| 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) |
| 2026-07-29 00:00 |
17:23:34.16 |
-14:19:50.4 |
HIP 85002 |
24.80 |
| 2026-07-29 12:00 |
17:23:32.63 |
-14:19:52.3 |
HIP 85002 |
24.58 |
| 2026-07-30 00:00 |
17:23:31.13 |
-14:19:54.3 |
HIP 85002 |
24.37 |
| 2026-07-30 12:00 |
17:23:29.63 |
-14:19:56.3 |
HIP 85002 |
24.17 |
| 2026-07-31 00:00 |
17:23:28.15 |
-14:19:58.4 |
HIP 85002 |
23.97 |
| 2026-07-31 12:00 |
17:23:26.68 |
-14:20:00.5 |
HIP 85002 |
23.78 |
| 2026-08-01 00:00 |
17:23:25.23 |
-14:20:02.7 |
HIP 85002 |
23.59 |
| 2026-08-01 12:00 |
17:23:23.79 |
-14:20:04.9 |
HIP 85002 |
23.41 |
| 2026-08-02 00:00 |
17:23:22.37 |
-14:20:07.1 |
HIP 85002 |
23.24 |
| 2026-08-02 12:00 |
17:23:20.96 |
-14:20:09.4 |
HIP 85002 |
23.07 |
| 2026-08-03 00:00 |
17:23:19.56 |
-14:20:11.7 |
HIP 85002 |
22.92 |
| 2026-08-03 12:00 |
17:23:18.18 |
-14:20:14.0 |
HIP 85002 |
22.76 |
| 2026-08-04 00:00 |
17:23:16.81 |
-14:20:16.4 |
HIP 85002 |
22.62 |
| 2026-08-04 12:00 |
17:23:15.46 |
-14:20:18.9 |
HIP 85002 |
22.48 |
| 2026-08-05 00:00 |
17:23:14.12 |
-14:20:21.3 |
HIP 85002 |
22.34 |
| 2026-08-05 12:00 |
17:23:12.80 |
-14:20:23.8 |
HIP 85002 |
22.21 |
| 2026-08-06 00:00 |
17:23:11.49 |
-14:20:26.4 |
HIP 85002 |
22.09 |
| 2026-08-06 12:00 |
17:23:10.20 |
-14:20:29.0 |
HIP 85002 |
21.98 |
| 2026-08-07 00:00 |
17:23:08.92 |
-14:20:31.6 |
HIP 85002 |
21.87 |
| 2026-08-07 12:00 |
17:23:07.66 |
-14:20:34.3 |
HIP 85002 |
21.77 |
| 2026-08-08 00:00 |
17:23:06.41 |
-14:20:37.0 |
HIP 85002 |
21.67 |
| 2026-08-08 12:00 |
17:23:05.18 |
-14:20:39.7 |
HIP 85002 |
21.58 |
| 2026-08-09 00:00 |
17:23:03.96 |
-14:20:42.5 |
HIP 85002 |
21.50 |
| 2026-08-09 12:00 |
17:23:02.76 |
-14:20:45.3 |
HIP 85002 |
21.42 |
| 2026-08-10 00:00 |
17:23:01.58 |
-14:20:48.1 |
HIP 85002 |
21.35 |
| 2026-08-10 12:00 |
17:23:00.41 |
-14:20:51.0 |
HIP 85002 |
21.28 |
| 2026-08-11 00:00 |
17:22:59.26 |
-14:20:54.0 |
HIP 85002 |
21.22 |
| 2026-08-11 12:00 |
17:22:58.12 |
-14:20:56.9 |
HIP 85002 |
21.17 |
| 2026-08-12 00:00 |
17:22:57.00 |
-14:21:00.0 |
HIP 85002 |
21.12 |
| 2026-08-12 12:00 |
17:22:55.90 |
-14:21:03.0 |
HIP 85002 |
21.07 |
| 2026-08-13 00:00 |
17:22:54.81 |
-14:21:06.0 |
HIP 85002 |
21.04 |
| 2026-08-13 12:00 |
17:22:53.74 |
-14:21:09.2 |
HIP 85002 |
21.00 |
| 2026-08-14 00:00 |
17:22:52.69 |
-14:21:12.3 |
HIP 85002 |
20.97 |
| 2026-08-14 12:00 |
17:22:51.65 |
-14:21:15.5 |
HIP 85002 |
20.95 |
| 2026-08-15 00:00 |
17:22:50.63 |
-14:21:18.7 |
HIP 85002 |
20.93 |
| 2026-08-15 12:00 |
17:22:49.62 |
-14:21:21.9 |
HIP 85002 |
20.92 |
| 2026-08-16 00:00 |
17:22:48.64 |
-14:21:25.2 |
HIP 85002 |
20.91 |
| 2026-08-16 12:00 |
17:22:47.67 |
-14:21:28.5 |
HIP 85002 |
20.90 |
| 2026-08-17 00:00 |
17:22:46.72 |
-14:21:31.9 |
HIP 85002 |
20.90 |
| 2026-08-17 12:00 |
17:22:45.78 |
-14:21:35.3 |
HIP 85002 |
20.91 |
| 2026-08-18 00:00 |
17:22:44.86 |
-14:21:38.7 |
HIP 85002 |
20.91 |
| 2026-08-18 12:00 |
17:22:43.96 |
-14:21:42.2 |
HIP 85002 |
20.92 |
| 2026-08-19 00:00 |
17:22:43.08 |
-14:21:45.7 |
HIP 85002 |
20.94 |