C/2011 L4 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	6 Mar 2013	1.2	0.351 AU	1.100 AU	23h59m	-18°56'	18.4°	63.1°	134°
Perihelion	11 Mar 2013	0.6	0.305 AU	1.119 AU	00h27m	-04°30'	15.1°	58.4°	93°
Today	20 Jun 2026	27.9	31.189 AU	30.480 AU	16h23m	+17°28'	133.5°	1.4°	151°

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. (5.5 + 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/2011 L4 (PANSTARRS) are:

    e (Eccentricity)                : 0.9999230
    q (Perihelion distance)         : 0.3046420
    i (Inclination)                 : 84.78920
    Ω (Longitude of ascending node) : 65.24890
    ω (Argument of perihelion)      : 333.72440
    L (Longitude of perihelion)     : 62.68159
    B (Latitude of perihelion)      : -26.15876
    T (Time of perihelion passage)  : 2456363.23240
    P (Orbital period in years)     : 248856.27

    Epoch                           : 2026 May 29
    Reference                       : MPC194124

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-06-19 00:00 UT   16 23 35.6   +17 28 37    30.467   31.184  134.1    1.3   152   27.9 
2026-06-20 00:00 UT   16 23 28.2   +17 28 22    30.477   31.188  133.7    1.4   151   27.9 
2026-06-20 05:59 UT   16 23 26.4   +17 28 19    30.480   31.189  133.5    1.4   151   27.9 
2026-06-21 00:00 UT   16 23 20.9   +17 28 07    30.488   31.192  133.1    1.4   150   27.9 
2026-06-22 00:00 UT   16 23 13.5   +17 27 50    30.499   31.197  132.6    1.4   149   27.9 
2026-06-23 00:00 UT   16 23 06.3   +17 27 31    30.510   31.201  132.1    1.4   148   27.9 
2026-06-24 00:00 UT   16 22 59.1   +17 27 12    30.521   31.205  131.6    1.4   147   27.9 
2026-06-25 00:00 UT   16 22 52.0   +17 26 51    30.533   31.210  131.0    1.4   146   27.9 
2026-06-26 00:00 UT   16 22 44.9   +17 26 29    30.544   31.214  130.5    1.4   145   27.9 
2026-06-27 00:00 UT   16 22 37.9   +17 26 06    30.556   31.218  129.9    1.4   143   27.9 
2026-06-28 00:00 UT   16 22 30.9   +17 25 42    30.568   31.223  129.3    1.4   142   27.9 
2026-06-29 00:00 UT   16 22 24.1   +17 25 16    30.580   31.227  128.7    1.5   141   27.9 
2026-06-30 00:00 UT   16 22 17.3   +17 24 50    30.593   31.231  128.1    1.5   140   27.9 

    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.