| Parameter |
Value |
| Designation |
C/2011 L1 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-12-18T07:14:56.696640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:51Z |
| Obs used |
140 |
| NEO |
- |
| M1 |
10.400 |
| K1 |
12.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-06-22.0000000 |
| e |
0.79679852 |
| q (au) |
2.242374 |
| a (au) |
11.035223 |
| i (deg) |
65.512678 |
| Ω (om, deg) |
252.363846 |
| ω (w, deg) |
294.470660 |
| M (ma, deg) |
4.992746 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.123 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.123 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.781 |
| k |
0.999 |
| 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 |
| 2011-06-02 |
2012-07-23 |
-10.7811 |
+4.882 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-25 00:00 |
22:39:24.83 |
+62:29:17.6 |
HIP 111706 |
22.10 |
| 2026-09-25 12:00 |
22:39:14.91 |
+62:28:32.8 |
HIP 111706 |
20.86 |
| 2026-09-26 00:00 |
22:39:05.04 |
+62:27:47.4 |
HIP 111706 |
19.63 |
| 2026-09-26 12:00 |
22:38:55.21 |
+62:27:01.3 |
HIP 111706 |
18.42 |
| 2026-09-27 00:00 |
22:38:45.44 |
+62:26:14.6 |
HIP 111706 |
17.22 |
| 2026-09-27 12:00 |
22:38:35.73 |
+62:25:27.1 |
HIP 111706 |
16.04 |
| 2026-09-28 00:00 |
22:38:26.06 |
+62:24:38.9 |
HIP 111706 |
14.89 |
| 2026-09-28 12:00 |
22:38:16.46 |
+62:23:50.1 |
HIP 111706 |
13.77 |
| 2026-09-29 00:00 |
22:38:06.90 |
+62:23:00.6 |
HIP 111706 |
12.69 |
| 2026-09-29 12:00 |
22:37:57.41 |
+62:22:10.5 |
HIP 111706 |
11.67 |
| 2026-09-30 00:00 |
22:37:47.97 |
+62:21:19.7 |
HIP 111706 |
10.72 |
| 2026-09-30 12:00 |
22:37:38.59 |
+62:20:28.2 |
HIP 111706 |
9.86 |
| 2026-10-01 00:00 |
22:37:29.27 |
+62:19:36.1 |
HIP 111706 |
9.12 |
| 2026-10-01 12:00 |
22:37:20.01 |
+62:18:43.3 |
HIP 111706 |
8.52 |
| 2026-10-02 00:00 |
22:37:10.81 |
+62:17:49.9 |
HIP 111706 |
8.12 |
| 2026-10-02 12:00 |
22:37:01.67 |
+62:16:55.8 |
HIP 111706 |
7.93 |
| 2026-10-03 00:00 |
22:36:52.60 |
+62:16:01.1 |
HIP 111706 |
7.97 |
| 2026-10-03 12:00 |
22:36:43.59 |
+62:15:05.7 |
HIP 111706 |
8.24 |
| 2026-10-04 00:00 |
22:36:34.64 |
+62:14:09.8 |
HIP 111706 |
8.71 |
| 2026-10-04 12:00 |
22:36:25.76 |
+62:13:13.2 |
HIP 111706 |
9.37 |
| 2026-10-05 00:00 |
22:36:16.95 |
+62:12:16.0 |
HIP 111706 |
10.16 |
| 2026-10-05 12:00 |
22:36:08.20 |
+62:11:18.1 |
HIP 111706 |
11.07 |
| 2026-10-06 00:00 |
22:35:59.53 |
+62:10:19.7 |
HIP 111706 |
12.07 |
| 2026-10-06 12:00 |
22:35:50.92 |
+62:09:20.7 |
HIP 111706 |
13.14 |
| 2026-10-07 00:00 |
22:35:42.38 |
+62:08:21.0 |
HIP 111706 |
14.26 |
| 2026-10-07 12:00 |
22:35:33.92 |
+62:07:20.8 |
HIP 111706 |
15.42 |
| 2026-10-08 00:00 |
22:35:25.53 |
+62:06:20.0 |
HIP 111706 |
16.62 |
| 2026-10-08 12:00 |
22:35:17.21 |
+62:05:18.5 |
HIP 111706 |
17.84 |
| 2026-10-09 00:00 |
22:35:08.96 |
+62:04:16.6 |
HIP 111305 |
17.47 |
| 2026-10-09 12:00 |
22:35:00.79 |
+62:03:14.0 |
HIP 111305 |
16.15 |
| 2026-10-10 00:00 |
22:34:52.70 |
+62:02:10.9 |
HIP 111305 |
14.86 |
| 2026-10-10 12:00 |
22:34:44.68 |
+62:01:07.2 |
HIP 111305 |
13.59 |
| 2026-10-11 00:00 |
22:34:36.74 |
+62:00:03.0 |
HIP 111305 |
12.35 |
| 2026-10-11 12:00 |
22:34:28.88 |
+61:58:58.2 |
HIP 111305 |
11.17 |
| 2026-10-12 00:00 |
22:34:21.09 |
+61:57:52.9 |
HIP 111305 |
10.05 |
| 2026-10-12 12:00 |
22:34:13.39 |
+61:56:47.0 |
HIP 111305 |
9.03 |
| 2026-10-13 00:00 |
22:34:05.77 |
+61:55:40.6 |
HIP 111305 |
8.15 |
| 2026-10-13 12:00 |
22:33:58.22 |
+61:54:33.7 |
HIP 111305 |
7.43 |
| 2026-10-14 00:00 |
22:33:50.76 |
+61:53:26.3 |
HIP 111379 |
6.76 |
| 2026-10-14 12:00 |
22:33:43.39 |
+61:52:18.4 |
HIP 111379 |
5.74 |
| 2026-10-15 00:00 |
22:33:36.09 |
+61:51:10.0 |
HIP 111379 |
4.91 |
| 2026-10-15 12:00 |
22:33:28.88 |
+61:50:01.0 |
HIP 111379 |
4.39 |
| 2026-10-16 00:00 |
22:33:21.75 |
+61:48:51.6 |
HIP 111379 |
4.30 |