| 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) |
| 2026-07-29 00:00 |
12:17:33.06 |
+24:47:35.7 |
HIP 59902 |
11.27 |
| 2026-07-29 12:00 |
12:17:49.06 |
+24:44:59.0 |
HIP 59902 |
11.43 |
| 2026-07-30 00:00 |
12:18:05.15 |
+24:42:22.2 |
HIP 59902 |
13.23 |
| 2026-07-30 12:00 |
12:18:21.33 |
+24:39:45.4 |
HIP 60063 |
14.30 |
| 2026-07-31 00:00 |
12:18:37.61 |
+24:37:08.6 |
HIP 60063 |
14.67 |
| 2026-07-31 12:00 |
12:18:53.97 |
+24:34:31.8 |
HIP 60063 |
16.33 |
| 2026-08-01 00:00 |
12:19:10.43 |
+24:31:54.9 |
HIP 60097 |
15.41 |
| 2026-08-01 12:00 |
12:19:26.98 |
+24:29:18.1 |
HIP 60097 |
12.25 |
| 2026-08-02 00:00 |
12:19:43.62 |
+24:26:41.2 |
HIP 60097 |
10.24 |
| 2026-08-02 12:00 |
12:20:00.35 |
+24:24:04.4 |
HIP 60097 |
10.12 |
| 2026-08-03 00:00 |
12:20:17.17 |
+24:21:27.6 |
HIP 60097 |
11.96 |
| 2026-08-03 12:00 |
12:20:34.08 |
+24:18:50.7 |
HIP 60097 |
15.08 |
| 2026-08-04 00:00 |
12:20:51.08 |
+24:16:13.9 |
HIP 60274 |
17.27 |
| 2026-08-04 12:00 |
12:21:08.16 |
+24:13:37.2 |
HIP 60274 |
17.97 |
| 2026-08-05 00:00 |
12:21:25.34 |
+24:11:00.4 |
HIP 60274 |
19.78 |
| 2026-08-05 12:00 |
12:21:42.59 |
+24:08:23.7 |
HIP 60274 |
22.44 |
| 2026-08-06 00:00 |
12:21:59.94 |
+24:05:47.0 |
HIP 60274 |
25.71 |
| 2026-08-06 12:00 |
12:22:17.37 |
+24:03:10.4 |
HIP 60489 |
24.55 |
| 2026-08-07 00:00 |
12:22:34.88 |
+24:00:33.8 |
HIP 60489 |
20.25 |
| 2026-08-07 12:00 |
12:22:52.48 |
+23:57:57.3 |
HIP 60489 |
16.20 |
| 2026-08-08 00:00 |
12:23:10.16 |
+23:55:20.8 |
HIP 60489 |
12.66 |
| 2026-08-08 12:00 |
12:23:27.93 |
+23:52:44.4 |
HIP 60489 |
10.19 |
| 2026-08-09 00:00 |
12:23:45.77 |
+23:50:08.1 |
HIP 60489 |
9.68 |
| 2026-08-09 12:00 |
12:24:03.70 |
+23:47:31.9 |
HIP 60489 |
11.42 |
| 2026-08-10 00:00 |
12:24:21.71 |
+23:44:55.7 |
HIP 60489 |
14.64 |
| 2026-08-10 12:00 |
12:24:39.80 |
+23:42:19.6 |
HIP 60599 |
15.51 |
| 2026-08-11 00:00 |
12:24:57.97 |
+23:39:43.7 |
HIP 60599 |
16.33 |
| 2026-08-11 12:00 |
12:25:16.22 |
+23:37:07.8 |
HIP 60640 |
16.92 |
| 2026-08-12 00:00 |
12:25:34.55 |
+23:34:32.1 |
HIP 60640 |
13.51 |
| 2026-08-12 12:00 |
12:25:52.96 |
+23:31:56.4 |
HIP 60640 |
11.31 |
| 2026-08-13 00:00 |
12:26:11.44 |
+23:29:20.9 |
HIP 60640 |
11.07 |
| 2026-08-13 12:00 |
12:26:30.00 |
+23:26:45.6 |
HIP 60640 |
12.92 |
| 2026-08-14 00:00 |
12:26:48.64 |
+23:24:10.3 |
HIP 60640 |
16.18 |
| 2026-08-14 12:00 |
12:27:07.35 |
+23:21:35.2 |
HIP 60830 |
18.45 |
| 2026-08-15 00:00 |
12:27:26.13 |
+23:19:00.3 |
HIP 60830 |
13.62 |
| 2026-08-15 12:00 |
12:27:44.99 |
+23:16:25.5 |
HIP 60830 |
9.00 |
| 2026-08-16 00:00 |
12:28:03.92 |
+23:13:50.9 |
HIP 60830 |
5.24 |
| 2026-08-16 12:00 |
12:28:22.93 |
+23:11:16.4 |
HIP 60830 |
5.02 |
| 2026-08-17 00:00 |
12:28:42.00 |
+23:08:42.1 |
HIP 60830 |
8.64 |
| 2026-08-17 12:00 |
12:29:01.15 |
+23:06:08.0 |
HIP 60830 |
13.27 |
| 2026-08-18 00:00 |
12:29:20.36 |
+23:03:34.1 |
HIP 60830 |
18.18 |
| 2026-08-18 12:00 |
12:29:39.65 |
+23:01:00.4 |
HIP 61028 |
13.61 |
| 2026-08-19 00:00 |
12:29:59.00 |
+22:58:26.9 |
HIP 61028 |
8.54 |