| Parameter |
Value |
| Designation |
C/2008 J4 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2008-06-19T09:29:06.619200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:19Z |
| Obs used |
22 |
| NEO |
- |
| M1 |
16.500 |
| K1 |
12.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2008-05-17.0000000 |
| e |
1.00771428 |
| q (au) |
0.449265 |
| a (au) |
-58.238132 |
| i (deg) |
87.477450 |
| Ω (om, deg) |
289.372326 |
| ω (w, deg) |
93.055804 |
| M (ma, deg) |
-0.074059 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.126 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.126 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.885 |
| 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) |
| 2026-06-01 00:00 |
06:38:41.07 |
-55:19:35.9 |
HIP 31804 |
2.91 |
| 2026-06-01 12:00 |
06:38:45.46 |
-55:19:17.2 |
HIP 31804 |
2.22 |
| 2026-06-02 00:00 |
06:38:49.87 |
-55:18:58.9 |
HIP 31804 |
1.55 |
| 2026-06-02 12:00 |
06:38:54.29 |
-55:18:40.8 |
HIP 31804 |
0.91 |
| 2026-06-03 00:00 |
06:38:58.74 |
-55:18:23.1 |
HIP 31804 |
0.48 |
| 2026-06-03 12:00 |
06:39:03.20 |
-55:18:05.6 |
HIP 31804 |
0.78 |
| 2026-06-04 00:00 |
06:39:07.68 |
-55:17:48.5 |
HIP 31804 |
1.41 |
| 2026-06-04 12:00 |
06:39:12.18 |
-55:17:31.7 |
HIP 31804 |
2.08 |
| 2026-06-05 00:00 |
06:39:16.69 |
-55:17:15.2 |
HIP 31804 |
2.77 |
| 2026-06-05 12:00 |
06:39:21.22 |
-55:16:59.1 |
HIP 31804 |
3.46 |
| 2026-06-06 00:00 |
06:39:25.77 |
-55:16:43.2 |
HIP 31804 |
4.16 |
| 2026-06-06 12:00 |
06:39:30.33 |
-55:16:27.7 |
HIP 31804 |
4.85 |
| 2026-06-07 00:00 |
06:39:34.90 |
-55:16:12.5 |
HIP 31804 |
5.55 |
| 2026-06-07 12:00 |
06:39:39.49 |
-55:15:57.6 |
HIP 31804 |
6.25 |
| 2026-06-08 00:00 |
06:39:44.10 |
-55:15:43.0 |
HIP 31804 |
6.95 |
| 2026-06-08 12:00 |
06:39:48.72 |
-55:15:28.7 |
HIP 31804 |
7.65 |
| 2026-06-09 00:00 |
06:39:53.36 |
-55:15:14.8 |
HIP 31804 |
8.35 |
| 2026-06-09 12:00 |
06:39:58.01 |
-55:15:01.2 |
HIP 31804 |
9.05 |
| 2026-06-10 00:00 |
06:40:02.67 |
-55:14:47.9 |
HIP 31804 |
9.75 |
| 2026-06-10 12:00 |
06:40:07.35 |
-55:14:35.0 |
HIP 31804 |
10.45 |
| 2026-06-11 00:00 |
06:40:12.04 |
-55:14:22.4 |
HIP 31804 |
11.15 |
| 2026-06-11 12:00 |
06:40:16.74 |
-55:14:10.1 |
HIP 31804 |
11.85 |
| 2026-06-12 00:00 |
06:40:21.45 |
-55:13:58.1 |
HIP 31804 |
12.55 |
| 2026-06-12 12:00 |
06:40:26.18 |
-55:13:46.5 |
HIP 31804 |
13.25 |
| 2026-06-13 00:00 |
06:40:30.92 |
-55:13:35.2 |
HIP 31804 |
13.95 |
| 2026-06-13 12:00 |
06:40:35.67 |
-55:13:24.2 |
HIP 31804 |
14.66 |
| 2026-06-14 00:00 |
06:40:40.43 |
-55:13:13.5 |
HIP 31804 |
15.36 |
| 2026-06-14 12:00 |
06:40:45.21 |
-55:13:03.2 |
HIP 31804 |
16.06 |
| 2026-06-15 00:00 |
06:40:49.99 |
-55:12:53.3 |
HIP 31804 |
16.76 |
| 2026-06-15 12:00 |
06:40:54.78 |
-55:12:43.6 |
HIP 31804 |
17.46 |
| 2026-06-16 00:00 |
06:40:59.58 |
-55:12:34.3 |
HIP 32156 |
17.24 |
| 2026-06-16 12:00 |
06:41:04.40 |
-55:12:25.4 |
HIP 32156 |
16.55 |
| 2026-06-17 00:00 |
06:41:09.22 |
-55:12:16.7 |
HIP 32156 |
15.85 |
| 2026-06-17 12:00 |
06:41:14.05 |
-55:12:08.5 |
HIP 32156 |
15.15 |
| 2026-06-18 00:00 |
06:41:18.89 |
-55:12:00.5 |
HIP 32156 |
14.46 |
| 2026-06-18 12:00 |
06:41:23.74 |
-55:11:52.9 |
HIP 32156 |
13.77 |
| 2026-06-19 00:00 |
06:41:28.59 |
-55:11:45.6 |
HIP 32156 |
13.08 |
| 2026-06-19 12:00 |
06:41:33.45 |
-55:11:38.7 |
HIP 32156 |
12.39 |
| 2026-06-20 00:00 |
06:41:38.32 |
-55:11:32.1 |
HIP 32156 |
11.71 |
| 2026-06-20 12:00 |
06:41:43.20 |
-55:11:25.8 |
HIP 32156 |
11.03 |
| 2026-06-21 00:00 |
06:41:48.08 |
-55:11:19.9 |
HIP 32156 |
10.36 |
| 2026-06-21 12:00 |
06:41:52.97 |
-55:11:14.3 |
HIP 32156 |
9.69 |
| 2026-06-22 00:00 |
06:41:57.87 |
-55:11:09.1 |
HIP 32156 |
9.03 |