| Parameter |
Value |
| Designation |
P/2008 Y12 (SOHO) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2008-12-22T11:21:24.419520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:27Z |
| Obs used |
76 |
| NEO |
Yes |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-10-24.0000000 |
| e |
0.97876170 |
| q (au) |
0.065376 |
| a (au) |
3.078198 |
| i (deg) |
23.345371 |
| Ω (om, deg) |
312.574737 |
| ω (w, deg) |
146.622073 |
| M (ma, deg) |
122.370129 |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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 |
19:18:33.79 |
-39:17:15.3 |
HIP 94878 |
3.61 |
| 2026-05-12 12:00 |
19:18:15.04 |
-39:19:11.3 |
HIP 94878 |
6.11 |
| 2026-05-13 00:00 |
19:17:55.98 |
-39:21:07.3 |
HIP 94878 |
9.80 |
| 2026-05-13 12:00 |
19:17:36.61 |
-39:23:03.0 |
HIP 94878 |
13.81 |
| 2026-05-14 00:00 |
19:17:16.93 |
-39:24:58.5 |
HIP 94878 |
17.96 |
| 2026-05-14 12:00 |
19:16:56.95 |
-39:26:53.8 |
HIP 94902 |
21.36 |
| 2026-05-15 00:00 |
19:16:36.66 |
-39:28:48.9 |
HIP 94625 |
18.35 |
| 2026-05-15 12:00 |
19:16:16.06 |
-39:30:43.7 |
HIP 94625 |
14.05 |
| 2026-05-16 00:00 |
19:15:55.16 |
-39:32:38.2 |
HIP 94625 |
9.81 |
| 2026-05-16 12:00 |
19:15:33.95 |
-39:34:32.4 |
HIP 94625 |
5.87 |
| 2026-05-17 00:00 |
19:15:12.45 |
-39:36:26.2 |
HIP 94625 |
3.67 |
| 2026-05-17 12:00 |
19:14:50.64 |
-39:38:19.7 |
HIP 94625 |
5.89 |
| 2026-05-18 00:00 |
19:14:28.54 |
-39:40:12.8 |
HIP 94625 |
9.97 |
| 2026-05-18 12:00 |
19:14:06.13 |
-39:42:05.4 |
HIP 94625 |
14.45 |
| 2026-05-19 00:00 |
19:13:43.43 |
-39:43:57.7 |
HIP 94625 |
19.09 |
| 2026-05-19 12:00 |
19:13:20.44 |
-39:45:49.4 |
HIP 94326 |
22.50 |
| 2026-05-20 00:00 |
19:12:57.16 |
-39:47:40.7 |
HIP 94326 |
21.09 |
| 2026-05-20 12:00 |
19:12:33.58 |
-39:49:31.4 |
HIP 94326 |
20.72 |
| 2026-05-21 00:00 |
19:12:09.72 |
-39:51:21.7 |
HIP 94326 |
21.48 |
| 2026-05-21 12:00 |
19:11:45.57 |
-39:53:11.3 |
HIP 94326 |
23.28 |
| 2026-05-22 00:00 |
19:11:21.14 |
-39:55:00.3 |
HIP 94130 |
20.18 |
| 2026-05-22 12:00 |
19:10:56.42 |
-39:56:48.8 |
HIP 94130 |
16.37 |
| 2026-05-23 00:00 |
19:10:31.43 |
-39:58:36.6 |
HIP 94130 |
13.37 |
| 2026-05-23 12:00 |
19:10:06.16 |
-40:00:23.7 |
HIP 94130 |
11.89 |
| 2026-05-24 00:00 |
19:09:40.61 |
-40:02:10.1 |
HIP 94130 |
12.54 |
| 2026-05-24 12:00 |
19:09:14.79 |
-40:03:55.8 |
HIP 94033 |
9.24 |
| 2026-05-25 00:00 |
19:08:48.70 |
-40:05:40.8 |
HIP 94033 |
8.26 |
| 2026-05-25 12:00 |
19:08:22.34 |
-40:07:25.0 |
HIP 94033 |
10.35 |
| 2026-05-26 00:00 |
19:07:55.72 |
-40:09:08.5 |
HIP 94033 |
14.27 |
| 2026-05-26 12:00 |
19:07:28.84 |
-40:10:51.1 |
HIP 94033 |
18.94 |
| 2026-05-27 00:00 |
19:07:01.69 |
-40:12:32.9 |
HIP 93848 |
18.86 |
| 2026-05-27 12:00 |
19:06:34.29 |
-40:14:13.8 |
HIP 93848 |
16.99 |
| 2026-05-28 00:00 |
19:06:06.63 |
-40:15:53.8 |
HIP 93848 |
16.81 |
| 2026-05-28 12:00 |
19:05:38.72 |
-40:17:32.9 |
HIP 93848 |
18.42 |
| 2026-05-29 00:00 |
19:05:10.56 |
-40:19:11.1 |
HIP 93611 |
16.37 |
| 2026-05-29 12:00 |
19:04:42.16 |
-40:20:48.3 |
HIP 93611 |
11.89 |
| 2026-05-30 00:00 |
19:04:13.51 |
-40:22:24.6 |
HIP 93611 |
8.85 |
| 2026-05-30 12:00 |
19:03:44.62 |
-40:23:59.8 |
HIP 93611 |
8.94 |
| 2026-05-31 00:00 |
19:03:15.49 |
-40:25:34.0 |
HIP 93611 |
12.14 |
| 2026-05-31 12:00 |
19:02:46.13 |
-40:27:07.2 |
HIP 93458 |
15.20 |
| 2026-06-01 00:00 |
19:02:16.54 |
-40:28:39.3 |
HIP 93458 |
11.46 |
| 2026-06-01 12:00 |
19:01:46.72 |
-40:30:10.3 |
HIP 93458 |
10.01 |
| 2026-06-02 00:00 |
19:01:16.67 |
-40:31:40.1 |
HIP 93458 |
11.78 |