| Parameter |
Value |
| Designation |
338P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2016-11-21T23:54:59.846400Z |
| Orbit solution date (soln_date, UTC) |
2025-02-13T09:13:12Z |
| Obs used |
882 |
| NEO |
- |
| M1 |
15.500 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-02-14.0000000 |
| e |
0.41033494 |
| q (au) |
2.301407 |
| a (au) |
3.902905 |
| i (deg) |
25.350404 |
| Ω (om, deg) |
9.805290 |
| ω (w, deg) |
4.508283 |
| M (ma, deg) |
57.394693 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.883 + 5.284\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.883 |
| n |
5.284 |
| gf |
0.999 |
| gb |
-0.937 |
| k |
1.000 |
| δ90 |
9.998 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
11:05:20.02 |
+19:02:51.0 |
HIP 54229 |
13.85 |
| 2026-09-20 12:00 |
11:05:45.76 |
+18:59:49.4 |
HIP 54229 |
9.56 |
| 2026-09-21 00:00 |
11:06:11.46 |
+18:56:48.4 |
HIP 54229 |
9.12 |
| 2026-09-21 12:00 |
11:06:37.12 |
+18:53:47.8 |
HIP 54229 |
12.93 |
| 2026-09-22 00:00 |
11:07:02.74 |
+18:50:47.8 |
HIP 54229 |
18.51 |
| 2026-09-22 12:00 |
11:07:28.31 |
+18:47:48.3 |
HIP 54229 |
24.68 |
| 2026-09-23 00:00 |
11:07:53.84 |
+18:44:49.3 |
HIP 54519 |
25.85 |
| 2026-09-23 12:00 |
11:08:19.32 |
+18:41:50.9 |
HIP 54519 |
23.99 |
| 2026-09-24 00:00 |
11:08:44.76 |
+18:38:53.0 |
HIP 54519 |
23.93 |
| 2026-09-24 12:00 |
11:09:10.15 |
+18:35:55.6 |
HIP 54519 |
25.68 |
| 2026-09-25 00:00 |
11:09:35.50 |
+18:32:58.8 |
HIP 54629 |
21.58 |
| 2026-09-25 12:00 |
11:10:00.80 |
+18:30:02.5 |
HIP 54629 |
14.92 |
| 2026-09-26 00:00 |
11:10:26.05 |
+18:27:06.7 |
HIP 54629 |
8.30 |
| 2026-09-26 12:00 |
11:10:51.25 |
+18:24:11.6 |
HIP 54629 |
2.02 |
| 2026-09-27 00:00 |
11:11:16.41 |
+18:21:16.9 |
HIP 54629 |
5.27 |
| 2026-09-27 12:00 |
11:11:41.51 |
+18:18:22.8 |
HIP 54629 |
11.80 |
| 2026-09-28 00:00 |
11:12:06.57 |
+18:15:29.3 |
HIP 54629 |
18.39 |
| 2026-09-28 12:00 |
11:12:31.58 |
+18:12:36.4 |
HIP 54629 |
24.98 |
| 2026-09-29 00:00 |
11:12:56.54 |
+18:09:44.0 |
HIP 54629 |
31.56 |
| 2026-09-29 12:00 |
11:13:21.45 |
+18:06:52.2 |
HIP 54629 |
38.13 |
| 2026-09-30 00:00 |
11:13:46.31 |
+18:04:01.0 |
HIP 54899 |
40.68 |
| 2026-09-30 12:00 |
11:14:11.11 |
+18:01:10.3 |
HIP 54899 |
36.91 |
| 2026-10-01 00:00 |
11:14:35.86 |
+17:58:20.2 |
HIP 54899 |
34.01 |
| 2026-10-01 12:00 |
11:15:00.57 |
+17:55:30.8 |
HIP 54899 |
32.19 |
| 2026-10-02 00:00 |
11:15:25.21 |
+17:52:41.9 |
HIP 54899 |
31.65 |
| 2026-10-02 12:00 |
11:15:49.81 |
+17:49:53.6 |
HIP 55128 |
28.29 |
| 2026-10-03 00:00 |
11:16:14.35 |
+17:47:05.9 |
HIP 55128 |
22.35 |
| 2026-10-03 12:00 |
11:16:38.83 |
+17:44:18.9 |
HIP 55128 |
16.82 |
| 2026-10-04 00:00 |
11:17:03.26 |
+17:41:32.4 |
HIP 55128 |
12.26 |
| 2026-10-04 12:00 |
11:17:27.63 |
+17:38:46.6 |
HIP 55128 |
10.05 |
| 2026-10-05 00:00 |
11:17:51.95 |
+17:36:01.4 |
HIP 55128 |
11.59 |
| 2026-10-05 12:00 |
11:18:16.21 |
+17:33:16.8 |
HIP 55128 |
15.80 |
| 2026-10-06 00:00 |
11:18:40.40 |
+17:30:32.8 |
HIP 55128 |
21.13 |
| 2026-10-06 12:00 |
11:19:04.54 |
+17:27:49.5 |
HIP 55382 |
21.58 |
| 2026-10-07 00:00 |
11:19:28.62 |
+17:25:06.9 |
HIP 55382 |
15.23 |
| 2026-10-07 12:00 |
11:19:52.64 |
+17:22:24.9 |
HIP 55382 |
8.89 |
| 2026-10-08 00:00 |
11:20:16.60 |
+17:19:43.5 |
HIP 55382 |
2.58 |
| 2026-10-08 12:00 |
11:20:40.50 |
+17:17:02.9 |
HIP 55382 |
3.73 |
| 2026-10-09 00:00 |
11:21:04.33 |
+17:14:22.9 |
HIP 55382 |
10.01 |
| 2026-10-09 12:00 |
11:21:28.10 |
+17:11:43.5 |
HIP 55382 |
16.28 |
| 2026-10-10 00:00 |
11:21:51.81 |
+17:09:04.9 |
HIP 55533 |
19.31 |
| 2026-10-10 12:00 |
11:22:15.45 |
+17:06:26.9 |
HIP 55614 |
19.86 |
| 2026-10-11 00:00 |
11:22:39.02 |
+17:03:49.6 |
HIP 55614 |
14.88 |