C/2025 D1 (Groeller)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	30 Jun 2025	18.9	14.917 AU	15.731 AU	09h09m	+36°54'	35.6°	2.3°	78°
Nearest approach	3 Feb 2028	18.3	14.127 AU	13.143 AU	08h58m	+13°41'	176.6°	0.2°	32°
Perihelion	20 May 2028	18.5	14.119 AU	14.426 AU	08h41m	+12°18'	70.4°	3.9°	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.)

The orbital elements of C/2025 D1 (Groeller) are:

            e (Eccentricity)                : 1.0029620
            q (Perihelion distance)         : 14.1187280
            i (Inclination)                 : 84.46370
            Ω (Longitude of ascending node) : 312.89880
            ω (Argument of perihelion)      : 185.89530
            L (Longitude of perihelion)     : 313.46955
            B (Latitude of perihelion)      : -5.86770
            T (Time of perihelion passage)  : 2461911.65220

            Epoch                           : 2025 Jun 28
            Reference                       : MPEC 2025-MC0

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. 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. (1.20 + 5 log[∆] + 10.00 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-06-30 00:00 UT   09 09 37.4   +36 54 51    15.730   14.917   35.8    2.3    78   18.9 
2025-06-30 04:31 UT   09 09 39.8   +36 54 18    15.731   14.917   35.6    2.3    78   18.9 
2025-07-01 00:00 UT   09 09 50.2   +36 51 57    15.737   14.916   35.0    2.2    78   18.9 
2025-07-02 00:00 UT   09 10 03.2   +36 49 03    15.743   14.914   34.3    2.2    77   18.9 
2025-07-03 00:00 UT   09 10 16.3   +36 46 10    15.749   14.913   33.6    2.2    76   18.9 
2025-07-04 00:00 UT   09 10 29.6   +36 43 17    15.755   14.911   32.8    2.1    75   18.9 
2025-07-05 00:00 UT   09 10 43.0   +36 40 26    15.761   14.910   32.1    2.1    74   18.9 
2025-07-06 00:00 UT   09 10 56.5   +36 37 34    15.767   14.908   31.4    2.0    73   18.9 
2025-07-07 00:00 UT   09 11 10.2   +36 34 43    15.772   14.907   30.7    2.0    72   18.9 
2025-07-08 00:00 UT   09 11 24.0   +36 31 53    15.777   14.906   30.0    2.0    71   18.9 
2025-07-09 00:00 UT   09 11 37.9   +36 29 04    15.782   14.904   29.3    1.9    70   18.9 
2025-07-10 00:00 UT   09 11 51.9   +36 26 15    15.787   14.903   28.7    1.9    68   18.9 

    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.