| Parameter |
Value |
| Designation |
139P/Vaisala-Oterma |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2008-04-22T08:33:50.682240Z |
| Orbit solution date (soln_date, UTC) |
2026-10-01T14:42:13Z |
| Obs used |
619 |
| NEO |
- |
| M1 |
7.200 |
| K1 |
18.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-06-28.0000000 |
| e |
0.24756102 |
| q (au) |
3.405092 |
| a (au) |
4.525406 |
| i (deg) |
2.331889 |
| Ω (om, deg) |
242.287967 |
| ω (w, deg) |
166.037787 |
| M (ma, deg) |
156.401048 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.857 + 5.997\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.857 |
| n |
5.997 |
| gf |
0.902 |
| gb |
-0.998 |
| k |
1.000 |
| δ90 |
4.190 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-25 00:00 |
23:42:09.67 |
+01:13:43.2 |
HIP 117012 |
17.61 |
| 2026-09-25 12:00 |
23:41:52.33 |
+01:11:40.9 |
HIP 117012 |
21.09 |
| 2026-09-26 00:00 |
23:41:35.03 |
+01:09:38.5 |
HIP 117012 |
25.01 |
| 2026-09-26 12:00 |
23:41:17.78 |
+01:07:36.2 |
HIP 117012 |
29.17 |
| 2026-09-27 00:00 |
23:41:00.58 |
+01:05:33.8 |
HIP 117012 |
33.48 |
| 2026-09-27 12:00 |
23:40:43.43 |
+01:03:31.5 |
HIP 117012 |
37.88 |
| 2026-09-28 00:00 |
23:40:26.35 |
+01:01:29.3 |
HIP 116646 |
35.09 |
| 2026-09-28 12:00 |
23:40:09.33 |
+00:59:27.2 |
HIP 116646 |
30.37 |
| 2026-09-29 00:00 |
23:39:52.37 |
+00:57:25.2 |
HIP 116646 |
25.67 |
| 2026-09-29 12:00 |
23:39:35.49 |
+00:55:23.4 |
HIP 116646 |
20.99 |
| 2026-09-30 00:00 |
23:39:18.68 |
+00:53:21.7 |
HIP 116646 |
16.33 |
| 2026-09-30 12:00 |
23:39:01.96 |
+00:51:20.3 |
HIP 116646 |
11.69 |
| 2026-10-01 00:00 |
23:38:45.31 |
+00:49:19.1 |
HIP 116646 |
7.08 |
| 2026-10-01 12:00 |
23:38:28.76 |
+00:47:18.2 |
HIP 116646 |
2.54 |
| 2026-10-02 00:00 |
23:38:12.29 |
+00:45:17.6 |
HIP 116646 |
2.25 |
| 2026-10-02 12:00 |
23:37:55.92 |
+00:43:17.3 |
HIP 116646 |
6.73 |
| 2026-10-03 00:00 |
23:37:39.65 |
+00:41:17.4 |
HIP 116646 |
11.25 |
| 2026-10-03 12:00 |
23:37:23.49 |
+00:39:17.8 |
HIP 116646 |
15.75 |
| 2026-10-04 00:00 |
23:37:07.43 |
+00:37:18.7 |
HIP 116646 |
20.23 |
| 2026-10-04 12:00 |
23:36:51.48 |
+00:35:19.9 |
HIP 116454 |
17.73 |
| 2026-10-05 00:00 |
23:36:35.65 |
+00:33:21.7 |
HIP 116454 |
13.31 |
| 2026-10-05 12:00 |
23:36:19.94 |
+00:31:24.0 |
HIP 116454 |
8.93 |
| 2026-10-06 00:00 |
23:36:04.36 |
+00:29:26.8 |
HIP 116454 |
4.60 |
| 2026-10-06 12:00 |
23:35:48.90 |
+00:27:30.1 |
HIP 116454 |
0.75 |
| 2026-10-07 00:00 |
23:35:33.57 |
+00:25:34.0 |
HIP 116454 |
4.14 |
| 2026-10-07 12:00 |
23:35:18.38 |
+00:23:38.6 |
HIP 116454 |
8.36 |
| 2026-10-08 00:00 |
23:35:03.33 |
+00:21:43.7 |
HIP 116454 |
12.57 |
| 2026-10-08 12:00 |
23:34:48.42 |
+00:19:49.6 |
HIP 116317 |
14.26 |
| 2026-10-09 00:00 |
23:34:33.66 |
+00:17:56.1 |
HIP 116317 |
10.24 |
| 2026-10-09 12:00 |
23:34:19.05 |
+00:16:03.4 |
HIP 116317 |
6.39 |
| 2026-10-10 00:00 |
23:34:04.59 |
+00:14:11.4 |
HIP 116317 |
3.29 |
| 2026-10-10 12:00 |
23:33:50.30 |
+00:12:20.2 |
HIP 116317 |
3.69 |
| 2026-10-11 00:00 |
23:33:36.16 |
+00:10:29.8 |
HIP 116317 |
6.95 |
| 2026-10-11 12:00 |
23:33:22.20 |
+00:08:40.2 |
HIP 116230 |
6.66 |
| 2026-10-12 00:00 |
23:33:08.40 |
+00:06:51.5 |
HIP 116230 |
4.89 |
| 2026-10-12 12:00 |
23:32:54.77 |
+00:05:03.7 |
HIP 116230 |
5.79 |
| 2026-10-13 00:00 |
23:32:41.32 |
+00:03:16.8 |
HIP 116230 |
8.51 |
| 2026-10-13 12:00 |
23:32:28.05 |
+00:01:30.8 |
HIP 116230 |
11.80 |
| 2026-10-14 00:00 |
23:32:14.96 |
-00:00:14.2 |
HIP 116230 |
15.26 |
| 2026-10-14 12:00 |
23:32:02.05 |
-00:01:58.3 |
HIP 116230 |
18.78 |
| 2026-10-15 00:00 |
23:31:49.34 |
-00:03:41.3 |
HIP 116230 |
22.29 |
| 2026-10-15 12:00 |
23:31:36.81 |
-00:05:23.3 |
HIP 116014 |
19.68 |
| 2026-10-16 00:00 |
23:31:24.48 |
-00:07:04.3 |
HIP 116014 |
16.27 |