73P/Schwassmann-Wachmann 3
Metadata
| Parameter | Value |
|---|---|
| Designation | 73P/Schwassmann-Wachmann 3 |
| Type | P |
| Perihelion (tp_cal, UTC) | 2022-08-25T14:11:28.976640Z |
| Orbit solution date (soln_date, UTC) | 2025-08-20T11:15:26Z |
| Obs used | 515 |
| NEO | Yes |
| M1 | 14.300 |
| K1 | 8.000 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2020-10-05.0000000 |
| e | 0.68565940 |
| q (au) | 0.972305 |
| a (au) | 3.093157 |
| i (deg) | 11.232390 |
| Ω (om, deg) | 69.644230 |
| ω (w, deg) | 199.450713 |
| M (ma, deg) | 235.062452 |
Magnitude
Scatter + Global Linear
$$ M_a = (13.529 + 3.580\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 13.529 |
| n | 3.580 |
| gf | 0.800 |
| gb | -0.500 |
| k | 1.000 |
| 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 |
|---|---|---|---|
| 2021-01-13 | 2022-07-21 | +1.3941 | -0.399 |
| 2022-07-21 | 2022-08-23 | -39.7191 | +1.616 |
| 2022-08-25 | 2022-10-19 | -39.2655 | +0.068 |
| 2022-10-19 | 2023-08-15 | +7.1396 | -4.477 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Finding Chart
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 08:35:47.56 | +23:38:15.6 | HIP 42303 | 23.94 |
| 2026-09-20 12:00 | 08:36:13.62 | +23:37:11.8 | HIP 42303 | 17.88 |
| 2026-09-21 00:00 | 08:36:39.60 | +23:36:08.2 | HIP 42303 | 11.84 |
| 2026-09-21 12:00 | 08:37:05.48 | +23:35:05.0 | HIP 42303 | 5.82 |
| 2026-09-22 00:00 | 08:37:31.28 | +23:34:02.0 | HIP 42303 | 0.43 |
| 2026-09-22 12:00 | 08:37:56.99 | +23:32:59.4 | HIP 42303 | 6.19 |
| 2026-09-23 00:00 | 08:38:22.61 | +23:31:57.1 | HIP 42403 | 10.62 |
| 2026-09-23 12:00 | 08:38:48.13 | +23:30:55.1 | HIP 42403 | 10.27 |
| 2026-09-24 00:00 | 08:39:13.57 | +23:29:53.5 | HIP 42403 | 12.98 |
| 2026-09-24 12:00 | 08:39:38.91 | +23:28:52.2 | HIP 42403 | 17.35 |
| 2026-09-25 00:00 | 08:40:04.16 | +23:27:51.2 | HIP 42403 | 22.40 |
| 2026-09-25 12:00 | 08:40:29.32 | +23:26:50.6 | HIP 42403 | 27.76 |
| 2026-09-26 00:00 | 08:40:54.38 | +23:25:50.4 | HIP 42681 | 26.47 |
| 2026-09-26 12:00 | 08:41:19.34 | +23:24:50.5 | HIP 42681 | 24.73 |
| 2026-09-27 00:00 | 08:41:44.21 | +23:23:51.0 | HIP 42681 | 24.29 |
| 2026-09-27 12:00 | 08:42:08.97 | +23:22:51.8 | HIP 42681 | 25.19 |
| 2026-09-28 00:00 | 08:42:33.64 | +23:21:53.1 | HIP 42681 | 27.29 |
| 2026-09-28 12:00 | 08:42:58.21 | +23:20:54.7 | HIP 42681 | 30.33 |
| 2026-09-29 00:00 | 08:43:22.68 | +23:19:56.8 | HIP 42681 | 34.05 |
| 2026-09-29 12:00 | 08:43:47.05 | +23:18:59.3 | HIP 42840 | 36.19 |
| 2026-09-30 00:00 | 08:44:11.31 | +23:18:02.1 | HIP 42840 | 35.73 |
| 2026-09-30 12:00 | 08:44:35.47 | +23:17:05.4 | HIP 42840 | 36.16 |
| 2026-10-01 00:00 | 08:44:59.52 | +23:16:09.2 | HIP 42840 | 37.44 |
| 2026-10-01 12:00 | 08:45:23.47 | +23:15:13.4 | HIP 43171 | 32.01 |
| 2026-10-02 00:00 | 08:45:47.30 | +23:14:18.0 | HIP 43171 | 26.53 |
| 2026-10-02 12:00 | 08:46:11.03 | +23:13:23.1 | HIP 43171 | 21.10 |
| 2026-10-03 00:00 | 08:46:34.65 | +23:12:28.7 | HIP 43171 | 15.78 |
| 2026-10-03 12:00 | 08:46:58.16 | +23:11:34.7 | HIP 43171 | 10.67 |
| 2026-10-04 00:00 | 08:47:21.56 | +23:10:41.2 | HIP 43171 | 6.24 |
| 2026-10-04 12:00 | 08:47:44.84 | +23:09:48.2 | HIP 43171 | 4.84 |
| 2026-10-05 00:00 | 08:48:08.00 | +23:08:55.8 | HIP 43171 | 8.15 |
| 2026-10-05 12:00 | 08:48:31.05 | +23:08:03.8 | HIP 43171 | 12.93 |
| 2026-10-06 00:00 | 08:48:53.98 | +23:07:12.4 | HIP 43171 | 18.02 |
| 2026-10-06 12:00 | 08:49:16.80 | +23:06:21.5 | HIP 43381 | 17.91 |
| 2026-10-07 00:00 | 08:49:39.49 | +23:05:31.1 | HIP 43381 | 14.07 |
| 2026-10-07 12:00 | 08:50:02.06 | +23:04:41.3 | HIP 43381 | 11.47 |
| 2026-10-08 00:00 | 08:50:24.50 | +23:03:52.1 | HIP 43381 | 10.97 |
| 2026-10-08 12:00 | 08:50:46.83 | +23:03:03.4 | HIP 43381 | 12.79 |
| 2026-10-09 00:00 | 08:51:09.02 | +23:02:15.3 | HIP 43381 | 16.14 |
| 2026-10-09 12:00 | 08:51:31.09 | +23:01:27.8 | HIP 43381 | 20.24 |
| 2026-10-10 00:00 | 08:51:53.03 | +23:00:40.8 | HIP 43614 | 22.87 |
| 2026-10-10 12:00 | 08:52:14.84 | +22:59:54.5 | HIP 43614 | 20.55 |
| 2026-10-11 00:00 | 08:52:36.52 | +22:59:08.8 | HIP 43614 | 19.31 |