C/1984 U2 (Shoemaker)
| 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) |
| 2026-02-03 00:00 |
17:29:34.92 |
-14:38:50.6 |
HIP 85679 |
15.74 |
| 2026-02-03 12:00 |
17:29:36.42 |
-14:38:47.8 |
HIP 85679 |
15.45 |
| 2026-02-04 00:00 |
17:29:37.90 |
-14:38:44.9 |
HIP 85679 |
15.16 |
| 2026-02-04 12:00 |
17:29:39.36 |
-14:38:42.0 |
HIP 85679 |
14.88 |
| 2026-02-05 00:00 |
17:29:40.81 |
-14:38:39.0 |
HIP 85679 |
14.61 |
| 2026-02-05 12:00 |
17:29:42.25 |
-14:38:36.0 |
HIP 85679 |
14.34 |
| 2026-02-06 00:00 |
17:29:43.66 |
-14:38:33.0 |
HIP 85679 |
14.08 |
| 2026-02-06 12:00 |
17:29:45.07 |
-14:38:29.9 |
HIP 85679 |
13.83 |
| 2026-02-07 00:00 |
17:29:46.45 |
-14:38:26.8 |
HIP 85679 |
13.59 |
| 2026-02-07 12:00 |
17:29:47.83 |
-14:38:23.7 |
HIP 85679 |
13.35 |
| 2026-02-08 00:00 |
17:29:49.18 |
-14:38:20.5 |
HIP 85679 |
13.12 |
| 2026-02-08 12:00 |
17:29:50.52 |
-14:38:17.3 |
HIP 85679 |
12.90 |
| 2026-02-09 00:00 |
17:29:51.85 |
-14:38:14.0 |
HIP 85679 |
12.69 |
| 2026-02-09 12:00 |
17:29:53.15 |
-14:38:10.7 |
HIP 85679 |
12.48 |
| 2026-02-10 00:00 |
17:29:54.44 |
-14:38:07.4 |
HIP 85679 |
12.28 |
| 2026-02-10 12:00 |
17:29:55.72 |
-14:38:04.0 |
HIP 85679 |
12.09 |
| 2026-02-11 00:00 |
17:29:56.98 |
-14:38:00.6 |
HIP 85679 |
11.91 |
| 2026-02-11 12:00 |
17:29:58.22 |
-14:37:57.2 |
HIP 85679 |
11.74 |
| 2026-02-12 00:00 |
17:29:59.45 |
-14:37:53.7 |
HIP 85679 |
11.58 |
| 2026-02-12 12:00 |
17:30:00.65 |
-14:37:50.2 |
HIP 85679 |
11.43 |
| 2026-02-13 00:00 |
17:30:01.85 |
-14:37:46.6 |
HIP 85679 |
11.28 |
| 2026-02-13 12:00 |
17:30:03.02 |
-14:37:43.0 |
HIP 85679 |
11.14 |
| 2026-02-14 00:00 |
17:30:04.18 |
-14:37:39.4 |
HIP 85679 |
11.02 |
| 2026-02-14 12:00 |
17:30:05.32 |
-14:37:35.7 |
HIP 85679 |
10.90 |
| 2026-02-15 00:00 |
17:30:06.44 |
-14:37:32.0 |
HIP 85679 |
10.79 |
| 2026-02-15 12:00 |
17:30:07.55 |
-14:37:28.3 |
HIP 85679 |
10.69 |
| 2026-02-16 00:00 |
17:30:08.64 |
-14:37:24.6 |
HIP 85679 |
10.60 |
| 2026-02-16 12:00 |
17:30:09.71 |
-14:37:20.8 |
HIP 85679 |
10.52 |
| 2026-02-17 00:00 |
17:30:10.76 |
-14:37:16.9 |
HIP 85679 |
10.44 |
| 2026-02-17 12:00 |
17:30:11.80 |
-14:37:13.1 |
HIP 85679 |
10.38 |
| 2026-02-18 00:00 |
17:30:12.82 |
-14:37:09.2 |
HIP 85679 |
10.32 |
| 2026-02-18 12:00 |
17:30:13.82 |
-14:37:05.3 |
HIP 85679 |
10.27 |
| 2026-02-19 00:00 |
17:30:14.80 |
-14:37:01.3 |
HIP 85679 |
10.23 |
| 2026-02-19 12:00 |
17:30:15.77 |
-14:36:57.3 |
HIP 85679 |
10.20 |
| 2026-02-20 00:00 |
17:30:16.71 |
-14:36:53.3 |
HIP 85679 |
10.18 |
| 2026-02-20 12:00 |
17:30:17.64 |
-14:36:49.2 |
HIP 85679 |
10.16 |
| 2026-02-21 00:00 |
17:30:18.55 |
-14:36:45.2 |
HIP 85679 |
10.15 |
| 2026-02-21 12:00 |
17:30:19.45 |
-14:36:41.0 |
HIP 85679 |
10.15 |
| 2026-02-22 00:00 |
17:30:20.32 |
-14:36:36.9 |
HIP 85679 |
10.15 |
| 2026-02-22 12:00 |
17:30:21.18 |
-14:36:32.7 |
HIP 85679 |
10.16 |
| 2026-02-23 00:00 |
17:30:22.01 |
-14:36:28.5 |
HIP 85679 |
10.18 |
| 2026-02-23 12:00 |
17:30:22.83 |
-14:36:24.3 |
HIP 85679 |
10.20 |
| 2026-02-24 00:00 |
17:30:23.63 |
-14:36:20.0 |
HIP 85679 |
10.23 |