| 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
$$
M_a = (10.374 + 4.415\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.374 |
| n |
4.415 |
| gf |
1.000 |
| 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 |
+0.0125 |
-1.630 |
| 2010-04-30 |
2010-09-19 |
+0.7906 |
-1.983 |
| 2010-09-19 |
2010-10-19 |
+22.6718 |
-9.981 |
| 2010-10-19 |
2011-11-26 |
-2.0378 |
+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) |
| 2026-03-26 00:00 |
04:35:44.31 |
-19:00:56.5 |
HIP 21409 |
12.47 |
| 2026-03-26 12:00 |
04:35:45.75 |
-19:00:25.8 |
HIP 21409 |
12.99 |
| 2026-03-27 00:00 |
04:35:47.22 |
-18:59:55.3 |
HIP 21409 |
13.51 |
| 2026-03-27 12:00 |
04:35:48.72 |
-18:59:24.9 |
HIP 21409 |
14.05 |
| 2026-03-28 00:00 |
04:35:50.25 |
-18:58:54.6 |
HIP 21409 |
14.58 |
| 2026-03-28 12:00 |
04:35:51.80 |
-18:58:24.3 |
HIP 21430 |
15.11 |
| 2026-03-29 00:00 |
04:35:53.38 |
-18:57:54.2 |
HIP 21430 |
14.55 |
| 2026-03-29 12:00 |
04:35:54.98 |
-18:57:24.2 |
HIP 21430 |
14.00 |
| 2026-03-30 00:00 |
04:35:56.62 |
-18:56:54.3 |
HIP 21430 |
13.45 |
| 2026-03-30 12:00 |
04:35:58.27 |
-18:56:24.5 |
HIP 21430 |
12.91 |
| 2026-03-31 00:00 |
04:35:59.96 |
-18:55:54.8 |
HIP 21430 |
12.38 |
| 2026-03-31 12:00 |
04:36:01.67 |
-18:55:25.2 |
HIP 21430 |
11.87 |
| 2026-04-01 00:00 |
04:36:03.40 |
-18:54:55.7 |
HIP 21430 |
11.37 |
| 2026-04-01 12:00 |
04:36:05.16 |
-18:54:26.4 |
HIP 21430 |
10.88 |
| 2026-04-02 00:00 |
04:36:06.95 |
-18:53:57.2 |
HIP 21430 |
10.42 |
| 2026-04-02 12:00 |
04:36:08.76 |
-18:53:28.0 |
HIP 21430 |
9.97 |
| 2026-04-03 00:00 |
04:36:10.59 |
-18:52:59.1 |
HIP 21430 |
9.56 |
| 2026-04-03 12:00 |
04:36:12.46 |
-18:52:30.2 |
HIP 21430 |
9.17 |
| 2026-04-04 00:00 |
04:36:14.34 |
-18:52:01.4 |
HIP 21430 |
8.82 |
| 2026-04-04 12:00 |
04:36:16.25 |
-18:51:32.8 |
HIP 21430 |
8.51 |
| 2026-04-05 00:00 |
04:36:18.19 |
-18:51:04.3 |
HIP 21430 |
8.25 |
| 2026-04-05 12:00 |
04:36:20.15 |
-18:50:36.0 |
HIP 21430 |
8.03 |
| 2026-04-06 00:00 |
04:36:22.13 |
-18:50:07.8 |
HIP 21430 |
7.87 |
| 2026-04-06 12:00 |
04:36:24.14 |
-18:49:39.7 |
HIP 21430 |
7.77 |
| 2026-04-07 00:00 |
04:36:26.17 |
-18:49:11.7 |
HIP 21430 |
7.74 |
| 2026-04-07 12:00 |
04:36:28.22 |
-18:48:43.9 |
HIP 21430 |
7.76 |
| 2026-04-08 00:00 |
04:36:30.30 |
-18:48:16.3 |
HIP 21430 |
7.85 |
| 2026-04-08 12:00 |
04:36:32.41 |
-18:47:48.8 |
HIP 21430 |
8.00 |
| 2026-04-09 00:00 |
04:36:34.53 |
-18:47:21.4 |
HIP 21430 |
8.21 |
| 2026-04-09 12:00 |
04:36:36.68 |
-18:46:54.1 |
HIP 21430 |
8.48 |
| 2026-04-10 00:00 |
04:36:38.85 |
-18:46:27.1 |
HIP 21430 |
8.79 |
| 2026-04-10 12:00 |
04:36:41.05 |
-18:46:00.1 |
HIP 21430 |
9.15 |
| 2026-04-11 00:00 |
04:36:43.26 |
-18:45:33.4 |
HIP 21430 |
9.56 |
| 2026-04-11 12:00 |
04:36:45.50 |
-18:45:06.7 |
HIP 21430 |
10.00 |
| 2026-04-12 00:00 |
04:36:47.76 |
-18:44:40.3 |
HIP 21430 |
10.47 |
| 2026-04-12 12:00 |
04:36:50.05 |
-18:44:14.0 |
HIP 21430 |
10.98 |
| 2026-04-13 00:00 |
04:36:52.35 |
-18:43:47.8 |
HIP 21430 |
11.50 |
| 2026-04-13 12:00 |
04:36:54.68 |
-18:43:21.8 |
HIP 21430 |
12.05 |
| 2026-04-14 00:00 |
04:36:57.03 |
-18:42:56.0 |
HIP 21430 |
12.63 |
| 2026-04-14 12:00 |
04:36:59.40 |
-18:42:30.4 |
HIP 21430 |
13.21 |
| 2026-04-15 00:00 |
04:37:01.79 |
-18:42:04.9 |
HIP 21430 |
13.82 |
| 2026-04-15 12:00 |
04:37:04.20 |
-18:41:39.6 |
HIP 21430 |
14.43 |
| 2026-04-16 00:00 |
04:37:06.64 |
-18:41:14.4 |
HIP 21430 |
15.07 |