C/2025 D1 (Groeller)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	13 Apr 2026	18.6	14.548 AU	14.278 AU	08h56m	+31°56'	103.7°	3.8°	110°
Nearest approach	3 Feb 2028	18.3	14.125 AU	13.141 AU	08h58m	+13°41'	176.6°	0.2°	32°
Perihelion	22 May 2028	18.5	14.116 AU	14.454 AU	08h42m	+12°15'	68.6°	3.8°	107°

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. (1.2 + 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/2025 D1 (Groeller) are:

    e (Eccentricity)                : 1.0031480
    q (Perihelion distance)         : 14.1163490
    i (Inclination)                 : 84.45020
    Ω (Longitude of ascending node) : 312.90320
    ω (Argument of perihelion)      : 185.94860
    L (Longitude of perihelion)     : 313.48055
    B (Latitude of perihelion)      : -5.92062
    T (Time of perihelion passage)  : 2461913.60570

    Epoch                           : 2026 Apr 13
    Reference                       : MPEC 2026-G41

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-04-12 00:00 UT   08 57 01.6   +31 59 55    14.252   14.550  105.4    3.8   111   18.6 
2026-04-13 00:00 UT   08 56 53.7   +31 57 50    14.267   14.549  104.4    3.8   110   18.6 
2026-04-13 17:30 UT   08 56 48.1   +31 56 18    14.278   14.548  103.7    3.8   110   18.6 
2026-04-14 00:00 UT   08 56 46.1   +31 55 44    14.282   14.548  103.5    3.8   110   18.6 
2026-04-15 00:00 UT   08 56 38.9   +31 53 36    14.297   14.547  102.5    3.9   110   18.6 
2026-04-16 00:00 UT   08 56 32.0   +31 51 28    14.312   14.546  101.5    3.9   109   18.6 
2026-04-17 00:00 UT   08 56 25.4   +31 49 18    14.327   14.545  100.6    3.9   109   18.6 
2026-04-18 00:00 UT   08 56 19.1   +31 47 08    14.342   14.544   99.6    3.9   109   18.6 
2026-04-19 00:00 UT   08 56 13.2   +31 44 56    14.357   14.543   98.7    3.9   109   18.6 
2026-04-20 00:00 UT   08 56 07.6   +31 42 43    14.373   14.542   97.7    3.9   108   18.6 
2026-04-21 00:00 UT   08 56 02.4   +31 40 29    14.388   14.540   96.8    3.9   108   18.6 
2026-04-22 00:00 UT   08 55 57.4   +31 38 14    14.403   14.539   95.8    3.9   108   18.6 
2026-04-23 00:00 UT   08 55 52.8   +31 35 58    14.419   14.538   94.9    4.0   108   18.6 

    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.