C/2017 S3 (PANSTARRS) - DISINTEGRATED
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Disintegration	26 Jul 2018	7.3	0.717 AU	0.957 AU	05h57m	+51°45'	42.5°	73.1°	306°
Nearest approach	7 Aug 2018	5.2	0.381 AU	0.756 AU	08h02m	+25°45'	18.5°	122.6°	297°
Perihelion	17 Aug 2018	-	0.203 AU	0.973 AU	09h30m	+02°33'	11.5°	95.4°	197°
Today	17 Dec 2025	-	21.044 AU	20.893 AU	13h47m	+62°33'	97.4°	2.7°	308°

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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 9.2 + 5 log[∆] + 12.3 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/2017 S3 (PANSTARRS) are:

    e (Eccentricity)                : 1.0000970
    q (Perihelion distance)         : 0.2034580
    i (Inclination)                 : 99.14200
    Ω (Longitude of ascending node) : 171.18370
    ω (Argument of perihelion)      : 255.74140
    L (Longitude of perihelion)     : 139.16986
    B (Latitude of perihelion)      : -73.11366
    T (Time of perihelion passage)  : 2458347.56100

    Epoch                           : 2023 Sep 24
    Reference                       : MPC114599

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-16 00:00 UT   13 46 55.9   +62 30 24    20.897   21.036   96.8    2.7   309   32.1 
2025-12-17 00:00 UT   13 47 09.2   +62 32 37    20.894   21.041   97.2    2.7   309   32.1 
2025-12-17 12:04 UT   13 47 15.7   +62 33 45    20.893   21.044   97.4    2.7   308   32.1 
2025-12-18 00:00 UT   13 47 22.1   +62 34 52    20.892   21.046   97.6    2.7   308   32.1 
2025-12-19 00:00 UT   13 47 34.8   +62 37 09    20.890   21.052   98.1    2.7   307   32.1 
2025-12-20 00:00 UT   13 47 47.1   +62 39 27    20.888   21.057   98.5    2.6   306   32.1 
2025-12-21 00:00 UT   13 47 59.1   +62 41 47    20.886   21.062   98.9    2.6   305   32.1 
2025-12-22 00:00 UT   13 48 10.8   +62 44 09    20.885   21.067   99.4    2.6   304   32.1 
2025-12-23 00:00 UT   13 48 22.1   +62 46 32    20.883   21.073   99.8    2.6   303   32.1 
2025-12-24 00:00 UT   13 48 33.1   +62 48 57    20.881   21.078  100.2    2.6   302   32.1 
2025-12-25 00:00 UT   13 48 43.8   +62 51 24    20.879   21.083  100.6    2.6   301   32.1 
2025-12-26 00:00 UT   13 48 54.2   +62 53 52    20.878   21.089  101.0    2.6   300   32.1 
2025-12-27 00:00 UT   13 49 04.2   +62 56 21    20.876   21.094  101.4    2.6   299   32.1 

    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.