| 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) |
| 2026-05-12 00:00 |
00:14:37.63 |
+12:24:37.2 |
HIP 1174 |
10.44 |
| 2026-05-12 12:00 |
00:14:39.76 |
+12:24:56.9 |
HIP 1174 |
10.76 |
| 2026-05-13 00:00 |
00:14:41.87 |
+12:25:16.5 |
HIP 1174 |
11.11 |
| 2026-05-13 12:00 |
00:14:43.96 |
+12:25:36.0 |
HIP 1174 |
11.47 |
| 2026-05-14 00:00 |
00:14:46.02 |
+12:25:55.4 |
HIP 1174 |
11.86 |
| 2026-05-14 12:00 |
00:14:48.07 |
+12:26:14.8 |
HIP 1174 |
12.25 |
| 2026-05-15 00:00 |
00:14:50.09 |
+12:26:34.1 |
HIP 1174 |
12.66 |
| 2026-05-15 12:00 |
00:14:52.09 |
+12:26:53.3 |
HIP 1174 |
13.09 |
| 2026-05-16 00:00 |
00:14:54.08 |
+12:27:12.5 |
HIP 1174 |
13.52 |
| 2026-05-16 12:00 |
00:14:56.03 |
+12:27:31.5 |
HIP 1174 |
13.96 |
| 2026-05-17 00:00 |
00:14:57.97 |
+12:27:50.5 |
HIP 1174 |
14.40 |
| 2026-05-17 12:00 |
00:14:59.89 |
+12:28:09.4 |
HIP 1174 |
14.85 |
| 2026-05-18 00:00 |
00:15:01.78 |
+12:28:28.2 |
HIP 1174 |
15.31 |
| 2026-05-18 12:00 |
00:15:03.65 |
+12:28:46.9 |
HIP 1174 |
15.77 |
| 2026-05-19 00:00 |
00:15:05.49 |
+12:29:05.5 |
HIP 1174 |
16.23 |
| 2026-05-19 12:00 |
00:15:07.32 |
+12:29:24.1 |
HIP 1174 |
16.69 |
| 2026-05-20 00:00 |
00:15:09.12 |
+12:29:42.5 |
HIP 1174 |
17.15 |
| 2026-05-20 12:00 |
00:15:10.90 |
+12:30:00.9 |
HIP 1174 |
17.61 |
| 2026-05-21 00:00 |
00:15:12.65 |
+12:30:19.1 |
HIP 1174 |
18.08 |
| 2026-05-21 12:00 |
00:15:14.38 |
+12:30:37.3 |
HIP 1174 |
18.54 |
| 2026-05-22 00:00 |
00:15:16.09 |
+12:30:55.3 |
HIP 1174 |
19.00 |
| 2026-05-22 12:00 |
00:15:17.77 |
+12:31:13.3 |
HIP 1174 |
19.46 |
| 2026-05-23 00:00 |
00:15:19.43 |
+12:31:31.2 |
HIP 1174 |
19.92 |
| 2026-05-23 12:00 |
00:15:21.07 |
+12:31:48.9 |
HIP 1174 |
20.37 |
| 2026-05-24 00:00 |
00:15:22.68 |
+12:32:06.6 |
HIP 1174 |
20.83 |
| 2026-05-24 12:00 |
00:15:24.27 |
+12:32:24.2 |
HIP 1174 |
21.28 |
| 2026-05-25 00:00 |
00:15:25.83 |
+12:32:41.6 |
HIP 1174 |
21.72 |
| 2026-05-25 12:00 |
00:15:27.37 |
+12:32:59.0 |
HIP 1174 |
22.17 |
| 2026-05-26 00:00 |
00:15:28.89 |
+12:33:16.2 |
HIP 1174 |
22.61 |
| 2026-05-26 12:00 |
00:15:30.38 |
+12:33:33.3 |
HIP 1174 |
23.04 |
| 2026-05-27 00:00 |
00:15:31.84 |
+12:33:50.4 |
HIP 1174 |
23.48 |
| 2026-05-27 12:00 |
00:15:33.28 |
+12:34:07.3 |
HIP 1174 |
23.91 |
| 2026-05-28 00:00 |
00:15:34.70 |
+12:34:24.1 |
HIP 1174 |
24.33 |
| 2026-05-28 12:00 |
00:15:36.09 |
+12:34:40.8 |
HIP 1174 |
24.75 |
| 2026-05-29 00:00 |
00:15:37.46 |
+12:34:57.3 |
HIP 1174 |
25.17 |
| 2026-05-29 12:00 |
00:15:38.80 |
+12:35:13.8 |
HIP 1174 |
25.58 |
| 2026-05-30 00:00 |
00:15:40.11 |
+12:35:30.1 |
HIP 1174 |
25.98 |
| 2026-05-30 12:00 |
00:15:41.40 |
+12:35:46.4 |
HIP 1174 |
26.39 |
| 2026-05-31 00:00 |
00:15:42.67 |
+12:36:02.5 |
HIP 1174 |
26.78 |
| 2026-05-31 12:00 |
00:15:43.91 |
+12:36:18.5 |
HIP 1174 |
27.18 |
| 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 |