81P/Wild 2
| Parameter |
Value |
| Designation |
81P/Wild 2 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2022-12-15T18:49:47.694720Z |
| Orbit solution date (soln_date, UTC) |
2024-09-12T12:06:16Z |
| Obs used |
2795 |
| NEO |
- |
| M1 |
9.800 |
| K1 |
12.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-11-21.0000000 |
| e |
0.53739891 |
| q (au) |
1.595856 |
| a (au) |
3.449746 |
| i (deg) |
3.237004 |
| Ω (om, deg) |
136.110221 |
| ω (w, deg) |
41.725231 |
| M (ma, deg) |
187.596681 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.748 + 5.344\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.748 |
| n |
5.344 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.866 |
| δ90 |
1.000 |
| 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 |
| 2020-09-17 |
2022-12-15 |
+5.8213 |
-3.117 |
| 2022-12-15 |
2023-03-16 |
+32.7150 |
-8.016 |
| 2023-03-16 |
2024-09-07 |
-2.7326 |
+0.980 |
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 |
23:25:44.39 |
-05:40:40.1 |
HIP 115639 |
20.09 |
| 2026-02-03 12:00 |
23:26:04.33 |
-05:38:31.0 |
HIP 115639 |
23.32 |
| 2026-02-04 00:00 |
23:26:24.33 |
-05:36:21.5 |
HIP 115720 |
22.75 |
| 2026-02-04 12:00 |
23:26:44.39 |
-05:34:11.7 |
HIP 115720 |
20.30 |
| 2026-02-05 00:00 |
23:27:04.51 |
-05:32:01.5 |
HIP 115720 |
19.12 |
| 2026-02-05 12:00 |
23:27:24.68 |
-05:29:51.0 |
HIP 115720 |
19.47 |
| 2026-02-06 00:00 |
23:27:44.91 |
-05:27:40.2 |
HIP 115892 |
15.97 |
| 2026-02-06 12:00 |
23:28:05.19 |
-05:25:29.0 |
HIP 115892 |
10.55 |
| 2026-02-07 00:00 |
23:28:25.53 |
-05:23:17.4 |
HIP 115892 |
5.27 |
| 2026-02-07 12:00 |
23:28:45.92 |
-05:21:05.6 |
HIP 115892 |
2.28 |
| 2026-02-08 00:00 |
23:29:06.37 |
-05:18:53.4 |
HIP 115892 |
6.63 |
| 2026-02-08 12:00 |
23:29:26.87 |
-05:16:40.9 |
HIP 115892 |
12.03 |
| 2026-02-09 00:00 |
23:29:47.42 |
-05:14:28.1 |
HIP 115892 |
17.54 |
| 2026-02-09 12:00 |
23:30:08.02 |
-05:12:14.9 |
HIP 116057 |
15.01 |
| 2026-02-10 00:00 |
23:30:28.67 |
-05:10:01.5 |
HIP 116057 |
9.59 |
| 2026-02-10 12:00 |
23:30:49.38 |
-05:07:47.7 |
HIP 116057 |
4.61 |
| 2026-02-11 00:00 |
23:31:10.13 |
-05:05:33.7 |
HIP 116057 |
3.70 |
| 2026-02-11 12:00 |
23:31:30.93 |
-05:03:19.4 |
HIP 116057 |
8.35 |
| 2026-02-12 00:00 |
23:31:51.78 |
-05:01:04.7 |
HIP 116057 |
13.78 |
| 2026-02-12 12:00 |
23:32:12.67 |
-04:58:49.8 |
HIP 116057 |
19.35 |
| 2026-02-13 00:00 |
23:32:33.62 |
-04:56:34.7 |
HIP 116294 |
21.42 |
| 2026-02-13 12:00 |
23:32:54.60 |
-04:54:19.2 |
HIP 116294 |
18.78 |
| 2026-02-14 00:00 |
23:33:15.64 |
-04:52:03.5 |
HIP 116294 |
17.65 |
| 2026-02-14 12:00 |
23:33:36.71 |
-04:49:47.5 |
HIP 116294 |
18.32 |
| 2026-02-15 00:00 |
23:33:57.83 |
-04:47:31.2 |
HIP 116294 |
20.62 |
| 2026-02-15 12:00 |
23:34:18.99 |
-04:45:14.7 |
HIP 116294 |
24.10 |
| 2026-02-16 00:00 |
23:34:40.20 |
-04:42:58.0 |
HIP 116266 |
25.98 |
| 2026-02-16 12:00 |
23:35:01.45 |
-04:40:41.0 |
HIP 116266 |
28.48 |
| 2026-02-17 00:00 |
23:35:22.73 |
-04:38:23.8 |
HIP 116266 |
31.84 |
| 2026-02-17 12:00 |
23:35:44.06 |
-04:36:06.3 |
HIP 116266 |
35.83 |
| 2026-02-18 00:00 |
23:36:05.42 |
-04:33:48.6 |
HIP 116587 |
39.84 |
| 2026-02-18 12:00 |
23:36:26.83 |
-04:31:30.7 |
HIP 116587 |
39.08 |
| 2026-02-19 00:00 |
23:36:48.27 |
-04:29:12.6 |
HIP 116587 |
39.18 |
| 2026-02-19 12:00 |
23:37:09.74 |
-04:26:54.3 |
HIP 116587 |
40.14 |
| 2026-02-20 00:00 |
23:37:31.26 |
-04:24:35.8 |
HIP 116753 |
36.45 |
| 2026-02-20 12:00 |
23:37:52.80 |
-04:22:17.1 |
HIP 116753 |
32.84 |
| 2026-02-21 00:00 |
23:38:14.39 |
-04:19:58.1 |
HIP 116753 |
29.95 |
| 2026-02-21 12:00 |
23:38:36.00 |
-04:17:39.0 |
HIP 116753 |
28.00 |
| 2026-02-22 00:00 |
23:38:57.65 |
-04:15:19.7 |
HIP 116753 |
27.20 |
| 2026-02-22 12:00 |
23:39:19.33 |
-04:13:00.3 |
HIP 116753 |
27.64 |
| 2026-02-23 00:00 |
23:39:41.04 |
-04:10:40.6 |
HIP 116864 |
28.28 |
| 2026-02-23 12:00 |
23:40:02.78 |
-04:08:20.8 |
HIP 116864 |
25.33 |
| 2026-02-24 00:00 |
23:40:24.55 |
-04:06:00.9 |
HIP 116864 |
23.51 |