| 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) |
| 2026-09-20 00:00 |
19:01:51.72 |
-17:51:38.1 |
HIP 93319 |
30.49 |
| 2026-09-20 12:00 |
19:01:53.04 |
-17:52:30.0 |
HIP 93319 |
31.35 |
| 2026-09-21 00:00 |
19:01:54.59 |
-17:53:21.5 |
HIP 93319 |
32.24 |
| 2026-09-21 12:00 |
19:01:56.37 |
-17:54:12.6 |
HIP 93644 |
32.64 |
| 2026-09-22 00:00 |
19:01:58.38 |
-17:55:03.2 |
HIP 93644 |
32.41 |
| 2026-09-22 12:00 |
19:02:00.61 |
-17:55:53.3 |
HIP 93644 |
32.16 |
| 2026-09-23 00:00 |
19:02:03.08 |
-17:56:43.0 |
HIP 93644 |
31.88 |
| 2026-09-23 12:00 |
19:02:05.77 |
-17:57:32.3 |
HIP 93644 |
31.58 |
| 2026-09-24 00:00 |
19:02:08.69 |
-17:58:21.1 |
HIP 93644 |
31.26 |
| 2026-09-24 12:00 |
19:02:11.84 |
-17:59:09.5 |
HIP 93644 |
30.92 |
| 2026-09-25 00:00 |
19:02:15.21 |
-17:59:57.4 |
HIP 93644 |
30.56 |
| 2026-09-25 12:00 |
19:02:18.81 |
-18:00:44.8 |
HIP 93644 |
30.20 |
| 2026-09-26 00:00 |
19:02:22.63 |
-18:01:31.8 |
HIP 93644 |
29.82 |
| 2026-09-26 12:00 |
19:02:26.67 |
-18:02:18.4 |
HIP 93644 |
29.44 |
| 2026-09-27 00:00 |
19:02:30.94 |
-18:03:04.4 |
HIP 93644 |
29.07 |
| 2026-09-27 12:00 |
19:02:35.43 |
-18:03:50.1 |
HIP 93644 |
28.69 |
| 2026-09-28 00:00 |
19:02:40.14 |
-18:04:35.2 |
HIP 93644 |
28.33 |
| 2026-09-28 12:00 |
19:02:45.07 |
-18:05:19.9 |
HIP 93644 |
27.99 |
| 2026-09-29 00:00 |
19:02:50.23 |
-18:06:04.1 |
HIP 93644 |
27.67 |
| 2026-09-29 12:00 |
19:02:55.60 |
-18:06:47.9 |
HIP 93644 |
27.39 |
| 2026-09-30 00:00 |
19:03:01.19 |
-18:07:31.2 |
HIP 93644 |
27.14 |
| 2026-09-30 12:00 |
19:03:07.00 |
-18:08:14.0 |
HIP 93644 |
26.94 |
| 2026-10-01 00:00 |
19:03:13.03 |
-18:08:56.3 |
HIP 93644 |
26.80 |
| 2026-10-01 12:00 |
19:03:19.28 |
-18:09:38.2 |
HIP 93644 |
26.72 |
| 2026-10-02 00:00 |
19:03:25.74 |
-18:10:19.6 |
HIP 93644 |
26.72 |
| 2026-10-02 12:00 |
19:03:32.42 |
-18:11:00.5 |
HIP 93644 |
26.79 |
| 2026-10-03 00:00 |
19:03:39.31 |
-18:11:40.9 |
HIP 93644 |
26.96 |
| 2026-10-03 12:00 |
19:03:46.42 |
-18:12:20.8 |
HIP 93644 |
27.23 |
| 2026-10-04 00:00 |
19:03:53.75 |
-18:13:00.2 |
HIP 93644 |
27.59 |
| 2026-10-04 12:00 |
19:04:01.28 |
-18:13:39.2 |
HIP 93693 |
27.73 |
| 2026-10-05 00:00 |
19:04:09.03 |
-18:14:17.6 |
HIP 93693 |
27.67 |
| 2026-10-05 12:00 |
19:04:17.00 |
-18:14:55.6 |
HIP 93693 |
27.73 |
| 2026-10-06 00:00 |
19:04:25.17 |
-18:15:33.1 |
HIP 93696 |
27.44 |
| 2026-10-06 12:00 |
19:04:33.56 |
-18:16:10.0 |
HIP 93696 |
26.51 |
| 2026-10-07 00:00 |
19:04:42.15 |
-18:16:46.5 |
HIP 93696 |
25.72 |
| 2026-10-07 12:00 |
19:04:50.96 |
-18:17:22.4 |
HIP 93696 |
25.09 |
| 2026-10-08 00:00 |
19:04:59.97 |
-18:17:57.9 |
HIP 93696 |
24.65 |
| 2026-10-08 12:00 |
19:05:09.20 |
-18:18:32.8 |
HIP 93696 |
24.43 |
| 2026-10-09 00:00 |
19:05:18.63 |
-18:19:07.2 |
HIP 93696 |
24.44 |
| 2026-10-09 12:00 |
19:05:28.26 |
-18:19:41.1 |
HIP 93696 |
24.69 |
| 2026-10-10 00:00 |
19:05:38.10 |
-18:20:14.5 |
HIP 93696 |
25.19 |
| 2026-10-10 12:00 |
19:05:48.15 |
-18:20:47.4 |
HIP 93696 |
25.94 |
| 2026-10-11 00:00 |
19:05:58.40 |
-18:21:19.7 |
HIP 93696 |
26.93 |