| Parameter |
Value |
| Designation |
C/2011 G1 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-09-16T09:53:33.371520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:48Z |
| Obs used |
487 |
| NEO |
- |
| M1 |
14.400 |
| K1 |
5.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-11-20.0000000 |
| e |
1.00100017 |
| q (au) |
2.155142 |
| a (au) |
-2154.765225 |
| i (deg) |
162.233498 |
| Ω (om, deg) |
152.590960 |
| ω (w, deg) |
354.550126 |
| M (ma, deg) |
0.000636 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.505 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.505 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.997 |
| 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 |
| 2011-04-05 |
2011-06-17 |
+0.1582 |
-0.303 |
| 2011-10-25 |
2011-12-30 |
+31.4390 |
-11.639 |
| 2011-12-30 |
2012-03-18 |
-17.9862 |
+7.533 |
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 |
00:10:11.23 |
+11:52:11.5 |
HIP 797 |
27.63 |
| 2026-03-26 12:00 |
00:10:14.46 |
+11:52:31.0 |
HIP 797 |
28.10 |
| 2026-03-27 00:00 |
00:10:17.69 |
+11:52:50.6 |
HIP 797 |
28.58 |
| 2026-03-27 12:00 |
00:10:20.91 |
+11:53:10.2 |
HIP 797 |
29.08 |
| 2026-03-28 00:00 |
00:10:24.14 |
+11:53:29.9 |
HIP 797 |
29.60 |
| 2026-03-28 12:00 |
00:10:27.36 |
+11:53:49.6 |
HIP 797 |
30.14 |
| 2026-03-29 00:00 |
00:10:30.57 |
+11:54:09.4 |
HIP 797 |
30.69 |
| 2026-03-29 12:00 |
00:10:33.79 |
+11:54:29.3 |
HIP 797 |
31.25 |
| 2026-03-30 00:00 |
00:10:37.00 |
+11:54:49.3 |
HIP 797 |
31.83 |
| 2026-03-30 12:00 |
00:10:40.21 |
+11:55:09.3 |
HIP 797 |
32.42 |
| 2026-03-31 00:00 |
00:10:43.41 |
+11:55:29.4 |
HIP 797 |
33.03 |
| 2026-03-31 12:00 |
00:10:46.61 |
+11:55:49.5 |
HIP 797 |
33.64 |
| 2026-04-01 00:00 |
00:10:49.80 |
+11:56:09.7 |
HIP 797 |
34.27 |
| 2026-04-01 12:00 |
00:10:53.00 |
+11:56:29.9 |
HIP 797 |
34.91 |
| 2026-04-02 00:00 |
00:10:56.18 |
+11:56:50.3 |
HIP 797 |
35.55 |
| 2026-04-02 12:00 |
00:10:59.36 |
+11:57:10.6 |
HIP 1059 |
35.12 |
| 2026-04-03 00:00 |
00:11:02.54 |
+11:57:31.0 |
HIP 1059 |
34.54 |
| 2026-04-03 12:00 |
00:11:05.71 |
+11:57:51.5 |
HIP 1059 |
33.97 |
| 2026-04-04 00:00 |
00:11:08.88 |
+11:58:12.0 |
HIP 1059 |
33.42 |
| 2026-04-04 12:00 |
00:11:12.04 |
+11:58:32.6 |
HIP 1059 |
32.88 |
| 2026-04-05 00:00 |
00:11:15.20 |
+11:58:53.2 |
HIP 1059 |
32.35 |
| 2026-04-05 12:00 |
00:11:18.35 |
+11:59:13.8 |
HIP 1059 |
31.84 |
| 2026-04-06 00:00 |
00:11:21.49 |
+11:59:34.5 |
HIP 1059 |
31.35 |
| 2026-04-06 12:00 |
00:11:24.63 |
+11:59:55.2 |
HIP 1038 |
30.68 |
| 2026-04-07 00:00 |
00:11:27.76 |
+12:00:16.0 |
HIP 1038 |
29.87 |
| 2026-04-07 12:00 |
00:11:30.88 |
+12:00:36.8 |
HIP 1038 |
29.07 |
| 2026-04-08 00:00 |
00:11:34.00 |
+12:00:57.7 |
HIP 1038 |
28.27 |
| 2026-04-08 12:00 |
00:11:37.11 |
+12:01:18.6 |
HIP 1038 |
27.47 |
| 2026-04-09 00:00 |
00:11:40.21 |
+12:01:39.5 |
HIP 1038 |
26.68 |
| 2026-04-09 12:00 |
00:11:43.30 |
+12:02:00.5 |
HIP 1038 |
25.89 |
| 2026-04-10 00:00 |
00:11:46.39 |
+12:02:21.5 |
HIP 1038 |
25.10 |
| 2026-04-10 12:00 |
00:11:49.47 |
+12:02:42.5 |
HIP 1038 |
24.32 |
| 2026-04-11 00:00 |
00:11:52.54 |
+12:03:03.5 |
HIP 1038 |
23.54 |
| 2026-04-11 12:00 |
00:11:55.60 |
+12:03:24.6 |
HIP 1038 |
22.77 |
| 2026-04-12 00:00 |
00:11:58.65 |
+12:03:45.7 |
HIP 1038 |
22.00 |
| 2026-04-12 12:00 |
00:12:01.69 |
+12:04:06.9 |
HIP 1038 |
21.24 |
| 2026-04-13 00:00 |
00:12:04.72 |
+12:04:28.0 |
HIP 1038 |
20.48 |
| 2026-04-13 12:00 |
00:12:07.75 |
+12:04:49.2 |
HIP 1038 |
19.73 |
| 2026-04-14 00:00 |
00:12:10.76 |
+12:05:10.4 |
HIP 1038 |
18.99 |
| 2026-04-14 12:00 |
00:12:13.77 |
+12:05:31.6 |
HIP 1038 |
18.25 |
| 2026-04-15 00:00 |
00:12:16.76 |
+12:05:52.8 |
HIP 1038 |
17.53 |
| 2026-04-15 12:00 |
00:12:19.75 |
+12:06:14.0 |
HIP 1038 |
16.81 |
| 2026-04-16 00:00 |
00:12:22.72 |
+12:06:35.3 |
HIP 1038 |
16.10 |