C/1987 W1 (Ichimura)
| Parameter |
Value |
| Designation |
C/1987 W1 (Ichimura) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1988-01-10T02:29:58.758720Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:36Z |
| Obs used |
48 |
| NEO |
- |
| M1 |
8.900 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1987-11-28.0000000 |
| e |
0.99999939 |
| q (au) |
0.199518 |
| a (au) |
327902.551553 |
| i (deg) |
41.620500 |
| Ω (om, deg) |
226.527901 |
| ω (w, deg) |
329.292632 |
| M (ma, deg) |
360.000000 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.504 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.504 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-1.000 |
| k |
0.824 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
00:19:39.03 |
+27:48:13.7 |
HIP 1699 |
23.03 |
| 2026-02-03 12:00 |
00:19:40.26 |
+27:48:10.4 |
HIP 1699 |
22.75 |
| 2026-02-04 00:00 |
00:19:41.51 |
+27:48:07.1 |
HIP 1699 |
22.47 |
| 2026-02-04 12:00 |
00:19:42.76 |
+27:48:04.0 |
HIP 1699 |
22.18 |
| 2026-02-05 00:00 |
00:19:44.04 |
+27:48:01.0 |
HIP 1699 |
21.90 |
| 2026-02-05 12:00 |
00:19:45.32 |
+27:47:58.2 |
HIP 1699 |
21.61 |
| 2026-02-06 00:00 |
00:19:46.62 |
+27:47:55.5 |
HIP 1699 |
21.32 |
| 2026-02-06 12:00 |
00:19:47.93 |
+27:47:52.9 |
HIP 1699 |
21.03 |
| 2026-02-07 00:00 |
00:19:49.25 |
+27:47:50.5 |
HIP 1699 |
20.73 |
| 2026-02-07 12:00 |
00:19:50.58 |
+27:47:48.2 |
HIP 1699 |
20.44 |
| 2026-02-08 00:00 |
00:19:51.93 |
+27:47:46.1 |
HIP 1699 |
20.14 |
| 2026-02-08 12:00 |
00:19:53.28 |
+27:47:44.0 |
HIP 1699 |
19.84 |
| 2026-02-09 00:00 |
00:19:54.65 |
+27:47:42.2 |
HIP 1699 |
19.53 |
| 2026-02-09 12:00 |
00:19:56.04 |
+27:47:40.4 |
HIP 1699 |
19.23 |
| 2026-02-10 00:00 |
00:19:57.43 |
+27:47:38.8 |
HIP 1699 |
18.92 |
| 2026-02-10 12:00 |
00:19:58.83 |
+27:47:37.3 |
HIP 1699 |
18.61 |
| 2026-02-11 00:00 |
00:20:00.25 |
+27:47:36.0 |
HIP 1699 |
18.30 |
| 2026-02-11 12:00 |
00:20:01.68 |
+27:47:34.8 |
HIP 1699 |
17.99 |
| 2026-02-12 00:00 |
00:20:03.12 |
+27:47:33.7 |
HIP 1699 |
17.67 |
| 2026-02-12 12:00 |
00:20:04.57 |
+27:47:32.8 |
HIP 1699 |
17.35 |
| 2026-02-13 00:00 |
00:20:06.03 |
+27:47:32.0 |
HIP 1699 |
17.03 |
| 2026-02-13 12:00 |
00:20:07.50 |
+27:47:31.4 |
HIP 1699 |
16.71 |
| 2026-02-14 00:00 |
00:20:08.98 |
+27:47:30.8 |
HIP 1699 |
16.39 |
| 2026-02-14 12:00 |
00:20:10.48 |
+27:47:30.5 |
HIP 1699 |
16.07 |
| 2026-02-15 00:00 |
00:20:11.98 |
+27:47:30.2 |
HIP 1699 |
15.74 |
| 2026-02-15 12:00 |
00:20:13.50 |
+27:47:30.1 |
HIP 1699 |
15.41 |
| 2026-02-16 00:00 |
00:20:15.02 |
+27:47:30.2 |
HIP 1699 |
15.08 |
| 2026-02-16 12:00 |
00:20:16.56 |
+27:47:30.3 |
HIP 1699 |
14.76 |
| 2026-02-17 00:00 |
00:20:18.10 |
+27:47:30.6 |
HIP 1699 |
14.42 |
| 2026-02-17 12:00 |
00:20:19.66 |
+27:47:31.1 |
HIP 1699 |
14.09 |
| 2026-02-18 00:00 |
00:20:21.22 |
+27:47:31.7 |
HIP 1699 |
13.76 |
| 2026-02-18 12:00 |
00:20:22.80 |
+27:47:32.4 |
HIP 1699 |
13.43 |
| 2026-02-19 00:00 |
00:20:24.39 |
+27:47:33.2 |
HIP 1699 |
13.09 |
| 2026-02-19 12:00 |
00:20:25.98 |
+27:47:34.2 |
HIP 1699 |
12.76 |
| 2026-02-20 00:00 |
00:20:27.58 |
+27:47:35.3 |
HIP 1699 |
12.42 |
| 2026-02-20 12:00 |
00:20:29.20 |
+27:47:36.6 |
HIP 1699 |
12.09 |
| 2026-02-21 00:00 |
00:20:30.82 |
+27:47:38.0 |
HIP 1699 |
11.75 |
| 2026-02-21 12:00 |
00:20:32.45 |
+27:47:39.5 |
HIP 1699 |
11.42 |
| 2026-02-22 00:00 |
00:20:34.09 |
+27:47:41.2 |
HIP 1699 |
11.08 |
| 2026-02-22 12:00 |
00:20:35.74 |
+27:47:43.0 |
HIP 1699 |
10.75 |
| 2026-02-23 00:00 |
00:20:37.40 |
+27:47:44.9 |
HIP 1699 |
10.42 |
| 2026-02-23 12:00 |
00:20:39.06 |
+27:47:47.0 |
HIP 1699 |
10.09 |
| 2026-02-24 00:00 |
00:20:40.74 |
+27:47:49.2 |
HIP 1699 |
9.76 |