| 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
$$
M_a = (11.884 + 5.283\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.884 |
| n |
5.283 |
| gf |
0.999 |
| gb |
-0.937 |
| k |
1.000 |
| δ90 |
9.997 |
| 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) |
| 2026-05-12 00:00 |
09:18:21.01 |
+34:49:10.0 |
HIP 45539 |
26.54 |
| 2026-05-12 12:00 |
09:18:35.30 |
+34:45:20.1 |
HIP 45539 |
31.35 |
| 2026-05-13 00:00 |
09:18:49.77 |
+34:41:30.2 |
HIP 45860 |
32.87 |
| 2026-05-13 12:00 |
09:19:04.42 |
+34:37:40.2 |
HIP 45860 |
28.30 |
| 2026-05-14 00:00 |
09:19:19.25 |
+34:33:50.1 |
HIP 45860 |
23.81 |
| 2026-05-14 12:00 |
09:19:34.25 |
+34:30:00.0 |
HIP 45860 |
19.49 |
| 2026-05-15 00:00 |
09:19:49.43 |
+34:26:09.7 |
HIP 45860 |
15.49 |
| 2026-05-15 12:00 |
09:20:04.78 |
+34:22:19.4 |
HIP 45860 |
12.17 |
| 2026-05-16 00:00 |
09:20:20.31 |
+34:18:29.1 |
HIP 45835 |
9.12 |
| 2026-05-16 12:00 |
09:20:36.00 |
+34:14:38.7 |
HIP 45835 |
4.24 |
| 2026-05-17 00:00 |
09:20:51.86 |
+34:10:48.2 |
HIP 45835 |
1.86 |
| 2026-05-17 12:00 |
09:21:07.89 |
+34:06:57.8 |
HIP 45835 |
6.35 |
| 2026-05-18 00:00 |
09:21:24.08 |
+34:03:07.2 |
HIP 45835 |
11.37 |
| 2026-05-18 12:00 |
09:21:40.44 |
+33:59:16.7 |
HIP 45835 |
16.47 |
| 2026-05-19 00:00 |
09:21:56.96 |
+33:55:26.1 |
HIP 46022 |
15.15 |
| 2026-05-19 12:00 |
09:22:13.63 |
+33:51:35.4 |
HIP 46022 |
11.97 |
| 2026-05-20 00:00 |
09:22:30.47 |
+33:47:44.8 |
HIP 46022 |
10.49 |
| 2026-05-20 12:00 |
09:22:47.46 |
+33:43:54.1 |
HIP 46022 |
11.42 |
| 2026-05-21 00:00 |
09:23:04.61 |
+33:40:03.5 |
HIP 46042 |
12.83 |
| 2026-05-21 12:00 |
09:23:21.91 |
+33:36:12.8 |
HIP 46042 |
8.38 |
| 2026-05-22 00:00 |
09:23:39.36 |
+33:32:22.1 |
HIP 46042 |
5.62 |
| 2026-05-22 12:00 |
09:23:56.95 |
+33:28:31.4 |
HIP 46042 |
7.03 |
| 2026-05-23 00:00 |
09:24:14.70 |
+33:24:40.7 |
HIP 46042 |
11.16 |
| 2026-05-23 12:00 |
09:24:32.59 |
+33:20:50.0 |
HIP 46042 |
16.05 |
| 2026-05-24 00:00 |
09:24:50.63 |
+33:16:59.4 |
HIP 46042 |
21.20 |
| 2026-05-24 12:00 |
09:25:08.81 |
+33:13:08.7 |
HIP 46341 |
23.49 |
| 2026-05-25 00:00 |
09:25:27.12 |
+33:09:18.0 |
HIP 46341 |
18.52 |
| 2026-05-25 12:00 |
09:25:45.58 |
+33:05:27.4 |
HIP 46341 |
13.87 |
| 2026-05-26 00:00 |
09:26:04.18 |
+33:01:36.8 |
HIP 46341 |
10.02 |
| 2026-05-26 12:00 |
09:26:22.91 |
+32:57:46.2 |
HIP 46341 |
8.25 |
| 2026-05-27 00:00 |
09:26:41.78 |
+32:53:55.6 |
HIP 46341 |
9.79 |
| 2026-05-27 12:00 |
09:27:00.78 |
+32:50:05.1 |
HIP 46341 |
13.58 |
| 2026-05-28 00:00 |
09:27:19.91 |
+32:46:14.6 |
HIP 46341 |
18.30 |
| 2026-05-28 12:00 |
09:27:39.17 |
+32:42:24.1 |
HIP 46341 |
23.40 |
| 2026-05-29 00:00 |
09:27:58.56 |
+32:38:33.6 |
HIP 46341 |
28.69 |
| 2026-05-29 12:00 |
09:28:18.07 |
+32:34:43.2 |
HIP 46660 |
32.31 |
| 2026-05-30 00:00 |
09:28:37.72 |
+32:30:52.8 |
HIP 46660 |
29.53 |
| 2026-05-30 12:00 |
09:28:57.48 |
+32:27:02.5 |
HIP 46660 |
27.62 |
| 2026-05-31 00:00 |
09:29:17.37 |
+32:23:12.1 |
HIP 46590 |
22.86 |
| 2026-05-31 12:00 |
09:29:37.38 |
+32:19:21.9 |
HIP 46590 |
17.73 |
| 2026-06-01 00:00 |
09:29:57.52 |
+32:15:31.6 |
HIP 46590 |
13.10 |
| 2026-06-01 12:00 |
09:30:17.77 |
+32:11:41.4 |
HIP 46590 |
9.73 |
| 2026-06-02 00:00 |
09:30:38.14 |
+32:07:51.3 |
HIP 46590 |
9.19 |