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	15 Jul 2025	27.6	29.701 AU	29.218 AU	16h20m	+17°36'	117.4°	1.7°	127°

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
2025-07-15 00:00 UT   16 20 39.1   +17 37 19    29.206   29.697  118.0    1.7   127   27.6 
2025-07-15 20:29 UT   16 20 34.3   +17 36 39    29.218   29.701  117.4    1.7   127   27.6 
2025-07-16 00:00 UT   16 20 33.4   +17 36 32    29.221   29.702  117.3    1.7   127   27.6 
2025-07-17 00:00 UT   16 20 27.9   +17 35 43    29.236   29.706  116.6    1.8   126   27.6 
2025-07-18 00:00 UT   16 20 22.4   +17 34 54    29.251   29.710  115.9    1.8   125   27.6 
2025-07-19 00:00 UT   16 20 17.1   +17 34 04    29.267   29.715  115.2    1.8   124   27.6 
2025-07-20 00:00 UT   16 20 11.8   +17 33 13    29.282   29.719  114.5    1.8   124   27.6 
2025-07-21 00:00 UT   16 20 06.7   +17 32 20    29.298   29.724  113.8    1.8   123   27.6 
2025-07-22 00:00 UT   16 20 01.7   +17 31 27    29.314   29.728  113.1    1.8   122   27.6 
2025-07-23 00:00 UT   16 19 56.8   +17 30 33    29.330   29.732  112.4    1.8   121   27.6 
2025-07-24 00:00 UT   16 19 52.0   +17 29 38    29.346   29.737  111.7    1.8   121   27.6 
2025-07-25 00:00 UT   16 19 47.4   +17 28 42    29.363   29.741  110.9    1.8   120   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.