C/1987 H1 (Shoemaker)
| Parameter |
Value |
| Designation |
C/1987 H1 (Shoemaker) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1986-11-17T00:37:43.749120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:33Z |
| Obs used |
126 |
| NEO |
- |
| M1 |
5.200 |
| K1 |
9.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1987-11-03.0000000 |
| e |
1.00321165 |
| q (au) |
5.457290 |
| a (au) |
-1699.216266 |
| i (deg) |
132.485156 |
| Ω (om, deg) |
268.336619 |
| ω (w, deg) |
16.992162 |
| M (ma, deg) |
0.004939 |
Magnitude
Scatter + Global Linear
$$
M_a = (2.864 + 5.022\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
2.864 |
| n |
5.022 |
| gf |
0.980 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.814 |
| 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) |
| 2026-02-03 00:00 |
06:50:14.87 |
+36:32:21.3 |
HIP 32798 |
8.24 |
| 2026-02-03 12:00 |
06:50:12.64 |
+36:32:18.6 |
HIP 32798 |
8.20 |
| 2026-02-04 00:00 |
06:50:10.42 |
+36:32:15.8 |
HIP 32798 |
8.18 |
| 2026-02-04 12:00 |
06:50:08.22 |
+36:32:12.9 |
HIP 32798 |
8.18 |
| 2026-02-05 00:00 |
06:50:06.02 |
+36:32:10.0 |
HIP 32728 |
7.97 |
| 2026-02-05 12:00 |
06:50:03.84 |
+36:32:07.0 |
HIP 32728 |
7.63 |
| 2026-02-06 00:00 |
06:50:01.67 |
+36:32:03.9 |
HIP 32728 |
7.30 |
| 2026-02-06 12:00 |
06:49:59.52 |
+36:32:00.8 |
HIP 32728 |
6.99 |
| 2026-02-07 00:00 |
06:49:57.38 |
+36:31:57.6 |
HIP 32728 |
6.69 |
| 2026-02-07 12:00 |
06:49:55.25 |
+36:31:54.3 |
HIP 32728 |
6.40 |
| 2026-02-08 00:00 |
06:49:53.14 |
+36:31:51.0 |
HIP 32728 |
6.14 |
| 2026-02-08 12:00 |
06:49:51.04 |
+36:31:47.6 |
HIP 32728 |
5.89 |
| 2026-02-09 00:00 |
06:49:48.95 |
+36:31:44.2 |
HIP 32728 |
5.66 |
| 2026-02-09 12:00 |
06:49:46.88 |
+36:31:40.7 |
HIP 32728 |
5.46 |
| 2026-02-10 00:00 |
06:49:44.82 |
+36:31:37.1 |
HIP 32728 |
5.29 |
| 2026-02-10 12:00 |
06:49:42.78 |
+36:31:33.4 |
HIP 32728 |
5.14 |
| 2026-02-11 00:00 |
06:49:40.75 |
+36:31:29.7 |
HIP 32728 |
5.02 |
| 2026-02-11 12:00 |
06:49:38.73 |
+36:31:26.0 |
HIP 32728 |
4.93 |
| 2026-02-12 00:00 |
06:49:36.73 |
+36:31:22.1 |
HIP 32728 |
4.87 |
| 2026-02-12 12:00 |
06:49:34.75 |
+36:31:18.3 |
HIP 32728 |
4.84 |
| 2026-02-13 00:00 |
06:49:32.78 |
+36:31:14.3 |
HIP 32728 |
4.85 |
| 2026-02-13 12:00 |
06:49:30.82 |
+36:31:10.3 |
HIP 32728 |
4.89 |
| 2026-02-14 00:00 |
06:49:28.88 |
+36:31:06.2 |
HIP 32728 |
4.96 |
| 2026-02-14 12:00 |
06:49:26.96 |
+36:31:02.1 |
HIP 32728 |
5.05 |
| 2026-02-15 00:00 |
06:49:25.05 |
+36:30:57.9 |
HIP 32728 |
5.17 |
| 2026-02-15 12:00 |
06:49:23.16 |
+36:30:53.6 |
HIP 32728 |
5.32 |
| 2026-02-16 00:00 |
06:49:21.28 |
+36:30:49.3 |
HIP 32728 |
5.48 |
| 2026-02-16 12:00 |
06:49:19.42 |
+36:30:44.9 |
HIP 32728 |
5.67 |
| 2026-02-17 00:00 |
06:49:17.58 |
+36:30:40.5 |
HIP 32728 |
5.87 |
| 2026-02-17 12:00 |
06:49:15.75 |
+36:30:36.0 |
HIP 32728 |
6.08 |
| 2026-02-18 00:00 |
06:49:13.94 |
+36:30:31.4 |
HIP 32728 |
6.30 |
| 2026-02-18 12:00 |
06:49:12.15 |
+36:30:26.8 |
HIP 32728 |
6.54 |
| 2026-02-19 00:00 |
06:49:10.37 |
+36:30:22.1 |
HIP 32728 |
6.78 |
| 2026-02-19 12:00 |
06:49:08.61 |
+36:30:17.4 |
HIP 32728 |
7.03 |
| 2026-02-20 00:00 |
06:49:06.87 |
+36:30:12.6 |
HIP 32728 |
7.29 |
| 2026-02-20 12:00 |
06:49:05.14 |
+36:30:07.8 |
HIP 32728 |
7.55 |
| 2026-02-21 00:00 |
06:49:03.43 |
+36:30:02.9 |
HIP 32728 |
7.82 |
| 2026-02-21 12:00 |
06:49:01.74 |
+36:29:57.9 |
HIP 32728 |
8.09 |
| 2026-02-22 00:00 |
06:49:00.07 |
+36:29:52.9 |
HIP 32728 |
8.36 |
| 2026-02-22 12:00 |
06:48:58.41 |
+36:29:47.8 |
HIP 32728 |
8.63 |
| 2026-02-23 00:00 |
06:48:56.78 |
+36:29:42.7 |
HIP 32728 |
8.91 |
| 2026-02-23 12:00 |
06:48:55.16 |
+36:29:37.5 |
HIP 32728 |
9.18 |
| 2026-02-24 00:00 |
06:48:53.55 |
+36:29:32.3 |
HIP 32728 |
9.46 |