39P/Oterma
| 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) |
| 2026-02-03 00:00 |
06:59:03.99 |
+22:46:44.3 |
HIP 33497 |
19.13 |
| 2026-02-03 12:00 |
06:58:53.08 |
+22:46:55.4 |
HIP 33497 |
16.73 |
| 2026-02-04 00:00 |
06:58:42.29 |
+22:47:06.3 |
HIP 33497 |
14.40 |
| 2026-02-04 12:00 |
06:58:31.62 |
+22:47:17.0 |
HIP 33497 |
12.17 |
| 2026-02-05 00:00 |
06:58:21.09 |
+22:47:27.4 |
HIP 33497 |
10.06 |
| 2026-02-05 12:00 |
06:58:10.68 |
+22:47:37.6 |
HIP 33497 |
8.16 |
| 2026-02-06 00:00 |
06:58:00.40 |
+22:47:47.6 |
HIP 33497 |
6.62 |
| 2026-02-06 12:00 |
06:57:50.25 |
+22:47:57.4 |
HIP 33497 |
5.69 |
| 2026-02-07 00:00 |
06:57:40.23 |
+22:48:07.0 |
HIP 33497 |
5.64 |
| 2026-02-07 12:00 |
06:57:30.35 |
+22:48:16.4 |
HIP 33497 |
6.47 |
| 2026-02-08 00:00 |
06:57:20.61 |
+22:48:25.5 |
HIP 33497 |
7.87 |
| 2026-02-08 12:00 |
06:57:11.00 |
+22:48:34.5 |
HIP 33497 |
9.57 |
| 2026-02-09 00:00 |
06:57:01.53 |
+22:48:43.2 |
HIP 33497 |
11.43 |
| 2026-02-09 12:00 |
06:56:52.20 |
+22:48:51.7 |
HIP 33497 |
13.35 |
| 2026-02-10 00:00 |
06:56:43.02 |
+22:49:00.0 |
HIP 33497 |
15.31 |
| 2026-02-10 12:00 |
06:56:33.97 |
+22:49:08.0 |
HIP 33497 |
17.27 |
| 2026-02-11 00:00 |
06:56:25.08 |
+22:49:15.8 |
HIP 33497 |
19.23 |
| 2026-02-11 12:00 |
06:56:16.32 |
+22:49:23.5 |
HIP 33497 |
21.17 |
| 2026-02-12 00:00 |
06:56:07.72 |
+22:49:30.9 |
HIP 33251 |
21.58 |
| 2026-02-12 12:00 |
06:55:59.26 |
+22:49:38.1 |
HIP 33251 |
20.40 |
| 2026-02-13 00:00 |
06:55:50.95 |
+22:49:45.0 |
HIP 33251 |
19.37 |
| 2026-02-13 12:00 |
06:55:42.80 |
+22:49:51.8 |
HIP 33251 |
18.50 |
| 2026-02-14 00:00 |
06:55:34.79 |
+22:49:58.3 |
HIP 33251 |
17.79 |
| 2026-02-14 12:00 |
06:55:26.94 |
+22:50:04.6 |
HIP 33251 |
17.26 |
| 2026-02-15 00:00 |
06:55:19.24 |
+22:50:10.7 |
HIP 33251 |
16.91 |
| 2026-02-15 12:00 |
06:55:11.70 |
+22:50:16.6 |
HIP 33251 |
16.74 |
| 2026-02-16 00:00 |
06:55:04.32 |
+22:50:22.3 |
HIP 33251 |
16.75 |
| 2026-02-16 12:00 |
06:54:57.09 |
+22:50:27.7 |
HIP 33251 |
16.93 |
| 2026-02-17 00:00 |
06:54:50.03 |
+22:50:32.9 |
HIP 33251 |
17.25 |
| 2026-02-17 12:00 |
06:54:43.12 |
+22:50:37.9 |
HIP 33097 |
15.86 |
| 2026-02-18 00:00 |
06:54:36.37 |
+22:50:42.7 |
HIP 33097 |
14.39 |
| 2026-02-18 12:00 |
06:54:29.79 |
+22:50:47.2 |
HIP 33097 |
12.97 |
| 2026-02-19 00:00 |
06:54:23.37 |
+22:50:51.6 |
HIP 33097 |
11.60 |
| 2026-02-19 12:00 |
06:54:17.11 |
+22:50:55.7 |
HIP 33097 |
10.31 |
| 2026-02-20 00:00 |
06:54:11.02 |
+22:50:59.6 |
HIP 33097 |
9.08 |
| 2026-02-20 12:00 |
06:54:05.09 |
+22:51:03.3 |
HIP 33097 |
7.95 |
| 2026-02-21 00:00 |
06:53:59.33 |
+22:51:06.8 |
HIP 33097 |
6.93 |
| 2026-02-21 12:00 |
06:53:53.73 |
+22:51:10.0 |
HIP 33097 |
6.06 |
| 2026-02-22 00:00 |
06:53:48.31 |
+22:51:13.0 |
HIP 33097 |
5.37 |
| 2026-02-22 12:00 |
06:53:43.05 |
+22:51:15.8 |
HIP 33097 |
4.92 |
| 2026-02-23 00:00 |
06:53:37.96 |
+22:51:18.4 |
HIP 33097 |
4.75 |
| 2026-02-23 12:00 |
06:53:33.03 |
+22:51:20.8 |
HIP 33097 |
4.84 |
| 2026-02-24 00:00 |
06:53:28.28 |
+22:51:22.9 |
HIP 33097 |
5.18 |