| Parameter |
Value |
| Designation |
139P/Vaisala-Oterma |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2008-04-20T10:37:01.891200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:27:39Z |
| Obs used |
546 |
| NEO |
- |
| M1 |
7.200 |
| K1 |
18.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-11-16.0000000 |
| e |
0.24752589 |
| q (au) |
3.402921 |
| a (au) |
4.522310 |
| i (deg) |
2.328730 |
| Ω (om, deg) |
242.377585 |
| ω (w, deg) |
165.725397 |
| M (ma, deg) |
96.291288 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.897 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.897 |
| n |
6.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
23:24:51.76 |
-01:30:10.1 |
HIP 115572 |
14.67 |
| 2026-05-12 12:00 |
23:25:18.00 |
-01:27:11.1 |
HIP 115572 |
19.87 |
| 2026-05-13 00:00 |
23:25:44.14 |
-01:24:12.5 |
HIP 115752 |
21.30 |
| 2026-05-13 12:00 |
23:26:10.18 |
-01:21:14.4 |
HIP 115752 |
14.19 |
| 2026-05-14 00:00 |
23:26:36.13 |
-01:18:16.8 |
HIP 115752 |
7.20 |
| 2026-05-14 12:00 |
23:27:01.98 |
-01:15:19.7 |
HIP 115752 |
1.99 |
| 2026-05-15 00:00 |
23:27:27.73 |
-01:12:23.2 |
HIP 115752 |
7.52 |
| 2026-05-15 12:00 |
23:27:53.37 |
-01:09:27.1 |
HIP 115752 |
14.44 |
| 2026-05-16 00:00 |
23:28:18.92 |
-01:06:31.6 |
HIP 115891 |
17.77 |
| 2026-05-16 12:00 |
23:28:44.37 |
-01:03:36.6 |
HIP 115951 |
11.58 |
| 2026-05-17 00:00 |
23:29:09.71 |
-01:00:42.2 |
HIP 115951 |
5.35 |
| 2026-05-17 12:00 |
23:29:34.94 |
-00:57:48.3 |
HIP 115951 |
4.49 |
| 2026-05-18 00:00 |
23:30:00.08 |
-00:54:55.0 |
HIP 115951 |
10.37 |
| 2026-05-18 12:00 |
23:30:25.10 |
-00:52:02.3 |
HIP 115951 |
17.02 |
| 2026-05-19 00:00 |
23:30:50.02 |
-00:49:10.1 |
HIP 116062 |
13.73 |
| 2026-05-19 12:00 |
23:31:14.84 |
-00:46:18.5 |
HIP 116062 |
11.04 |
| 2026-05-20 00:00 |
23:31:39.54 |
-00:43:27.5 |
HIP 116062 |
12.17 |
| 2026-05-20 12:00 |
23:32:04.14 |
-00:40:37.0 |
HIP 116209 |
14.58 |
| 2026-05-21 00:00 |
23:32:28.62 |
-00:37:47.2 |
HIP 116209 |
13.56 |
| 2026-05-21 12:00 |
23:32:53.00 |
-00:34:58.0 |
HIP 116209 |
15.67 |
| 2026-05-22 00:00 |
23:33:17.26 |
-00:32:09.3 |
HIP 116320 |
14.20 |
| 2026-05-22 12:00 |
23:33:41.41 |
-00:29:21.3 |
HIP 116320 |
7.57 |
| 2026-05-23 00:00 |
23:34:05.45 |
-00:26:34.0 |
HIP 116320 |
1.23 |
| 2026-05-23 12:00 |
23:34:29.38 |
-00:23:47.2 |
HIP 116320 |
5.76 |
| 2026-05-24 00:00 |
23:34:53.19 |
-00:21:01.1 |
HIP 116320 |
12.29 |
| 2026-05-24 12:00 |
23:35:16.89 |
-00:18:15.6 |
HIP 116320 |
18.81 |
| 2026-05-25 00:00 |
23:35:40.47 |
-00:15:30.8 |
HIP 116320 |
25.31 |
| 2026-05-25 12:00 |
23:36:03.93 |
-00:12:46.6 |
HIP 116320 |
31.78 |
| 2026-05-26 00:00 |
23:36:27.28 |
-00:10:03.0 |
HIP 116454 |
38.01 |
| 2026-05-26 12:00 |
23:36:50.51 |
-00:07:20.2 |
HIP 116454 |
37.36 |
| 2026-05-27 00:00 |
23:37:13.62 |
-00:04:38.0 |
HIP 116454 |
37.79 |
| 2026-05-27 12:00 |
23:37:36.61 |
-00:01:56.4 |
HIP 116454 |
39.26 |
| 2026-05-28 00:00 |
23:37:59.48 |
+00:00:44.4 |
HIP 116454 |
41.64 |
| 2026-05-28 12:00 |
23:38:22.23 |
+00:03:24.6 |
HIP 116823 |
40.69 |
| 2026-05-29 00:00 |
23:38:44.86 |
+00:06:04.1 |
HIP 116823 |
34.49 |
| 2026-05-29 12:00 |
23:39:07.37 |
+00:08:42.9 |
HIP 116823 |
28.35 |
| 2026-05-30 00:00 |
23:39:29.75 |
+00:11:20.9 |
HIP 116823 |
22.28 |
| 2026-05-30 12:00 |
23:39:52.01 |
+00:13:58.3 |
HIP 116823 |
16.32 |
| 2026-05-31 00:00 |
23:40:14.14 |
+00:16:34.9 |
HIP 116823 |
10.63 |
| 2026-05-31 12:00 |
23:40:36.15 |
+00:19:10.8 |
HIP 116823 |
5.87 |
| 2026-06-01 00:00 |
23:40:58.03 |
+00:21:46.0 |
HIP 116823 |
5.47 |
| 2026-06-01 12:00 |
23:41:19.78 |
+00:24:20.5 |
HIP 116823 |
9.89 |
| 2026-06-02 00:00 |
23:41:41.40 |
+00:26:54.2 |
HIP 116823 |
15.40 |