| Parameter |
Value |
| Designation |
C/2011 R1 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2012-10-19T14:54:08.481600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:56Z |
| Obs used |
1454 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
6.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-10-24.0000000 |
| e |
1.00074117 |
| q (au) |
2.079571 |
| a (au) |
-2805.810838 |
| i (deg) |
116.196842 |
| Ω (om, deg) |
221.408458 |
| ω (w, deg) |
308.861192 |
| M (ma, deg) |
0.000029 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.666 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.666 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.998 |
| 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 |
| 2010-10-11 |
2012-04-01 |
+7.1902 |
-6.300 |
| 2012-04-01 |
2012-10-15 |
-6.1910 |
-0.092 |
| 2012-12-23 |
2013-02-17 |
+39.6659 |
-16.680 |
| 2013-02-17 |
2014-04-11 |
+3.1359 |
-1.430 |
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 |
11:16:19.31 |
+77:48:28.3 |
HIP 54821 |
14.53 |
| 2026-09-20 12:00 |
11:16:34.81 |
+77:48:34.1 |
HIP 54821 |
15.15 |
| 2026-09-21 00:00 |
11:16:50.30 |
+77:48:40.4 |
HIP 54821 |
15.80 |
| 2026-09-21 12:00 |
11:17:05.77 |
+77:48:47.1 |
HIP 54821 |
16.46 |
| 2026-09-22 00:00 |
11:17:21.22 |
+77:48:54.2 |
HIP 54821 |
17.15 |
| 2026-09-22 12:00 |
11:17:36.65 |
+77:49:01.7 |
HIP 54821 |
17.85 |
| 2026-09-23 00:00 |
11:17:52.06 |
+77:49:09.6 |
HIP 54821 |
18.57 |
| 2026-09-23 12:00 |
11:18:07.45 |
+77:49:18.0 |
HIP 54821 |
19.29 |
| 2026-09-24 00:00 |
11:18:22.82 |
+77:49:26.8 |
HIP 54821 |
20.03 |
| 2026-09-24 12:00 |
11:18:38.17 |
+77:49:36.0 |
HIP 54821 |
20.78 |
| 2026-09-25 00:00 |
11:18:53.49 |
+77:49:45.6 |
HIP 54821 |
21.53 |
| 2026-09-25 12:00 |
11:19:08.79 |
+77:49:55.6 |
HIP 54821 |
22.30 |
| 2026-09-26 00:00 |
11:19:24.07 |
+77:50:06.1 |
HIP 54821 |
23.07 |
| 2026-09-26 12:00 |
11:19:39.32 |
+77:50:16.9 |
HIP 54821 |
23.85 |
| 2026-09-27 00:00 |
11:19:54.55 |
+77:50:28.2 |
HIP 54821 |
24.63 |
| 2026-09-27 12:00 |
11:20:09.75 |
+77:50:39.9 |
HIP 54821 |
25.42 |
| 2026-09-28 00:00 |
11:20:24.92 |
+77:50:52.0 |
HIP 54821 |
26.21 |
| 2026-09-28 12:00 |
11:20:40.07 |
+77:51:04.6 |
HIP 54821 |
27.01 |
| 2026-09-29 00:00 |
11:20:55.18 |
+77:51:17.6 |
HIP 54821 |
27.81 |
| 2026-09-29 12:00 |
11:21:10.27 |
+77:51:30.9 |
HIP 54821 |
28.61 |
| 2026-09-30 00:00 |
11:21:25.33 |
+77:51:44.7 |
HIP 54821 |
29.42 |
| 2026-09-30 12:00 |
11:21:40.36 |
+77:51:58.9 |
HIP 55561 |
29.81 |
| 2026-10-01 00:00 |
11:21:55.36 |
+77:52:13.6 |
HIP 55561 |
29.96 |
| 2026-10-01 12:00 |
11:22:10.33 |
+77:52:28.6 |
HIP 55561 |
30.15 |
| 2026-10-02 00:00 |
11:22:25.26 |
+77:52:44.1 |
HIP 55561 |
30.36 |
| 2026-10-02 12:00 |
11:22:40.16 |
+77:53:00.0 |
HIP 55561 |
30.60 |
| 2026-10-03 00:00 |
11:22:55.03 |
+77:53:16.3 |
HIP 55561 |
30.87 |
| 2026-10-03 12:00 |
11:23:09.86 |
+77:53:33.0 |
HIP 56222 |
30.06 |
| 2026-10-04 00:00 |
11:23:24.66 |
+77:53:50.2 |
HIP 56222 |
29.24 |
| 2026-10-04 12:00 |
11:23:39.42 |
+77:54:07.8 |
HIP 56222 |
28.43 |
| 2026-10-05 00:00 |
11:23:54.14 |
+77:54:25.7 |
HIP 56222 |
27.62 |
| 2026-10-05 12:00 |
11:24:08.83 |
+77:54:44.2 |
HIP 56222 |
26.80 |
| 2026-10-06 00:00 |
11:24:23.47 |
+77:55:03.0 |
HIP 56222 |
25.98 |
| 2026-10-06 12:00 |
11:24:38.08 |
+77:55:22.2 |
HIP 56222 |
25.16 |
| 2026-10-07 00:00 |
11:24:52.65 |
+77:55:41.9 |
HIP 56222 |
24.35 |
| 2026-10-07 12:00 |
11:25:07.17 |
+77:56:02.0 |
HIP 56222 |
23.53 |
| 2026-10-08 00:00 |
11:25:21.65 |
+77:56:22.5 |
HIP 56222 |
22.70 |
| 2026-10-08 12:00 |
11:25:36.09 |
+77:56:43.4 |
HIP 56222 |
21.88 |
| 2026-10-09 00:00 |
11:25:50.49 |
+77:57:04.7 |
HIP 56222 |
21.06 |
| 2026-10-09 12:00 |
11:26:04.83 |
+77:57:26.5 |
HIP 56222 |
20.23 |
| 2026-10-10 00:00 |
11:26:19.14 |
+77:57:48.6 |
HIP 56222 |
19.41 |
| 2026-10-10 12:00 |
11:26:33.39 |
+77:58:11.2 |
HIP 56222 |
18.58 |
| 2026-10-11 00:00 |
11:26:47.60 |
+77:58:34.2 |
HIP 56222 |
17.75 |