| 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 |
-1.000 |
| 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) |
| 2026-06-01 00:00 |
00:15:45.12 |
+12:36:34.3 |
HIP 1174 |
27.56 |
| 2026-06-01 12:00 |
00:15:46.31 |
+12:36:50.1 |
HIP 1174 |
27.95 |
| 2026-06-02 00:00 |
00:15:47.47 |
+12:37:05.7 |
HIP 1174 |
28.32 |
| 2026-06-02 12:00 |
00:15:48.61 |
+12:37:21.2 |
HIP 1174 |
28.70 |
| 2026-06-03 00:00 |
00:15:49.72 |
+12:37:36.5 |
HIP 1174 |
29.06 |
| 2026-06-03 12:00 |
00:15:50.80 |
+12:37:51.8 |
HIP 1174 |
29.42 |
| 2026-06-04 00:00 |
00:15:51.86 |
+12:38:06.9 |
HIP 1174 |
29.78 |
| 2026-06-04 12:00 |
00:15:52.89 |
+12:38:21.9 |
HIP 1174 |
30.13 |
| 2026-06-05 00:00 |
00:15:53.89 |
+12:38:36.7 |
HIP 1174 |
30.47 |
| 2026-06-05 12:00 |
00:15:54.87 |
+12:38:51.5 |
HIP 1439 |
30.53 |
| 2026-06-06 00:00 |
00:15:55.82 |
+12:39:06.0 |
HIP 1439 |
30.25 |
| 2026-06-06 12:00 |
00:15:56.75 |
+12:39:20.5 |
HIP 1439 |
29.98 |
| 2026-06-07 00:00 |
00:15:57.64 |
+12:39:34.8 |
HIP 1439 |
29.71 |
| 2026-06-07 12:00 |
00:15:58.51 |
+12:39:49.0 |
HIP 1439 |
29.45 |
| 2026-06-08 00:00 |
00:15:59.36 |
+12:40:03.0 |
HIP 1439 |
29.20 |
| 2026-06-08 12:00 |
00:16:00.17 |
+12:40:16.9 |
HIP 1439 |
28.95 |
| 2026-06-09 00:00 |
00:16:00.96 |
+12:40:30.7 |
HIP 1439 |
28.72 |
| 2026-06-09 12:00 |
00:16:01.72 |
+12:40:44.3 |
HIP 1439 |
28.49 |
| 2026-06-10 00:00 |
00:16:02.46 |
+12:40:57.8 |
HIP 1439 |
28.27 |
| 2026-06-10 12:00 |
00:16:03.16 |
+12:41:11.1 |
HIP 1439 |
28.06 |
| 2026-06-11 00:00 |
00:16:03.84 |
+12:41:24.3 |
HIP 1439 |
27.86 |
| 2026-06-11 12:00 |
00:16:04.49 |
+12:41:37.3 |
HIP 1439 |
27.66 |
| 2026-06-12 00:00 |
00:16:05.12 |
+12:41:50.2 |
HIP 1439 |
27.48 |
| 2026-06-12 12:00 |
00:16:05.71 |
+12:42:03.0 |
HIP 1439 |
27.30 |
| 2026-06-13 00:00 |
00:16:06.28 |
+12:42:15.6 |
HIP 1439 |
27.13 |
| 2026-06-13 12:00 |
00:16:06.82 |
+12:42:28.0 |
HIP 1439 |
26.97 |
| 2026-06-14 00:00 |
00:16:07.33 |
+12:42:40.3 |
HIP 1439 |
26.82 |
| 2026-06-14 12:00 |
00:16:07.81 |
+12:42:52.4 |
HIP 1439 |
26.68 |
| 2026-06-15 00:00 |
00:16:08.27 |
+12:43:04.4 |
HIP 1439 |
26.54 |
| 2026-06-15 12:00 |
00:16:08.69 |
+12:43:16.2 |
HIP 1439 |
26.41 |
| 2026-06-16 00:00 |
00:16:09.09 |
+12:43:27.9 |
HIP 1439 |
26.30 |
| 2026-06-16 12:00 |
00:16:09.46 |
+12:43:39.4 |
HIP 1439 |
26.19 |
| 2026-06-17 00:00 |
00:16:09.80 |
+12:43:50.7 |
HIP 1439 |
26.09 |
| 2026-06-17 12:00 |
00:16:10.11 |
+12:44:01.9 |
HIP 1439 |
25.99 |
| 2026-06-18 00:00 |
00:16:10.40 |
+12:44:12.9 |
HIP 1439 |
25.91 |
| 2026-06-18 12:00 |
00:16:10.65 |
+12:44:23.8 |
HIP 1439 |
25.83 |
| 2026-06-19 00:00 |
00:16:10.88 |
+12:44:34.5 |
HIP 1439 |
25.77 |
| 2026-06-19 12:00 |
00:16:11.07 |
+12:44:45.0 |
HIP 1439 |
25.71 |
| 2026-06-20 00:00 |
00:16:11.24 |
+12:44:55.4 |
HIP 1439 |
25.66 |
| 2026-06-20 12:00 |
00:16:11.38 |
+12:45:05.6 |
HIP 1439 |
25.61 |
| 2026-06-21 00:00 |
00:16:11.49 |
+12:45:15.6 |
HIP 1439 |
25.58 |
| 2026-06-21 12:00 |
00:16:11.57 |
+12:45:25.5 |
HIP 1439 |
25.55 |
| 2026-06-22 00:00 |
00:16:11.62 |
+12:45:35.1 |
HIP 1439 |
25.53 |