| Parameter |
Value |
| Designation |
C/1984 U2 (Shoemaker) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1985-01-03T21:17:59.058240Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:31Z |
| Obs used |
147 |
| NEO |
- |
| M1 |
10.100 |
| K1 |
20.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1985-01-03.0000000 |
| e |
0.97091010 |
| q (au) |
1.214513 |
| a (au) |
41.750335 |
| i (deg) |
13.881367 |
| Ω (om, deg) |
223.475527 |
| ω (w, deg) |
229.212904 |
| M (ma, deg) |
359.996758 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.650 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.650 |
| n |
6.000 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.827 |
| δ90 |
1.000 |
| 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 |
| 1984-10-25 |
1985-01-02 |
-8.6747 |
+1.412 |
| 1985-01-04 |
1985-03-13 |
+0.7232 |
+0.888 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
17:27:26.45 |
-14:20:57.8 |
HIP 85471 |
9.03 |
| 2026-06-01 12:00 |
17:27:24.32 |
-14:20:54.8 |
HIP 85471 |
9.45 |
| 2026-06-02 00:00 |
17:27:22.19 |
-14:20:51.9 |
HIP 85471 |
9.87 |
| 2026-06-02 12:00 |
17:27:20.05 |
-14:20:48.9 |
HIP 85471 |
10.31 |
| 2026-06-03 00:00 |
17:27:17.90 |
-14:20:46.0 |
HIP 85471 |
10.76 |
| 2026-06-03 12:00 |
17:27:15.76 |
-14:20:43.2 |
HIP 85471 |
11.21 |
| 2026-06-04 00:00 |
17:27:13.61 |
-14:20:40.4 |
HIP 85471 |
11.67 |
| 2026-06-04 12:00 |
17:27:11.46 |
-14:20:37.6 |
HIP 85471 |
12.13 |
| 2026-06-05 00:00 |
17:27:09.30 |
-14:20:34.9 |
HIP 85471 |
12.60 |
| 2026-06-05 12:00 |
17:27:07.14 |
-14:20:32.2 |
HIP 85471 |
13.08 |
| 2026-06-06 00:00 |
17:27:04.98 |
-14:20:29.5 |
HIP 85471 |
13.56 |
| 2026-06-06 12:00 |
17:27:02.82 |
-14:20:26.9 |
HIP 85471 |
14.04 |
| 2026-06-07 00:00 |
17:27:00.65 |
-14:20:24.4 |
HIP 85471 |
14.53 |
| 2026-06-07 12:00 |
17:26:58.49 |
-14:20:21.8 |
HIP 85471 |
15.02 |
| 2026-06-08 00:00 |
17:26:56.32 |
-14:20:19.3 |
HIP 85471 |
15.52 |
| 2026-06-08 12:00 |
17:26:54.14 |
-14:20:16.9 |
HIP 85471 |
16.02 |
| 2026-06-09 00:00 |
17:26:51.97 |
-14:20:14.4 |
HIP 85471 |
16.52 |
| 2026-06-09 12:00 |
17:26:49.79 |
-14:20:12.1 |
HIP 85471 |
17.02 |
| 2026-06-10 00:00 |
17:26:47.62 |
-14:20:09.7 |
HIP 85471 |
17.52 |
| 2026-06-10 12:00 |
17:26:45.44 |
-14:20:07.4 |
HIP 85471 |
18.03 |
| 2026-06-11 00:00 |
17:26:43.26 |
-14:20:05.2 |
HIP 85471 |
18.53 |
| 2026-06-11 12:00 |
17:26:41.08 |
-14:20:03.0 |
HIP 85471 |
19.04 |
| 2026-06-12 00:00 |
17:26:38.90 |
-14:20:00.8 |
HIP 85471 |
19.55 |
| 2026-06-12 12:00 |
17:26:36.72 |
-14:19:58.7 |
HIP 85471 |
20.07 |
| 2026-06-13 00:00 |
17:26:34.54 |
-14:19:56.6 |
HIP 85471 |
20.58 |
| 2026-06-13 12:00 |
17:26:32.35 |
-14:19:54.5 |
HIP 85471 |
21.09 |
| 2026-06-14 00:00 |
17:26:30.17 |
-14:19:52.5 |
HIP 85471 |
21.61 |
| 2026-06-14 12:00 |
17:26:27.99 |
-14:19:50.5 |
HIP 85471 |
22.12 |
| 2026-06-15 00:00 |
17:26:25.81 |
-14:19:48.6 |
HIP 85471 |
22.64 |
| 2026-06-15 12:00 |
17:26:23.63 |
-14:19:46.7 |
HIP 85471 |
23.15 |
| 2026-06-16 00:00 |
17:26:21.45 |
-14:19:44.9 |
HIP 85471 |
23.67 |
| 2026-06-16 12:00 |
17:26:19.27 |
-14:19:43.1 |
HIP 85471 |
24.19 |
| 2026-06-17 00:00 |
17:26:17.09 |
-14:19:41.3 |
HIP 85471 |
24.71 |
| 2026-06-17 12:00 |
17:26:14.91 |
-14:19:39.6 |
HIP 85239 |
24.38 |
| 2026-06-18 00:00 |
17:26:12.74 |
-14:19:38.0 |
HIP 85239 |
24.03 |
| 2026-06-18 12:00 |
17:26:10.56 |
-14:19:36.3 |
HIP 85239 |
23.69 |
| 2026-06-19 00:00 |
17:26:08.39 |
-14:19:34.8 |
HIP 85239 |
23.36 |
| 2026-06-19 12:00 |
17:26:06.22 |
-14:19:33.2 |
HIP 85239 |
23.03 |
| 2026-06-20 00:00 |
17:26:04.05 |
-14:19:31.7 |
HIP 85239 |
22.71 |
| 2026-06-20 12:00 |
17:26:01.89 |
-14:19:30.3 |
HIP 85239 |
22.40 |
| 2026-06-21 00:00 |
17:25:59.72 |
-14:19:28.9 |
HIP 85239 |
22.10 |
| 2026-06-21 12:00 |
17:25:57.56 |
-14:19:27.5 |
HIP 85239 |
21.81 |
| 2026-06-22 00:00 |
17:25:55.40 |
-14:19:26.2 |
HIP 85239 |
21.52 |