| Parameter |
Value |
| Designation |
C/2011 C1 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-04-18T00:03:10.460160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:48Z |
| Obs used |
613 |
| NEO |
- |
| M1 |
12.700 |
| K1 |
17.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-04-15.0000000 |
| e |
0.99743318 |
| q (au) |
0.883378 |
| a (au) |
344.152599 |
| i (deg) |
16.825617 |
| Ω (om, deg) |
192.438367 |
| ω (w, deg) |
84.473509 |
| M (ma, deg) |
359.999537 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.233 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.233 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.772 |
| 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 |
| 2011-01-14 |
2011-03-19 |
+10.0801 |
-0.697 |
| 2011-03-19 |
2011-04-17 |
+45.5484 |
-0.310 |
| 2011-04-18 |
2011-06-07 |
-12.9367 |
-3.109 |
| 2011-06-07 |
2011-08-07 |
-10.1926 |
-2.073 |
| 2011-08-07 |
2011-11-18 |
+22.7627 |
-11.126 |
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 |
05:19:18.16 |
+07:59:50.9 |
HIP 24703 |
21.08 |
| 2026-09-20 12:00 |
05:19:17.83 |
+07:59:36.8 |
HIP 24703 |
21.08 |
| 2026-09-21 00:00 |
05:19:17.47 |
+07:59:22.6 |
HIP 24703 |
21.07 |
| 2026-09-21 12:00 |
05:19:17.08 |
+07:59:08.5 |
HIP 24703 |
21.06 |
| 2026-09-22 00:00 |
05:19:16.67 |
+07:58:54.3 |
HIP 24703 |
21.04 |
| 2026-09-22 12:00 |
05:19:16.22 |
+07:58:40.1 |
HIP 24703 |
21.02 |
| 2026-09-23 00:00 |
05:19:15.74 |
+07:58:25.9 |
HIP 24703 |
21.00 |
| 2026-09-23 12:00 |
05:19:15.23 |
+07:58:11.7 |
HIP 24703 |
20.97 |
| 2026-09-24 00:00 |
05:19:14.69 |
+07:57:57.4 |
HIP 24703 |
20.94 |
| 2026-09-24 12:00 |
05:19:14.13 |
+07:57:43.2 |
HIP 24703 |
20.91 |
| 2026-09-25 00:00 |
05:19:13.53 |
+07:57:28.9 |
HIP 24703 |
20.88 |
| 2026-09-25 12:00 |
05:19:12.90 |
+07:57:14.6 |
HIP 24703 |
20.84 |
| 2026-09-26 00:00 |
05:19:12.25 |
+07:57:00.3 |
HIP 24703 |
20.80 |
| 2026-09-26 12:00 |
05:19:11.56 |
+07:56:46.0 |
HIP 24703 |
20.75 |
| 2026-09-27 00:00 |
05:19:10.84 |
+07:56:31.7 |
HIP 24703 |
20.71 |
| 2026-09-27 12:00 |
05:19:10.10 |
+07:56:17.4 |
HIP 24703 |
20.66 |
| 2026-09-28 00:00 |
05:19:09.32 |
+07:56:03.1 |
HIP 24703 |
20.61 |
| 2026-09-28 12:00 |
05:19:08.52 |
+07:55:48.7 |
HIP 24703 |
20.56 |
| 2026-09-29 00:00 |
05:19:07.68 |
+07:55:34.4 |
HIP 24703 |
20.50 |
| 2026-09-29 12:00 |
05:19:06.82 |
+07:55:20.0 |
HIP 24703 |
20.45 |
| 2026-09-30 00:00 |
05:19:05.92 |
+07:55:05.7 |
HIP 24703 |
20.39 |
| 2026-09-30 12:00 |
05:19:05.00 |
+07:54:51.3 |
HIP 24703 |
20.33 |
| 2026-10-01 00:00 |
05:19:04.04 |
+07:54:37.0 |
HIP 24703 |
20.28 |
| 2026-10-01 12:00 |
05:19:03.06 |
+07:54:22.6 |
HIP 24703 |
20.22 |
| 2026-10-02 00:00 |
05:19:02.05 |
+07:54:08.2 |
HIP 24703 |
20.16 |
| 2026-10-02 12:00 |
05:19:01.01 |
+07:53:53.9 |
HIP 24703 |
20.10 |
| 2026-10-03 00:00 |
05:18:59.94 |
+07:53:39.5 |
HIP 24703 |
20.04 |
| 2026-10-03 12:00 |
05:18:58.84 |
+07:53:25.2 |
HIP 24703 |
19.98 |
| 2026-10-04 00:00 |
05:18:57.71 |
+07:53:10.8 |
HIP 24703 |
19.93 |
| 2026-10-04 12:00 |
05:18:56.55 |
+07:52:56.5 |
HIP 24703 |
19.87 |
| 2026-10-05 00:00 |
05:18:55.36 |
+07:52:42.1 |
HIP 24703 |
19.82 |
| 2026-10-05 12:00 |
05:18:54.14 |
+07:52:27.8 |
HIP 24703 |
19.77 |
| 2026-10-06 00:00 |
05:18:52.90 |
+07:52:13.5 |
HIP 24703 |
19.72 |
| 2026-10-06 12:00 |
05:18:51.62 |
+07:51:59.2 |
HIP 24703 |
19.67 |
| 2026-10-07 00:00 |
05:18:50.32 |
+07:51:44.9 |
HIP 24703 |
19.62 |
| 2026-10-07 12:00 |
05:18:48.99 |
+07:51:30.6 |
HIP 24703 |
19.58 |
| 2026-10-08 00:00 |
05:18:47.62 |
+07:51:16.3 |
HIP 24703 |
19.55 |
| 2026-10-08 12:00 |
05:18:46.23 |
+07:51:02.1 |
HIP 24703 |
19.51 |
| 2026-10-09 00:00 |
05:18:44.81 |
+07:50:47.8 |
HIP 24703 |
19.48 |
| 2026-10-09 12:00 |
05:18:43.37 |
+07:50:33.6 |
HIP 24703 |
19.46 |
| 2026-10-10 00:00 |
05:18:41.89 |
+07:50:19.4 |
HIP 24703 |
19.44 |
| 2026-10-10 12:00 |
05:18:40.39 |
+07:50:05.2 |
HIP 24703 |
19.43 |
| 2026-10-11 00:00 |
05:18:38.86 |
+07:49:51.0 |
HIP 24703 |
19.42 |