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	8 Aug 2025	27.6	29.804 AU	29.601 AU	16h18m	+17°14'	100.5°	1.9°	111°

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
2025-08-08 00:00 UT   16 18 55.3   +17 14 14    29.599   29.803  100.6    1.9   111   27.6 
2025-08-08 02:14 UT   16 18 55.0   +17 14 08    29.601   29.804  100.5    1.9   111   27.6 
2025-08-09 00:00 UT   16 18 52.5   +17 13 07    29.617   29.808   99.8    1.9   110   27.6 
2025-08-10 00:00 UT   16 18 49.9   +17 11 59    29.634   29.812   99.1    1.9   110   27.6 
2025-08-11 00:00 UT   16 18 47.4   +17 10 51    29.652   29.816   98.3    1.9   109   27.6 
2025-08-12 00:00 UT   16 18 45.1   +17 09 42    29.670   29.821   97.6    1.9   108   27.6 
2025-08-13 00:00 UT   16 18 42.8   +17 08 32    29.687   29.825   96.8    1.9   108   27.6 
2025-08-14 00:00 UT   16 18 40.8   +17 07 22    29.705   29.830   96.1    1.9   107   27.6 
2025-08-15 00:00 UT   16 18 38.8   +17 06 11    29.723   29.834   95.3    1.9   107   27.6 
2025-08-16 00:00 UT   16 18 37.0   +17 05 00    29.740   29.838   94.5    1.9   106   27.6 
2025-08-17 00:00 UT   16 18 35.3   +17 03 49    29.758   29.843   93.8    1.9   105   27.6 
2025-08-18 00:00 UT   16 18 33.8   +17 02 37    29.776   29.847   93.0    1.9   105   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.