| Parameter |
Value |
| Designation |
118P/Shoemaker-Levy 4 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2022-11-22T22:36:34.951680Z |
| Orbit solution date (soln_date, UTC) |
2025-08-01T13:53:05Z |
| Obs used |
1771 |
| NEO |
- |
| M1 |
12.400 |
| K1 |
11.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-06-23.0000000 |
| e |
0.45507750 |
| q (au) |
1.831356 |
| a (au) |
3.360765 |
| i (deg) |
10.093960 |
| Ω (om, deg) |
142.114993 |
| ω (w, deg) |
314.438274 |
| M (ma, deg) |
277.143222 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.603 + 5.506\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.603 |
| n |
5.506 |
| gf |
1.000 |
| gb |
-0.907 |
| 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 |
| 2021-05-25 |
2022-11-22 |
+1.8100 |
-0.886 |
| 2022-11-24 |
2024-05-31 |
+0.5960 |
-0.576 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
19:44:34.77 |
-15:14:14.6 |
HIP 97190 |
11.96 |
| 2026-03-26 12:00 |
19:44:50.99 |
-15:13:17.3 |
HIP 97190 |
8.52 |
| 2026-03-27 00:00 |
19:45:07.07 |
-15:12:20.0 |
HIP 97190 |
5.90 |
| 2026-03-27 12:00 |
19:45:23.00 |
-15:11:23.0 |
HIP 97190 |
5.36 |
| 2026-03-28 00:00 |
19:45:38.78 |
-15:10:26.1 |
HIP 97190 |
7.32 |
| 2026-03-28 12:00 |
19:45:54.41 |
-15:09:29.3 |
HIP 97190 |
10.41 |
| 2026-03-29 00:00 |
19:46:09.90 |
-15:08:32.8 |
HIP 97273 |
11.46 |
| 2026-03-29 12:00 |
19:46:25.23 |
-15:07:36.4 |
HIP 97273 |
12.98 |
| 2026-03-30 00:00 |
19:46:40.41 |
-15:06:40.2 |
HIP 97273 |
15.31 |
| 2026-03-30 12:00 |
19:46:55.45 |
-15:05:44.2 |
HIP 97273 |
18.11 |
| 2026-03-31 00:00 |
19:47:10.33 |
-15:04:48.4 |
HIP 97273 |
21.18 |
| 2026-03-31 12:00 |
19:47:25.05 |
-15:03:52.7 |
HIP 97273 |
24.39 |
| 2026-04-01 00:00 |
19:47:39.63 |
-15:02:57.3 |
HIP 97273 |
27.69 |
| 2026-04-01 12:00 |
19:47:54.05 |
-15:02:02.1 |
HIP 97422 |
28.06 |
| 2026-04-02 00:00 |
19:48:08.31 |
-15:01:07.2 |
HIP 97422 |
27.12 |
| 2026-04-02 12:00 |
19:48:22.42 |
-15:00:12.4 |
HIP 97422 |
26.64 |
| 2026-04-03 00:00 |
19:48:36.37 |
-14:59:17.9 |
HIP 97521 |
25.41 |
| 2026-04-03 12:00 |
19:48:50.16 |
-14:58:23.6 |
HIP 97614 |
22.43 |
| 2026-04-04 00:00 |
19:49:03.79 |
-14:57:29.6 |
HIP 97614 |
19.08 |
| 2026-04-04 12:00 |
19:49:17.26 |
-14:56:35.8 |
HIP 97614 |
15.78 |
| 2026-04-05 00:00 |
19:49:30.57 |
-14:55:42.2 |
HIP 97614 |
12.57 |
| 2026-04-05 12:00 |
19:49:43.72 |
-14:54:48.9 |
HIP 97614 |
9.49 |
| 2026-04-06 00:00 |
19:49:56.71 |
-14:53:55.9 |
HIP 97614 |
6.65 |
| 2026-04-06 12:00 |
19:50:09.53 |
-14:53:03.2 |
HIP 97614 |
4.46 |
| 2026-04-07 00:00 |
19:50:22.19 |
-14:52:10.7 |
HIP 97614 |
4.02 |
| 2026-04-07 12:00 |
19:50:34.69 |
-14:51:18.6 |
HIP 97614 |
5.70 |
| 2026-04-08 00:00 |
19:50:47.01 |
-14:50:26.7 |
HIP 97614 |
8.24 |
| 2026-04-08 12:00 |
19:50:59.17 |
-14:49:35.1 |
HIP 97736 |
10.73 |
| 2026-04-09 00:00 |
19:51:11.16 |
-14:48:43.8 |
HIP 97736 |
7.71 |
| 2026-04-09 12:00 |
19:51:22.98 |
-14:47:52.9 |
HIP 97736 |
4.73 |
| 2026-04-10 00:00 |
19:51:34.63 |
-14:47:02.2 |
HIP 97736 |
1.79 |
| 2026-04-10 12:00 |
19:51:46.11 |
-14:46:11.9 |
HIP 97736 |
1.11 |
| 2026-04-11 00:00 |
19:51:57.42 |
-14:45:21.9 |
HIP 97736 |
3.97 |
| 2026-04-11 12:00 |
19:52:08.55 |
-14:44:32.3 |
HIP 97736 |
6.78 |
| 2026-04-12 00:00 |
19:52:19.51 |
-14:43:43.0 |
HIP 97736 |
9.56 |
| 2026-04-12 12:00 |
19:52:30.29 |
-14:42:54.1 |
HIP 97849 |
11.01 |
| 2026-04-13 00:00 |
19:52:40.90 |
-14:42:05.5 |
HIP 97849 |
8.54 |
| 2026-04-13 12:00 |
19:52:51.33 |
-14:41:17.3 |
HIP 97849 |
6.27 |
| 2026-04-14 00:00 |
19:53:01.58 |
-14:40:29.4 |
HIP 97849 |
4.46 |
| 2026-04-14 12:00 |
19:53:11.65 |
-14:39:42.0 |
HIP 97849 |
3.74 |
| 2026-04-15 00:00 |
19:53:21.54 |
-14:38:54.9 |
HIP 97849 |
4.57 |
| 2026-04-15 12:00 |
19:53:31.25 |
-14:38:08.2 |
HIP 97849 |
6.32 |
| 2026-04-16 00:00 |
19:53:40.78 |
-14:37:21.9 |
HIP 97849 |
8.40 |