| Parameter |
Value |
| Designation |
P/2013 J2 (McNaught) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2013-08-22T23:57:25.464960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:35Z |
| Obs used |
1606 |
| NEO |
- |
| M1 |
12.800 |
| K1 |
7.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-09-18.0000000 |
| e |
0.65614970 |
| q (au) |
2.147830 |
| a (au) |
6.246411 |
| i (deg) |
15.495560 |
| Ω (om, deg) |
289.393509 |
| ω (w, deg) |
37.889335 |
| M (ma, deg) |
1.641578 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.547 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.547 |
| n |
2.000 |
| gf |
0.999 |
| gb |
-0.947 |
| k |
1.000 |
| 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) |
| 2026-07-29 00:00 |
11:46:22.32 |
-14:06:10.6 |
HIP 57459 |
7.31 |
| 2026-07-29 12:00 |
11:46:35.65 |
-14:06:47.9 |
HIP 57459 |
6.27 |
| 2026-07-30 00:00 |
11:46:49.07 |
-14:07:26.0 |
HIP 57459 |
6.87 |
| 2026-07-30 12:00 |
11:47:02.56 |
-14:08:05.0 |
HIP 57459 |
8.80 |
| 2026-07-31 00:00 |
11:47:16.13 |
-14:08:44.8 |
HIP 57459 |
11.43 |
| 2026-07-31 12:00 |
11:47:29.79 |
-14:09:25.4 |
HIP 57459 |
14.38 |
| 2026-08-01 00:00 |
11:47:43.53 |
-14:10:06.9 |
HIP 57459 |
17.52 |
| 2026-08-01 12:00 |
11:47:57.34 |
-14:10:49.2 |
HIP 57611 |
14.56 |
| 2026-08-02 00:00 |
11:48:11.24 |
-14:11:32.4 |
HIP 57611 |
11.72 |
| 2026-08-02 12:00 |
11:48:25.22 |
-14:12:16.4 |
HIP 57611 |
9.29 |
| 2026-08-03 00:00 |
11:48:39.27 |
-14:13:01.2 |
HIP 57611 |
7.67 |
| 2026-08-03 12:00 |
11:48:53.40 |
-14:13:46.8 |
HIP 57611 |
7.45 |
| 2026-08-04 00:00 |
11:49:07.61 |
-14:14:33.3 |
HIP 57611 |
8.77 |
| 2026-08-04 12:00 |
11:49:21.90 |
-14:15:20.6 |
HIP 57611 |
11.11 |
| 2026-08-05 00:00 |
11:49:36.26 |
-14:16:08.7 |
HIP 57611 |
13.99 |
| 2026-08-05 12:00 |
11:49:50.70 |
-14:16:57.6 |
HIP 57611 |
17.14 |
| 2026-08-06 00:00 |
11:50:05.22 |
-14:17:47.3 |
HIP 57611 |
20.45 |
| 2026-08-06 12:00 |
11:50:19.80 |
-14:18:37.8 |
HIP 57611 |
23.87 |
| 2026-08-07 00:00 |
11:50:34.47 |
-14:19:29.2 |
HIP 57789 |
25.82 |
| 2026-08-07 12:00 |
11:50:49.21 |
-14:20:21.4 |
HIP 57789 |
24.32 |
| 2026-08-08 00:00 |
11:51:04.02 |
-14:21:14.3 |
HIP 57789 |
23.29 |
| 2026-08-08 12:00 |
11:51:18.90 |
-14:22:08.1 |
HIP 57894 |
21.99 |
| 2026-08-09 00:00 |
11:51:33.86 |
-14:23:02.7 |
HIP 57894 |
20.09 |
| 2026-08-09 12:00 |
11:51:48.89 |
-14:23:58.0 |
HIP 57894 |
18.77 |
| 2026-08-10 00:00 |
11:52:03.99 |
-14:24:54.2 |
HIP 57894 |
18.14 |
| 2026-08-10 12:00 |
11:52:19.16 |
-14:25:51.2 |
HIP 57962 |
17.53 |
| 2026-08-11 00:00 |
11:52:34.40 |
-14:26:48.9 |
HIP 57962 |
14.00 |
| 2026-08-11 12:00 |
11:52:49.71 |
-14:27:47.4 |
HIP 57962 |
10.65 |
| 2026-08-12 00:00 |
11:53:05.09 |
-14:28:46.8 |
HIP 57962 |
7.73 |
| 2026-08-12 12:00 |
11:53:20.54 |
-14:29:46.9 |
HIP 57962 |
5.96 |
| 2026-08-13 00:00 |
11:53:36.06 |
-14:30:47.7 |
HIP 57962 |
6.44 |
| 2026-08-13 12:00 |
11:53:51.64 |
-14:31:49.4 |
HIP 57962 |
8.81 |
| 2026-08-14 00:00 |
11:54:07.29 |
-14:32:51.8 |
HIP 57962 |
12.03 |
| 2026-08-14 12:00 |
11:54:23.00 |
-14:33:55.0 |
HIP 57962 |
15.59 |
| 2026-08-15 00:00 |
11:54:38.78 |
-14:34:58.9 |
HIP 57962 |
19.32 |
| 2026-08-15 12:00 |
11:54:54.63 |
-14:36:03.7 |
HIP 57962 |
23.14 |
| 2026-08-16 00:00 |
11:55:10.54 |
-14:37:09.1 |
HIP 57962 |
27.02 |
| 2026-08-16 12:00 |
11:55:26.51 |
-14:38:15.3 |
HIP 57962 |
30.95 |
| 2026-08-17 00:00 |
11:55:42.54 |
-14:39:22.3 |
HIP 57962 |
34.91 |
| 2026-08-17 12:00 |
11:55:58.64 |
-14:40:30.0 |
HIP 57962 |
38.91 |
| 2026-08-18 00:00 |
11:56:14.80 |
-14:41:38.5 |
HIP 58424 |
38.20 |
| 2026-08-18 12:00 |
11:56:31.01 |
-14:42:47.6 |
HIP 58424 |
34.12 |
| 2026-08-19 00:00 |
11:56:47.29 |
-14:43:57.6 |
HIP 58424 |
30.01 |