| Parameter |
Value |
| Designation |
39P/Oterma |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2023-04-09T06:48:51.543360Z |
| Orbit solution date (soln_date, UTC) |
2024-01-16T15:22:33Z |
| Obs used |
287 |
| NEO |
- |
| M1 |
6.800 |
| K1 |
14.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-12-03.0000000 |
| e |
0.22841232 |
| q (au) |
5.712314 |
| a (au) |
7.403325 |
| i (deg) |
1.478237 |
| Ω (om, deg) |
303.635589 |
| ω (w, deg) |
89.704331 |
| M (ma, deg) |
210.802445 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.853 + 5.174\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.853 |
| n |
5.174 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
1.000 |
| 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 |
| 2019-02-11 |
2022-08-03 |
-95.1181 |
+75.118 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-25 00:00 |
08:48:42.05 |
+17:25:12.0 |
HIP 43206 |
8.65 |
| 2026-09-25 12:00 |
08:48:58.74 |
+17:24:01.4 |
HIP 43206 |
12.50 |
| 2026-09-26 00:00 |
08:49:15.33 |
+17:22:51.1 |
HIP 43206 |
16.48 |
| 2026-09-26 12:00 |
08:49:31.84 |
+17:21:41.1 |
HIP 43206 |
20.49 |
| 2026-09-27 00:00 |
08:49:48.26 |
+17:20:31.2 |
HIP 43412 |
21.48 |
| 2026-09-27 12:00 |
08:50:04.58 |
+17:19:21.7 |
HIP 43412 |
18.74 |
| 2026-09-28 00:00 |
08:50:20.82 |
+17:18:12.4 |
HIP 43412 |
16.55 |
| 2026-09-28 12:00 |
08:50:36.96 |
+17:17:03.3 |
HIP 43412 |
15.16 |
| 2026-09-29 00:00 |
08:50:53.01 |
+17:15:54.5 |
HIP 43412 |
14.76 |
| 2026-09-29 12:00 |
08:51:08.96 |
+17:14:46.0 |
HIP 43412 |
15.41 |
| 2026-09-30 00:00 |
08:51:24.83 |
+17:13:37.7 |
HIP 43412 |
16.99 |
| 2026-09-30 12:00 |
08:51:40.59 |
+17:12:29.7 |
HIP 43412 |
19.24 |
| 2026-10-01 00:00 |
08:51:56.26 |
+17:11:22.0 |
HIP 43635 |
21.04 |
| 2026-10-01 12:00 |
08:52:11.84 |
+17:10:14.6 |
HIP 43635 |
18.64 |
| 2026-10-02 00:00 |
08:52:27.32 |
+17:09:07.4 |
HIP 43635 |
16.81 |
| 2026-10-02 12:00 |
08:52:42.70 |
+17:08:00.6 |
HIP 43635 |
15.75 |
| 2026-10-03 00:00 |
08:52:57.98 |
+17:06:54.0 |
HIP 43635 |
15.58 |
| 2026-10-03 12:00 |
08:53:13.17 |
+17:05:47.8 |
HIP 43635 |
16.32 |
| 2026-10-04 00:00 |
08:53:28.25 |
+17:04:41.8 |
HIP 43635 |
17.85 |
| 2026-10-04 12:00 |
08:53:43.24 |
+17:03:36.2 |
HIP 43635 |
19.96 |
| 2026-10-05 00:00 |
08:53:58.12 |
+17:02:30.8 |
HIP 43635 |
22.48 |
| 2026-10-05 12:00 |
08:54:12.90 |
+17:01:25.8 |
HIP 43811 |
20.84 |
| 2026-10-06 00:00 |
08:54:27.58 |
+17:00:21.2 |
HIP 43811 |
18.91 |
| 2026-10-06 12:00 |
08:54:42.15 |
+16:59:16.8 |
HIP 43811 |
17.54 |
| 2026-10-07 00:00 |
08:54:56.62 |
+16:58:12.8 |
HIP 43811 |
16.87 |
| 2026-10-07 12:00 |
08:55:10.98 |
+16:57:09.1 |
HIP 43811 |
16.96 |
| 2026-10-08 00:00 |
08:55:25.24 |
+16:56:05.8 |
HIP 43811 |
17.79 |
| 2026-10-08 12:00 |
08:55:39.39 |
+16:55:02.9 |
HIP 43811 |
19.24 |
| 2026-10-09 00:00 |
08:55:53.43 |
+16:54:00.2 |
HIP 43811 |
21.17 |
| 2026-10-09 12:00 |
08:56:07.37 |
+16:52:58.0 |
HIP 43957 |
21.39 |
| 2026-10-10 00:00 |
08:56:21.19 |
+16:51:56.1 |
HIP 43957 |
20.14 |
| 2026-10-10 12:00 |
08:56:34.91 |
+16:50:54.6 |
HIP 43957 |
19.44 |
| 2026-10-11 00:00 |
08:56:48.52 |
+16:49:53.4 |
HIP 43957 |
19.33 |
| 2026-10-11 12:00 |
08:57:02.01 |
+16:48:52.7 |
HIP 43957 |
19.81 |
| 2026-10-12 00:00 |
08:57:15.39 |
+16:47:52.3 |
HIP 43957 |
20.83 |
| 2026-10-12 12:00 |
08:57:28.66 |
+16:46:52.3 |
HIP 43957 |
22.30 |
| 2026-10-13 00:00 |
08:57:41.82 |
+16:45:52.7 |
HIP 43957 |
24.12 |
| 2026-10-13 12:00 |
08:57:54.86 |
+16:44:53.5 |
HIP 44141 |
21.92 |
| 2026-10-14 00:00 |
08:58:07.79 |
+16:43:54.7 |
HIP 44141 |
18.69 |
| 2026-10-14 12:00 |
08:58:20.61 |
+16:42:56.3 |
HIP 44141 |
15.48 |
| 2026-10-15 00:00 |
08:58:33.30 |
+16:41:58.3 |
HIP 44141 |
12.32 |
| 2026-10-15 12:00 |
08:58:45.89 |
+16:41:00.7 |
HIP 44141 |
9.20 |
| 2026-10-16 00:00 |
08:58:58.35 |
+16:40:03.6 |
HIP 44141 |
6.15 |