153P/Ikeya-Zhang
Metadata
| Parameter | Value |
|---|---|
| Designation | 153P/Ikeya-Zhang |
| Type | P |
| Perihelion (tp_cal, UTC) | 2002-03-18T23:31:25.772160Z |
| Orbit solution date (soln_date, UTC) | 2020-06-17T10:40:41Z |
| Obs used | 1893 |
| NEO | - |
| M1 | 4.000 |
| K1 | 15.000 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2002-05-08.0000000 |
| e | 0.99008066 |
| q (au) | 0.507070 |
| a (au) | 51.119322 |
| i (deg) | 28.120957 |
| Ω (om, deg) | 93.369457 |
| ω (w, deg) | 34.668179 |
| M (ma, deg) | 0.134887 |
Magnitude
Scatter + Global Linear
$$ M_a = (6.663 + 3.285\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 6.663 |
| n | 3.285 |
| gf | 0.800 |
| gb | -0.500 |
| k | 0.926 |
| 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 |
|---|---|---|---|
| 2001-08-25 | 2002-02-03 | +7.8285 | +1.084 |
| 2002-02-03 | 2002-03-18 | +3.0730 | +0.799 |
| 2002-03-19 | 2002-06-13 | +0.2070 | +0.282 |
| 2002-06-13 | 2002-10-11 | +6.0428 | -0.737 |
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 | 19:55:55.14 | -32:38:36.8 | HIP 98012 | 26.35 |
| 2026-09-20 12:00 | 19:55:53.63 | -32:38:33.3 | HIP 98012 | 26.28 |
| 2026-09-21 00:00 | 19:55:52.15 | -32:38:29.7 | HIP 98012 | 26.21 |
| 2026-09-21 12:00 | 19:55:50.70 | -32:38:25.9 | HIP 98012 | 26.16 |
| 2026-09-22 00:00 | 19:55:49.27 | -32:38:22.1 | HIP 98012 | 26.11 |
| 2026-09-22 12:00 | 19:55:47.86 | -32:38:18.3 | HIP 98012 | 26.07 |
| 2026-09-23 00:00 | 19:55:46.48 | -32:38:14.3 | HIP 98012 | 26.03 |
| 2026-09-23 12:00 | 19:55:45.13 | -32:38:10.2 | HIP 98012 | 26.00 |
| 2026-09-24 00:00 | 19:55:43.80 | -32:38:06.0 | HIP 98012 | 25.98 |
| 2026-09-24 12:00 | 19:55:42.50 | -32:38:01.7 | HIP 98012 | 25.96 |
| 2026-09-25 00:00 | 19:55:41.22 | -32:37:57.4 | HIP 97896 | 25.79 |
| 2026-09-25 12:00 | 19:55:39.97 | -32:37:52.9 | HIP 97896 | 25.53 |
| 2026-09-26 00:00 | 19:55:38.75 | -32:37:48.4 | HIP 97896 | 25.28 |
| 2026-09-26 12:00 | 19:55:37.55 | -32:37:43.8 | HIP 97896 | 25.03 |
| 2026-09-27 00:00 | 19:55:36.38 | -32:37:39.0 | HIP 97896 | 24.79 |
| 2026-09-27 12:00 | 19:55:35.23 | -32:37:34.2 | HIP 97896 | 24.56 |
| 2026-09-28 00:00 | 19:55:34.11 | -32:37:29.3 | HIP 97896 | 24.33 |
| 2026-09-28 12:00 | 19:55:33.02 | -32:37:24.3 | HIP 97896 | 24.11 |
| 2026-09-29 00:00 | 19:55:31.95 | -32:37:19.3 | HIP 97896 | 23.89 |
| 2026-09-29 12:00 | 19:55:30.91 | -32:37:14.1 | HIP 97896 | 23.69 |
| 2026-09-30 00:00 | 19:55:29.90 | -32:37:08.8 | HIP 97896 | 23.48 |
| 2026-09-30 12:00 | 19:55:28.91 | -32:37:03.5 | HIP 97896 | 23.29 |
| 2026-10-01 00:00 | 19:55:27.95 | -32:36:58.1 | HIP 97896 | 23.10 |
| 2026-10-01 12:00 | 19:55:27.01 | -32:36:52.6 | HIP 97896 | 22.91 |
| 2026-10-02 00:00 | 19:55:26.11 | -32:36:47.0 | HIP 97896 | 22.74 |
| 2026-10-02 12:00 | 19:55:25.23 | -32:36:41.3 | HIP 97896 | 22.56 |
| 2026-10-03 00:00 | 19:55:24.38 | -32:36:35.5 | HIP 97896 | 22.40 |
| 2026-10-03 12:00 | 19:55:23.55 | -32:36:29.6 | HIP 97896 | 22.24 |
| 2026-10-04 00:00 | 19:55:22.75 | -32:36:23.7 | HIP 97896 | 22.09 |
| 2026-10-04 12:00 | 19:55:21.98 | -32:36:17.7 | HIP 97896 | 21.95 |
| 2026-10-05 00:00 | 19:55:21.24 | -32:36:11.6 | HIP 97896 | 21.81 |
| 2026-10-05 12:00 | 19:55:20.52 | -32:36:05.4 | HIP 97896 | 21.68 |
| 2026-10-06 00:00 | 19:55:19.83 | -32:35:59.1 | HIP 97896 | 21.55 |
| 2026-10-06 12:00 | 19:55:19.17 | -32:35:52.7 | HIP 97896 | 21.43 |
| 2026-10-07 00:00 | 19:55:18.54 | -32:35:46.3 | HIP 97896 | 21.32 |
| 2026-10-07 12:00 | 19:55:17.93 | -32:35:39.8 | HIP 97896 | 21.22 |
| 2026-10-08 00:00 | 19:55:17.36 | -32:35:33.2 | HIP 97896 | 21.12 |
| 2026-10-08 12:00 | 19:55:16.81 | -32:35:26.5 | HIP 97896 | 21.03 |
| 2026-10-09 00:00 | 19:55:16.29 | -32:35:19.7 | HIP 97896 | 20.95 |
| 2026-10-09 12:00 | 19:55:15.79 | -32:35:12.9 | HIP 97896 | 20.87 |
| 2026-10-10 00:00 | 19:55:15.33 | -32:35:06.0 | HIP 97896 | 20.80 |
| 2026-10-10 12:00 | 19:55:14.89 | -32:34:59.0 | HIP 97896 | 20.73 |
| 2026-10-11 00:00 | 19:55:14.48 | -32:34:51.9 | HIP 97896 | 20.68 |