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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 20:00:24.09 | -32:35:13.1 | HIP 98319 | 23.33 |
| 2026-07-29 12:00 | 20:00:20.92 | -32:35:20.3 | HIP 98319 | 22.65 |
| 2026-07-30 00:00 | 20:00:17.75 | -32:35:27.3 | HIP 98319 | 21.97 |
| 2026-07-30 12:00 | 20:00:14.58 | -32:35:34.3 | HIP 98319 | 21.29 |
| 2026-07-31 00:00 | 20:00:11.42 | -32:35:41.1 | HIP 98319 | 20.62 |
| 2026-07-31 12:00 | 20:00:08.26 | -32:35:47.9 | HIP 98319 | 19.95 |
| 2026-08-01 00:00 | 20:00:05.11 | -32:35:54.6 | HIP 98319 | 19.28 |
| 2026-08-01 12:00 | 20:00:01.96 | -32:36:01.2 | HIP 98319 | 18.61 |
| 2026-08-02 00:00 | 19:59:58.82 | -32:36:07.7 | HIP 98319 | 17.94 |
| 2026-08-02 12:00 | 19:59:55.68 | -32:36:14.1 | HIP 98319 | 17.27 |
| 2026-08-03 00:00 | 19:59:52.56 | -32:36:20.5 | HIP 98319 | 16.60 |
| 2026-08-03 12:00 | 19:59:49.43 | -32:36:26.7 | HIP 98319 | 15.94 |
| 2026-08-04 00:00 | 19:59:46.32 | -32:36:32.8 | HIP 98319 | 15.28 |
| 2026-08-04 12:00 | 19:59:43.21 | -32:36:38.9 | HIP 98319 | 14.62 |
| 2026-08-05 00:00 | 19:59:40.10 | -32:36:44.8 | HIP 98319 | 13.96 |
| 2026-08-05 12:00 | 19:59:37.01 | -32:36:50.7 | HIP 98319 | 13.30 |
| 2026-08-06 00:00 | 19:59:33.92 | -32:36:56.4 | HIP 98319 | 12.65 |
| 2026-08-06 12:00 | 19:59:30.84 | -32:37:02.1 | HIP 98319 | 11.99 |
| 2026-08-07 00:00 | 19:59:27.77 | -32:37:07.6 | HIP 98319 | 11.34 |
| 2026-08-07 12:00 | 19:59:24.70 | -32:37:13.1 | HIP 98319 | 10.69 |
| 2026-08-08 00:00 | 19:59:21.65 | -32:37:18.5 | HIP 98319 | 10.04 |
| 2026-08-08 12:00 | 19:59:18.60 | -32:37:23.8 | HIP 98319 | 9.40 |
| 2026-08-09 00:00 | 19:59:15.56 | -32:37:28.9 | HIP 98319 | 8.76 |
| 2026-08-09 12:00 | 19:59:12.53 | -32:37:34.0 | HIP 98319 | 8.12 |
| 2026-08-10 00:00 | 19:59:09.52 | -32:37:39.0 | HIP 98319 | 7.48 |
| 2026-08-10 12:00 | 19:59:06.51 | -32:37:43.8 | HIP 98319 | 6.85 |
| 2026-08-11 00:00 | 19:59:03.51 | -32:37:48.6 | HIP 98319 | 6.22 |
| 2026-08-11 12:00 | 19:59:00.52 | -32:37:53.3 | HIP 98319 | 5.59 |
| 2026-08-12 00:00 | 19:58:57.54 | -32:37:57.9 | HIP 98319 | 4.96 |
| 2026-08-12 12:00 | 19:58:54.57 | -32:38:02.3 | HIP 98319 | 4.34 |
| 2026-08-13 00:00 | 19:58:51.62 | -32:38:06.7 | HIP 98319 | 3.73 |
| 2026-08-13 12:00 | 19:58:48.67 | -32:38:11.0 | HIP 98319 | 3.12 |
| 2026-08-14 00:00 | 19:58:45.74 | -32:38:15.2 | HIP 98319 | 2.53 |
| 2026-08-14 12:00 | 19:58:42.81 | -32:38:19.2 | HIP 98319 | 1.95 |
| 2026-08-15 00:00 | 19:58:39.90 | -32:38:23.2 | HIP 98319 | 1.40 |
| 2026-08-15 12:00 | 19:58:37.01 | -32:38:27.1 | HIP 98319 | 0.95 |
| 2026-08-16 00:00 | 19:58:34.12 | -32:38:30.8 | HIP 98319 | 0.77 |
| 2026-08-16 12:00 | 19:58:31.25 | -32:38:34.5 | HIP 98319 | 1.01 |
| 2026-08-17 00:00 | 19:58:28.39 | -32:38:38.0 | HIP 98319 | 1.48 |
| 2026-08-17 12:00 | 19:58:25.54 | -32:38:41.5 | HIP 98319 | 2.01 |
| 2026-08-18 00:00 | 19:58:22.71 | -32:38:44.8 | HIP 98319 | 2.58 |
| 2026-08-18 12:00 | 19:58:19.89 | -32:38:48.1 | HIP 98319 | 3.15 |
| 2026-08-19 00:00 | 19:58:17.09 | -32:38:51.2 | HIP 98319 | 3.73 |