| 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) |
| 2026-05-12 00:00 |
13:41:12.42 |
-01:50:53.8 |
HIP 66886 |
20.85 |
| 2026-05-12 12:00 |
13:40:52.02 |
-01:49:07.5 |
HIP 66643 |
22.91 |
| 2026-05-13 00:00 |
13:40:31.77 |
-01:47:22.6 |
HIP 66643 |
17.85 |
| 2026-05-13 12:00 |
13:40:11.68 |
-01:45:39.0 |
HIP 66643 |
13.08 |
| 2026-05-14 00:00 |
13:39:51.74 |
-01:43:56.9 |
HIP 66643 |
8.97 |
| 2026-05-14 12:00 |
13:39:31.95 |
-01:42:16.1 |
HIP 66643 |
6.74 |
| 2026-05-15 00:00 |
13:39:12.33 |
-01:40:36.8 |
HIP 66643 |
8.05 |
| 2026-05-15 12:00 |
13:38:52.87 |
-01:38:58.9 |
HIP 66643 |
11.70 |
| 2026-05-16 00:00 |
13:38:33.57 |
-01:37:22.4 |
HIP 66643 |
16.14 |
| 2026-05-16 12:00 |
13:38:14.44 |
-01:35:47.4 |
HIP 66643 |
20.83 |
| 2026-05-17 00:00 |
13:37:55.48 |
-01:34:13.9 |
HIP 66643 |
25.61 |
| 2026-05-17 12:00 |
13:37:36.69 |
-01:32:41.8 |
HIP 66391 |
21.56 |
| 2026-05-18 00:00 |
13:37:18.07 |
-01:31:11.2 |
HIP 66391 |
17.73 |
| 2026-05-18 12:00 |
13:36:59.64 |
-01:29:42.1 |
HIP 66391 |
14.60 |
| 2026-05-19 00:00 |
13:36:41.38 |
-01:28:14.4 |
HIP 66391 |
12.62 |
| 2026-05-19 12:00 |
13:36:23.30 |
-01:26:48.3 |
HIP 66391 |
12.31 |
| 2026-05-20 00:00 |
13:36:05.40 |
-01:25:23.7 |
HIP 66391 |
13.72 |
| 2026-05-20 12:00 |
13:35:47.69 |
-01:24:00.5 |
HIP 66391 |
16.38 |
| 2026-05-21 00:00 |
13:35:30.16 |
-01:22:38.9 |
HIP 66391 |
19.74 |
| 2026-05-21 12:00 |
13:35:12.82 |
-01:21:18.8 |
HIP 66391 |
23.48 |
| 2026-05-22 00:00 |
13:34:55.67 |
-01:20:00.3 |
HIP 66391 |
27.42 |
| 2026-05-22 12:00 |
13:34:38.71 |
-01:18:43.2 |
HIP 66391 |
31.46 |
| 2026-05-23 00:00 |
13:34:21.95 |
-01:17:27.7 |
HIP 66367 |
35.53 |
| 2026-05-23 12:00 |
13:34:05.38 |
-01:16:13.7 |
HIP 65987 |
35.13 |
| 2026-05-24 00:00 |
13:33:49.00 |
-01:15:01.2 |
HIP 65987 |
30.99 |
| 2026-05-24 12:00 |
13:33:32.82 |
-01:13:50.3 |
HIP 65987 |
26.95 |
| 2026-05-25 00:00 |
13:33:16.84 |
-01:12:40.9 |
HIP 65987 |
23.01 |
| 2026-05-25 12:00 |
13:33:01.06 |
-01:11:33.0 |
HIP 65987 |
19.21 |
| 2026-05-26 00:00 |
13:32:45.48 |
-01:10:26.7 |
HIP 65987 |
15.61 |
| 2026-05-26 12:00 |
13:32:30.10 |
-01:09:21.9 |
HIP 65987 |
12.32 |
| 2026-05-27 00:00 |
13:32:14.93 |
-01:08:18.7 |
HIP 65987 |
9.61 |
| 2026-05-27 12:00 |
13:31:59.95 |
-01:07:16.9 |
HIP 65987 |
7.99 |
| 2026-05-28 00:00 |
13:31:45.19 |
-01:06:16.8 |
HIP 65987 |
8.07 |
| 2026-05-28 12:00 |
13:31:30.63 |
-01:05:18.2 |
HIP 65987 |
9.74 |
| 2026-05-29 00:00 |
13:31:16.27 |
-01:04:21.1 |
HIP 65987 |
12.32 |
| 2026-05-29 12:00 |
13:31:02.13 |
-01:03:25.5 |
HIP 65987 |
15.31 |
| 2026-05-30 00:00 |
13:30:48.19 |
-01:02:31.5 |
HIP 65987 |
18.49 |
| 2026-05-30 12:00 |
13:30:34.47 |
-01:01:39.0 |
HIP 65987 |
21.74 |
| 2026-05-31 00:00 |
13:30:20.95 |
-01:00:48.1 |
HIP 65840 |
24.50 |
| 2026-05-31 12:00 |
13:30:07.65 |
-00:59:58.7 |
HIP 65840 |
24.37 |
| 2026-06-01 00:00 |
13:29:54.55 |
-00:59:10.9 |
HIP 65840 |
24.70 |
| 2026-06-01 12:00 |
13:29:41.67 |
-00:58:24.5 |
HIP 65708 |
22.28 |
| 2026-06-02 00:00 |
13:29:29.00 |
-00:57:39.7 |
HIP 65708 |
19.06 |