| Parameter |
Value |
| Designation |
C/1984 U1 (Shoemaker) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1984-09-03T10:51:18.192960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:31Z |
| Obs used |
60 |
| NEO |
- |
| M1 |
8.100 |
| K1 |
7.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1985-06-15.0000000 |
| e |
0.99440837 |
| q (au) |
5.489111 |
| a (au) |
981.666043 |
| i (deg) |
179.212301 |
| Ω (om, deg) |
238.298457 |
| ω (w, deg) |
182.819832 |
| M (ma, deg) |
0.009118 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.829 + 3.472\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.829 |
| n |
3.472 |
| gf |
1.000 |
| gb |
-0.502 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
17:59:05.20 |
-23:50:52.0 |
HIP 88116 |
9.87 |
| 2026-05-12 12:00 |
17:59:03.46 |
-23:50:52.1 |
HIP 88116 |
10.26 |
| 2026-05-13 00:00 |
17:59:01.71 |
-23:50:52.1 |
HIP 88116 |
10.66 |
| 2026-05-13 12:00 |
17:58:59.95 |
-23:50:52.2 |
HIP 88116 |
11.05 |
| 2026-05-14 00:00 |
17:58:58.17 |
-23:50:52.3 |
HIP 88116 |
11.45 |
| 2026-05-14 12:00 |
17:58:56.39 |
-23:50:52.3 |
HIP 88116 |
11.86 |
| 2026-05-15 00:00 |
17:58:54.60 |
-23:50:52.4 |
HIP 87981 |
11.86 |
| 2026-05-15 12:00 |
17:58:52.79 |
-23:50:52.4 |
HIP 87981 |
11.59 |
| 2026-05-16 00:00 |
17:58:50.97 |
-23:50:52.5 |
HIP 87981 |
11.32 |
| 2026-05-16 12:00 |
17:58:49.15 |
-23:50:52.5 |
HIP 87981 |
11.06 |
| 2026-05-17 00:00 |
17:58:47.31 |
-23:50:52.6 |
HIP 87981 |
10.81 |
| 2026-05-17 12:00 |
17:58:45.46 |
-23:50:52.6 |
HIP 87981 |
10.57 |
| 2026-05-18 00:00 |
17:58:43.60 |
-23:50:52.7 |
HIP 87981 |
10.34 |
| 2026-05-18 12:00 |
17:58:41.74 |
-23:50:52.7 |
HIP 87981 |
10.12 |
| 2026-05-19 00:00 |
17:58:39.86 |
-23:50:52.7 |
HIP 87981 |
9.91 |
| 2026-05-19 12:00 |
17:58:37.97 |
-23:50:52.8 |
HIP 87981 |
9.71 |
| 2026-05-20 00:00 |
17:58:36.08 |
-23:50:52.8 |
HIP 87981 |
9.53 |
| 2026-05-20 12:00 |
17:58:34.17 |
-23:50:52.8 |
HIP 87981 |
9.37 |
| 2026-05-21 00:00 |
17:58:32.25 |
-23:50:52.8 |
HIP 87981 |
9.22 |
| 2026-05-21 12:00 |
17:58:30.33 |
-23:50:52.9 |
HIP 87981 |
9.10 |
| 2026-05-22 00:00 |
17:58:28.40 |
-23:50:52.9 |
HIP 87981 |
8.99 |
| 2026-05-22 12:00 |
17:58:26.46 |
-23:50:52.9 |
HIP 87981 |
8.90 |
| 2026-05-23 00:00 |
17:58:24.51 |
-23:50:52.9 |
HIP 87981 |
8.83 |
| 2026-05-23 12:00 |
17:58:22.55 |
-23:50:52.9 |
HIP 87981 |
8.78 |
| 2026-05-24 00:00 |
17:58:20.58 |
-23:50:52.9 |
HIP 87981 |
8.76 |
| 2026-05-24 12:00 |
17:58:18.60 |
-23:50:52.9 |
HIP 87981 |
8.76 |
| 2026-05-25 00:00 |
17:58:16.62 |
-23:50:52.9 |
HIP 87981 |
8.78 |
| 2026-05-25 12:00 |
17:58:14.63 |
-23:50:52.9 |
HIP 87981 |
8.83 |
| 2026-05-26 00:00 |
17:58:12.63 |
-23:50:52.9 |
HIP 87981 |
8.90 |
| 2026-05-26 12:00 |
17:58:10.62 |
-23:50:52.9 |
HIP 87981 |
8.99 |
| 2026-05-27 00:00 |
17:58:08.61 |
-23:50:52.9 |
HIP 87981 |
9.11 |
| 2026-05-27 12:00 |
17:58:06.59 |
-23:50:52.8 |
HIP 87981 |
9.25 |
| 2026-05-28 00:00 |
17:58:04.56 |
-23:50:52.8 |
HIP 87981 |
9.41 |
| 2026-05-28 12:00 |
17:58:02.52 |
-23:50:52.8 |
HIP 87981 |
9.58 |
| 2026-05-29 00:00 |
17:58:00.48 |
-23:50:52.7 |
HIP 87981 |
9.78 |
| 2026-05-29 12:00 |
17:57:58.43 |
-23:50:52.7 |
HIP 87981 |
10.00 |
| 2026-05-30 00:00 |
17:57:56.38 |
-23:50:52.7 |
HIP 87981 |
10.24 |
| 2026-05-30 12:00 |
17:57:54.31 |
-23:50:52.6 |
HIP 87981 |
10.49 |
| 2026-05-31 00:00 |
17:57:52.24 |
-23:50:52.6 |
HIP 87981 |
10.76 |
| 2026-05-31 12:00 |
17:57:50.17 |
-23:50:52.5 |
HIP 87981 |
11.04 |
| 2026-06-01 00:00 |
17:57:48.09 |
-23:50:52.5 |
HIP 87880 |
10.78 |
| 2026-06-01 12:00 |
17:57:46.00 |
-23:50:52.4 |
HIP 87880 |
10.38 |
| 2026-06-02 00:00 |
17:57:43.91 |
-23:50:52.3 |
HIP 87880 |
9.97 |