| 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 |
7.671 |
| 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) |
| 2026-05-12 00:00 |
03:13:55.89 |
+46:22:21.5 |
HIP 14946 |
15.52 |
| 2026-05-12 12:00 |
03:14:01.35 |
+46:22:42.1 |
HIP 14946 |
16.50 |
| 2026-05-13 00:00 |
03:14:06.82 |
+46:23:02.9 |
HIP 15145 |
16.59 |
| 2026-05-13 12:00 |
03:14:12.28 |
+46:23:23.9 |
HIP 15145 |
15.68 |
| 2026-05-14 00:00 |
03:14:17.74 |
+46:23:45.2 |
HIP 15145 |
14.79 |
| 2026-05-14 12:00 |
03:14:23.20 |
+46:24:06.6 |
HIP 15145 |
13.91 |
| 2026-05-15 00:00 |
03:14:28.66 |
+46:24:28.3 |
HIP 15145 |
13.04 |
| 2026-05-15 12:00 |
03:14:34.12 |
+46:24:50.2 |
HIP 15145 |
12.19 |
| 2026-05-16 00:00 |
03:14:39.57 |
+46:25:12.3 |
HIP 15145 |
11.37 |
| 2026-05-16 12:00 |
03:14:45.02 |
+46:25:34.6 |
HIP 15145 |
10.58 |
| 2026-05-17 00:00 |
03:14:50.47 |
+46:25:57.1 |
HIP 15145 |
9.82 |
| 2026-05-17 12:00 |
03:14:55.92 |
+46:26:19.9 |
HIP 15145 |
9.11 |
| 2026-05-18 00:00 |
03:15:01.36 |
+46:26:42.8 |
HIP 15145 |
8.46 |
| 2026-05-18 12:00 |
03:15:06.80 |
+46:27:05.9 |
HIP 15145 |
7.88 |
| 2026-05-19 00:00 |
03:15:12.23 |
+46:27:29.3 |
HIP 15145 |
7.39 |
| 2026-05-19 12:00 |
03:15:17.66 |
+46:27:52.9 |
HIP 15145 |
7.00 |
| 2026-05-20 00:00 |
03:15:23.08 |
+46:28:16.6 |
HIP 15145 |
6.75 |
| 2026-05-20 12:00 |
03:15:28.50 |
+46:28:40.6 |
HIP 15145 |
6.64 |
| 2026-05-21 00:00 |
03:15:33.91 |
+46:29:04.8 |
HIP 15145 |
6.68 |
| 2026-05-21 12:00 |
03:15:39.31 |
+46:29:29.1 |
HIP 15145 |
6.87 |
| 2026-05-22 00:00 |
03:15:44.71 |
+46:29:53.7 |
HIP 15145 |
7.20 |
| 2026-05-22 12:00 |
03:15:50.10 |
+46:30:18.4 |
HIP 15145 |
7.64 |
| 2026-05-23 00:00 |
03:15:55.48 |
+46:30:43.4 |
HIP 15145 |
8.18 |
| 2026-05-23 12:00 |
03:16:00.86 |
+46:31:08.6 |
HIP 15145 |
8.80 |
| 2026-05-24 00:00 |
03:16:06.22 |
+46:31:33.9 |
HIP 15145 |
9.49 |
| 2026-05-24 12:00 |
03:16:11.58 |
+46:31:59.5 |
HIP 15145 |
10.23 |
| 2026-05-25 00:00 |
03:16:16.93 |
+46:32:25.2 |
HIP 15145 |
11.02 |
| 2026-05-25 12:00 |
03:16:22.27 |
+46:32:51.1 |
HIP 15145 |
11.83 |
| 2026-05-26 00:00 |
03:16:27.60 |
+46:33:17.2 |
HIP 15145 |
12.67 |
| 2026-05-26 12:00 |
03:16:32.92 |
+46:33:43.5 |
HIP 15145 |
13.54 |
| 2026-05-27 00:00 |
03:16:38.24 |
+46:34:10.0 |
HIP 15145 |
14.42 |
| 2026-05-27 12:00 |
03:16:43.54 |
+46:34:36.7 |
HIP 15364 |
14.05 |
| 2026-05-28 00:00 |
03:16:48.83 |
+46:35:03.5 |
HIP 15364 |
13.16 |
| 2026-05-28 12:00 |
03:16:54.11 |
+46:35:30.6 |
HIP 15364 |
12.30 |
| 2026-05-29 00:00 |
03:16:59.37 |
+46:35:57.8 |
HIP 15364 |
11.46 |
| 2026-05-29 12:00 |
03:17:04.63 |
+46:36:25.2 |
HIP 15364 |
10.66 |
| 2026-05-30 00:00 |
03:17:09.87 |
+46:36:52.7 |
HIP 15364 |
9.90 |
| 2026-05-30 12:00 |
03:17:15.11 |
+46:37:20.5 |
HIP 15364 |
9.19 |
| 2026-05-31 00:00 |
03:17:20.33 |
+46:37:48.4 |
HIP 15364 |
8.55 |
| 2026-05-31 12:00 |
03:17:25.53 |
+46:38:16.5 |
HIP 15364 |
7.98 |
| 2026-06-01 00:00 |
03:17:30.73 |
+46:38:44.8 |
HIP 15364 |
7.51 |
| 2026-06-01 12:00 |
03:17:35.91 |
+46:39:13.3 |
HIP 15364 |
7.16 |
| 2026-06-02 00:00 |
03:17:41.07 |
+46:39:41.9 |
HIP 15364 |
6.95 |