| 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) |
| 2026-07-29 00:00 |
03:24:42.47 |
+47:46:44.0 |
HIP 15911 |
21.93 |
| 2026-07-29 12:00 |
03:24:44.09 |
+47:47:22.2 |
HIP 15911 |
22.54 |
| 2026-07-30 00:00 |
03:24:45.67 |
+47:48:00.5 |
HIP 15911 |
23.16 |
| 2026-07-30 12:00 |
03:24:47.20 |
+47:48:38.6 |
HIP 15911 |
23.78 |
| 2026-07-31 00:00 |
03:24:48.69 |
+47:49:16.8 |
HIP 15911 |
24.40 |
| 2026-07-31 12:00 |
03:24:50.13 |
+47:49:55.0 |
HIP 15911 |
25.03 |
| 2026-08-01 00:00 |
03:24:51.52 |
+47:50:33.1 |
HIP 15911 |
25.65 |
| 2026-08-01 12:00 |
03:24:52.87 |
+47:51:11.2 |
HIP 15911 |
26.28 |
| 2026-08-02 00:00 |
03:24:54.18 |
+47:51:49.2 |
HIP 15911 |
26.92 |
| 2026-08-02 12:00 |
03:24:55.44 |
+47:52:27.2 |
HIP 15911 |
27.55 |
| 2026-08-03 00:00 |
03:24:56.65 |
+47:53:05.2 |
HIP 15911 |
28.18 |
| 2026-08-03 12:00 |
03:24:57.81 |
+47:53:43.2 |
HIP 16079 |
28.27 |
| 2026-08-04 00:00 |
03:24:58.93 |
+47:54:21.1 |
HIP 16079 |
27.72 |
| 2026-08-04 12:00 |
03:25:00.01 |
+47:54:59.0 |
HIP 16079 |
27.17 |
| 2026-08-05 00:00 |
03:25:01.04 |
+47:55:36.8 |
HIP 16079 |
26.64 |
| 2026-08-05 12:00 |
03:25:02.02 |
+47:56:14.6 |
HIP 16079 |
26.12 |
| 2026-08-06 00:00 |
03:25:02.95 |
+47:56:52.3 |
HIP 16079 |
25.61 |
| 2026-08-06 12:00 |
03:25:03.83 |
+47:57:30.0 |
HIP 16079 |
25.11 |
| 2026-08-07 00:00 |
03:25:04.67 |
+47:58:07.6 |
HIP 16079 |
24.63 |
| 2026-08-07 12:00 |
03:25:05.46 |
+47:58:45.2 |
HIP 16079 |
24.16 |
| 2026-08-08 00:00 |
03:25:06.21 |
+47:59:22.7 |
HIP 16079 |
23.71 |
| 2026-08-08 12:00 |
03:25:06.90 |
+48:00:00.2 |
HIP 16079 |
23.28 |
| 2026-08-09 00:00 |
03:25:07.55 |
+48:00:37.6 |
HIP 16079 |
22.86 |
| 2026-08-09 12:00 |
03:25:08.15 |
+48:01:14.9 |
HIP 16079 |
22.46 |
| 2026-08-10 00:00 |
03:25:08.70 |
+48:01:52.2 |
HIP 16079 |
22.07 |
| 2026-08-10 12:00 |
03:25:09.21 |
+48:02:29.4 |
HIP 16079 |
21.71 |
| 2026-08-11 00:00 |
03:25:09.66 |
+48:03:06.6 |
HIP 16079 |
21.36 |
| 2026-08-11 12:00 |
03:25:10.07 |
+48:03:43.7 |
HIP 16079 |
21.04 |
| 2026-08-12 00:00 |
03:25:10.43 |
+48:04:20.7 |
HIP 15898 |
20.73 |
| 2026-08-12 12:00 |
03:25:10.73 |
+48:04:57.6 |
HIP 15898 |
20.13 |
| 2026-08-13 00:00 |
03:25:10.99 |
+48:05:34.4 |
HIP 15898 |
19.54 |
| 2026-08-13 12:00 |
03:25:11.21 |
+48:06:11.2 |
HIP 15898 |
18.95 |
| 2026-08-14 00:00 |
03:25:11.37 |
+48:06:47.9 |
HIP 15898 |
18.36 |
| 2026-08-14 12:00 |
03:25:11.48 |
+48:07:24.5 |
HIP 15898 |
17.77 |
| 2026-08-15 00:00 |
03:25:11.54 |
+48:08:01.0 |
HIP 15898 |
17.18 |
| 2026-08-15 12:00 |
03:25:11.55 |
+48:08:37.4 |
HIP 15898 |
16.59 |
| 2026-08-16 00:00 |
03:25:11.52 |
+48:09:13.7 |
HIP 15898 |
16.00 |
| 2026-08-16 12:00 |
03:25:11.43 |
+48:09:49.9 |
HIP 15898 |
15.41 |
| 2026-08-17 00:00 |
03:25:11.30 |
+48:10:26.1 |
HIP 15898 |
14.83 |
| 2026-08-17 12:00 |
03:25:11.11 |
+48:11:02.1 |
HIP 15898 |
14.24 |
| 2026-08-18 00:00 |
03:25:10.88 |
+48:11:38.1 |
HIP 15898 |
13.66 |
| 2026-08-18 12:00 |
03:25:10.60 |
+48:12:13.9 |
HIP 15898 |
13.07 |
| 2026-08-19 00:00 |
03:25:10.26 |
+48:12:49.6 |
HIP 15898 |
12.49 |