 Nov 2013	-6.3	0.014 AU	0.997 AU	16h17m	-21°34'	0.6°	42.9°	125°
Nearest approach	26 Dec 2013	6.7	1.002 AU	0.430 AU	16h25m	+52°44'	80.0°	75.1°	334°
Today	7 Jan 2026	27.6	29.650 AU	28.700 AU	07h26m	+37°22'	164.7°	0.5°	192°

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. (8.5 + 5 log[∆] + 8.0 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)                : 1.0000030
    q (Perihelion distance)         : 0.0142520
    i (Inclination)                 : 58.46740
    Ω (Longitude of ascending node) : 297.01950
    ω (Argument of perihelion)      : 345.12200
    L (Longitude of perihelion)     : 289.10945
    B (Latitude of perihelion)      : -12.64144
    T (Time of perihelion passage)  : 2456624.48480

    Epoch                           : 2026 Jan 06
    Reference                       : MPEC 2025-W75

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-01-06 00:00 UT   07 27 07.6   +37 21 55    28.694   29.644  164.5    0.5   198   27.6 
2026-01-07 00:00 UT   07 26 57.2   +37 22 14    28.698   29.648  164.7    0.5   194   27.6 
2026-01-07 11:41 UT   07 26 52.2   +37 22 24    28.700   29.650  164.7    0.5   192   27.6 
2026-01-08 00:00 UT   07 26 46.8   +37 22 33    28.702   29.653  164.7    0.5   190   27.6 
2026-01-09 00:00 UT   07 26 36.4   +37 22 51    28.707   29.657  164.7    0.5   186   27.6 
2026-01-10 00:00 UT   07 26 26.0   +37 23 09    28.712   29.662  164.6    0.5   182   27.6 
2026-01-11 00:00 UT   07 26 15.6   +37 23 26    28.717   29.666  164.5    0.5   178   27.6 
2026-01-12 00:00 UT   07 26 05.2   +37 23 42    28.722   29.671  164.3    0.5   174   27.6 
2026-01-13 00:00 UT   07 25 54.8   +37 23 58    28.728   29.675  164.0    0.5   171   27.6 
2026-01-14 00:00 UT   07 25 44.5   +37 24 13    28.734   29.680  163.6    0.5   167   27.6 
2026-01-15 00:00 UT   07 25 34.1   +37 24 27    28.740   29.684  163.2    0.5   164   27.6 
2026-01-16 00:00 UT   07 25 23.7   +37 24 40    28.747   29.689  162.8    0.6   160   27.6 
2026-01-17 00:00 UT   07 25 13.4   +37 24 53    28.754   29.693  162.3    0.6   157   27.6 

    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.