| 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
$$
M_a = (10.506 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.506 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-1.000 |
| k |
0.843 |
| 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) |
| 2026-06-01 00:00 |
00:26:02.57 |
+28:24:11.8 |
HIP 1990 |
22.62 |
| 2026-06-01 12:00 |
00:26:03.45 |
+28:24:26.7 |
HIP 1990 |
22.93 |
| 2026-06-02 00:00 |
00:26:04.32 |
+28:24:41.5 |
HIP 1990 |
23.24 |
| 2026-06-02 12:00 |
00:26:05.18 |
+28:24:56.3 |
HIP 1990 |
23.55 |
| 2026-06-03 00:00 |
00:26:06.02 |
+28:25:11.0 |
HIP 1990 |
23.85 |
| 2026-06-03 12:00 |
00:26:06.84 |
+28:25:25.8 |
HIP 1990 |
24.16 |
| 2026-06-04 00:00 |
00:26:07.65 |
+28:25:40.5 |
HIP 1990 |
24.46 |
| 2026-06-04 12:00 |
00:26:08.45 |
+28:25:55.1 |
HIP 1990 |
24.76 |
| 2026-06-05 00:00 |
00:26:09.23 |
+28:26:09.8 |
HIP 1990 |
25.05 |
| 2026-06-05 12:00 |
00:26:10.00 |
+28:26:24.4 |
HIP 1990 |
25.35 |
| 2026-06-06 00:00 |
00:26:10.75 |
+28:26:38.9 |
HIP 1990 |
25.64 |
| 2026-06-06 12:00 |
00:26:11.49 |
+28:26:53.5 |
HIP 1990 |
25.93 |
| 2026-06-07 00:00 |
00:26:12.22 |
+28:27:08.0 |
HIP 1990 |
26.22 |
| 2026-06-07 12:00 |
00:26:12.92 |
+28:27:22.4 |
HIP 1990 |
26.51 |
| 2026-06-08 00:00 |
00:26:13.62 |
+28:27:36.9 |
HIP 1990 |
26.79 |
| 2026-06-08 12:00 |
00:26:14.30 |
+28:27:51.2 |
HIP 1990 |
27.08 |
| 2026-06-09 00:00 |
00:26:14.96 |
+28:28:05.6 |
HIP 2200 |
27.13 |
| 2026-06-09 12:00 |
00:26:15.61 |
+28:28:19.9 |
HIP 2200 |
27.18 |
| 2026-06-10 00:00 |
00:26:16.25 |
+28:28:34.1 |
HIP 2200 |
27.23 |
| 2026-06-10 12:00 |
00:26:16.86 |
+28:28:48.3 |
HIP 2200 |
27.29 |
| 2026-06-11 00:00 |
00:26:17.47 |
+28:29:02.5 |
HIP 2200 |
27.35 |
| 2026-06-11 12:00 |
00:26:18.06 |
+28:29:16.6 |
HIP 2055 |
27.36 |
| 2026-06-12 00:00 |
00:26:18.63 |
+28:29:30.7 |
HIP 2055 |
27.15 |
| 2026-06-12 12:00 |
00:26:19.19 |
+28:29:44.7 |
HIP 2055 |
26.93 |
| 2026-06-13 00:00 |
00:26:19.73 |
+28:29:58.7 |
HIP 2055 |
26.72 |
| 2026-06-13 12:00 |
00:26:20.26 |
+28:30:12.6 |
HIP 2055 |
26.50 |
| 2026-06-14 00:00 |
00:26:20.77 |
+28:30:26.5 |
HIP 2055 |
26.29 |
| 2026-06-14 12:00 |
00:26:21.27 |
+28:30:40.3 |
HIP 2055 |
26.08 |
| 2026-06-15 00:00 |
00:26:21.75 |
+28:30:54.1 |
HIP 2055 |
25.87 |
| 2026-06-15 12:00 |
00:26:22.21 |
+28:31:07.8 |
HIP 2055 |
25.66 |
| 2026-06-16 00:00 |
00:26:22.66 |
+28:31:21.4 |
HIP 2055 |
25.45 |
| 2026-06-16 12:00 |
00:26:23.09 |
+28:31:35.0 |
HIP 2055 |
25.25 |
| 2026-06-17 00:00 |
00:26:23.51 |
+28:31:48.6 |
HIP 2055 |
25.04 |
| 2026-06-17 12:00 |
00:26:23.91 |
+28:32:02.1 |
HIP 2055 |
24.84 |
| 2026-06-18 00:00 |
00:26:24.30 |
+28:32:15.5 |
HIP 2055 |
24.63 |
| 2026-06-18 12:00 |
00:26:24.67 |
+28:32:28.9 |
HIP 2055 |
24.43 |
| 2026-06-19 00:00 |
00:26:25.03 |
+28:32:42.2 |
HIP 2055 |
24.23 |
| 2026-06-19 12:00 |
00:26:25.36 |
+28:32:55.4 |
HIP 2055 |
24.03 |
| 2026-06-20 00:00 |
00:26:25.69 |
+28:33:08.6 |
HIP 2055 |
23.83 |
| 2026-06-20 12:00 |
00:26:25.99 |
+28:33:21.7 |
HIP 2055 |
23.63 |
| 2026-06-21 00:00 |
00:26:26.29 |
+28:33:34.7 |
HIP 2055 |
23.43 |
| 2026-06-21 12:00 |
00:26:26.56 |
+28:33:47.7 |
HIP 2055 |
23.23 |
| 2026-06-22 00:00 |
00:26:26.82 |
+28:34:00.6 |
HIP 2055 |
23.04 |