| 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) |
| 2026-09-20 00:00 |
17:41:12.49 |
-37:39:36.8 |
HIP 86418 |
27.15 |
| 2026-09-20 12:00 |
17:41:16.47 |
-37:38:09.5 |
HIP 86418 |
26.85 |
| 2026-09-21 00:00 |
17:41:20.67 |
-37:36:42.7 |
HIP 86418 |
26.69 |
| 2026-09-21 12:00 |
17:41:25.09 |
-37:35:16.2 |
HIP 86418 |
26.67 |
| 2026-09-22 00:00 |
17:41:29.73 |
-37:33:50.2 |
HIP 86418 |
26.80 |
| 2026-09-22 12:00 |
17:41:34.59 |
-37:32:24.7 |
HIP 86461 |
26.49 |
| 2026-09-23 00:00 |
17:41:39.65 |
-37:30:59.5 |
HIP 86461 |
26.31 |
| 2026-09-23 12:00 |
17:41:44.94 |
-37:29:34.8 |
HIP 86461 |
26.28 |
| 2026-09-24 00:00 |
17:41:50.43 |
-37:28:10.6 |
HIP 86461 |
26.41 |
| 2026-09-24 12:00 |
17:41:56.13 |
-37:26:46.8 |
HIP 86461 |
26.70 |
| 2026-09-25 00:00 |
17:42:02.04 |
-37:25:23.4 |
HIP 86461 |
27.15 |
| 2026-09-25 12:00 |
17:42:08.16 |
-37:24:00.5 |
HIP 86484 |
27.32 |
| 2026-09-26 00:00 |
17:42:14.48 |
-37:22:38.0 |
HIP 86698 |
26.91 |
| 2026-09-26 12:00 |
17:42:21.01 |
-37:21:15.9 |
HIP 86698 |
25.26 |
| 2026-09-27 00:00 |
17:42:27.74 |
-37:19:54.3 |
HIP 86698 |
23.64 |
| 2026-09-27 12:00 |
17:42:34.67 |
-37:18:33.1 |
HIP 86698 |
22.07 |
| 2026-09-28 00:00 |
17:42:41.80 |
-37:17:12.4 |
HIP 86698 |
20.56 |
| 2026-09-28 12:00 |
17:42:49.13 |
-37:15:52.1 |
HIP 86698 |
19.14 |
| 2026-09-29 00:00 |
17:42:56.65 |
-37:14:32.2 |
HIP 86698 |
17.84 |
| 2026-09-29 12:00 |
17:43:04.37 |
-37:13:12.8 |
HIP 86698 |
16.70 |
| 2026-09-30 00:00 |
17:43:12.29 |
-37:11:53.9 |
HIP 86698 |
15.75 |
| 2026-09-30 12:00 |
17:43:20.40 |
-37:10:35.4 |
HIP 86698 |
15.04 |
| 2026-10-01 00:00 |
17:43:28.70 |
-37:09:17.3 |
HIP 86698 |
14.63 |
| 2026-10-01 12:00 |
17:43:37.18 |
-37:07:59.6 |
HIP 86698 |
14.54 |
| 2026-10-02 00:00 |
17:43:45.86 |
-37:06:42.4 |
HIP 86698 |
14.80 |
| 2026-10-02 12:00 |
17:43:54.73 |
-37:05:25.7 |
HIP 86698 |
15.40 |
| 2026-10-03 00:00 |
17:44:03.78 |
-37:04:09.3 |
HIP 86698 |
16.30 |
| 2026-10-03 12:00 |
17:44:13.02 |
-37:02:53.5 |
HIP 86698 |
17.48 |
| 2026-10-04 00:00 |
17:44:22.45 |
-37:01:38.0 |
HIP 86698 |
18.89 |
| 2026-10-04 12:00 |
17:44:32.05 |
-37:00:23.0 |
HIP 86698 |
20.49 |
| 2026-10-05 00:00 |
17:44:41.84 |
-36:59:08.4 |
HIP 86922 |
20.41 |
| 2026-10-05 12:00 |
17:44:51.81 |
-36:57:54.3 |
HIP 86922 |
18.30 |
| 2026-10-06 00:00 |
17:45:01.96 |
-36:56:40.6 |
HIP 86922 |
16.23 |
| 2026-10-06 12:00 |
17:45:12.28 |
-36:55:27.3 |
HIP 86922 |
14.25 |
| 2026-10-07 00:00 |
17:45:22.78 |
-36:54:14.5 |
HIP 86922 |
12.42 |
| 2026-10-07 12:00 |
17:45:33.46 |
-36:53:02.1 |
HIP 86922 |
10.82 |
| 2026-10-08 00:00 |
17:45:44.31 |
-36:51:50.1 |
HIP 86922 |
9.61 |
| 2026-10-08 12:00 |
17:45:55.33 |
-36:50:38.6 |
HIP 86922 |
8.96 |
| 2026-10-09 00:00 |
17:46:06.53 |
-36:49:27.5 |
HIP 86922 |
9.01 |
| 2026-10-09 12:00 |
17:46:17.89 |
-36:48:16.8 |
HIP 86951 |
9.09 |
| 2026-10-10 00:00 |
17:46:29.42 |
-36:47:06.6 |
HIP 86951 |
8.96 |
| 2026-10-10 12:00 |
17:46:41.12 |
-36:45:56.8 |
HIP 86951 |
9.59 |
| 2026-10-11 00:00 |
17:46:52.99 |
-36:44:47.4 |
HIP 86951 |
10.87 |