| 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
$$
M_a = (5.830 + 3.472\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.830 |
| n |
3.472 |
| gf |
1.000 |
| gb |
-0.500 |
| 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) |
| 2026-09-20 00:00 |
17:51:59.07 |
-23:49:43.7 |
HIP 87399 |
10.16 |
| 2026-09-20 12:00 |
17:51:58.95 |
-23:49:43.5 |
HIP 87399 |
10.15 |
| 2026-09-21 00:00 |
17:51:58.85 |
-23:49:43.2 |
HIP 87399 |
10.14 |
| 2026-09-21 12:00 |
17:51:58.77 |
-23:49:43.0 |
HIP 87399 |
10.12 |
| 2026-09-22 00:00 |
17:51:58.71 |
-23:49:42.7 |
HIP 87399 |
10.11 |
| 2026-09-22 12:00 |
17:51:58.66 |
-23:49:42.5 |
HIP 87399 |
10.11 |
| 2026-09-23 00:00 |
17:51:58.64 |
-23:49:42.3 |
HIP 87399 |
10.10 |
| 2026-09-23 12:00 |
17:51:58.63 |
-23:49:42.1 |
HIP 87399 |
10.10 |
| 2026-09-24 00:00 |
17:51:58.63 |
-23:49:41.9 |
HIP 87399 |
10.09 |
| 2026-09-24 12:00 |
17:51:58.66 |
-23:49:41.6 |
HIP 87399 |
10.09 |
| 2026-09-25 00:00 |
17:51:58.70 |
-23:49:41.4 |
HIP 87399 |
10.09 |
| 2026-09-25 12:00 |
17:51:58.76 |
-23:49:41.2 |
HIP 87399 |
10.10 |
| 2026-09-26 00:00 |
17:51:58.84 |
-23:49:41.0 |
HIP 87399 |
10.10 |
| 2026-09-26 12:00 |
17:51:58.94 |
-23:49:40.8 |
HIP 87399 |
10.11 |
| 2026-09-27 00:00 |
17:51:59.05 |
-23:49:40.6 |
HIP 87399 |
10.12 |
| 2026-09-27 12:00 |
17:51:59.18 |
-23:49:40.4 |
HIP 87399 |
10.13 |
| 2026-09-28 00:00 |
17:51:59.33 |
-23:49:40.2 |
HIP 87399 |
10.14 |
| 2026-09-28 12:00 |
17:51:59.50 |
-23:49:40.0 |
HIP 87399 |
10.16 |
| 2026-09-29 00:00 |
17:51:59.68 |
-23:49:39.9 |
HIP 87399 |
10.17 |
| 2026-09-29 12:00 |
17:51:59.88 |
-23:49:39.7 |
HIP 87399 |
10.19 |
| 2026-09-30 00:00 |
17:52:00.10 |
-23:49:39.5 |
HIP 87399 |
10.21 |
| 2026-09-30 12:00 |
17:52:00.34 |
-23:49:39.3 |
HIP 87399 |
10.23 |
| 2026-10-01 00:00 |
17:52:00.59 |
-23:49:39.2 |
HIP 87399 |
10.26 |
| 2026-10-01 12:00 |
17:52:00.86 |
-23:49:39.0 |
HIP 87399 |
10.29 |
| 2026-10-02 00:00 |
17:52:01.15 |
-23:49:38.8 |
HIP 87399 |
10.32 |
| 2026-10-02 12:00 |
17:52:01.45 |
-23:49:38.7 |
HIP 87399 |
10.35 |
| 2026-10-03 00:00 |
17:52:01.78 |
-23:49:38.5 |
HIP 87399 |
10.38 |
| 2026-10-03 12:00 |
17:52:02.12 |
-23:49:38.4 |
HIP 87399 |
10.42 |
| 2026-10-04 00:00 |
17:52:02.48 |
-23:49:38.2 |
HIP 87399 |
10.46 |
| 2026-10-04 12:00 |
17:52:02.85 |
-23:49:38.1 |
HIP 87399 |
10.50 |
| 2026-10-05 00:00 |
17:52:03.24 |
-23:49:38.0 |
HIP 87399 |
10.55 |
| 2026-10-05 12:00 |
17:52:03.65 |
-23:49:37.8 |
HIP 87399 |
10.59 |
| 2026-10-06 00:00 |
17:52:04.08 |
-23:49:37.7 |
HIP 87399 |
10.64 |
| 2026-10-06 12:00 |
17:52:04.52 |
-23:49:37.6 |
HIP 87399 |
10.70 |
| 2026-10-07 00:00 |
17:52:04.98 |
-23:49:37.5 |
HIP 87399 |
10.75 |
| 2026-10-07 12:00 |
17:52:05.46 |
-23:49:37.3 |
HIP 87399 |
10.81 |
| 2026-10-08 00:00 |
17:52:05.96 |
-23:49:37.2 |
HIP 87399 |
10.87 |
| 2026-10-08 12:00 |
17:52:06.47 |
-23:49:37.1 |
HIP 87399 |
10.94 |
| 2026-10-09 00:00 |
17:52:07.00 |
-23:49:37.0 |
HIP 87399 |
11.01 |
| 2026-10-09 12:00 |
17:52:07.54 |
-23:49:36.9 |
HIP 87399 |
11.08 |
| 2026-10-10 00:00 |
17:52:08.11 |
-23:49:36.8 |
HIP 87399 |
11.15 |
| 2026-10-10 12:00 |
17:52:08.69 |
-23:49:36.7 |
HIP 87399 |
11.23 |
| 2026-10-11 00:00 |
17:52:09.28 |
-23:49:36.6 |
HIP 87399 |
11.31 |