| Parameter |
Value |
| Designation |
446P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2012-08-14T16:28:43.587840Z |
| Orbit solution date (soln_date, UTC) |
2024-07-13T19:12:22Z |
| Obs used |
396 |
| NEO |
- |
| M1 |
17.500 |
| K1 |
6.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-01-08.0000000 |
| e |
0.64668523 |
| q (au) |
1.618504 |
| a (au) |
4.580911 |
| i (deg) |
16.571891 |
| Ω (om, deg) |
336.425077 |
| ω (w, deg) |
344.682612 |
| M (ma, deg) |
88.091854 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.429 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.429 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.849 |
| k |
0.999 |
| δ90 |
10.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
09:39:00.06 |
+19:43:19.3 |
HIP 47352 |
34.56 |
| 2026-09-20 12:00 |
09:39:14.47 |
+19:42:08.3 |
HIP 47352 |
36.02 |
| 2026-09-21 00:00 |
09:39:28.82 |
+19:40:57.5 |
HIP 47352 |
37.76 |
| 2026-09-21 12:00 |
09:39:43.11 |
+19:39:47.1 |
HIP 47352 |
39.74 |
| 2026-09-22 00:00 |
09:39:57.35 |
+19:38:37.0 |
HIP 47352 |
41.91 |
| 2026-09-22 12:00 |
09:40:11.53 |
+19:37:27.3 |
HIP 47352 |
44.25 |
| 2026-09-23 00:00 |
09:40:25.64 |
+19:36:17.9 |
HIP 47545 |
42.65 |
| 2026-09-23 12:00 |
09:40:39.70 |
+19:35:08.9 |
HIP 47545 |
40.39 |
| 2026-09-24 00:00 |
09:40:53.69 |
+19:34:00.2 |
HIP 47545 |
38.33 |
| 2026-09-24 12:00 |
09:41:07.62 |
+19:32:51.9 |
HIP 47545 |
36.50 |
| 2026-09-25 00:00 |
09:41:21.50 |
+19:31:44.0 |
HIP 47545 |
34.92 |
| 2026-09-25 12:00 |
09:41:35.30 |
+19:30:36.4 |
HIP 47545 |
33.64 |
| 2026-09-26 00:00 |
09:41:49.05 |
+19:29:29.2 |
HIP 47545 |
32.67 |
| 2026-09-26 12:00 |
09:42:02.73 |
+19:28:22.4 |
HIP 47545 |
32.05 |
| 2026-09-27 00:00 |
09:42:16.35 |
+19:27:15.9 |
HIP 47545 |
31.78 |
| 2026-09-27 12:00 |
09:42:29.90 |
+19:26:09.8 |
HIP 47545 |
31.88 |
| 2026-09-28 00:00 |
09:42:43.38 |
+19:25:04.1 |
HIP 47545 |
32.34 |
| 2026-09-28 12:00 |
09:42:56.80 |
+19:23:58.8 |
HIP 47545 |
33.12 |
| 2026-09-29 00:00 |
09:43:10.15 |
+19:22:53.9 |
HIP 47786 |
30.37 |
| 2026-09-29 12:00 |
09:43:23.44 |
+19:21:49.4 |
HIP 47786 |
27.53 |
| 2026-09-30 00:00 |
09:43:36.66 |
+19:20:45.2 |
HIP 47786 |
24.83 |
| 2026-09-30 12:00 |
09:43:49.80 |
+19:19:41.5 |
HIP 47786 |
22.30 |
| 2026-10-01 00:00 |
09:44:02.88 |
+19:18:38.2 |
HIP 47786 |
20.00 |
| 2026-10-01 12:00 |
09:44:15.89 |
+19:17:35.2 |
HIP 47786 |
18.02 |
| 2026-10-02 00:00 |
09:44:28.83 |
+19:16:32.7 |
HIP 47786 |
16.45 |
| 2026-10-02 12:00 |
09:44:41.69 |
+19:15:30.6 |
HIP 47786 |
15.41 |
| 2026-10-03 00:00 |
09:44:54.49 |
+19:14:29.0 |
HIP 47786 |
15.00 |
| 2026-10-03 12:00 |
09:45:07.21 |
+19:13:27.7 |
HIP 47786 |
15.26 |
| 2026-10-04 00:00 |
09:45:19.86 |
+19:12:26.9 |
HIP 47786 |
16.15 |
| 2026-10-04 12:00 |
09:45:32.43 |
+19:11:26.5 |
HIP 47786 |
17.56 |
| 2026-10-05 00:00 |
09:45:44.93 |
+19:10:26.6 |
HIP 47786 |
19.37 |
| 2026-10-05 12:00 |
09:45:57.35 |
+19:09:27.0 |
HIP 47786 |
21.46 |
| 2026-10-06 00:00 |
09:46:09.69 |
+19:08:28.0 |
HIP 48021 |
23.22 |
| 2026-10-06 12:00 |
09:46:21.96 |
+19:07:29.4 |
HIP 48021 |
21.97 |
| 2026-10-07 00:00 |
09:46:34.15 |
+19:06:31.2 |
HIP 48021 |
21.10 |
| 2026-10-07 12:00 |
09:46:46.26 |
+19:05:33.5 |
HIP 48021 |
20.63 |
| 2026-10-08 00:00 |
09:46:58.30 |
+19:04:36.2 |
HIP 48021 |
20.61 |
| 2026-10-08 12:00 |
09:47:10.25 |
+19:03:39.5 |
HIP 48021 |
21.00 |
| 2026-10-09 00:00 |
09:47:22.12 |
+19:02:43.2 |
HIP 48103 |
21.00 |
| 2026-10-09 12:00 |
09:47:33.91 |
+19:01:47.3 |
HIP 48103 |
18.37 |
| 2026-10-10 00:00 |
09:47:45.61 |
+19:00:52.0 |
HIP 48103 |
15.87 |
| 2026-10-10 12:00 |
09:47:57.24 |
+18:59:57.1 |
HIP 48103 |
13.55 |
| 2026-10-11 00:00 |
09:48:08.77 |
+18:59:02.7 |
HIP 48103 |
11.51 |