| 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) |
| 2026-05-12 00:00 |
19:57:27.54 |
-14:09:01.5 |
HIP 98304 |
16.35 |
| 2026-05-12 12:00 |
19:57:26.44 |
-14:08:45.0 |
HIP 98304 |
16.45 |
| 2026-05-13 00:00 |
19:57:25.12 |
-14:08:29.2 |
HIP 98304 |
16.60 |
| 2026-05-13 12:00 |
19:57:23.59 |
-14:08:14.2 |
HIP 98304 |
16.82 |
| 2026-05-14 00:00 |
19:57:21.84 |
-14:07:59.9 |
HIP 98304 |
17.09 |
| 2026-05-14 12:00 |
19:57:19.87 |
-14:07:46.2 |
HIP 98304 |
17.43 |
| 2026-05-15 00:00 |
19:57:17.69 |
-14:07:33.4 |
HIP 98304 |
17.83 |
| 2026-05-15 12:00 |
19:57:15.29 |
-14:07:21.2 |
HIP 98304 |
18.30 |
| 2026-05-16 00:00 |
19:57:12.67 |
-14:07:09.8 |
HIP 98304 |
18.83 |
| 2026-05-16 12:00 |
19:57:09.83 |
-14:06:59.1 |
HIP 98304 |
19.42 |
| 2026-05-17 00:00 |
19:57:06.78 |
-14:06:49.2 |
HIP 98304 |
20.07 |
| 2026-05-17 12:00 |
19:57:03.50 |
-14:06:40.1 |
HIP 98304 |
20.78 |
| 2026-05-18 00:00 |
19:57:00.01 |
-14:06:31.7 |
HIP 98304 |
21.55 |
| 2026-05-18 12:00 |
19:56:56.31 |
-14:06:24.0 |
HIP 98304 |
22.39 |
| 2026-05-19 00:00 |
19:56:52.38 |
-14:06:17.1 |
HIP 98304 |
23.28 |
| 2026-05-19 12:00 |
19:56:48.24 |
-14:06:11.0 |
HIP 98304 |
24.24 |
| 2026-05-20 00:00 |
19:56:43.88 |
-14:06:05.6 |
HIP 98304 |
25.25 |
| 2026-05-20 12:00 |
19:56:39.30 |
-14:06:01.0 |
HIP 98304 |
26.32 |
| 2026-05-21 00:00 |
19:56:34.50 |
-14:05:57.2 |
HIP 98304 |
27.45 |
| 2026-05-21 12:00 |
19:56:29.49 |
-14:05:54.1 |
HIP 98014 |
27.84 |
| 2026-05-22 00:00 |
19:56:24.27 |
-14:05:51.9 |
HIP 98014 |
26.89 |
| 2026-05-22 12:00 |
19:56:18.83 |
-14:05:50.4 |
HIP 98014 |
25.95 |
| 2026-05-23 00:00 |
19:56:13.17 |
-14:05:49.7 |
HIP 98014 |
25.02 |
| 2026-05-23 12:00 |
19:56:07.29 |
-14:05:49.7 |
HIP 98014 |
24.10 |
| 2026-05-24 00:00 |
19:56:01.21 |
-14:05:50.6 |
HIP 98014 |
23.22 |
| 2026-05-24 12:00 |
19:55:54.90 |
-14:05:52.2 |
HIP 98014 |
22.39 |
| 2026-05-25 00:00 |
19:55:48.39 |
-14:05:54.6 |
HIP 98014 |
21.61 |
| 2026-05-25 12:00 |
19:55:41.66 |
-14:05:57.8 |
HIP 98014 |
20.92 |
| 2026-05-26 00:00 |
19:55:34.72 |
-14:06:01.8 |
HIP 98014 |
20.33 |
| 2026-05-26 12:00 |
19:55:27.56 |
-14:06:06.6 |
HIP 98014 |
19.86 |
| 2026-05-27 00:00 |
19:55:20.19 |
-14:06:12.2 |
HIP 98014 |
19.54 |
| 2026-05-27 12:00 |
19:55:12.61 |
-14:06:18.6 |
HIP 98014 |
19.39 |
| 2026-05-28 00:00 |
19:55:04.82 |
-14:06:25.7 |
HIP 98014 |
19.43 |
| 2026-05-28 12:00 |
19:54:56.82 |
-14:06:33.7 |
HIP 98014 |
19.67 |
| 2026-05-29 00:00 |
19:54:48.60 |
-14:06:42.5 |
HIP 98014 |
20.12 |
| 2026-05-29 12:00 |
19:54:40.18 |
-14:06:52.0 |
HIP 98014 |
20.78 |
| 2026-05-30 00:00 |
19:54:31.55 |
-14:07:02.4 |
HIP 98014 |
21.64 |
| 2026-05-30 12:00 |
19:54:22.71 |
-14:07:13.5 |
HIP 98014 |
22.71 |
| 2026-05-31 00:00 |
19:54:13.66 |
-14:07:25.5 |
HIP 98014 |
23.95 |
| 2026-05-31 12:00 |
19:54:04.41 |
-14:07:38.2 |
HIP 98014 |
25.37 |
| 2026-06-01 00:00 |
19:53:54.94 |
-14:07:51.8 |
HIP 98014 |
26.95 |
| 2026-06-01 12:00 |
19:53:45.27 |
-14:08:06.1 |
HIP 98014 |
28.67 |
| 2026-06-02 00:00 |
19:53:35.40 |
-14:08:21.3 |
HIP 97849 |
28.70 |