C/2011 G1 (McNaught)
| 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) |
| 2026-02-03 00:00 |
00:05:15.27 |
+11:29:54.1 |
HIP 326 |
21.14 |
| 2026-02-03 12:00 |
00:05:17.46 |
+11:29:58.8 |
HIP 326 |
21.60 |
| 2026-02-04 00:00 |
00:05:19.67 |
+11:30:03.7 |
HIP 326 |
22.06 |
| 2026-02-04 12:00 |
00:05:21.90 |
+11:30:08.9 |
HIP 326 |
22.54 |
| 2026-02-05 00:00 |
00:05:24.15 |
+11:30:14.2 |
HIP 326 |
23.02 |
| 2026-02-05 12:00 |
00:05:26.42 |
+11:30:19.7 |
HIP 326 |
23.52 |
| 2026-02-06 00:00 |
00:05:28.71 |
+11:30:25.4 |
HIP 326 |
24.02 |
| 2026-02-06 12:00 |
00:05:31.02 |
+11:30:31.3 |
HIP 326 |
24.53 |
| 2026-02-07 00:00 |
00:05:33.35 |
+11:30:37.4 |
HIP 326 |
25.05 |
| 2026-02-07 12:00 |
00:05:35.70 |
+11:30:43.7 |
HIP 326 |
25.58 |
| 2026-02-08 00:00 |
00:05:38.08 |
+11:30:50.1 |
HIP 326 |
26.12 |
| 2026-02-08 12:00 |
00:05:40.47 |
+11:30:56.8 |
HIP 326 |
26.66 |
| 2026-02-09 00:00 |
00:05:42.88 |
+11:31:03.7 |
HIP 326 |
27.21 |
| 2026-02-09 12:00 |
00:05:45.31 |
+11:31:10.8 |
HIP 326 |
27.78 |
| 2026-02-10 00:00 |
00:05:47.75 |
+11:31:18.0 |
HIP 326 |
28.34 |
| 2026-02-10 12:00 |
00:05:50.22 |
+11:31:25.5 |
HIP 326 |
28.92 |
| 2026-02-11 00:00 |
00:05:52.71 |
+11:31:33.1 |
HIP 326 |
29.50 |
| 2026-02-11 12:00 |
00:05:55.21 |
+11:31:40.9 |
HIP 326 |
30.09 |
| 2026-02-12 00:00 |
00:05:57.74 |
+11:31:48.9 |
HIP 326 |
30.69 |
| 2026-02-12 12:00 |
00:06:00.28 |
+11:31:57.1 |
HIP 326 |
31.29 |
| 2026-02-13 00:00 |
00:06:02.84 |
+11:32:05.5 |
HIP 326 |
31.90 |
| 2026-02-13 12:00 |
00:06:05.41 |
+11:32:14.1 |
HIP 326 |
32.52 |
| 2026-02-14 00:00 |
00:06:08.01 |
+11:32:22.9 |
HIP 326 |
33.14 |
| 2026-02-14 12:00 |
00:06:10.62 |
+11:32:31.8 |
HIP 326 |
33.77 |
| 2026-02-15 00:00 |
00:06:13.24 |
+11:32:40.9 |
HIP 326 |
34.41 |
| 2026-02-15 12:00 |
00:06:15.89 |
+11:32:50.2 |
HIP 326 |
35.05 |
| 2026-02-16 00:00 |
00:06:18.55 |
+11:32:59.7 |
HIP 326 |
35.70 |
| 2026-02-16 12:00 |
00:06:21.23 |
+11:33:09.4 |
HIP 326 |
36.35 |
| 2026-02-17 00:00 |
00:06:23.92 |
+11:33:19.2 |
HIP 326 |
37.01 |
| 2026-02-17 12:00 |
00:06:26.63 |
+11:33:29.2 |
HIP 326 |
37.67 |
| 2026-02-18 00:00 |
00:06:29.35 |
+11:33:39.4 |
HIP 694 |
37.98 |
| 2026-02-18 12:00 |
00:06:32.09 |
+11:33:49.8 |
HIP 694 |
37.56 |
| 2026-02-19 00:00 |
00:06:34.85 |
+11:34:00.3 |
HIP 694 |
37.15 |
| 2026-02-19 12:00 |
00:06:37.62 |
+11:34:11.0 |
HIP 694 |
36.74 |
| 2026-02-20 00:00 |
00:06:40.40 |
+11:34:21.9 |
HIP 694 |
36.35 |
| 2026-02-20 12:00 |
00:06:43.20 |
+11:34:33.0 |
HIP 694 |
35.96 |
| 2026-02-21 00:00 |
00:06:46.01 |
+11:34:44.2 |
HIP 694 |
35.58 |
| 2026-02-21 12:00 |
00:06:48.84 |
+11:34:55.6 |
HIP 694 |
35.21 |
| 2026-02-22 00:00 |
00:06:51.68 |
+11:35:07.1 |
HIP 694 |
34.86 |
| 2026-02-22 12:00 |
00:06:54.53 |
+11:35:18.9 |
HIP 694 |
34.51 |
| 2026-02-23 00:00 |
00:06:57.40 |
+11:35:30.7 |
HIP 694 |
34.18 |
| 2026-02-23 12:00 |
00:07:00.28 |
+11:35:42.8 |
HIP 694 |
33.86 |
| 2026-02-24 00:00 |
00:07:03.17 |
+11:35:55.0 |
HIP 694 |
33.55 |