254P/McNaught
Metadata
| Parameter | Value |
|---|---|
| Designation | 254P/McNaught |
| Type | P |
| Perihelion (tp_cal, UTC) | 2020-09-29T14:09:37.918080Z |
| Orbit solution date (soln_date, UTC) | 2025-04-11T14:45:15Z |
| Obs used | 830 |
| NEO | - |
| M1 | 12.900 |
| K1 | 4.500 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2020-07-27.0000000 |
| e | 0.32030878 |
| q (au) | 3.136955 |
| a (au) | 4.615264 |
| i (deg) | 32.571192 |
| Ω (om, deg) | 129.173115 |
| ω (w, deg) | 219.466903 |
| M (ma, deg) | 353.579415 |
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) |
|---|---|---|---|---|
| 2026-02-03 00:00 | 12:40:27.13 | +24:32:53.6 | HIP 61813 | 7.72 |
| 2026-02-03 12:00 | 12:40:23.08 | +24:36:00.4 | HIP 61813 | 4.87 |
| 2026-02-04 00:00 | 12:40:18.86 | +24:39:07.7 | HIP 61813 | 2.95 |
| 2026-02-04 12:00 | 12:40:14.46 | +24:42:15.4 | HIP 61813 | 3.86 |
| 2026-02-05 00:00 | 12:40:09.88 | +24:45:23.4 | HIP 61813 | 6.54 |
| 2026-02-05 12:00 | 12:40:05.14 | +24:48:31.8 | HIP 61813 | 9.62 |
| 2026-02-06 00:00 | 12:40:00.22 | +24:51:40.6 | HIP 61813 | 12.83 |
| 2026-02-06 12:00 | 12:39:55.12 | +24:54:49.7 | HIP 61813 | 16.10 |
| 2026-02-07 00:00 | 12:39:49.86 | +24:57:59.1 | HIP 61813 | 19.41 |
| 2026-02-07 12:00 | 12:39:44.42 | +25:01:08.8 | HIP 61813 | 22.76 |
| 2026-02-08 00:00 | 12:39:38.81 | +25:04:18.8 | HIP 61813 | 26.13 |
| 2026-02-08 12:00 | 12:39:33.03 | +25:07:29.0 | HIP 61813 | 29.52 |
| 2026-02-09 00:00 | 12:39:27.07 | +25:10:39.4 | HIP 61602 | 28.75 |
| 2026-02-09 12:00 | 12:39:20.95 | +25:13:50.0 | HIP 61834 | 28.04 |
| 2026-02-10 00:00 | 12:39:14.66 | +25:17:00.8 | HIP 61834 | 25.99 |
| 2026-02-10 12:00 | 12:39:08.20 | +25:20:11.8 | HIP 61834 | 24.30 |
| 2026-02-11 00:00 | 12:39:01.57 | +25:23:22.9 | HIP 61834 | 23.04 |
| 2026-02-11 12:00 | 12:38:54.77 | +25:26:34.1 | HIP 61834 | 22.31 |
| 2026-02-12 00:00 | 12:38:47.80 | +25:29:45.4 | HIP 61834 | 22.15 |
| 2026-02-12 12:00 | 12:38:40.67 | +25:32:56.7 | HIP 61834 | 22.60 |
| 2026-02-13 00:00 | 12:38:33.38 | +25:36:08.1 | HIP 61834 | 23.62 |
| 2026-02-13 12:00 | 12:38:25.91 | +25:39:19.5 | HIP 61834 | 25.15 |
| 2026-02-14 00:00 | 12:38:18.29 | +25:42:30.9 | HIP 61546 | 22.75 |
| 2026-02-14 12:00 | 12:38:10.50 | +25:45:42.3 | HIP 61546 | 20.52 |
| 2026-02-15 00:00 | 12:38:02.55 | +25:48:53.6 | HIP 61546 | 18.70 |
| 2026-02-15 12:00 | 12:37:54.44 | +25:52:04.9 | HIP 61546 | 17.43 |
| 2026-02-16 00:00 | 12:37:46.16 | +25:55:16.0 | HIP 61546 | 16.84 |
| 2026-02-16 12:00 | 12:37:37.73 | +25:58:27.0 | HIP 61546 | 17.03 |
| 2026-02-17 00:00 | 12:37:29.14 | +26:01:37.8 | HIP 61546 | 17.97 |
| 2026-02-17 12:00 | 12:37:20.40 | +26:04:48.5 | HIP 61546 | 19.57 |
| 2026-02-18 00:00 | 12:37:11.50 | +26:07:59.0 | HIP 61546 | 21.69 |
| 2026-02-18 12:00 | 12:37:02.44 | +26:11:09.2 | HIP 61546 | 24.19 |
| 2026-02-19 00:00 | 12:36:53.24 | +26:14:19.2 | HIP 61546 | 26.99 |
| 2026-02-19 12:00 | 12:36:43.88 | +26:17:28.8 | HIP 61546 | 29.99 |
| 2026-02-20 00:00 | 12:36:34.37 | +26:20:38.2 | HIP 61355 | 30.02 |
| 2026-02-20 12:00 | 12:36:24.71 | +26:23:47.3 | HIP 61355 | 28.40 |
| 2026-02-21 00:00 | 12:36:14.90 | +26:26:56.0 | HIP 61355 | 27.21 |
| 2026-02-21 12:00 | 12:36:04.95 | +26:30:04.3 | HIP 61355 | 26.48 |
| 2026-02-22 00:00 | 12:35:54.85 | +26:33:12.2 | HIP 61355 | 26.28 |
| 2026-02-22 12:00 | 12:35:44.61 | +26:36:19.6 | HIP 61355 | 26.62 |
| 2026-02-23 00:00 | 12:35:34.23 | +26:39:26.6 | HIP 61355 | 27.48 |
| 2026-02-23 12:00 | 12:35:23.71 | +26:42:33.2 | HIP 61355 | 28.82 |
| 2026-02-24 00:00 | 12:35:13.05 | +26:45:39.2 | HIP 61243 | 29.75 |