| 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
$$
M_a = (2.870 + 5.022\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
2.870 |
| n |
5.022 |
| gf |
0.969 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.415 |
| 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) |
| 2026-09-20 00:00 |
06:56:27.70 |
+36:01:56.2 |
HIP 33329 |
23.96 |
| 2026-09-20 12:00 |
06:56:28.21 |
+36:02:00.8 |
HIP 33329 |
24.07 |
| 2026-09-21 00:00 |
06:56:28.71 |
+36:02:05.6 |
HIP 33329 |
24.17 |
| 2026-09-21 12:00 |
06:56:29.18 |
+36:02:10.3 |
HIP 33329 |
24.27 |
| 2026-09-22 00:00 |
06:56:29.64 |
+36:02:15.1 |
HIP 33329 |
24.38 |
| 2026-09-22 12:00 |
06:56:30.08 |
+36:02:20.0 |
HIP 33329 |
24.48 |
| 2026-09-23 00:00 |
06:56:30.49 |
+36:02:24.8 |
HIP 33329 |
24.58 |
| 2026-09-23 12:00 |
06:56:30.89 |
+36:02:29.8 |
HIP 33329 |
24.69 |
| 2026-09-24 00:00 |
06:56:31.27 |
+36:02:34.7 |
HIP 33329 |
24.79 |
| 2026-09-24 12:00 |
06:56:31.62 |
+36:02:39.7 |
HIP 33329 |
24.89 |
| 2026-09-25 00:00 |
06:56:31.96 |
+36:02:44.7 |
HIP 33329 |
24.99 |
| 2026-09-25 12:00 |
06:56:32.28 |
+36:02:49.8 |
HIP 33329 |
25.09 |
| 2026-09-26 00:00 |
06:56:32.58 |
+36:02:54.9 |
HIP 33329 |
25.19 |
| 2026-09-26 12:00 |
06:56:32.86 |
+36:03:00.0 |
HIP 33329 |
25.29 |
| 2026-09-27 00:00 |
06:56:33.11 |
+36:03:05.1 |
HIP 33329 |
25.39 |
| 2026-09-27 12:00 |
06:56:33.35 |
+36:03:10.3 |
HIP 33329 |
25.48 |
| 2026-09-28 00:00 |
06:56:33.57 |
+36:03:15.6 |
HIP 33329 |
25.58 |
| 2026-09-28 12:00 |
06:56:33.77 |
+36:03:20.8 |
HIP 33329 |
25.67 |
| 2026-09-29 00:00 |
06:56:33.95 |
+36:03:26.1 |
HIP 33329 |
25.77 |
| 2026-09-29 12:00 |
06:56:34.10 |
+36:03:31.4 |
HIP 33329 |
25.86 |
| 2026-09-30 00:00 |
06:56:34.24 |
+36:03:36.8 |
HIP 33329 |
25.96 |
| 2026-09-30 12:00 |
06:56:34.36 |
+36:03:42.2 |
HIP 33329 |
26.05 |
| 2026-10-01 00:00 |
06:56:34.45 |
+36:03:47.6 |
HIP 33329 |
26.14 |
| 2026-10-01 12:00 |
06:56:34.53 |
+36:03:53.0 |
HIP 33329 |
26.23 |
| 2026-10-02 00:00 |
06:56:34.59 |
+36:03:58.5 |
HIP 33329 |
26.32 |
| 2026-10-02 12:00 |
06:56:34.62 |
+36:04:04.0 |
HIP 33329 |
26.41 |
| 2026-10-03 00:00 |
06:56:34.64 |
+36:04:09.5 |
HIP 33329 |
26.50 |
| 2026-10-03 12:00 |
06:56:34.63 |
+36:04:15.1 |
HIP 33329 |
26.59 |
| 2026-10-04 00:00 |
06:56:34.60 |
+36:04:20.7 |
HIP 33329 |
26.68 |
| 2026-10-04 12:00 |
06:56:34.56 |
+36:04:26.3 |
HIP 33329 |
26.76 |
| 2026-10-05 00:00 |
06:56:34.49 |
+36:04:32.0 |
HIP 33329 |
26.85 |
| 2026-10-05 12:00 |
06:56:34.40 |
+36:04:37.6 |
HIP 33329 |
26.93 |
| 2026-10-06 00:00 |
06:56:34.29 |
+36:04:43.3 |
HIP 33329 |
27.02 |
| 2026-10-06 12:00 |
06:56:34.16 |
+36:04:49.1 |
HIP 33329 |
27.10 |
| 2026-10-07 00:00 |
06:56:34.01 |
+36:04:54.8 |
HIP 33329 |
27.18 |
| 2026-10-07 12:00 |
06:56:33.84 |
+36:05:00.6 |
HIP 33329 |
27.26 |
| 2026-10-08 00:00 |
06:56:33.65 |
+36:05:06.4 |
HIP 33329 |
27.35 |
| 2026-10-08 12:00 |
06:56:33.44 |
+36:05:12.2 |
HIP 33329 |
27.43 |
| 2026-10-09 00:00 |
06:56:33.20 |
+36:05:18.1 |
HIP 33329 |
27.51 |
| 2026-10-09 12:00 |
06:56:32.95 |
+36:05:24.0 |
HIP 33329 |
27.58 |
| 2026-10-10 00:00 |
06:56:32.67 |
+36:05:29.9 |
HIP 33329 |
27.66 |
| 2026-10-10 12:00 |
06:56:32.38 |
+36:05:35.8 |
HIP 33329 |
27.74 |
| 2026-10-11 00:00 |
06:56:32.06 |
+36:05:41.7 |
HIP 33329 |
27.82 |