| Parameter |
Value |
| Designation |
P/2003 T12 (SOHO) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2012-01-26T10:43:04.114560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:34Z |
| Obs used |
491 |
| NEO |
Yes |
| M1 |
19.600 |
| K1 |
21.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-05-25.0000000 |
| e |
0.77616614 |
| q (au) |
0.574806 |
| a (au) |
2.568002 |
| i (deg) |
11.475154 |
| Ω (om, deg) |
176.465715 |
| ω (w, deg) |
217.668833 |
| M (ma, deg) |
28.633414 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.124 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.124 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.800 |
| δ90 |
10.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2016-02-21 |
2016-05-05 |
+25.0682 |
+4.478 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
13:58:06.93 |
-05:23:00.1 |
HIP 68192 |
9.00 |
| 2026-09-20 12:00 |
13:58:28.85 |
-05:25:09.5 |
HIP 68192 |
12.82 |
| 2026-09-21 00:00 |
13:58:50.84 |
-05:27:19.0 |
HIP 68348 |
9.36 |
| 2026-09-21 12:00 |
13:59:12.90 |
-05:29:28.5 |
HIP 68348 |
5.48 |
| 2026-09-22 00:00 |
13:59:35.03 |
-05:31:38.0 |
HIP 68348 |
6.50 |
| 2026-09-22 12:00 |
13:59:57.22 |
-05:33:47.5 |
HIP 68348 |
11.16 |
| 2026-09-23 00:00 |
14:00:19.48 |
-05:35:57.0 |
HIP 68348 |
16.66 |
| 2026-09-23 12:00 |
14:00:41.81 |
-05:38:06.6 |
HIP 68524 |
15.51 |
| 2026-09-24 00:00 |
14:01:04.20 |
-05:40:16.1 |
HIP 68524 |
9.83 |
| 2026-09-24 12:00 |
14:01:26.66 |
-05:42:25.7 |
HIP 68524 |
4.89 |
| 2026-09-25 00:00 |
14:01:49.18 |
-05:44:35.2 |
HIP 68524 |
4.80 |
| 2026-09-25 12:00 |
14:02:11.76 |
-05:46:44.7 |
HIP 68592 |
8.97 |
| 2026-09-26 00:00 |
14:02:34.41 |
-05:48:54.3 |
HIP 68592 |
9.93 |
| 2026-09-26 12:00 |
14:02:57.12 |
-05:51:03.7 |
HIP 68592 |
13.78 |
| 2026-09-27 00:00 |
14:03:19.89 |
-05:53:13.2 |
HIP 68592 |
18.83 |
| 2026-09-27 12:00 |
14:03:42.72 |
-05:55:22.6 |
HIP 68592 |
24.36 |
| 2026-09-28 00:00 |
14:04:05.61 |
-05:57:32.0 |
HIP 68592 |
30.11 |
| 2026-09-28 12:00 |
14:04:28.56 |
-05:59:41.4 |
HIP 68892 |
28.44 |
| 2026-09-29 00:00 |
14:04:51.57 |
-06:01:50.7 |
HIP 68892 |
22.39 |
| 2026-09-29 12:00 |
14:05:14.64 |
-06:04:00.0 |
HIP 68892 |
16.38 |
| 2026-09-30 00:00 |
14:05:37.77 |
-06:06:09.2 |
HIP 68892 |
10.49 |
| 2026-09-30 12:00 |
14:06:00.95 |
-06:08:18.4 |
HIP 68892 |
5.19 |
| 2026-10-01 00:00 |
14:06:24.20 |
-06:10:27.5 |
HIP 68892 |
4.43 |
| 2026-10-01 12:00 |
14:06:47.50 |
-06:12:36.5 |
HIP 68892 |
9.41 |
| 2026-10-02 00:00 |
14:07:10.85 |
-06:14:45.5 |
HIP 68892 |
15.30 |
| 2026-10-02 12:00 |
14:07:34.26 |
-06:16:54.4 |
HIP 68892 |
21.37 |
| 2026-10-03 00:00 |
14:07:57.73 |
-06:19:03.2 |
HIP 68892 |
27.51 |
| 2026-10-03 12:00 |
14:08:21.25 |
-06:21:11.9 |
HIP 68892 |
33.69 |
| 2026-10-04 00:00 |
14:08:44.83 |
-06:23:20.6 |
HIP 69236 |
27.77 |
| 2026-10-04 12:00 |
14:09:08.46 |
-06:25:29.1 |
HIP 69236 |
21.52 |
| 2026-10-05 00:00 |
14:09:32.14 |
-06:27:37.6 |
HIP 69236 |
15.27 |
| 2026-10-05 12:00 |
14:09:55.87 |
-06:29:45.9 |
HIP 69236 |
9.01 |
| 2026-10-06 00:00 |
14:10:19.66 |
-06:31:54.2 |
HIP 69236 |
2.81 |
| 2026-10-06 12:00 |
14:10:43.49 |
-06:34:02.3 |
HIP 69236 |
3.69 |
| 2026-10-07 00:00 |
14:11:07.38 |
-06:36:10.3 |
HIP 69236 |
9.94 |
| 2026-10-07 12:00 |
14:11:31.32 |
-06:38:18.2 |
HIP 69236 |
16.24 |
| 2026-10-08 00:00 |
14:11:55.30 |
-06:40:25.9 |
HIP 69236 |
22.56 |
| 2026-10-08 12:00 |
14:12:19.33 |
-06:42:33.5 |
HIP 69485 |
23.29 |
| 2026-10-09 00:00 |
14:12:43.41 |
-06:44:41.0 |
HIP 69485 |
17.49 |
| 2026-10-09 12:00 |
14:13:07.54 |
-06:46:48.3 |
HIP 69485 |
12.24 |
| 2026-10-10 00:00 |
14:13:31.72 |
-06:48:55.4 |
HIP 69485 |
8.64 |
| 2026-10-10 12:00 |
14:13:55.94 |
-06:51:02.4 |
HIP 69485 |
8.97 |
| 2026-10-11 00:00 |
14:14:20.20 |
-06:53:09.3 |
HIP 69556 |
10.25 |