| 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
$$
M_a = (5.999 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.999 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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 |
-97.1894 |
+76.977 |
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 |
07:13:05.74 |
+22:13:30.8 |
HIP 34779 |
15.32 |
| 2026-05-12 12:00 |
07:13:23.40 |
+22:12:57.2 |
HIP 34779 |
19.43 |
| 2026-05-13 00:00 |
07:13:41.15 |
+22:12:23.4 |
HIP 34779 |
23.57 |
| 2026-05-13 12:00 |
07:13:58.99 |
+22:11:49.3 |
HIP 35106 |
25.93 |
| 2026-05-14 00:00 |
07:14:16.92 |
+22:11:14.9 |
HIP 35106 |
22.18 |
| 2026-05-14 12:00 |
07:14:34.93 |
+22:10:40.2 |
HIP 35106 |
18.60 |
| 2026-05-15 00:00 |
07:14:53.03 |
+22:10:05.2 |
HIP 35106 |
15.32 |
| 2026-05-15 12:00 |
07:15:11.22 |
+22:09:30.0 |
HIP 35106 |
12.62 |
| 2026-05-16 00:00 |
07:15:29.49 |
+22:08:54.5 |
HIP 35106 |
10.95 |
| 2026-05-16 12:00 |
07:15:47.85 |
+22:08:18.7 |
HIP 35106 |
10.82 |
| 2026-05-17 00:00 |
07:16:06.28 |
+22:07:42.6 |
HIP 35106 |
12.30 |
| 2026-05-17 12:00 |
07:16:24.80 |
+22:07:06.2 |
HIP 35106 |
14.94 |
| 2026-05-18 00:00 |
07:16:43.40 |
+22:06:29.5 |
HIP 35106 |
18.25 |
| 2026-05-18 12:00 |
07:17:02.09 |
+22:05:52.6 |
HIP 35106 |
21.95 |
| 2026-05-19 00:00 |
07:17:20.85 |
+22:05:15.4 |
HIP 35106 |
25.87 |
| 2026-05-19 12:00 |
07:17:39.68 |
+22:04:37.9 |
HIP 35481 |
24.35 |
| 2026-05-20 00:00 |
07:17:58.60 |
+22:04:00.1 |
HIP 35481 |
19.92 |
| 2026-05-20 12:00 |
07:18:17.59 |
+22:03:22.0 |
HIP 35481 |
15.48 |
| 2026-05-21 00:00 |
07:18:36.66 |
+22:02:43.6 |
HIP 35481 |
11.01 |
| 2026-05-21 12:00 |
07:18:55.80 |
+22:02:05.0 |
HIP 35481 |
6.53 |
| 2026-05-22 00:00 |
07:19:15.02 |
+22:01:26.1 |
HIP 35481 |
2.05 |
| 2026-05-22 12:00 |
07:19:34.31 |
+22:00:46.8 |
HIP 35481 |
2.52 |
| 2026-05-23 00:00 |
07:19:53.67 |
+22:00:07.4 |
HIP 35550 |
3.39 |
| 2026-05-23 12:00 |
07:20:13.10 |
+21:59:27.6 |
HIP 35550 |
1.42 |
| 2026-05-24 00:00 |
07:20:32.61 |
+21:58:47.5 |
HIP 35550 |
5.85 |
| 2026-05-24 12:00 |
07:20:52.18 |
+21:58:07.2 |
HIP 35550 |
10.42 |
| 2026-05-25 00:00 |
07:21:11.82 |
+21:57:26.5 |
HIP 35550 |
15.01 |
| 2026-05-25 12:00 |
07:21:31.53 |
+21:56:45.6 |
HIP 35550 |
19.63 |
| 2026-05-26 00:00 |
07:21:51.31 |
+21:56:04.4 |
HIP 35807 |
17.50 |
| 2026-05-26 12:00 |
07:22:11.15 |
+21:55:22.9 |
HIP 35807 |
13.08 |
| 2026-05-27 00:00 |
07:22:31.06 |
+21:54:41.2 |
HIP 35807 |
8.89 |
| 2026-05-27 12:00 |
07:22:51.03 |
+21:53:59.1 |
HIP 35807 |
5.52 |
| 2026-05-28 00:00 |
07:23:11.07 |
+21:53:16.8 |
HIP 35807 |
5.08 |
| 2026-05-28 12:00 |
07:23:31.17 |
+21:52:34.2 |
HIP 35807 |
8.10 |
| 2026-05-29 00:00 |
07:23:51.34 |
+21:51:51.3 |
HIP 35888 |
9.61 |
| 2026-05-29 12:00 |
07:24:11.56 |
+21:51:08.1 |
HIP 35888 |
9.57 |
| 2026-05-30 00:00 |
07:24:31.85 |
+21:50:24.6 |
HIP 35888 |
11.68 |
| 2026-05-30 12:00 |
07:24:52.20 |
+21:49:40.9 |
HIP 35888 |
15.06 |
| 2026-05-31 00:00 |
07:25:12.60 |
+21:48:56.9 |
HIP 36086 |
13.30 |
| 2026-05-31 12:00 |
07:25:33.07 |
+21:48:12.5 |
HIP 36086 |
9.38 |
| 2026-06-01 00:00 |
07:25:53.59 |
+21:47:27.9 |
HIP 36086 |
6.71 |
| 2026-06-01 12:00 |
07:26:14.18 |
+21:46:43.0 |
HIP 36086 |
6.98 |
| 2026-06-02 00:00 |
07:26:34.82 |
+21:45:57.9 |
HIP 36086 |
9.97 |