| Parameter |
Value |
| Designation |
254P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2020-09-29T14:29:03.868800Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T14:43:32Z |
| Obs used |
834 |
| NEO |
- |
| M1 |
12.900 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-08-07.0000000 |
| e |
0.32026893 |
| q (au) |
3.136948 |
| a (au) |
4.614984 |
| i (deg) |
32.571408 |
| Ω (om, deg) |
129.173330 |
| ω (w, deg) |
219.469297 |
| M (ma, deg) |
354.671045 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.492 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.492 |
| n |
6.000 |
| gf |
0.899 |
| gb |
-0.531 |
| k |
0.991 |
| δ90 |
3.786 |
| 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) |
| 2026-09-25 00:00 |
12:56:20.85 |
+20:03:49.9 |
HIP 63149 |
2.50 |
| 2026-09-25 12:00 |
12:56:43.70 |
+20:01:45.1 |
HIP 63149 |
6.88 |
| 2026-09-26 00:00 |
12:57:06.59 |
+19:59:40.9 |
HIP 63149 |
12.44 |
| 2026-09-26 12:00 |
12:57:29.50 |
+19:57:37.3 |
HIP 63149 |
18.12 |
| 2026-09-27 00:00 |
12:57:52.43 |
+19:55:34.2 |
HIP 63149 |
23.85 |
| 2026-09-27 12:00 |
12:58:15.39 |
+19:53:31.8 |
HIP 63352 |
22.13 |
| 2026-09-28 00:00 |
12:58:38.37 |
+19:51:29.9 |
HIP 63352 |
18.52 |
| 2026-09-28 12:00 |
12:59:01.37 |
+19:49:28.6 |
HIP 63352 |
16.22 |
| 2026-09-29 00:00 |
12:59:24.39 |
+19:47:27.9 |
HIP 63352 |
15.82 |
| 2026-09-29 12:00 |
12:59:47.44 |
+19:45:27.9 |
HIP 63484 |
12.31 |
| 2026-09-30 00:00 |
13:00:10.51 |
+19:43:28.4 |
HIP 63484 |
7.02 |
| 2026-09-30 12:00 |
13:00:33.60 |
+19:41:29.5 |
HIP 63484 |
3.73 |
| 2026-10-01 00:00 |
13:00:56.71 |
+19:39:31.3 |
HIP 63484 |
6.75 |
| 2026-10-01 12:00 |
13:01:19.84 |
+19:37:33.7 |
HIP 63484 |
12.01 |
| 2026-10-02 00:00 |
13:01:42.99 |
+19:35:36.7 |
HIP 63484 |
17.61 |
| 2026-10-02 12:00 |
13:02:06.16 |
+19:33:40.4 |
HIP 63484 |
23.31 |
| 2026-10-03 00:00 |
13:02:29.35 |
+19:31:44.7 |
HIP 63680 |
25.09 |
| 2026-10-03 12:00 |
13:02:52.55 |
+19:29:49.6 |
HIP 63767 |
19.77 |
| 2026-10-04 00:00 |
13:03:15.77 |
+19:27:55.2 |
HIP 63767 |
13.97 |
| 2026-10-04 12:00 |
13:03:39.01 |
+19:26:01.5 |
HIP 63767 |
8.18 |
| 2026-10-05 00:00 |
13:04:02.27 |
+19:24:08.4 |
HIP 63767 |
2.42 |
| 2026-10-05 12:00 |
13:04:25.54 |
+19:22:16.0 |
HIP 63767 |
3.46 |
| 2026-10-06 00:00 |
13:04:48.83 |
+19:20:24.2 |
HIP 63767 |
9.24 |
| 2026-10-06 12:00 |
13:05:12.13 |
+19:18:33.2 |
HIP 63767 |
15.04 |
| 2026-10-07 00:00 |
13:05:35.44 |
+19:16:42.8 |
HIP 63767 |
20.83 |
| 2026-10-07 12:00 |
13:05:58.77 |
+19:14:53.2 |
HIP 63767 |
26.63 |
| 2026-10-08 00:00 |
13:06:22.11 |
+19:13:04.2 |
HIP 63767 |
32.43 |
| 2026-10-08 12:00 |
13:06:45.47 |
+19:11:15.9 |
HIP 64084 |
34.10 |
| 2026-10-09 00:00 |
13:07:08.83 |
+19:09:28.4 |
HIP 64084 |
33.41 |
| 2026-10-09 12:00 |
13:07:32.21 |
+19:07:41.6 |
HIP 64084 |
33.70 |
| 2026-10-10 00:00 |
13:07:55.59 |
+19:05:55.5 |
HIP 64169 |
32.87 |
| 2026-10-10 12:00 |
13:08:18.99 |
+19:04:10.1 |
HIP 64169 |
28.83 |
| 2026-10-11 00:00 |
13:08:42.39 |
+19:02:25.5 |
HIP 64169 |
25.49 |
| 2026-10-11 12:00 |
13:09:05.81 |
+19:00:41.6 |
HIP 64169 |
23.15 |
| 2026-10-12 00:00 |
13:09:29.22 |
+18:58:58.4 |
HIP 64169 |
22.15 |
| 2026-10-12 12:00 |
13:09:52.65 |
+18:57:16.1 |
HIP 64169 |
22.64 |
| 2026-10-13 00:00 |
13:10:16.08 |
+18:55:34.4 |
HIP 64169 |
24.55 |
| 2026-10-13 12:00 |
13:10:39.52 |
+18:53:53.6 |
HIP 64429 |
26.52 |
| 2026-10-14 00:00 |
13:11:02.96 |
+18:52:13.5 |
HIP 64429 |
20.80 |
| 2026-10-14 12:00 |
13:11:26.41 |
+18:50:34.2 |
HIP 64429 |
15.14 |
| 2026-10-15 00:00 |
13:11:49.86 |
+18:48:55.7 |
HIP 64429 |
9.64 |
| 2026-10-15 12:00 |
13:12:13.31 |
+18:47:17.9 |
HIP 64429 |
4.88 |
| 2026-10-16 00:00 |
13:12:36.77 |
+18:45:41.0 |
HIP 64449 |
0.61 |