| Parameter |
Value |
| Designation |
C/2009 F4 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-12-31T20:49:26.964480Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:30Z |
| Obs used |
1187 |
| NEO |
- |
| M1 |
5.800 |
| K1 |
7.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-10-20.0000000 |
| e |
1.00181059 |
| q (au) |
5.454873 |
| a (au) |
-3012.758168 |
| i (deg) |
79.347294 |
| Ω (om, deg) |
53.583284 |
| ω (w, deg) |
260.381258 |
| M (ma, deg) |
-0.000434 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.682 + 5.729\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.682 |
| n |
5.729 |
| gf |
0.914 |
| gb |
-0.944 |
| k |
1.000 |
| δ90 |
7.672 |
| 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 |
03:23:06.28 |
+48:45:42.2 |
HIP 15819 |
11.61 |
| 2026-09-20 12:00 |
03:23:02.79 |
+48:46:06.6 |
HIP 15819 |
12.28 |
| 2026-09-21 00:00 |
03:22:59.25 |
+48:46:30.8 |
HIP 15819 |
12.96 |
| 2026-09-21 12:00 |
03:22:55.67 |
+48:46:54.7 |
HIP 15819 |
13.63 |
| 2026-09-22 00:00 |
03:22:52.05 |
+48:47:18.4 |
HIP 15819 |
14.32 |
| 2026-09-22 12:00 |
03:22:48.38 |
+48:47:41.8 |
HIP 15819 |
15.00 |
| 2026-09-23 00:00 |
03:22:44.67 |
+48:48:05.0 |
HIP 15819 |
15.70 |
| 2026-09-23 12:00 |
03:22:40.92 |
+48:48:28.0 |
HIP 15819 |
16.39 |
| 2026-09-24 00:00 |
03:22:37.12 |
+48:48:50.6 |
HIP 15669 |
17.08 |
| 2026-09-24 12:00 |
03:22:33.28 |
+48:49:13.1 |
HIP 15669 |
16.48 |
| 2026-09-25 00:00 |
03:22:29.40 |
+48:49:35.3 |
HIP 15669 |
15.89 |
| 2026-09-25 12:00 |
03:22:25.48 |
+48:49:57.2 |
HIP 15669 |
15.31 |
| 2026-09-26 00:00 |
03:22:21.51 |
+48:50:18.9 |
HIP 15669 |
14.75 |
| 2026-09-26 12:00 |
03:22:17.51 |
+48:50:40.3 |
HIP 15669 |
14.20 |
| 2026-09-27 00:00 |
03:22:13.46 |
+48:51:01.4 |
HIP 15669 |
13.68 |
| 2026-09-27 12:00 |
03:22:09.37 |
+48:51:22.3 |
HIP 15669 |
13.19 |
| 2026-09-28 00:00 |
03:22:05.24 |
+48:51:42.9 |
HIP 15669 |
12.72 |
| 2026-09-28 12:00 |
03:22:01.07 |
+48:52:03.3 |
HIP 15669 |
12.29 |
| 2026-09-29 00:00 |
03:21:56.86 |
+48:52:23.4 |
HIP 15669 |
11.90 |
| 2026-09-29 12:00 |
03:21:52.60 |
+48:52:43.2 |
HIP 15669 |
11.54 |
| 2026-09-30 00:00 |
03:21:48.31 |
+48:53:02.8 |
HIP 15669 |
11.24 |
| 2026-09-30 12:00 |
03:21:43.98 |
+48:53:22.1 |
HIP 15669 |
10.98 |
| 2026-10-01 00:00 |
03:21:39.61 |
+48:53:41.1 |
HIP 15669 |
10.78 |
| 2026-10-01 12:00 |
03:21:35.20 |
+48:53:59.8 |
HIP 15669 |
10.65 |
| 2026-10-02 00:00 |
03:21:30.75 |
+48:54:18.3 |
HIP 15669 |
10.57 |
| 2026-10-02 12:00 |
03:21:26.27 |
+48:54:36.5 |
HIP 15669 |
10.56 |
| 2026-10-03 00:00 |
03:21:21.74 |
+48:54:54.4 |
HIP 15669 |
10.62 |
| 2026-10-03 12:00 |
03:21:17.18 |
+48:55:12.0 |
HIP 15669 |
10.75 |
| 2026-10-04 00:00 |
03:21:12.58 |
+48:55:29.3 |
HIP 15669 |
10.94 |
| 2026-10-04 12:00 |
03:21:07.94 |
+48:55:46.4 |
HIP 15669 |
11.19 |
| 2026-10-05 00:00 |
03:21:03.27 |
+48:56:03.2 |
HIP 15669 |
11.50 |
| 2026-10-05 12:00 |
03:20:58.56 |
+48:56:19.7 |
HIP 15669 |
11.87 |
| 2026-10-06 00:00 |
03:20:53.81 |
+48:56:35.9 |
HIP 15499 |
11.97 |
| 2026-10-06 12:00 |
03:20:49.03 |
+48:56:51.8 |
HIP 15499 |
11.24 |
| 2026-10-07 00:00 |
03:20:44.21 |
+48:57:07.4 |
HIP 15499 |
10.52 |
| 2026-10-07 12:00 |
03:20:39.35 |
+48:57:22.7 |
HIP 15499 |
9.80 |
| 2026-10-08 00:00 |
03:20:34.46 |
+48:57:37.8 |
HIP 15499 |
9.10 |
| 2026-10-08 12:00 |
03:20:29.54 |
+48:57:52.5 |
HIP 15499 |
8.42 |
| 2026-10-09 00:00 |
03:20:24.58 |
+48:58:06.9 |
HIP 15499 |
7.77 |
| 2026-10-09 12:00 |
03:20:19.59 |
+48:58:21.1 |
HIP 15499 |
7.15 |
| 2026-10-10 00:00 |
03:20:14.57 |
+48:58:34.9 |
HIP 15499 |
6.57 |
| 2026-10-10 12:00 |
03:20:09.51 |
+48:58:48.5 |
HIP 15499 |
6.06 |
| 2026-10-11 00:00 |
03:20:04.42 |
+48:59:01.7 |
HIP 15499 |
5.62 |