| Parameter |
Value |
| Designation |
C/2009 K5 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-04-30T00:35:23.349120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:31Z |
| Obs used |
2488 |
| NEO |
- |
| M1 |
11.900 |
| K1 |
5.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-07-13.0000000 |
| e |
1.00083854 |
| q (au) |
1.422401 |
| a (au) |
-1696.276803 |
| i (deg) |
103.879390 |
| Ω (om, deg) |
257.856328 |
| ω (w, deg) |
66.174175 |
| M (ma, deg) |
0.001044 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.374 + 4.416\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.374 |
| n |
4.416 |
| gf |
0.999 |
| gb |
-0.589 |
| 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 |
| 2009-05-27 |
2010-04-29 |
+0.0122 |
-1.630 |
| 2010-04-30 |
2010-09-19 |
+0.7909 |
-1.983 |
| 2010-09-19 |
2010-10-19 |
+22.6695 |
-9.980 |
| 2010-10-19 |
2011-11-26 |
-2.0385 |
+1.098 |
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 |
04:48:45.36 |
-19:39:35.0 |
HIP 22310 |
7.44 |
| 2026-09-20 12:00 |
04:48:44.42 |
-19:40:11.7 |
HIP 22310 |
6.92 |
| 2026-09-21 00:00 |
04:48:43.46 |
-19:40:48.4 |
HIP 22310 |
6.42 |
| 2026-09-21 12:00 |
04:48:42.47 |
-19:41:25.1 |
HIP 22310 |
5.95 |
| 2026-09-22 00:00 |
04:48:41.44 |
-19:42:01.8 |
HIP 22310 |
5.50 |
| 2026-09-22 12:00 |
04:48:40.39 |
-19:42:38.4 |
HIP 22310 |
5.10 |
| 2026-09-23 00:00 |
04:48:39.30 |
-19:43:15.0 |
HIP 22310 |
4.74 |
| 2026-09-23 12:00 |
04:48:38.19 |
-19:43:51.6 |
HIP 22310 |
4.45 |
| 2026-09-24 00:00 |
04:48:37.05 |
-19:44:28.1 |
HIP 22310 |
4.24 |
| 2026-09-24 12:00 |
04:48:35.87 |
-19:45:04.6 |
HIP 22310 |
4.11 |
| 2026-09-25 00:00 |
04:48:34.67 |
-19:45:41.0 |
HIP 22310 |
4.09 |
| 2026-09-25 12:00 |
04:48:33.44 |
-19:46:17.4 |
HIP 22310 |
4.17 |
| 2026-09-26 00:00 |
04:48:32.18 |
-19:46:53.7 |
HIP 22310 |
4.34 |
| 2026-09-26 12:00 |
04:48:30.89 |
-19:47:30.0 |
HIP 22315 |
4.04 |
| 2026-09-27 00:00 |
04:48:29.56 |
-19:48:06.3 |
HIP 22315 |
3.37 |
| 2026-09-27 12:00 |
04:48:28.21 |
-19:48:42.5 |
HIP 22315 |
2.68 |
| 2026-09-28 00:00 |
04:48:26.84 |
-19:49:18.6 |
HIP 22315 |
2.00 |
| 2026-09-28 12:00 |
04:48:25.43 |
-19:49:54.6 |
HIP 22315 |
1.32 |
| 2026-09-29 00:00 |
04:48:23.99 |
-19:50:30.6 |
HIP 22315 |
0.65 |
| 2026-09-29 12:00 |
04:48:22.52 |
-19:51:06.6 |
HIP 22315 |
0.21 |
| 2026-09-30 00:00 |
04:48:21.03 |
-19:51:42.4 |
HIP 22315 |
0.79 |
| 2026-09-30 12:00 |
04:48:19.50 |
-19:52:18.2 |
HIP 22315 |
1.48 |
| 2026-10-01 00:00 |
04:48:17.95 |
-19:52:53.9 |
HIP 22315 |
2.18 |
| 2026-10-01 12:00 |
04:48:16.37 |
-19:53:29.6 |
HIP 22315 |
2.87 |
| 2026-10-02 00:00 |
04:48:14.75 |
-19:54:05.1 |
HIP 22315 |
3.58 |
| 2026-10-02 12:00 |
04:48:13.11 |
-19:54:40.6 |
HIP 22315 |
4.28 |
| 2026-10-03 00:00 |
04:48:11.45 |
-19:55:16.0 |
HIP 22315 |
4.99 |
| 2026-10-03 12:00 |
04:48:09.75 |
-19:55:51.3 |
HIP 22315 |
5.70 |
| 2026-10-04 00:00 |
04:48:08.02 |
-19:56:26.5 |
HIP 22315 |
6.42 |
| 2026-10-04 12:00 |
04:48:06.27 |
-19:57:01.7 |
HIP 22315 |
7.13 |
| 2026-10-05 00:00 |
04:48:04.49 |
-19:57:36.7 |
HIP 22315 |
7.85 |
| 2026-10-05 12:00 |
04:48:02.68 |
-19:58:11.7 |
HIP 22315 |
8.57 |
| 2026-10-06 00:00 |
04:48:00.84 |
-19:58:46.5 |
HIP 22315 |
9.29 |
| 2026-10-06 12:00 |
04:47:58.97 |
-19:59:21.2 |
HIP 22315 |
10.02 |
| 2026-10-07 00:00 |
04:47:57.08 |
-19:59:55.9 |
HIP 22315 |
10.75 |
| 2026-10-07 12:00 |
04:47:55.16 |
-20:00:30.4 |
HIP 22315 |
11.48 |
| 2026-10-08 00:00 |
04:47:53.21 |
-20:01:04.8 |
HIP 22315 |
12.21 |
| 2026-10-08 12:00 |
04:47:51.23 |
-20:01:39.1 |
HIP 22315 |
12.95 |
| 2026-10-09 00:00 |
04:47:49.23 |
-20:02:13.2 |
HIP 22315 |
13.68 |
| 2026-10-09 12:00 |
04:47:47.19 |
-20:02:47.3 |
HIP 22315 |
14.42 |
| 2026-10-10 00:00 |
04:47:45.13 |
-20:03:21.2 |
HIP 22315 |
15.17 |
| 2026-10-10 12:00 |
04:47:43.05 |
-20:03:55.0 |
HIP 22315 |
15.91 |
| 2026-10-11 00:00 |
04:47:40.94 |
-20:04:28.7 |
HIP 22315 |
16.66 |