| Parameter |
Value |
| Designation |
318P/McNaught-Hartley |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2015-10-21T00:27:13.642560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:28:23Z |
| Obs used |
442 |
| NEO |
- |
| M1 |
9.600 |
| K1 |
13.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-04-13.0000000 |
| e |
0.67524420 |
| q (au) |
2.445459 |
| a (au) |
7.530148 |
| i (deg) |
17.894853 |
| Ω (om, deg) |
35.754310 |
| ω (w, deg) |
313.177220 |
| M (ma, deg) |
298.659661 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.986 + 4.792\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.986 |
| n |
4.792 |
| gf |
0.995 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
2.292 |
| 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 |
11:32:53.96 |
+16:49:42.4 |
HIP 56473 |
26.04 |
| 2026-06-01 12:00 |
11:32:53.27 |
+16:49:07.9 |
HIP 56473 |
26.17 |
| 2026-06-02 00:00 |
11:32:52.66 |
+16:48:33.0 |
HIP 56473 |
26.30 |
| 2026-06-02 12:00 |
11:32:52.12 |
+16:47:57.6 |
HIP 56276 |
25.96 |
| 2026-06-03 00:00 |
11:32:51.65 |
+16:47:21.7 |
HIP 56276 |
25.36 |
| 2026-06-03 12:00 |
11:32:51.26 |
+16:46:45.4 |
HIP 56276 |
24.77 |
| 2026-06-04 00:00 |
11:32:50.95 |
+16:46:08.7 |
HIP 56276 |
24.17 |
| 2026-06-04 12:00 |
11:32:50.71 |
+16:45:31.5 |
HIP 56276 |
23.57 |
| 2026-06-05 00:00 |
11:32:50.54 |
+16:44:53.8 |
HIP 56276 |
22.98 |
| 2026-06-05 12:00 |
11:32:50.45 |
+16:44:15.8 |
HIP 56276 |
22.39 |
| 2026-06-06 00:00 |
11:32:50.44 |
+16:43:37.2 |
HIP 56276 |
21.80 |
| 2026-06-06 12:00 |
11:32:50.50 |
+16:42:58.3 |
HIP 56276 |
21.21 |
| 2026-06-07 00:00 |
11:32:50.63 |
+16:42:18.9 |
HIP 56276 |
20.63 |
| 2026-06-07 12:00 |
11:32:50.84 |
+16:41:39.0 |
HIP 56276 |
20.06 |
| 2026-06-08 00:00 |
11:32:51.13 |
+16:40:58.8 |
HIP 56276 |
19.49 |
| 2026-06-08 12:00 |
11:32:51.48 |
+16:40:18.1 |
HIP 56276 |
18.94 |
| 2026-06-09 00:00 |
11:32:51.92 |
+16:39:37.0 |
HIP 56276 |
18.39 |
| 2026-06-09 12:00 |
11:32:52.43 |
+16:38:55.4 |
HIP 56276 |
17.86 |
| 2026-06-10 00:00 |
11:32:53.01 |
+16:38:13.4 |
HIP 56276 |
17.34 |
| 2026-06-10 12:00 |
11:32:53.67 |
+16:37:31.1 |
HIP 56276 |
16.85 |
| 2026-06-11 00:00 |
11:32:54.40 |
+16:36:48.3 |
HIP 56276 |
16.37 |
| 2026-06-11 12:00 |
11:32:55.21 |
+16:36:05.1 |
HIP 56276 |
15.93 |
| 2026-06-12 00:00 |
11:32:56.09 |
+16:35:21.4 |
HIP 56276 |
15.51 |
| 2026-06-12 12:00 |
11:32:57.04 |
+16:34:37.4 |
HIP 56276 |
15.12 |
| 2026-06-13 00:00 |
11:32:58.07 |
+16:33:53.0 |
HIP 56276 |
14.77 |
| 2026-06-13 12:00 |
11:32:59.17 |
+16:33:08.1 |
HIP 56276 |
14.47 |
| 2026-06-14 00:00 |
11:33:00.35 |
+16:32:22.9 |
HIP 56276 |
14.21 |
| 2026-06-14 12:00 |
11:33:01.60 |
+16:31:37.3 |
HIP 56276 |
14.01 |
| 2026-06-15 00:00 |
11:33:02.92 |
+16:30:51.2 |
HIP 56276 |
13.86 |
| 2026-06-15 12:00 |
11:33:04.32 |
+16:30:04.8 |
HIP 56276 |
13.78 |
| 2026-06-16 00:00 |
11:33:05.79 |
+16:29:18.0 |
HIP 56276 |
13.75 |
| 2026-06-16 12:00 |
11:33:07.33 |
+16:28:30.8 |
HIP 56276 |
13.80 |
| 2026-06-17 00:00 |
11:33:08.94 |
+16:27:43.3 |
HIP 56276 |
13.92 |
| 2026-06-17 12:00 |
11:33:10.63 |
+16:26:55.3 |
HIP 56276 |
14.10 |
| 2026-06-18 00:00 |
11:33:12.39 |
+16:26:07.0 |
HIP 56276 |
14.36 |
| 2026-06-18 12:00 |
11:33:14.22 |
+16:25:18.3 |
HIP 56276 |
14.68 |
| 2026-06-19 00:00 |
11:33:16.13 |
+16:24:29.2 |
HIP 56276 |
15.07 |
| 2026-06-19 12:00 |
11:33:18.10 |
+16:23:39.8 |
HIP 56276 |
15.53 |
| 2026-06-20 00:00 |
11:33:20.15 |
+16:22:50.1 |
HIP 56276 |
16.04 |
| 2026-06-20 12:00 |
11:33:22.27 |
+16:22:00.0 |
HIP 56276 |
16.62 |
| 2026-06-21 00:00 |
11:33:24.46 |
+16:21:09.4 |
HIP 56276 |
17.24 |
| 2026-06-21 12:00 |
11:33:26.71 |
+16:20:18.6 |
HIP 56276 |
17.92 |
| 2026-06-22 00:00 |
11:33:29.04 |
+16:19:27.4 |
HIP 56276 |
18.65 |