C/2025 D1 (Groeller)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	22 Mar 2026	18.6	14.573 AU	13.972 AU	09h00m	+32°38'	125.5°	3.2°	118°
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)                : 1.0031120
    q (Perihelion distance)         : 14.1166090
    i (Inclination)                 : 84.45100
    Ω (Longitude of ascending node) : 312.90300
    ω (Argument of perihelion)      : 185.94310
    L (Longitude of perihelion)     : 313.47973
    B (Latitude of perihelion)      : -5.91515
    T (Time of perihelion passage)  : 2461913.41290

    Epoch                           : 2026 Mar 21
    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
2026-03-21 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 26    13.969   14.574  125.8    3.2   118   18.6 
2026-03-22 06:04 UT   09 00 56.5   +32 38 02    13.972   14.573  125.5    3.2   118   18.6 
2026-03-23 00:00 UT   09 00 45.7   +32 36 51    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   14.571  123.8    3.3   117   18.6 
2026-03-25 00:00 UT   09 00 17.8   +32 33 35    14.006   14.570  122.8    3.3   117   18.6 
2026-03-26 00:00 UT   09 00 04.3   +32 31 56    14.018   14.569  121.9    3.3   116   18.6 
2026-03-27 00:00 UT   08 59 51.1   +32 30 14    14.031   14.568  120.9    3.4   116   18.6 
2026-03-28 00:00 UT   08 59 38.2   +32 28 31    14.044   14.567  119.9    3.4   116   18.6 
2026-03-29 00:00 UT   08 59 25.6   +32 26 47    14.057   14.566  119.0    3.4   115   18.6 
2026-03-30 00:00 UT   08 59 13.2   +32 25 01    14.070   14.565  118.0    3.5   115   18.6 
2026-03-31 00:00 UT   08 59 01.2   +32 23 13    14.083   14.564  117.0    3.5   114   18.6 
2026-04-01 00:00 UT   08 58 49.5   +32 21 24    14.096   14.563  116.0    3.5   114   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.