| 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) |
| 2026-07-29 00:00 |
08:09:10.46 |
+19:51:19.1 |
HIP 39869 |
8.92 |
| 2026-07-29 12:00 |
08:09:33.22 |
+19:50:06.2 |
HIP 39869 |
13.26 |
| 2026-07-30 00:00 |
08:09:55.96 |
+19:48:53.1 |
HIP 39869 |
18.23 |
| 2026-07-30 12:00 |
08:10:18.68 |
+19:47:39.8 |
HIP 39869 |
23.43 |
| 2026-07-31 00:00 |
08:10:41.38 |
+19:46:26.4 |
HIP 39934 |
28.31 |
| 2026-07-31 12:00 |
08:11:04.07 |
+19:45:12.9 |
HIP 39934 |
32.99 |
| 2026-08-01 00:00 |
08:11:26.73 |
+19:43:59.2 |
HIP 40327 |
36.99 |
| 2026-08-01 12:00 |
08:11:49.38 |
+19:42:45.4 |
HIP 40327 |
31.58 |
| 2026-08-02 00:00 |
08:12:12.00 |
+19:41:31.4 |
HIP 40327 |
26.20 |
| 2026-08-02 12:00 |
08:12:34.60 |
+19:40:17.3 |
HIP 40327 |
20.87 |
| 2026-08-03 00:00 |
08:12:57.18 |
+19:39:03.0 |
HIP 40327 |
15.63 |
| 2026-08-03 12:00 |
08:13:19.74 |
+19:37:48.7 |
HIP 40327 |
10.62 |
| 2026-08-04 00:00 |
08:13:42.28 |
+19:36:34.1 |
HIP 40327 |
6.38 |
| 2026-08-04 12:00 |
08:14:04.79 |
+19:35:19.5 |
HIP 40327 |
5.30 |
| 2026-08-05 00:00 |
08:14:27.28 |
+19:34:04.7 |
HIP 40327 |
8.65 |
| 2026-08-05 12:00 |
08:14:49.74 |
+19:32:49.8 |
HIP 40327 |
13.44 |
| 2026-08-06 00:00 |
08:15:12.18 |
+19:31:34.8 |
HIP 40327 |
18.58 |
| 2026-08-06 12:00 |
08:15:34.59 |
+19:30:19.7 |
HIP 40327 |
23.85 |
| 2026-08-07 00:00 |
08:15:56.98 |
+19:29:04.4 |
HIP 40327 |
29.17 |
| 2026-08-07 12:00 |
08:16:19.34 |
+19:27:49.0 |
HIP 40644 |
30.87 |
| 2026-08-08 00:00 |
08:16:41.67 |
+19:26:33.5 |
HIP 40644 |
28.53 |
| 2026-08-08 12:00 |
08:17:03.98 |
+19:25:17.9 |
HIP 40644 |
27.09 |
| 2026-08-09 00:00 |
08:17:26.25 |
+19:24:02.2 |
HIP 40644 |
26.68 |
| 2026-08-09 12:00 |
08:17:48.50 |
+19:22:46.4 |
HIP 40700 |
26.67 |
| 2026-08-10 00:00 |
08:18:10.72 |
+19:21:30.5 |
HIP 40700 |
24.02 |
| 2026-08-10 12:00 |
08:18:32.90 |
+19:20:14.5 |
HIP 40836 |
22.00 |
| 2026-08-11 00:00 |
08:18:55.05 |
+19:18:58.4 |
HIP 40836 |
17.68 |
| 2026-08-11 12:00 |
08:19:17.18 |
+19:17:42.2 |
HIP 40836 |
14.11 |
| 2026-08-12 00:00 |
08:19:39.26 |
+19:16:25.9 |
HIP 40836 |
11.97 |
| 2026-08-12 12:00 |
08:20:01.32 |
+19:15:09.5 |
HIP 40836 |
12.04 |
| 2026-08-13 00:00 |
08:20:23.34 |
+19:13:53.1 |
HIP 40836 |
14.28 |
| 2026-08-13 12:00 |
08:20:45.33 |
+19:12:36.5 |
HIP 40836 |
17.89 |
| 2026-08-14 00:00 |
08:21:07.28 |
+19:11:19.9 |
HIP 40836 |
22.20 |
| 2026-08-14 12:00 |
08:21:29.19 |
+19:10:03.3 |
HIP 40836 |
26.88 |
| 2026-08-15 00:00 |
08:21:51.07 |
+19:08:46.5 |
HIP 40836 |
31.76 |
| 2026-08-15 12:00 |
08:22:12.90 |
+19:07:29.7 |
HIP 40836 |
36.75 |
| 2026-08-16 00:00 |
08:22:34.70 |
+19:06:12.8 |
HIP 41233 |
32.13 |
| 2026-08-16 12:00 |
08:22:56.47 |
+19:04:55.9 |
HIP 41233 |
27.26 |
| 2026-08-17 00:00 |
08:23:18.19 |
+19:03:38.9 |
HIP 41233 |
22.59 |
| 2026-08-17 12:00 |
08:23:39.87 |
+19:02:21.9 |
HIP 41233 |
18.27 |
| 2026-08-18 00:00 |
08:24:01.51 |
+19:01:04.8 |
HIP 41233 |
14.59 |
| 2026-08-18 12:00 |
08:24:23.11 |
+18:59:47.6 |
HIP 41233 |
12.17 |
| 2026-08-19 00:00 |
08:24:44.67 |
+18:58:30.5 |
HIP 41233 |
11.77 |