| 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 |
0.999 |
| 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 |
+10.0795 |
-0.697 |
| 2011-03-19 |
2011-04-17 |
+45.5485 |
-0.310 |
| 2011-04-18 |
2011-06-07 |
-12.9373 |
-3.109 |
| 2011-06-07 |
2011-08-07 |
-10.1929 |
-2.073 |
| 2011-08-07 |
2011-11-18 |
+22.7570 |
-11.124 |
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 |
05:04:59.21 |
+07:55:07.4 |
HIP 23683 |
6.98 |
| 2026-03-26 12:00 |
05:05:00.42 |
+07:55:21.9 |
HIP 23683 |
6.63 |
| 2026-03-27 00:00 |
05:05:01.66 |
+07:55:36.4 |
HIP 23683 |
6.27 |
| 2026-03-27 12:00 |
05:05:02.93 |
+07:55:50.9 |
HIP 23683 |
5.91 |
| 2026-03-28 00:00 |
05:05:04.23 |
+07:56:05.4 |
HIP 23683 |
5.55 |
| 2026-03-28 12:00 |
05:05:05.56 |
+07:56:19.9 |
HIP 23683 |
5.19 |
| 2026-03-29 00:00 |
05:05:06.91 |
+07:56:34.4 |
HIP 23683 |
4.83 |
| 2026-03-29 12:00 |
05:05:08.30 |
+07:56:48.8 |
HIP 23683 |
4.48 |
| 2026-03-30 00:00 |
05:05:09.71 |
+07:57:03.3 |
HIP 23683 |
4.12 |
| 2026-03-30 12:00 |
05:05:11.14 |
+07:57:17.7 |
HIP 23683 |
3.78 |
| 2026-03-31 00:00 |
05:05:12.61 |
+07:57:32.1 |
HIP 23683 |
3.44 |
| 2026-03-31 12:00 |
05:05:14.10 |
+07:57:46.5 |
HIP 23683 |
3.13 |
| 2026-04-01 00:00 |
05:05:15.62 |
+07:58:00.9 |
HIP 23683 |
2.84 |
| 2026-04-01 12:00 |
05:05:17.17 |
+07:58:15.3 |
HIP 23683 |
2.60 |
| 2026-04-02 00:00 |
05:05:18.74 |
+07:58:29.6 |
HIP 23683 |
2.40 |
| 2026-04-02 12:00 |
05:05:20.34 |
+07:58:43.9 |
HIP 23683 |
2.28 |
| 2026-04-03 00:00 |
05:05:21.97 |
+07:58:58.2 |
HIP 23683 |
2.25 |
| 2026-04-03 12:00 |
05:05:23.62 |
+07:59:12.5 |
HIP 23683 |
2.31 |
| 2026-04-04 00:00 |
05:05:25.30 |
+07:59:26.8 |
HIP 23683 |
2.46 |
| 2026-04-04 12:00 |
05:05:27.01 |
+07:59:41.0 |
HIP 23683 |
2.69 |
| 2026-04-05 00:00 |
05:05:28.74 |
+07:59:55.3 |
HIP 23683 |
2.98 |
| 2026-04-05 12:00 |
05:05:30.50 |
+08:00:09.5 |
HIP 23683 |
3.32 |
| 2026-04-06 00:00 |
05:05:32.28 |
+08:00:23.6 |
HIP 23683 |
3.70 |
| 2026-04-06 12:00 |
05:05:34.09 |
+08:00:37.8 |
HIP 23683 |
4.10 |
| 2026-04-07 00:00 |
05:05:35.93 |
+08:00:51.9 |
HIP 23683 |
4.53 |
| 2026-04-07 12:00 |
05:05:37.79 |
+08:01:06.0 |
HIP 23683 |
4.98 |
| 2026-04-08 00:00 |
05:05:39.68 |
+08:01:20.0 |
HIP 23683 |
5.44 |
| 2026-04-08 12:00 |
05:05:41.59 |
+08:01:34.0 |
HIP 23683 |
5.92 |
| 2026-04-09 00:00 |
05:05:43.53 |
+08:01:48.0 |
HIP 23683 |
6.41 |
| 2026-04-09 12:00 |
05:05:45.49 |
+08:02:02.0 |
HIP 23683 |
6.91 |
| 2026-04-10 00:00 |
05:05:47.48 |
+08:02:15.9 |
HIP 23683 |
7.42 |
| 2026-04-10 12:00 |
05:05:49.49 |
+08:02:29.8 |
HIP 23683 |
7.94 |
| 2026-04-11 00:00 |
05:05:51.53 |
+08:02:43.7 |
HIP 23683 |
8.46 |
| 2026-04-11 12:00 |
05:05:53.59 |
+08:02:57.5 |
HIP 23683 |
9.00 |
| 2026-04-12 00:00 |
05:05:55.67 |
+08:03:11.3 |
HIP 23683 |
9.54 |
| 2026-04-12 12:00 |
05:05:57.78 |
+08:03:25.0 |
HIP 23683 |
10.08 |
| 2026-04-13 00:00 |
05:05:59.91 |
+08:03:38.7 |
HIP 23683 |
10.64 |
| 2026-04-13 12:00 |
05:06:02.07 |
+08:03:52.4 |
HIP 23683 |
11.20 |
| 2026-04-14 00:00 |
05:06:04.25 |
+08:04:06.0 |
HIP 23683 |
11.76 |
| 2026-04-14 12:00 |
05:06:06.45 |
+08:04:19.6 |
HIP 23683 |
12.34 |
| 2026-04-15 00:00 |
05:06:08.68 |
+08:04:33.1 |
HIP 23683 |
12.91 |
| 2026-04-15 12:00 |
05:06:10.93 |
+08:04:46.6 |
HIP 23683 |
13.50 |
| 2026-04-16 00:00 |
05:06:13.21 |
+08:05:00.1 |
HIP 23683 |
14.09 |