| 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) |
| 2026-07-29 00:00 |
07:44:24.36 |
+25:39:16.2 |
HIP 37704 |
8.72 |
| 2026-07-29 12:00 |
07:44:55.03 |
+25:38:11.5 |
HIP 37704 |
14.00 |
| 2026-07-30 00:00 |
07:45:25.69 |
+25:37:06.6 |
HIP 37704 |
20.34 |
| 2026-07-30 12:00 |
07:45:56.35 |
+25:36:01.6 |
HIP 37848 |
23.92 |
| 2026-07-31 00:00 |
07:46:27.00 |
+25:34:56.3 |
HIP 37848 |
27.33 |
| 2026-07-31 12:00 |
07:46:57.64 |
+25:33:50.9 |
HIP 37971 |
27.64 |
| 2026-08-01 00:00 |
07:47:28.27 |
+25:32:45.2 |
HIP 37971 |
29.51 |
| 2026-08-01 12:00 |
07:47:58.90 |
+25:31:39.4 |
HIP 37971 |
32.78 |
| 2026-08-02 00:00 |
07:48:29.51 |
+25:30:33.4 |
HIP 37971 |
37.10 |
| 2026-08-02 12:00 |
07:49:00.11 |
+25:29:27.3 |
HIP 38312 |
35.02 |
| 2026-08-03 00:00 |
07:49:30.70 |
+25:28:21.0 |
HIP 38312 |
29.28 |
| 2026-08-03 12:00 |
07:50:01.28 |
+25:27:14.5 |
HIP 38312 |
24.22 |
| 2026-08-04 00:00 |
07:50:31.85 |
+25:26:07.8 |
HIP 38312 |
20.34 |
| 2026-08-04 12:00 |
07:51:02.40 |
+25:25:01.0 |
HIP 38312 |
18.41 |
| 2026-08-05 00:00 |
07:51:32.94 |
+25:23:54.0 |
HIP 38312 |
19.02 |
| 2026-08-05 12:00 |
07:52:03.47 |
+25:22:46.9 |
HIP 38312 |
21.96 |
| 2026-08-06 00:00 |
07:52:33.98 |
+25:21:39.6 |
HIP 38312 |
26.46 |
| 2026-08-06 12:00 |
07:53:04.47 |
+25:20:32.1 |
HIP 38630 |
22.24 |
| 2026-08-07 00:00 |
07:53:34.95 |
+25:19:24.5 |
HIP 38630 |
15.45 |
| 2026-08-07 12:00 |
07:54:05.41 |
+25:18:16.8 |
HIP 38630 |
8.95 |
| 2026-08-08 00:00 |
07:54:35.86 |
+25:17:08.9 |
HIP 38630 |
4.35 |
| 2026-08-08 12:00 |
07:55:06.29 |
+25:16:00.8 |
HIP 38630 |
7.41 |
| 2026-08-09 00:00 |
07:55:36.69 |
+25:14:52.7 |
HIP 38630 |
13.72 |
| 2026-08-09 12:00 |
07:56:07.08 |
+25:13:44.3 |
HIP 38630 |
20.46 |
| 2026-08-10 00:00 |
07:56:37.45 |
+25:12:35.9 |
HIP 38630 |
27.31 |
| 2026-08-10 12:00 |
07:57:07.79 |
+25:11:27.3 |
HIP 38630 |
34.20 |
| 2026-08-11 00:00 |
07:57:38.12 |
+25:10:18.7 |
HIP 38752 |
37.44 |
| 2026-08-11 12:00 |
07:58:08.42 |
+25:09:09.9 |
HIP 39148 |
31.99 |
| 2026-08-12 00:00 |
07:58:38.69 |
+25:08:00.9 |
HIP 39148 |
25.06 |
| 2026-08-12 12:00 |
07:59:08.94 |
+25:06:51.9 |
HIP 39148 |
18.14 |
| 2026-08-13 00:00 |
07:59:39.17 |
+25:05:42.8 |
HIP 39148 |
11.26 |
| 2026-08-13 12:00 |
08:00:09.37 |
+25:04:33.6 |
HIP 39148 |
4.56 |
| 2026-08-14 00:00 |
08:00:39.54 |
+25:03:24.2 |
HIP 39148 |
3.32 |
| 2026-08-14 12:00 |
08:01:09.68 |
+25:02:14.8 |
HIP 39263 |
8.33 |
| 2026-08-15 00:00 |
08:01:39.80 |
+25:01:05.3 |
HIP 39263 |
4.37 |
| 2026-08-15 12:00 |
08:02:09.88 |
+24:59:55.7 |
HIP 39297 |
1.68 |
| 2026-08-16 00:00 |
08:02:39.94 |
+24:58:46.0 |
HIP 39297 |
7.83 |
| 2026-08-16 12:00 |
08:03:09.96 |
+24:57:36.2 |
HIP 39297 |
14.67 |
| 2026-08-17 00:00 |
08:03:39.96 |
+24:56:26.4 |
HIP 39297 |
21.54 |
| 2026-08-17 12:00 |
08:04:09.92 |
+24:55:16.4 |
HIP 39387 |
24.27 |
| 2026-08-18 00:00 |
08:04:39.84 |
+24:54:06.5 |
HIP 39387 |
27.92 |
| 2026-08-18 12:00 |
08:05:09.74 |
+24:52:56.4 |
HIP 39387 |
32.62 |
| 2026-08-19 00:00 |
08:05:39.60 |
+24:51:46.3 |
HIP 39811 |
34.41 |