C/2025 D1 (Groeller)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	14 Mar 2026	18.6	14.582 AU	13.888 AU	09h02m	+32°49'	132.8°	2.9°	122°
Nearest approach	3 Feb 2028	18.3	14.125 AU	13.141 AU	08h58m	+13°41'	176.6°	0.2°	32°
Perihelion	21 May 2028	18.5	14.117 AU	14.451 AU	08h41m	+12°16'	68.8°	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)                : 1.0031100
    q (Perihelion distance)         : 14.1166800
    i (Inclination)                 : 84.45120
    Ω (Longitude of ascending node) : 312.90290
    ω (Argument of perihelion)      : 185.94160
    L (Longitude of perihelion)     : 313.47946
    B (Latitude of perihelion)      : -5.91366
    T (Time of perihelion passage)  : 2461913.35550

    Epoch                           : 2026 Mar 14
    Reference                       : MPEC 2026-EC7

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-03-13 00:00 UT   09 03 21.9   +32 51 26    13.870   14.584  134.5    2.8   123   18.5 
2026-03-14 00:00 UT   09 03 05.1   +32 50 06    13.880   14.583  133.5    2.8   122   18.6 
2026-03-14 18:11 UT   09 02 52.6   +32 49 04    13.888   14.582  132.8    2.9   122   18.6 
2026-03-15 00:00 UT   09 02 48.6   +32 48 44    13.891   14.582  132.6    2.9   122   18.6 
2026-03-16 00:00 UT   09 02 32.3   +32 47 21    13.901   14.581  131.6    2.9   121   18.6 
2026-03-17 00:00 UT   09 02 16.3   +32 45 56    13.912   14.579  130.6    3.0   121   18.6 
2026-03-18 00:00 UT   09 02 00.5   +32 44 29    13.923   14.578  129.7    3.0   120   18.6 
2026-03-19 00:00 UT   09 01 45.0   +32 43 01    13.934   14.577  128.7    3.1   120   18.6 
2026-03-20 00:00 UT   09 01 29.8   +32 41 31    13.946   14.576  127.7    3.1   119   18.6 
2026-03-21 00:00 UT   09 01 14.8   +32 39 59    13.957   14.575  126.7    3.1   119   18.6 
2026-03-22 00:00 UT   09 01 00.1   +32 38 25    13.969   14.574  125.8    3.2   118   18.6 
2026-03-23 00:00 UT   09 00 45.7   +32 36 50    13.981   14.573  124.8    3.2   118   18.6 
2026-03-24 00:00 UT   09 00 31.6   +32 35 14    13.993   14.572  123.8    3.3   117   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.