| 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) |
| 2026-05-12 00:00 |
06:30:25.34 |
+27:38:56.5 |
HIP 30934 |
11.75 |
| 2026-05-12 12:00 |
06:30:48.61 |
+27:38:27.9 |
HIP 30934 |
16.92 |
| 2026-05-13 00:00 |
06:31:11.98 |
+27:37:59.1 |
HIP 30934 |
22.12 |
| 2026-05-13 12:00 |
06:31:35.47 |
+27:37:30.1 |
HIP 30934 |
27.34 |
| 2026-05-14 00:00 |
06:31:59.07 |
+27:37:01.0 |
HIP 31319 |
28.14 |
| 2026-05-14 12:00 |
06:32:22.78 |
+27:36:31.7 |
HIP 31319 |
22.87 |
| 2026-05-15 00:00 |
06:32:46.59 |
+27:36:02.2 |
HIP 31319 |
17.58 |
| 2026-05-15 12:00 |
06:33:10.51 |
+27:35:32.6 |
HIP 31319 |
12.27 |
| 2026-05-16 00:00 |
06:33:34.54 |
+27:35:02.8 |
HIP 31319 |
6.96 |
| 2026-05-16 12:00 |
06:33:58.67 |
+27:34:32.9 |
HIP 31319 |
1.88 |
| 2026-05-17 00:00 |
06:34:22.91 |
+27:34:02.7 |
HIP 31319 |
4.05 |
| 2026-05-17 12:00 |
06:34:47.25 |
+27:33:32.4 |
HIP 31319 |
9.38 |
| 2026-05-18 00:00 |
06:35:11.69 |
+27:33:01.9 |
HIP 31319 |
14.79 |
| 2026-05-18 12:00 |
06:35:36.23 |
+27:32:31.2 |
HIP 31568 |
19.31 |
| 2026-05-19 00:00 |
06:36:00.87 |
+27:32:00.4 |
HIP 31568 |
16.29 |
| 2026-05-19 12:00 |
06:36:25.61 |
+27:31:29.4 |
HIP 31568 |
14.77 |
| 2026-05-20 00:00 |
06:36:50.44 |
+27:30:58.1 |
HIP 31568 |
15.23 |
| 2026-05-20 12:00 |
06:37:15.37 |
+27:30:26.7 |
HIP 31568 |
17.53 |
| 2026-05-21 00:00 |
06:37:40.40 |
+27:29:55.1 |
HIP 31568 |
21.10 |
| 2026-05-21 12:00 |
06:38:05.52 |
+27:29:23.4 |
HIP 31568 |
25.42 |
| 2026-05-22 00:00 |
06:38:30.73 |
+27:28:51.4 |
HIP 31568 |
30.18 |
| 2026-05-22 12:00 |
06:38:56.04 |
+27:28:19.2 |
HIP 31759 |
34.30 |
| 2026-05-23 00:00 |
06:39:21.43 |
+27:27:46.8 |
HIP 31759 |
34.98 |
| 2026-05-23 12:00 |
06:39:46.92 |
+27:27:14.3 |
HIP 32044 |
34.08 |
| 2026-05-24 00:00 |
06:40:12.49 |
+27:26:41.5 |
HIP 32044 |
29.62 |
| 2026-05-24 12:00 |
06:40:38.15 |
+27:26:08.6 |
HIP 32044 |
25.64 |
| 2026-05-25 00:00 |
06:41:03.90 |
+27:25:35.4 |
HIP 32044 |
22.42 |
| 2026-05-25 12:00 |
06:41:29.74 |
+27:25:02.1 |
HIP 32044 |
20.35 |
| 2026-05-26 00:00 |
06:41:55.66 |
+27:24:28.5 |
HIP 32044 |
19.79 |
| 2026-05-26 12:00 |
06:42:21.66 |
+27:23:54.7 |
HIP 32209 |
16.30 |
| 2026-05-27 00:00 |
06:42:47.75 |
+27:23:20.7 |
HIP 32209 |
11.42 |
| 2026-05-27 12:00 |
06:43:13.92 |
+27:22:46.5 |
HIP 32209 |
7.93 |
| 2026-05-28 00:00 |
06:43:40.17 |
+27:22:12.1 |
HIP 32209 |
7.97 |
| 2026-05-28 12:00 |
06:44:06.50 |
+27:21:37.5 |
HIP 32265 |
7.27 |
| 2026-05-29 00:00 |
06:44:32.92 |
+27:21:02.7 |
HIP 32265 |
9.03 |
| 2026-05-29 12:00 |
06:44:59.41 |
+27:20:27.6 |
HIP 32265 |
13.41 |
| 2026-05-30 00:00 |
06:45:25.98 |
+27:19:52.4 |
HIP 32265 |
18.68 |
| 2026-05-30 12:00 |
06:45:52.63 |
+27:19:16.9 |
HIP 32389 |
21.47 |
| 2026-05-31 00:00 |
06:46:19.35 |
+27:18:41.2 |
HIP 32389 |
23.82 |
| 2026-05-31 12:00 |
06:46:46.15 |
+27:18:05.2 |
HIP 32389 |
27.31 |
| 2026-06-01 00:00 |
06:47:13.03 |
+27:17:29.1 |
HIP 32689 |
26.74 |
| 2026-06-01 12:00 |
06:47:39.98 |
+27:16:52.7 |
HIP 32689 |
20.78 |
| 2026-06-02 00:00 |
06:48:07.01 |
+27:16:16.1 |
HIP 32689 |
14.86 |