C/2008 J4 (McNaught)
| 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) |
| 2026-02-03 00:00 |
06:37:52.61 |
-57:37:59.6 |
HIP 31664 |
11.91 |
| 2026-02-03 12:00 |
06:37:48.00 |
-57:37:34.6 |
HIP 31664 |
11.41 |
| 2026-02-04 00:00 |
06:37:43.43 |
-57:37:09.2 |
HIP 31664 |
10.93 |
| 2026-02-04 12:00 |
06:37:38.89 |
-57:36:43.5 |
HIP 31664 |
10.47 |
| 2026-02-05 00:00 |
06:37:34.38 |
-57:36:17.6 |
HIP 31569 |
9.83 |
| 2026-02-05 12:00 |
06:37:29.90 |
-57:35:51.2 |
HIP 31569 |
9.11 |
| 2026-02-06 00:00 |
06:37:25.45 |
-57:35:24.6 |
HIP 31569 |
8.39 |
| 2026-02-06 12:00 |
06:37:21.03 |
-57:34:57.7 |
HIP 31569 |
7.68 |
| 2026-02-07 00:00 |
06:37:16.65 |
-57:34:30.5 |
HIP 31569 |
6.97 |
| 2026-02-07 12:00 |
06:37:12.30 |
-57:34:02.9 |
HIP 31569 |
6.28 |
| 2026-02-08 00:00 |
06:37:07.99 |
-57:33:35.1 |
HIP 31569 |
5.61 |
| 2026-02-08 12:00 |
06:37:03.71 |
-57:33:06.9 |
HIP 31569 |
4.96 |
| 2026-02-09 00:00 |
06:36:59.46 |
-57:32:38.5 |
HIP 31569 |
4.34 |
| 2026-02-09 12:00 |
06:36:55.24 |
-57:32:09.8 |
HIP 31569 |
3.77 |
| 2026-02-10 00:00 |
06:36:51.07 |
-57:31:40.7 |
HIP 31569 |
3.28 |
| 2026-02-10 12:00 |
06:36:46.92 |
-57:31:11.4 |
HIP 31569 |
2.90 |
| 2026-02-11 00:00 |
06:36:42.81 |
-57:30:41.8 |
HIP 31569 |
2.68 |
| 2026-02-11 12:00 |
06:36:38.74 |
-57:30:11.9 |
HIP 31569 |
2.66 |
| 2026-02-12 00:00 |
06:36:34.70 |
-57:29:41.8 |
HIP 31569 |
2.85 |
| 2026-02-12 12:00 |
06:36:30.70 |
-57:29:11.3 |
HIP 31569 |
3.21 |
| 2026-02-13 00:00 |
06:36:26.74 |
-57:28:40.6 |
HIP 31569 |
3.69 |
| 2026-02-13 12:00 |
06:36:22.82 |
-57:28:09.6 |
HIP 31569 |
4.24 |
| 2026-02-14 00:00 |
06:36:18.93 |
-57:27:38.3 |
HIP 31569 |
4.85 |
| 2026-02-14 12:00 |
06:36:15.08 |
-57:27:06.8 |
HIP 31569 |
5.50 |
| 2026-02-15 00:00 |
06:36:11.26 |
-57:26:35.0 |
HIP 31569 |
6.16 |
| 2026-02-15 12:00 |
06:36:07.49 |
-57:26:02.9 |
HIP 31569 |
6.85 |
| 2026-02-16 00:00 |
06:36:03.75 |
-57:25:30.6 |
HIP 31569 |
7.54 |
| 2026-02-16 12:00 |
06:36:00.05 |
-57:24:58.0 |
HIP 31569 |
8.25 |
| 2026-02-17 00:00 |
06:35:56.40 |
-57:24:25.2 |
HIP 31569 |
8.96 |
| 2026-02-17 12:00 |
06:35:52.78 |
-57:23:52.1 |
HIP 31442 |
9.43 |
| 2026-02-18 00:00 |
06:35:49.20 |
-57:23:18.8 |
HIP 31442 |
8.71 |
| 2026-02-18 12:00 |
06:35:45.66 |
-57:22:45.2 |
HIP 31442 |
7.98 |
| 2026-02-19 00:00 |
06:35:42.16 |
-57:22:11.4 |
HIP 31442 |
7.26 |
| 2026-02-19 12:00 |
06:35:38.70 |
-57:21:37.4 |
HIP 31442 |
6.53 |
| 2026-02-20 00:00 |
06:35:35.28 |
-57:21:03.1 |
HIP 31442 |
5.81 |
| 2026-02-20 12:00 |
06:35:31.91 |
-57:20:28.6 |
HIP 31442 |
5.09 |
| 2026-02-21 00:00 |
06:35:28.57 |
-57:19:53.8 |
HIP 31442 |
4.38 |
| 2026-02-21 12:00 |
06:35:25.28 |
-57:19:18.9 |
HIP 31442 |
3.67 |
| 2026-02-22 00:00 |
06:35:22.02 |
-57:18:43.7 |
HIP 31442 |
2.97 |
| 2026-02-22 12:00 |
06:35:18.81 |
-57:18:08.3 |
HIP 31442 |
2.28 |
| 2026-02-23 00:00 |
06:35:15.64 |
-57:17:32.7 |
HIP 31442 |
1.64 |
| 2026-02-23 12:00 |
06:35:12.52 |
-57:16:56.9 |
HIP 31442 |
1.11 |
| 2026-02-24 00:00 |
06:35:09.43 |
-57:16:20.8 |
HIP 31442 |
0.91 |