| Parameter |
Value |
| Designation |
C/2025 D1 (Groeller) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2028-05-18T08:26:24.901440Z |
| Orbit solution date (soln_date, UTC) |
2026-04-08T14:12:15Z |
| Obs used |
183 |
| NEO |
- |
| M1 |
5.300 |
| K1 |
8.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2025-02-20T07:52:55.833600Z |
| Discovery magnitude (MPC) |
20.64 G |
| Discovery observatory (MPC) |
V00 · Kitt Peak-Bok |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2024-04-23.0000000 |
| e |
1.00293203 |
| q (au) |
14.122734 |
| a (au) |
-4816.715820 |
| i (deg) |
84.497131 |
| Ω (om, deg) |
312.882118 |
| ω (w, deg) |
185.843793 |
| M (ma, deg) |
-0.004382 |
Magnitude
Scatter + Global Linear
$$
M_a = (3.890 + 3.315\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
3.890 |
| n |
3.315 |
| gf |
0.973 |
| gb |
-0.696 |
| k |
1.000 |
| δ90 |
9.982 |
| Parameter |
Symbol |
Range |
Description |
| Absolute magnitude at 1 AU from Sun and Earth |
H0 |
-5 to 20 |
Intrinsic brightness of the comet |
| Photometric slope parameter |
n |
2 to 6 |
Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor |
gf |
0.8 to 1 |
Degree of forward scattering |
| Backward scattering asymmetry factor |
gb |
-1 to -0.5 |
Degree of backward scattering |
| Partitioning coefficient |
k |
0.8 to 1 |
Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio |
δ90 |
1 to 10 |
Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
08:55:25.28 |
+30:50:10.2 |
HIP 43721 |
21.63 |
| 2026-05-12 12:00 |
08:55:26.05 |
+30:48:54.4 |
HIP 43721 |
20.87 |
| 2026-05-13 00:00 |
08:55:26.89 |
+30:47:38.4 |
HIP 43721 |
20.17 |
| 2026-05-13 12:00 |
08:55:27.81 |
+30:46:22.2 |
HIP 43721 |
19.55 |
| 2026-05-14 00:00 |
08:55:28.80 |
+30:45:05.9 |
HIP 43721 |
19.00 |
| 2026-05-14 12:00 |
08:55:29.86 |
+30:43:49.5 |
HIP 43721 |
18.54 |
| 2026-05-15 00:00 |
08:55:31.00 |
+30:42:32.9 |
HIP 43721 |
18.17 |
| 2026-05-15 12:00 |
08:55:32.21 |
+30:41:16.2 |
HIP 43721 |
17.90 |
| 2026-05-16 00:00 |
08:55:33.49 |
+30:39:59.3 |
HIP 43721 |
17.74 |
| 2026-05-16 12:00 |
08:55:34.84 |
+30:38:42.3 |
HIP 43721 |
17.69 |
| 2026-05-17 00:00 |
08:55:36.26 |
+30:37:25.2 |
HIP 43721 |
17.75 |
| 2026-05-17 12:00 |
08:55:37.76 |
+30:36:07.9 |
HIP 43721 |
17.93 |
| 2026-05-18 00:00 |
08:55:39.32 |
+30:34:50.5 |
HIP 43721 |
18.21 |
| 2026-05-18 12:00 |
08:55:40.96 |
+30:33:33.0 |
HIP 43721 |
18.60 |
| 2026-05-19 00:00 |
08:55:42.66 |
+30:32:15.3 |
HIP 43721 |
19.10 |
| 2026-05-19 12:00 |
08:55:44.44 |
+30:30:57.6 |
HIP 43721 |
19.69 |
| 2026-05-20 00:00 |
08:55:46.28 |
+30:29:39.7 |
HIP 43721 |
20.37 |
| 2026-05-20 12:00 |
08:55:48.20 |
+30:28:21.7 |
HIP 43721 |
21.12 |
| 2026-05-21 00:00 |
08:55:50.18 |
+30:27:03.6 |
HIP 43721 |
21.95 |
| 2026-05-21 12:00 |
08:55:52.23 |
+30:25:45.4 |
HIP 43721 |
22.85 |
| 2026-05-22 00:00 |
08:55:54.35 |
+30:24:27.0 |
HIP 43732 |
22.69 |
| 2026-05-22 12:00 |
08:55:56.53 |
+30:23:08.6 |
HIP 43732 |
22.49 |
| 2026-05-23 00:00 |
08:55:58.79 |
+30:21:50.1 |
HIP 43732 |
22.38 |
| 2026-05-23 12:00 |
08:56:01.11 |
+30:20:31.4 |
HIP 43732 |
22.37 |
| 2026-05-24 00:00 |
08:56:03.49 |
+30:19:12.7 |
HIP 43732 |
22.47 |
| 2026-05-24 12:00 |
08:56:05.94 |
+30:17:53.9 |
HIP 43732 |
22.67 |
| 2026-05-25 00:00 |
08:56:08.46 |
+30:16:34.9 |
HIP 43732 |
22.96 |
| 2026-05-25 12:00 |
08:56:11.04 |
+30:15:15.9 |
HIP 44031 |
23.27 |
| 2026-05-26 00:00 |
08:56:13.68 |
+30:13:56.8 |
HIP 44031 |
22.67 |
| 2026-05-26 12:00 |
08:56:16.39 |
+30:12:37.6 |
HIP 44031 |
22.13 |
| 2026-05-27 00:00 |
08:56:19.17 |
+30:11:18.3 |
HIP 44031 |
21.66 |
| 2026-05-27 12:00 |
08:56:22.00 |
+30:09:58.9 |
HIP 44031 |
21.27 |
| 2026-05-28 00:00 |
08:56:24.90 |
+30:08:39.4 |
HIP 44031 |
20.95 |
| 2026-05-28 12:00 |
08:56:27.87 |
+30:07:19.9 |
HIP 44031 |
20.73 |
| 2026-05-29 00:00 |
08:56:30.89 |
+30:06:00.3 |
HIP 44031 |
20.59 |
| 2026-05-29 12:00 |
08:56:33.98 |
+30:04:40.6 |
HIP 44031 |
20.55 |
| 2026-05-30 00:00 |
08:56:37.12 |
+30:03:20.8 |
HIP 44031 |
20.60 |
| 2026-05-30 12:00 |
08:56:40.33 |
+30:02:01.0 |
HIP 44031 |
20.76 |
| 2026-05-31 00:00 |
08:56:43.60 |
+30:00:41.1 |
HIP 44031 |
21.01 |
| 2026-05-31 12:00 |
08:56:46.93 |
+29:59:21.1 |
HIP 44031 |
21.35 |
| 2026-06-01 00:00 |
08:56:50.32 |
+29:58:01.0 |
HIP 44031 |
21.78 |
| 2026-06-01 12:00 |
08:56:53.77 |
+29:56:40.9 |
HIP 44031 |
22.31 |
| 2026-06-02 00:00 |
08:56:57.28 |
+29:55:20.7 |
HIP 44031 |
22.92 |