| Parameter |
Value |
| Designation |
284P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-09-14T05:45:32.915520Z |
| Orbit solution date (soln_date, UTC) |
2024-02-21T14:09:44Z |
| Obs used |
1370 |
| NEO |
- |
| M1 |
9.300 |
| K1 |
17.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-07-22.0000000 |
| e |
0.37568432 |
| q (au) |
2.292800 |
| a (au) |
3.672500 |
| i (deg) |
11.859915 |
| Ω (om, deg) |
144.293116 |
| ω (w, deg) |
202.773845 |
| M (ma, deg) |
198.916990 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.012 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.012 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.551 |
| 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 |
| 2020-04-17 |
2021-09-14 |
+3.2889 |
-0.825 |
| 2021-09-14 |
2024-02-04 |
-0.6016 |
-0.069 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
13:33:17.97 |
-00:15:33.2 |
HIP 66212 |
14.96 |
| 2026-09-20 12:00 |
13:33:44.75 |
-00:18:21.1 |
HIP 66212 |
7.92 |
| 2026-09-21 00:00 |
13:34:11.59 |
-00:21:08.9 |
HIP 66212 |
2.61 |
| 2026-09-21 12:00 |
13:34:38.50 |
-00:23:56.6 |
HIP 66212 |
7.53 |
| 2026-09-22 00:00 |
13:35:05.46 |
-00:26:44.3 |
HIP 66249 |
10.79 |
| 2026-09-22 12:00 |
13:35:32.49 |
-00:29:31.8 |
HIP 66353 |
8.48 |
| 2026-09-23 00:00 |
13:35:59.58 |
-00:32:19.3 |
HIP 66353 |
2.33 |
| 2026-09-23 12:00 |
13:36:26.73 |
-00:35:06.7 |
HIP 66353 |
6.81 |
| 2026-09-24 00:00 |
13:36:53.94 |
-00:37:54.1 |
HIP 66353 |
13.98 |
| 2026-09-24 12:00 |
13:37:21.20 |
-00:40:41.3 |
HIP 66353 |
21.29 |
| 2026-09-25 00:00 |
13:37:48.53 |
-00:43:28.4 |
HIP 66367 |
26.50 |
| 2026-09-25 12:00 |
13:38:15.92 |
-00:46:15.5 |
HIP 66367 |
31.76 |
| 2026-09-26 00:00 |
13:38:43.36 |
-00:49:02.4 |
HIP 66367 |
37.76 |
| 2026-09-26 12:00 |
13:39:10.86 |
-00:51:49.2 |
HIP 66391 |
43.76 |
| 2026-09-27 00:00 |
13:39:38.42 |
-00:54:35.9 |
HIP 66643 |
41.09 |
| 2026-09-27 12:00 |
13:40:06.03 |
-00:57:22.5 |
HIP 66643 |
38.95 |
| 2026-09-28 00:00 |
13:40:33.70 |
-01:00:08.9 |
HIP 66927 |
38.07 |
| 2026-09-28 12:00 |
13:41:01.43 |
-01:02:55.3 |
HIP 66927 |
30.62 |
| 2026-09-29 00:00 |
13:41:29.21 |
-01:05:41.5 |
HIP 66927 |
23.16 |
| 2026-09-29 12:00 |
13:41:57.05 |
-01:08:27.5 |
HIP 66927 |
15.71 |
| 2026-09-30 00:00 |
13:42:24.94 |
-01:11:13.4 |
HIP 66927 |
8.31 |
| 2026-09-30 12:00 |
13:42:52.89 |
-01:13:59.2 |
HIP 66927 |
1.95 |
| 2026-10-01 00:00 |
13:43:20.89 |
-01:16:44.8 |
HIP 66927 |
7.17 |
| 2026-10-01 12:00 |
13:43:48.94 |
-01:19:30.3 |
HIP 66927 |
14.58 |
| 2026-10-02 00:00 |
13:44:17.05 |
-01:22:15.6 |
HIP 66927 |
22.09 |
| 2026-10-02 12:00 |
13:44:45.21 |
-01:25:00.8 |
HIP 66927 |
29.62 |
| 2026-10-03 00:00 |
13:45:13.42 |
-01:27:45.8 |
HIP 66927 |
37.18 |
| 2026-10-03 12:00 |
13:45:41.68 |
-01:30:30.6 |
HIP 67339 |
36.35 |
| 2026-10-04 00:00 |
13:46:10.00 |
-01:33:15.2 |
HIP 67339 |
29.06 |
| 2026-10-04 12:00 |
13:46:38.37 |
-01:35:59.7 |
HIP 67339 |
21.97 |
| 2026-10-05 00:00 |
13:47:06.78 |
-01:38:43.9 |
HIP 67339 |
15.37 |
| 2026-10-05 12:00 |
13:47:35.25 |
-01:41:28.0 |
HIP 67339 |
10.26 |
| 2026-10-06 00:00 |
13:48:03.76 |
-01:44:11.8 |
HIP 67339 |
9.51 |
| 2026-10-06 12:00 |
13:48:32.33 |
-01:46:55.5 |
HIP 67412 |
13.07 |
| 2026-10-07 00:00 |
13:49:00.94 |
-01:49:38.9 |
HIP 67439 |
7.32 |
| 2026-10-07 12:00 |
13:49:29.60 |
-01:52:22.2 |
HIP 67439 |
4.59 |
| 2026-10-08 00:00 |
13:49:58.30 |
-01:55:05.2 |
HIP 67439 |
10.31 |
| 2026-10-08 12:00 |
13:50:27.06 |
-01:57:48.0 |
HIP 67439 |
17.59 |
| 2026-10-09 00:00 |
13:50:55.86 |
-02:00:30.5 |
HIP 67439 |
25.12 |
| 2026-10-09 12:00 |
13:51:24.70 |
-02:03:12.8 |
HIP 67723 |
23.60 |
| 2026-10-10 00:00 |
13:51:53.59 |
-02:05:54.9 |
HIP 67723 |
17.33 |
| 2026-10-10 12:00 |
13:52:22.52 |
-02:08:36.7 |
HIP 67723 |
12.73 |
| 2026-10-11 00:00 |
13:52:51.50 |
-02:11:18.2 |
HIP 67723 |
11.97 |