C/2015 G2 (MASTER)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	11 May 2015	8.3	0.794 AU	0.481 AU	03h18m	-32°31'	50.3°	101.9°	177°
Perihelion	20 May 2015	8.9	0.771 AU	0.637 AU	06h06m	-16°01'	49.6°	91.4°	135°
Today	13 May 2026	32.6	27.052 AU	27.953 AU	03h04m	+44°31'	26.3°	0.9°	351°

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)                : 1.0002690
    q (Perihelion distance)         : 0.7711020
    i (Inclination)                 : 147.39310
    Ω (Longitude of ascending node) : 109.52180
    ω (Argument of perihelion)      : 256.83890
    L (Longitude of perihelion)     : 35.03550
    B (Latitude of perihelion)      : -31.64927
    T (Time of perihelion passage)  : 2457163.15980

    Epoch                           : 2026 May 13
    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
2026-05-12 00:00 UT   03 04 02.1   +44 30 40    27.942   27.043   26.6    1.0   355   32.6 
2026-05-13 00:00 UT   03 04 12.8   +44 31 13    27.948   27.048   26.4    1.0   353   32.6 
2026-05-13 20:07 UT   03 04 21.8   +44 31 42    27.953   27.052   26.3    0.9   351   32.6 
2026-05-14 00:00 UT   03 04 23.5   +44 31 48    27.954   27.053   26.3    0.9   351   32.6 
2026-05-15 00:00 UT   03 04 34.2   +44 32 23    27.960   27.057   26.2    0.9   349   32.6 
2026-05-16 00:00 UT   03 04 44.9   +44 32 59    27.965   27.062   26.1    0.9   346   32.6 
2026-05-17 00:00 UT   03 04 55.6   +44 33 37    27.970   27.066   26.1    0.9   344   32.6 
2026-05-18 00:00 UT   03 05 06.2   +44 34 15    27.975   27.071   26.0    0.9   342   32.6 
2026-05-19 00:00 UT   03 05 16.9   +44 34 53    27.980   27.076   26.1    0.9   340   32.6 
2026-05-20 00:00 UT   03 05 27.5   +44 35 33    27.984   27.080   26.1    0.9   338   32.6 
2026-05-21 00:00 UT   03 05 38.0   +44 36 13    27.989   27.085   26.2    0.9   336   32.6 
2026-05-22 00:00 UT   03 05 48.5   +44 36 54    27.992   27.089   26.3    0.9   334   32.6 
2026-05-23 00:00 UT   03 05 59.0   +44 37 36    27.996   27.094   26.4    1.0   332   32.6 

    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.