| Parameter |
Value |
| Designation |
C/2005 L3 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2008-01-16T08:18:53.772480Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:51Z |
| Obs used |
5219 |
| NEO |
- |
| M1 |
8.400 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2008-09-20.0000000 |
| e |
0.99958663 |
| q (au) |
5.593628 |
| a (au) |
13531.707446 |
| i (deg) |
139.449247 |
| Ω (om, deg) |
288.739815 |
| ω (w, deg) |
47.133870 |
| M (ma, deg) |
0.000155 |
Magnitude
Scatter + Global Linear
$$
M_a = (5.595 + 2.591\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
5.595 |
| n |
2.591 |
| gf |
1.000 |
| gb |
-0.502 |
| k |
1.000 |
| 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 |
| 2004-07-16 |
2008-01-12 |
+3.1774 |
-2.093 |
| 2008-01-25 |
2010-02-06 |
-2.6501 |
+1.894 |
| 2010-02-06 |
2014-01-09 |
-0.3685 |
+0.184 |
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 |
07:28:07.84 |
+21:56:15.7 |
HIP 36215 |
11.08 |
| 2026-09-20 12:00 |
07:28:08.89 |
+21:56:10.4 |
HIP 36215 |
11.33 |
| 2026-09-21 00:00 |
07:28:09.92 |
+21:56:05.1 |
HIP 36215 |
11.58 |
| 2026-09-21 12:00 |
07:28:10.91 |
+21:55:59.9 |
HIP 36215 |
11.82 |
| 2026-09-22 00:00 |
07:28:11.88 |
+21:55:54.7 |
HIP 36215 |
12.05 |
| 2026-09-22 12:00 |
07:28:12.81 |
+21:55:49.6 |
HIP 36215 |
12.28 |
| 2026-09-23 00:00 |
07:28:13.72 |
+21:55:44.5 |
HIP 36215 |
12.50 |
| 2026-09-23 12:00 |
07:28:14.60 |
+21:55:39.5 |
HIP 36215 |
12.72 |
| 2026-09-24 00:00 |
07:28:15.46 |
+21:55:34.6 |
HIP 36215 |
12.93 |
| 2026-09-24 12:00 |
07:28:16.28 |
+21:55:29.7 |
HIP 36215 |
13.14 |
| 2026-09-25 00:00 |
07:28:17.08 |
+21:55:24.8 |
HIP 36215 |
13.33 |
| 2026-09-25 12:00 |
07:28:17.85 |
+21:55:20.1 |
HIP 36215 |
13.53 |
| 2026-09-26 00:00 |
07:28:18.58 |
+21:55:15.4 |
HIP 36215 |
13.71 |
| 2026-09-26 12:00 |
07:28:19.29 |
+21:55:10.7 |
HIP 36215 |
13.89 |
| 2026-09-27 00:00 |
07:28:19.98 |
+21:55:06.1 |
HIP 36215 |
14.07 |
| 2026-09-27 12:00 |
07:28:20.63 |
+21:55:01.6 |
HIP 36215 |
14.24 |
| 2026-09-28 00:00 |
07:28:21.25 |
+21:54:57.1 |
HIP 36215 |
14.40 |
| 2026-09-28 12:00 |
07:28:21.84 |
+21:54:52.7 |
HIP 36215 |
14.55 |
| 2026-09-29 00:00 |
07:28:22.41 |
+21:54:48.4 |
HIP 36215 |
14.70 |
| 2026-09-29 12:00 |
07:28:22.94 |
+21:54:44.1 |
HIP 36215 |
14.85 |
| 2026-09-30 00:00 |
07:28:23.45 |
+21:54:39.9 |
HIP 36215 |
14.98 |
| 2026-09-30 12:00 |
07:28:23.93 |
+21:54:35.7 |
HIP 36215 |
15.11 |
| 2026-10-01 00:00 |
07:28:24.37 |
+21:54:31.6 |
HIP 36215 |
15.24 |
| 2026-10-01 12:00 |
07:28:24.79 |
+21:54:27.5 |
HIP 36215 |
15.36 |
| 2026-10-02 00:00 |
07:28:25.18 |
+21:54:23.5 |
HIP 36215 |
15.47 |
| 2026-10-02 12:00 |
07:28:25.53 |
+21:54:19.6 |
HIP 36215 |
15.57 |
| 2026-10-03 00:00 |
07:28:25.86 |
+21:54:15.8 |
HIP 36215 |
15.67 |
| 2026-10-03 12:00 |
07:28:26.16 |
+21:54:12.0 |
HIP 36215 |
15.76 |
| 2026-10-04 00:00 |
07:28:26.42 |
+21:54:08.2 |
HIP 36215 |
15.85 |
| 2026-10-04 12:00 |
07:28:26.66 |
+21:54:04.6 |
HIP 36215 |
15.93 |
| 2026-10-05 00:00 |
07:28:26.87 |
+21:54:00.9 |
HIP 36215 |
16.00 |
| 2026-10-05 12:00 |
07:28:27.04 |
+21:53:57.4 |
HIP 36215 |
16.07 |
| 2026-10-06 00:00 |
07:28:27.19 |
+21:53:53.9 |
HIP 36215 |
16.13 |
| 2026-10-06 12:00 |
07:28:27.30 |
+21:53:50.5 |
HIP 36215 |
16.18 |
| 2026-10-07 00:00 |
07:28:27.38 |
+21:53:47.1 |
HIP 36215 |
16.23 |
| 2026-10-07 12:00 |
07:28:27.44 |
+21:53:43.8 |
HIP 36215 |
16.27 |
| 2026-10-08 00:00 |
07:28:27.46 |
+21:53:40.6 |
HIP 36215 |
16.30 |
| 2026-10-08 12:00 |
07:28:27.45 |
+21:53:37.4 |
HIP 36215 |
16.33 |
| 2026-10-09 00:00 |
07:28:27.41 |
+21:53:34.3 |
HIP 36215 |
16.35 |
| 2026-10-09 12:00 |
07:28:27.34 |
+21:53:31.3 |
HIP 36215 |
16.36 |
| 2026-10-10 00:00 |
07:28:27.23 |
+21:53:28.3 |
HIP 36215 |
16.37 |
| 2026-10-10 12:00 |
07:28:27.10 |
+21:53:25.4 |
HIP 36215 |
16.37 |
| 2026-10-11 00:00 |
07:28:26.93 |
+21:53:22.6 |
HIP 36215 |
16.37 |