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	1 Dec 2025	32.2	26.301 AU	25.446 AU	03h00m	+46°13'	149.5°	1.1°	135°

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. 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. (11.0 + 5 log[∆] + 10.0 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/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)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-11-30 00:00 UT   03 00 57.0   +46 15 08    25.431   26.292  150.2    1.1   139   32.2 
2025-12-01 00:00 UT   03 00 44.2   +46 14 11    25.439   26.297  149.8    1.1   137   32.2 
2025-12-01 20:03 UT   03 00 33.5   +46 13 22    25.446   26.301  149.5    1.1   135   32.2 
2025-12-02 00:00 UT   03 00 31.4   +46 13 12    25.448   26.302  149.4    1.1   135   32.2 
2025-12-03 00:00 UT   03 00 18.8   +46 12 13    25.456   26.306  149.0    1.1   133   32.2 
2025-12-04 00:00 UT   03 00 06.4   +46 11 13    25.465   26.311  148.5    1.1   131   32.2 
2025-12-05 00:00 UT   02 59 54.0   +46 10 11    25.474   26.316  148.0    1.1   129   32.2 
2025-12-06 00:00 UT   02 59 41.7   +46 09 09    25.483   26.320  147.5    1.2   128   32.2 
2025-12-07 00:00 UT   02 59 29.5   +46 08 06    25.493   26.325  147.0    1.2   126   32.2 
2025-12-08 00:00 UT   02 59 17.5   +46 07 03    25.503   26.330  146.4    1.2   124   32.2 
2025-12-09 00:00 UT   02 59 05.6   +46 05 58    25.513   26.335  145.9    1.2   123   32.2 
2025-12-10 00:00 UT   02 58 53.8   +46 04 53    25.523   26.339  145.3    1.2   121   32.2 
2025-12-11 00:00 UT   02 58 42.2   +46 03 47    25.534   26.344  144.7    1.2   119   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.