C/2017 S3 (PANSTARRS) - DISINTEGRATED
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Disintegration	26 Jul 2018	7.2	0.709 AU	0.944 AU	06h00m	+51°49'	42.2°	74.3°	307°
Nearest approach	7 Aug 2018	5.3	0.383 AU	0.754 AU	08h01m	+26°12'	18.5°	122.8°	299°
Perihelion	16 Aug 2018	-	0.202 AU	0.973 AU	09h29m	+02°44'	11.5°	95.4°	198°
Today	15 May 2026	-	21.825 AU	21.781 AU	13h16m	+66°35'	91.1°	2.7°	149°

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)                : 1.0000840
    q (Perihelion distance)         : 0.2024740
    i (Inclination)                 : 98.72360
    Ω (Longitude of ascending node) : 170.32170
    ω (Argument of perihelion)      : 255.57220
    L (Longitude of perihelion)     : 139.80150
    B (Latitude of perihelion)      : -73.18796
    T (Time of perihelion passage)  : 2458347.22370

    Epoch                           : 2026 May 14
    Reference                       : MPEC 2026-E44

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-05-14 00:00 UT   13 17 09.6   +66 37 27    21.762   21.817   91.8    2.7   151   32.4 
2026-05-15 00:00 UT   13 16 48.8   +66 36 20    21.774   21.822   91.3    2.7   150   32.4 
2026-05-15 12:51 UT   13 16 37.9   +66 35 44    21.781   21.825   91.1    2.7   149   32.4 
2026-05-16 00:00 UT   13 16 28.4   +66 35 12    21.787   21.827   90.9    2.7   149   32.4 
2026-05-17 00:00 UT   13 16 08.2   +66 34 00    21.800   21.832   90.5    2.7   148   32.4 
2026-05-18 00:00 UT   13 15 48.4   +66 32 47    21.813   21.838   90.0    2.7   147   32.4 
2026-05-19 00:00 UT   13 15 28.8   +66 31 31    21.826   21.843   89.6    2.7   146   32.4 
2026-05-20 00:00 UT   13 15 09.6   +66 30 12    21.839   21.848   89.2    2.7   145   32.4 
2026-05-21 00:00 UT   13 14 50.7   +66 28 52    21.851   21.853   88.7    2.7   144   32.4 
2026-05-22 00:00 UT   13 14 32.1   +66 27 29    21.864   21.858   88.3    2.7   143   32.4 
2026-05-23 00:00 UT   13 14 13.9   +66 26 04    21.877   21.864   87.9    2.7   142   32.4 
2026-05-24 00:00 UT   13 13 56.0   +66 24 36    21.890   21.869   87.4    2.7   141   32.4 
2026-05-25 00:00 UT   13 13 38.4   +66 23 07    21.903   21.874   87.0    2.7   140   32.4 

    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.