31P/Schwassmann-Wachmann 2
| Parameter |
Value |
| Designation |
31P/Schwassmann-Wachmann 2 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2010-09-29T11:16:57.953280Z |
| Orbit solution date (soln_date, UTC) |
2025-11-23T22:21:40Z |
| Obs used |
1028 |
| NEO |
- |
| M1 |
4.200 |
| K1 |
23.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-02-16.0000000 |
| e |
0.19303098 |
| q (au) |
3.424308 |
| a (au) |
4.243419 |
| i (deg) |
4.546365 |
| Ω (om, deg) |
114.186460 |
| ω (w, deg) |
17.932787 |
| M (ma, deg) |
15.732489 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.954 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.954 |
| n |
2.000 |
| gf |
0.962 |
| gb |
-0.501 |
| k |
1.000 |
| δ90 |
9.174 |
| 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) |
| 2026-02-03 00:00 |
00:48:20.60 |
+00:42:35.5 |
HIP 3793 |
19.13 |
| 2026-02-03 12:00 |
00:48:42.21 |
+00:45:14.9 |
HIP 3793 |
15.57 |
| 2026-02-04 00:00 |
00:49:03.94 |
+00:47:54.7 |
HIP 3793 |
13.83 |
| 2026-02-04 12:00 |
00:49:25.79 |
+00:50:35.1 |
HIP 3793 |
14.61 |
| 2026-02-05 00:00 |
00:49:47.75 |
+00:53:16.1 |
HIP 3793 |
17.63 |
| 2026-02-05 12:00 |
00:50:09.83 |
+00:55:57.5 |
HIP 4007 |
19.12 |
| 2026-02-06 00:00 |
00:50:32.02 |
+00:58:39.5 |
HIP 4007 |
14.12 |
| 2026-02-06 12:00 |
00:50:54.33 |
+01:01:22.0 |
HIP 4007 |
10.44 |
| 2026-02-07 00:00 |
00:51:16.74 |
+01:04:05.0 |
HIP 4007 |
9.77 |
| 2026-02-07 12:00 |
00:51:39.27 |
+01:06:48.6 |
HIP 4007 |
12.64 |
| 2026-02-08 00:00 |
00:52:01.91 |
+01:09:32.6 |
HIP 4007 |
17.41 |
| 2026-02-08 12:00 |
00:52:24.66 |
+01:12:17.1 |
HIP 4007 |
22.95 |
| 2026-02-09 00:00 |
00:52:47.53 |
+01:15:02.1 |
HIP 4007 |
28.83 |
| 2026-02-09 12:00 |
00:53:10.49 |
+01:17:47.5 |
HIP 4007 |
34.90 |
| 2026-02-10 00:00 |
00:53:33.57 |
+01:20:33.5 |
HIP 4203 |
34.04 |
| 2026-02-10 12:00 |
00:53:56.76 |
+01:23:19.9 |
HIP 4203 |
31.57 |
| 2026-02-11 00:00 |
00:54:20.05 |
+01:26:06.7 |
HIP 4203 |
30.28 |
| 2026-02-11 12:00 |
00:54:43.44 |
+01:28:54.0 |
HIP 4203 |
30.34 |
| 2026-02-12 00:00 |
00:55:06.95 |
+01:31:41.8 |
HIP 4203 |
31.77 |
| 2026-02-12 12:00 |
00:55:30.55 |
+01:34:30.0 |
HIP 4465 |
28.83 |
| 2026-02-13 00:00 |
00:55:54.26 |
+01:37:18.6 |
HIP 4465 |
25.27 |
| 2026-02-13 12:00 |
00:56:18.07 |
+01:40:07.7 |
HIP 4500 |
21.56 |
| 2026-02-14 00:00 |
00:56:41.99 |
+01:42:57.2 |
HIP 4500 |
15.00 |
| 2026-02-14 12:00 |
00:57:06.00 |
+01:45:47.1 |
HIP 4500 |
8.52 |
| 2026-02-15 00:00 |
00:57:30.12 |
+01:48:37.4 |
HIP 4500 |
2.81 |
| 2026-02-15 12:00 |
00:57:54.33 |
+01:51:28.1 |
HIP 4500 |
5.68 |
| 2026-02-16 00:00 |
00:58:18.65 |
+01:54:19.2 |
HIP 4500 |
12.11 |
| 2026-02-16 12:00 |
00:58:43.06 |
+01:57:10.7 |
HIP 4504 |
17.40 |
| 2026-02-17 00:00 |
00:59:07.57 |
+02:00:02.5 |
HIP 4504 |
22.05 |
| 2026-02-17 12:00 |
00:59:32.17 |
+02:02:54.8 |
HIP 4504 |
27.61 |
| 2026-02-18 00:00 |
00:59:56.87 |
+02:05:47.4 |
HIP 4738 |
32.21 |
| 2026-02-18 12:00 |
01:00:21.67 |
+02:08:40.4 |
HIP 4738 |
27.36 |
| 2026-02-19 00:00 |
01:00:46.56 |
+02:11:33.7 |
HIP 4738 |
23.51 |
| 2026-02-19 12:00 |
01:01:11.54 |
+02:14:27.3 |
HIP 4825 |
20.90 |
| 2026-02-20 00:00 |
01:01:36.61 |
+02:17:21.3 |
HIP 4825 |
15.32 |
| 2026-02-20 12:00 |
01:02:01.78 |
+02:20:15.7 |
HIP 4825 |
11.31 |
| 2026-02-21 00:00 |
01:02:27.03 |
+02:23:10.3 |
HIP 4886 |
10.51 |
| 2026-02-21 12:00 |
01:02:52.38 |
+02:26:05.3 |
HIP 4886 |
12.52 |
| 2026-02-22 00:00 |
01:03:17.81 |
+02:29:00.5 |
HIP 4886 |
17.34 |
| 2026-02-22 12:00 |
01:03:43.33 |
+02:31:56.1 |
HIP 5060 |
19.96 |
| 2026-02-23 00:00 |
01:04:08.94 |
+02:34:52.0 |
HIP 5060 |
18.23 |
| 2026-02-23 12:00 |
01:04:34.63 |
+02:37:48.1 |
HIP 5060 |
19.11 |
| 2026-02-24 00:00 |
01:05:00.41 |
+02:40:44.6 |
HIP 5134 |
16.11 |