254P/McNaught
Metadata
| 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
$$ M_a = (13.009 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 13.009 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.500 |
| k | 0.800 |
| δ90 | 10.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 2020-10-03 | 2021-08-10 | -37.9052 | +20.265 |
| 2021-08-10 | 2025-03-31 | +10.0743 | -6.134 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Finding Chart
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 12:21:31.59 | +29:22:09.4 | HIP 60196 | 14.82 |
| 2026-03-26 12:00 | 12:21:16.27 | +29:24:03.7 | HIP 60196 | 11.09 |
| 2026-03-27 00:00 | 12:21:00.94 | +29:25:56.2 | HIP 60196 | 7.50 |
| 2026-03-27 12:00 | 12:20:45.62 | +29:27:47.0 | HIP 60196 | 4.36 |
| 2026-03-28 00:00 | 12:20:30.31 | +29:29:36.0 | HIP 60196 | 3.31 |
| 2026-03-28 12:00 | 12:20:15.00 | +29:31:23.3 | HIP 60196 | 5.63 |
| 2026-03-29 00:00 | 12:19:59.69 | +29:33:08.9 | HIP 60196 | 9.00 |
| 2026-03-29 12:00 | 12:19:44.40 | +29:34:52.7 | HIP 60196 | 12.58 |
| 2026-03-30 00:00 | 12:19:29.13 | +29:36:34.7 | HIP 60196 | 16.22 |
| 2026-03-30 12:00 | 12:19:13.87 | +29:38:14.9 | HIP 60196 | 19.89 |
| 2026-03-31 00:00 | 12:18:58.62 | +29:39:53.3 | HIP 60196 | 23.55 |
| 2026-03-31 12:00 | 12:18:43.40 | +29:41:30.0 | HIP 59877 | 26.20 |
| 2026-04-01 00:00 | 12:18:28.20 | +29:43:04.8 | HIP 59877 | 23.49 |
| 2026-04-01 12:00 | 12:18:13.03 | +29:44:37.8 | HIP 59877 | 21.06 |
| 2026-04-02 00:00 | 12:17:57.89 | +29:46:09.0 | HIP 59877 | 19.01 |
| 2026-04-02 12:00 | 12:17:42.77 | +29:47:38.4 | HIP 59877 | 17.46 |
| 2026-04-03 00:00 | 12:17:27.69 | +29:49:06.0 | HIP 59877 | 16.55 |
| 2026-04-03 12:00 | 12:17:12.65 | +29:50:31.7 | HIP 59877 | 16.36 |
| 2026-04-04 00:00 | 12:16:57.64 | +29:51:55.6 | HIP 59877 | 16.90 |
| 2026-04-04 12:00 | 12:16:42.67 | +29:53:17.6 | HIP 59877 | 18.11 |
| 2026-04-05 00:00 | 12:16:27.75 | +29:54:37.8 | HIP 59877 | 19.85 |
| 2026-04-05 12:00 | 12:16:12.86 | +29:55:56.1 | HIP 59735 | 19.91 |
| 2026-04-06 00:00 | 12:15:58.03 | +29:57:12.5 | HIP 59735 | 16.64 |
| 2026-04-06 12:00 | 12:15:43.25 | +29:58:27.1 | HIP 59735 | 13.51 |
| 2026-04-07 00:00 | 12:15:28.51 | +29:59:39.9 | HIP 59735 | 10.59 |
| 2026-04-07 12:00 | 12:15:13.83 | +30:00:50.7 | HIP 59735 | 8.10 |
| 2026-04-08 00:00 | 12:14:59.21 | +30:01:59.7 | HIP 59735 | 6.51 |
| 2026-04-08 12:00 | 12:14:44.65 | +30:03:06.8 | HIP 59735 | 6.49 |
| 2026-04-09 00:00 | 12:14:30.15 | +30:04:12.0 | HIP 59735 | 8.02 |
| 2026-04-09 12:00 | 12:14:15.71 | +30:05:15.3 | HIP 59611 | 9.88 |
| 2026-04-10 00:00 | 12:14:01.33 | +30:06:16.7 | HIP 59611 | 6.73 |
| 2026-04-10 12:00 | 12:13:47.03 | +30:07:16.2 | HIP 59611 | 3.81 |
| 2026-04-11 00:00 | 12:13:32.79 | +30:08:13.9 | HIP 59611 | 2.18 |
| 2026-04-11 12:00 | 12:13:18.63 | +30:09:09.6 | HIP 59611 | 3.94 |
| 2026-04-12 00:00 | 12:13:04.54 | +30:10:03.5 | HIP 59611 | 6.80 |
| 2026-04-12 12:00 | 12:12:50.53 | +30:10:55.4 | HIP 59594 | 8.32 |
| 2026-04-13 00:00 | 12:12:36.60 | +30:11:45.4 | HIP 59594 | 10.16 |
| 2026-04-13 12:00 | 12:12:22.75 | +30:12:33.6 | HIP 59594 | 12.51 |
| 2026-04-14 00:00 | 12:12:08.98 | +30:13:19.8 | HIP 59594 | 15.12 |
| 2026-04-14 12:00 | 12:11:55.30 | +30:14:04.1 | HIP 59594 | 17.87 |
| 2026-04-15 00:00 | 12:11:41.71 | +30:14:46.6 | HIP 59594 | 20.68 |
| 2026-04-15 12:00 | 12:11:28.21 | +30:15:27.1 | HIP 59311 | 19.87 |
| 2026-04-16 00:00 | 12:11:14.80 | +30:16:05.7 | HIP 59311 | 16.98 |