C/2011 L4 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	4 Mar 2013	0.7	0.320 AU	1.089 AU	23h55m	-16°05'	16.9°	64.0°	123°
Perihelion	8 Mar 2013	0.4	0.296 AU	1.098 AU	00h14m	-05°54'	15.3°	61.8°	93°
Today	1 Jul 2025	27.5	29.639 AU	29.020 AU	16h22m	+17°46'	126.6°	1.6°	139°

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/2011 L4 (PANSTARRS) are:

            e (Eccentricity)                : 0.9998370
            q (Perihelion distance)         : 0.2963480
            i (Inclination)                 : 84.04880
            Ω (Longitude of ascending node) : 65.86430
            ω (Argument of perihelion)      : 333.47960
            L (Longitude of perihelion)     : 62.90247
            B (Latitude of perihelion)      : -26.36641
            T (Time of perihelion passage)  : 2456359.52500
            P (Orbital period in years)     : 77521.40

            Epoch                           : 2020 Sep 26
            Reference                       : MPC115880

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

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. (5.50 + 5 log[∆] + 10.00 log[r]).

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
2025-07-01 00:00 UT   16 22 08.9   +17 46 24    29.010   29.635  127.1    1.6   139   27.5 
2025-07-01 18:10 UT   16 22 03.6   +17 46 01    29.020   29.639  126.6    1.6   139   27.5 
2025-07-02 00:00 UT   16 22 01.9   +17 45 53    29.023   29.640  126.5    1.6   138   27.5 
2025-07-03 00:00 UT   16 21 55.0   +17 45 20    29.036   29.644  125.9    1.6   138   27.5 
2025-07-04 00:00 UT   16 21 48.1   +17 44 46    29.049   29.648  125.3    1.6   137   27.5 
2025-07-05 00:00 UT   16 21 41.4   +17 44 11    29.063   29.653  124.6    1.6   136   27.5 
2025-07-06 00:00 UT   16 21 34.7   +17 43 35    29.076   29.657  124.0    1.6   135   27.5 
2025-07-07 00:00 UT   16 21 28.2   +17 42 58    29.090   29.662  123.3    1.6   134   27.5 
2025-07-08 00:00 UT   16 21 21.7   +17 42 19    29.104   29.666  122.7    1.7   133   27.5 
2025-07-09 00:00 UT   16 21 15.3   +17 41 40    29.118   29.671  122.0    1.7   132   27.5 
2025-07-10 00:00 UT   16 21 09.0   +17 40 59    29.132   29.675  121.4    1.7   131   27.5 
2025-07-11 00:00 UT   16 21 02.9   +17 40 17    29.147   29.679  120.7    1.7   130   27.5 

    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.