| 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) |
| 2026-09-20 00:00 |
17:22:24.38 |
-14:26:23.9 |
HIP 85002 |
25.20 |
| 2026-09-20 12:00 |
17:22:24.70 |
-14:26:28.9 |
HIP 85002 |
25.28 |
| 2026-09-21 00:00 |
17:22:25.04 |
-14:26:33.9 |
HIP 85002 |
25.37 |
| 2026-09-21 12:00 |
17:22:25.39 |
-14:26:38.9 |
HIP 85002 |
25.45 |
| 2026-09-22 00:00 |
17:22:25.77 |
-14:26:43.9 |
HIP 85002 |
25.53 |
| 2026-09-22 12:00 |
17:22:26.16 |
-14:26:48.9 |
HIP 85002 |
25.61 |
| 2026-09-23 00:00 |
17:22:26.57 |
-14:26:54.0 |
HIP 85002 |
25.70 |
| 2026-09-23 12:00 |
17:22:27.00 |
-14:26:59.0 |
HIP 85002 |
25.78 |
| 2026-09-24 00:00 |
17:22:27.45 |
-14:27:04.1 |
HIP 85002 |
25.87 |
| 2026-09-24 12:00 |
17:22:27.92 |
-14:27:09.1 |
HIP 85002 |
25.95 |
| 2026-09-25 00:00 |
17:22:28.40 |
-14:27:14.2 |
HIP 85002 |
26.04 |
| 2026-09-25 12:00 |
17:22:28.91 |
-14:27:19.3 |
HIP 85002 |
26.12 |
| 2026-09-26 00:00 |
17:22:29.43 |
-14:27:24.3 |
HIP 85002 |
26.21 |
| 2026-09-26 12:00 |
17:22:29.97 |
-14:27:29.4 |
HIP 85002 |
26.30 |
| 2026-09-27 00:00 |
17:22:30.53 |
-14:27:34.5 |
HIP 85002 |
26.39 |
| 2026-09-27 12:00 |
17:22:31.11 |
-14:27:39.6 |
HIP 85002 |
26.48 |
| 2026-09-28 00:00 |
17:22:31.70 |
-14:27:44.8 |
HIP 85002 |
26.57 |
| 2026-09-28 12:00 |
17:22:32.32 |
-14:27:49.9 |
HIP 85002 |
26.66 |
| 2026-09-29 00:00 |
17:22:32.95 |
-14:27:55.0 |
HIP 85002 |
26.76 |
| 2026-09-29 12:00 |
17:22:33.60 |
-14:28:00.1 |
HIP 85002 |
26.85 |
| 2026-09-30 00:00 |
17:22:34.27 |
-14:28:05.3 |
HIP 85002 |
26.95 |
| 2026-09-30 12:00 |
17:22:34.95 |
-14:28:10.4 |
HIP 85002 |
27.05 |
| 2026-10-01 00:00 |
17:22:35.66 |
-14:28:15.5 |
HIP 85002 |
27.14 |
| 2026-10-01 12:00 |
17:22:36.38 |
-14:28:20.7 |
HIP 85002 |
27.24 |
| 2026-10-02 00:00 |
17:22:37.12 |
-14:28:25.8 |
HIP 85002 |
27.35 |
| 2026-10-02 12:00 |
17:22:37.88 |
-14:28:31.0 |
HIP 85002 |
27.45 |
| 2026-10-03 00:00 |
17:22:38.65 |
-14:28:36.1 |
HIP 85002 |
27.55 |
| 2026-10-03 12:00 |
17:22:39.45 |
-14:28:41.3 |
HIP 85002 |
27.66 |
| 2026-10-04 00:00 |
17:22:40.26 |
-14:28:46.5 |
HIP 85002 |
27.77 |
| 2026-10-04 12:00 |
17:22:41.09 |
-14:28:51.6 |
HIP 85002 |
27.88 |
| 2026-10-05 00:00 |
17:22:41.94 |
-14:28:56.8 |
HIP 85002 |
27.99 |
| 2026-10-05 12:00 |
17:22:42.80 |
-14:29:02.0 |
HIP 85002 |
28.10 |
| 2026-10-06 00:00 |
17:22:43.69 |
-14:29:07.1 |
HIP 85002 |
28.22 |
| 2026-10-06 12:00 |
17:22:44.59 |
-14:29:12.3 |
HIP 85002 |
28.34 |
| 2026-10-07 00:00 |
17:22:45.51 |
-14:29:17.5 |
HIP 85026 |
28.30 |
| 2026-10-07 12:00 |
17:22:46.44 |
-14:29:22.6 |
HIP 85026 |
28.22 |
| 2026-10-08 00:00 |
17:22:47.40 |
-14:29:27.8 |
HIP 85026 |
28.14 |
| 2026-10-08 12:00 |
17:22:48.37 |
-14:29:32.9 |
HIP 85026 |
28.07 |
| 2026-10-09 00:00 |
17:22:49.35 |
-14:29:38.1 |
HIP 85026 |
27.99 |
| 2026-10-09 12:00 |
17:22:50.36 |
-14:29:43.3 |
HIP 85026 |
27.92 |
| 2026-10-10 00:00 |
17:22:51.38 |
-14:29:48.4 |
HIP 85026 |
27.85 |
| 2026-10-10 12:00 |
17:22:52.42 |
-14:29:53.6 |
HIP 85026 |
27.79 |
| 2026-10-11 00:00 |
17:22:53.48 |
-14:29:58.7 |
HIP 85026 |
27.72 |