73P/Schwassmann-Wachmann 3
| 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)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
06:13:04.40 |
+28:55:40.5 |
HIP 29352 |
23.99 |
| 2026-02-03 12:00 |
06:12:46.72 |
+28:55:28.6 |
HIP 29352 |
20.11 |
| 2026-02-04 00:00 |
06:12:29.27 |
+28:55:16.2 |
HIP 29352 |
16.29 |
| 2026-02-04 12:00 |
06:12:12.04 |
+28:55:03.5 |
HIP 29352 |
12.51 |
| 2026-02-05 00:00 |
06:11:55.05 |
+28:54:50.3 |
HIP 29352 |
8.79 |
| 2026-02-05 12:00 |
06:11:38.29 |
+28:54:36.6 |
HIP 29352 |
5.12 |
| 2026-02-06 00:00 |
06:11:21.77 |
+28:54:22.6 |
HIP 29352 |
1.50 |
| 2026-02-06 12:00 |
06:11:05.48 |
+28:54:08.2 |
HIP 29352 |
2.09 |
| 2026-02-07 00:00 |
06:10:49.43 |
+28:53:53.4 |
HIP 29352 |
5.61 |
| 2026-02-07 12:00 |
06:10:33.62 |
+28:53:38.1 |
HIP 29352 |
9.08 |
| 2026-02-08 00:00 |
06:10:18.05 |
+28:53:22.5 |
HIP 29352 |
12.49 |
| 2026-02-08 12:00 |
06:10:02.73 |
+28:53:06.6 |
HIP 29198 |
14.72 |
| 2026-02-09 00:00 |
06:09:47.65 |
+28:52:50.3 |
HIP 29198 |
13.31 |
| 2026-02-09 12:00 |
06:09:32.81 |
+28:52:33.6 |
HIP 29198 |
12.62 |
| 2026-02-10 00:00 |
06:09:18.23 |
+28:52:16.6 |
HIP 29198 |
12.73 |
| 2026-02-10 12:00 |
06:09:03.89 |
+28:51:59.2 |
HIP 29198 |
13.59 |
| 2026-02-11 00:00 |
06:08:49.81 |
+28:51:41.5 |
HIP 29198 |
15.04 |
| 2026-02-11 12:00 |
06:08:35.97 |
+28:51:23.5 |
HIP 29198 |
16.89 |
| 2026-02-12 00:00 |
06:08:22.39 |
+28:51:05.2 |
HIP 29198 |
19.01 |
| 2026-02-12 12:00 |
06:08:09.06 |
+28:50:46.6 |
HIP 29198 |
21.28 |
| 2026-02-13 00:00 |
06:07:55.99 |
+28:50:27.7 |
HIP 29042 |
22.43 |
| 2026-02-13 12:00 |
06:07:43.18 |
+28:50:08.5 |
HIP 29042 |
21.83 |
| 2026-02-14 00:00 |
06:07:30.62 |
+28:49:49.0 |
HIP 28904 |
19.44 |
| 2026-02-14 12:00 |
06:07:18.32 |
+28:49:29.3 |
HIP 28904 |
17.04 |
| 2026-02-15 00:00 |
06:07:06.28 |
+28:49:09.3 |
HIP 28904 |
14.80 |
| 2026-02-15 12:00 |
06:06:54.50 |
+28:48:49.1 |
HIP 28904 |
12.77 |
| 2026-02-16 00:00 |
06:06:42.98 |
+28:48:28.6 |
HIP 28904 |
11.02 |
| 2026-02-16 12:00 |
06:06:31.72 |
+28:48:07.8 |
HIP 28904 |
9.68 |
| 2026-02-17 00:00 |
06:06:20.73 |
+28:47:46.9 |
HIP 28904 |
8.87 |
| 2026-02-17 12:00 |
06:06:10.00 |
+28:47:25.7 |
HIP 28904 |
8.69 |
| 2026-02-18 00:00 |
06:05:59.54 |
+28:47:04.3 |
HIP 28904 |
9.15 |
| 2026-02-18 12:00 |
06:05:49.34 |
+28:46:42.7 |
HIP 28904 |
10.11 |
| 2026-02-19 00:00 |
06:05:39.40 |
+28:46:20.9 |
HIP 28904 |
11.41 |
| 2026-02-19 12:00 |
06:05:29.73 |
+28:45:58.9 |
HIP 28904 |
12.93 |
| 2026-02-20 00:00 |
06:05:20.33 |
+28:45:36.7 |
HIP 28904 |
14.57 |
| 2026-02-20 12:00 |
06:05:11.19 |
+28:45:14.3 |
HIP 28904 |
16.27 |
| 2026-02-21 00:00 |
06:05:02.32 |
+28:44:51.8 |
HIP 28904 |
18.00 |
| 2026-02-21 12:00 |
06:04:53.72 |
+28:44:29.1 |
HIP 28846 |
19.27 |
| 2026-02-22 00:00 |
06:04:45.38 |
+28:44:06.2 |
HIP 28846 |
20.23 |
| 2026-02-22 12:00 |
06:04:37.31 |
+28:43:43.2 |
HIP 28846 |
21.30 |
| 2026-02-23 00:00 |
06:04:29.51 |
+28:43:20.0 |
HIP 28649 |
19.95 |
| 2026-02-23 12:00 |
06:04:21.97 |
+28:42:56.7 |
HIP 28649 |
18.26 |
| 2026-02-24 00:00 |
06:04:14.71 |
+28:42:33.3 |
HIP 28649 |
16.63 |