| Parameter |
Value |
| Designation |
C/1955 O1 (Honda) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1955-08-04T01:29:30.019200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:12Z |
| Obs used |
43 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1955-09-09.0000000 |
| e |
1.00111104 |
| q (au) |
0.884615 |
| a (au) |
-796.204707 |
| i (deg) |
107.523427 |
| Ω (om, deg) |
339.422185 |
| ω (w, deg) |
348.195749 |
| M (ma, deg) |
0.001577 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.055 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.055 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.520 |
| k |
0.800 |
| 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 |
| 1955-08-06 |
1955-09-03 |
-19.9934 |
+0.158 |
| 1955-09-03 |
1955-11-23 |
+9.5187 |
-1.437 |
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 |
11:47:41.19 |
+25:01:10.6 |
HIP 57351 |
29.87 |
| 2026-09-20 12:00 |
11:47:42.40 |
+25:01:04.0 |
HIP 57351 |
30.16 |
| 2026-09-21 00:00 |
11:47:43.61 |
+25:00:57.5 |
HIP 57351 |
30.45 |
| 2026-09-21 12:00 |
11:47:44.83 |
+25:00:51.0 |
HIP 57420 |
30.74 |
| 2026-09-22 00:00 |
11:47:46.04 |
+25:00:44.5 |
HIP 57420 |
30.83 |
| 2026-09-22 12:00 |
11:47:47.25 |
+25:00:38.1 |
HIP 57420 |
30.92 |
| 2026-09-23 00:00 |
11:47:48.47 |
+25:00:31.8 |
HIP 57420 |
31.02 |
| 2026-09-23 12:00 |
11:47:49.68 |
+25:00:25.6 |
HIP 57420 |
31.12 |
| 2026-09-24 00:00 |
11:47:50.89 |
+25:00:19.4 |
HIP 57420 |
31.23 |
| 2026-09-24 12:00 |
11:47:52.10 |
+25:00:13.3 |
HIP 57420 |
31.33 |
| 2026-09-25 00:00 |
11:47:53.31 |
+25:00:07.3 |
HIP 57420 |
31.44 |
| 2026-09-25 12:00 |
11:47:54.52 |
+25:00:01.3 |
HIP 57420 |
31.56 |
| 2026-09-26 00:00 |
11:47:55.73 |
+24:59:55.4 |
HIP 57420 |
31.67 |
| 2026-09-26 12:00 |
11:47:56.93 |
+24:59:49.5 |
HIP 57420 |
31.79 |
| 2026-09-27 00:00 |
11:47:58.14 |
+24:59:43.7 |
HIP 57420 |
31.91 |
| 2026-09-27 12:00 |
11:47:59.34 |
+24:59:38.0 |
HIP 57420 |
32.04 |
| 2026-09-28 00:00 |
11:48:00.55 |
+24:59:32.4 |
HIP 57420 |
32.17 |
| 2026-09-28 12:00 |
11:48:01.75 |
+24:59:26.8 |
HIP 57420 |
32.30 |
| 2026-09-29 00:00 |
11:48:02.95 |
+24:59:21.3 |
HIP 57420 |
32.43 |
| 2026-09-29 12:00 |
11:48:04.15 |
+24:59:15.9 |
HIP 57420 |
32.56 |
| 2026-09-30 00:00 |
11:48:05.34 |
+24:59:10.5 |
HIP 57420 |
32.70 |
| 2026-09-30 12:00 |
11:48:06.54 |
+24:59:05.2 |
HIP 57420 |
32.84 |
| 2026-10-01 00:00 |
11:48:07.73 |
+24:59:00.0 |
HIP 57420 |
32.98 |
| 2026-10-01 12:00 |
11:48:08.92 |
+24:58:54.8 |
HIP 57420 |
33.13 |
| 2026-10-02 00:00 |
11:48:10.11 |
+24:58:49.7 |
HIP 57420 |
33.27 |
| 2026-10-02 12:00 |
11:48:11.30 |
+24:58:44.7 |
HIP 57420 |
33.42 |
| 2026-10-03 00:00 |
11:48:12.48 |
+24:58:39.8 |
HIP 57420 |
33.57 |
| 2026-10-03 12:00 |
11:48:13.67 |
+24:58:34.9 |
HIP 57420 |
33.73 |
| 2026-10-04 00:00 |
11:48:14.85 |
+24:58:30.1 |
HIP 57420 |
33.88 |
| 2026-10-04 12:00 |
11:48:16.02 |
+24:58:25.4 |
HIP 57420 |
34.04 |
| 2026-10-05 00:00 |
11:48:17.20 |
+24:58:20.8 |
HIP 57420 |
34.20 |
| 2026-10-05 12:00 |
11:48:18.37 |
+24:58:16.2 |
HIP 57420 |
34.36 |
| 2026-10-06 00:00 |
11:48:19.54 |
+24:58:11.7 |
HIP 57420 |
34.52 |
| 2026-10-06 12:00 |
11:48:20.71 |
+24:58:07.3 |
HIP 57420 |
34.69 |
| 2026-10-07 00:00 |
11:48:21.88 |
+24:58:03.0 |
HIP 57420 |
34.85 |
| 2026-10-07 12:00 |
11:48:23.04 |
+24:57:58.7 |
HIP 57420 |
35.02 |
| 2026-10-08 00:00 |
11:48:24.20 |
+24:57:54.5 |
HIP 57420 |
35.19 |
| 2026-10-08 12:00 |
11:48:25.35 |
+24:57:50.4 |
HIP 57420 |
35.36 |
| 2026-10-09 00:00 |
11:48:26.50 |
+24:57:46.4 |
HIP 57420 |
35.53 |
| 2026-10-09 12:00 |
11:48:27.65 |
+24:57:42.4 |
HIP 57420 |
35.71 |
| 2026-10-10 00:00 |
11:48:28.80 |
+24:57:38.5 |
HIP 57513 |
35.85 |
| 2026-10-10 12:00 |
11:48:29.94 |
+24:57:34.7 |
HIP 57513 |
35.91 |
| 2026-10-11 00:00 |
11:48:31.08 |
+24:57:31.0 |
HIP 57513 |
35.97 |