C/2015 G2 (MASTER)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	14 May 2015	8.3	0.808 AU	0.467 AU	03h24m	-33°04'	51.5°	101.5°	179°
Perihelion	25 May 2015	9.0	0.777 AU	0.673 AU	06h32m	-13°58'	50.1°	88.3°	133°
Today	15 Sep 2025	32.2	25.938 AU	25.565 AU	03h16m	+46°27'	110.7°	2.1°	242°

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/2015 G2 (MASTER) are:

            e (Eccentricity)                : 1.0006430
            q (Perihelion distance)         : 0.7771870
            i (Inclination)                 : 147.66290
            Ω (Longitude of ascending node) : 110.24850
            ω (Argument of perihelion)      : 257.61690
            L (Longitude of perihelion)     : 34.81490
            B (Latitude of perihelion)      : -31.49710
            T (Time of perihelion passage)  : 2457167.77290

            Epoch                           : 2020 Sep 26
            Reference                       : MPC109142

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

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. (11.00 + 5 log[∆] + 10.00 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.30. (See Marcus 2007)

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
2025-09-15 00:00 UT   03 16 16.9   +46 26 50    25.573   25.934  110.0    2.1   242   32.2 
2025-09-15 20:01 UT   03 16 10.6   +46 27 23    25.565   25.938  110.7    2.1   242   32.2 
2025-09-16 00:00 UT   03 16 09.3   +46 27 29    25.564   25.939  110.8    2.1   242   32.2 
2025-09-17 00:00 UT   03 16 01.5   +46 28 06    25.554   25.943  111.7    2.1   241   32.2 
2025-09-18 00:00 UT   03 15 53.6   +46 28 43    25.545   25.948  112.5    2.0   241   32.2 
2025-09-19 00:00 UT   03 15 45.4   +46 29 18    25.537   25.953  113.4    2.0   240   32.2 
2025-09-20 00:00 UT   03 15 37.0   +46 29 52    25.528   25.958  114.3    2.0   239   32.2 
2025-09-21 00:00 UT   03 15 28.5   +46 30 25    25.519   25.962  115.1    2.0   239   32.2 
2025-09-22 00:00 UT   03 15 19.7   +46 30 57    25.511   25.967  116.0    2.0   238   32.2 
2025-09-23 00:00 UT   03 15 10.8   +46 31 28    25.502   25.972  116.8    2.0   238   32.2 
2025-09-24 00:00 UT   03 15 01.7   +46 31 57    25.494   25.976  117.7    2.0   237   32.2 
2025-09-25 00:00 UT   03 14 52.4   +46 32 26    25.486   25.981  118.6    1.9   236   32.2 

    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.