C/2013 G2 (McNaught)
| Parameter |
Value |
| Designation |
C/2013 G2 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2012-12-06T08:24:02.825280Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:32Z |
| Obs used |
111 |
| NEO |
- |
| M1 |
13.700 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-05-24.0000000 |
| e |
1.00017667 |
| q (au) |
2.154122 |
| a (au) |
-12193.190355 |
| i (deg) |
96.001965 |
| Ω (om, deg) |
274.112530 |
| ω (w, deg) |
293.912193 |
| M (ma, deg) |
0.000123 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.810 + 2.787\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.810 |
| n |
2.787 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
17:30:29.56 |
+56:59:46.5 |
HIP 85794 |
12.14 |
| 2026-02-03 12:00 |
17:30:34.19 |
+57:00:37.1 |
HIP 85794 |
11.94 |
| 2026-02-04 00:00 |
17:30:38.77 |
+57:01:28.1 |
HIP 85796 |
11.84 |
| 2026-02-04 12:00 |
17:30:43.30 |
+57:02:19.3 |
HIP 85796 |
11.82 |
| 2026-02-05 00:00 |
17:30:47.78 |
+57:03:10.9 |
HIP 85796 |
11.90 |
| 2026-02-05 12:00 |
17:30:52.22 |
+57:04:02.8 |
HIP 85796 |
12.09 |
| 2026-02-06 00:00 |
17:30:56.61 |
+57:04:55.0 |
HIP 85796 |
12.37 |
| 2026-02-06 12:00 |
17:31:00.95 |
+57:05:47.5 |
HIP 85796 |
12.74 |
| 2026-02-07 00:00 |
17:31:05.24 |
+57:06:40.3 |
HIP 85796 |
13.19 |
| 2026-02-07 12:00 |
17:31:09.47 |
+57:07:33.4 |
HIP 85796 |
13.71 |
| 2026-02-08 00:00 |
17:31:13.66 |
+57:08:26.8 |
HIP 85796 |
14.31 |
| 2026-02-08 12:00 |
17:31:17.80 |
+57:09:20.5 |
HIP 85796 |
14.96 |
| 2026-02-09 00:00 |
17:31:21.89 |
+57:10:14.4 |
HIP 85796 |
15.66 |
| 2026-02-09 12:00 |
17:31:25.93 |
+57:11:08.7 |
HIP 85796 |
16.40 |
| 2026-02-10 00:00 |
17:31:29.91 |
+57:12:03.2 |
HIP 85796 |
17.19 |
| 2026-02-10 12:00 |
17:31:33.84 |
+57:12:58.1 |
HIP 85796 |
18.01 |
| 2026-02-11 00:00 |
17:31:37.72 |
+57:13:53.2 |
HIP 85796 |
18.86 |
| 2026-02-11 12:00 |
17:31:41.55 |
+57:14:48.5 |
HIP 85796 |
19.73 |
| 2026-02-12 00:00 |
17:31:45.33 |
+57:15:44.2 |
HIP 85796 |
20.62 |
| 2026-02-12 12:00 |
17:31:49.05 |
+57:16:40.1 |
HIP 85796 |
21.54 |
| 2026-02-13 00:00 |
17:31:52.71 |
+57:17:36.3 |
HIP 85923 |
20.75 |
| 2026-02-13 12:00 |
17:31:56.33 |
+57:18:32.7 |
HIP 85923 |
19.72 |
| 2026-02-14 00:00 |
17:31:59.89 |
+57:19:29.4 |
HIP 85923 |
18.69 |
| 2026-02-14 12:00 |
17:32:03.39 |
+57:20:26.3 |
HIP 85923 |
17.66 |
| 2026-02-15 00:00 |
17:32:06.84 |
+57:21:23.4 |
HIP 85923 |
16.65 |
| 2026-02-15 12:00 |
17:32:10.23 |
+57:22:20.9 |
HIP 85923 |
15.64 |
| 2026-02-16 00:00 |
17:32:13.57 |
+57:23:18.5 |
HIP 85923 |
14.64 |
| 2026-02-16 12:00 |
17:32:16.85 |
+57:24:16.4 |
HIP 85923 |
13.66 |
| 2026-02-17 00:00 |
17:32:20.07 |
+57:25:14.5 |
HIP 85923 |
12.69 |
| 2026-02-17 12:00 |
17:32:23.24 |
+57:26:12.8 |
HIP 85923 |
11.74 |
| 2026-02-18 00:00 |
17:32:26.35 |
+57:27:11.4 |
HIP 85923 |
10.81 |
| 2026-02-18 12:00 |
17:32:29.40 |
+57:28:10.1 |
HIP 85923 |
9.92 |
| 2026-02-19 00:00 |
17:32:32.40 |
+57:29:09.1 |
HIP 85923 |
9.07 |
| 2026-02-19 12:00 |
17:32:35.33 |
+57:30:08.3 |
HIP 85923 |
8.28 |
| 2026-02-20 00:00 |
17:32:38.21 |
+57:31:07.7 |
HIP 85923 |
7.55 |
| 2026-02-20 12:00 |
17:32:41.03 |
+57:32:07.3 |
HIP 85923 |
6.93 |
| 2026-02-21 00:00 |
17:32:43.79 |
+57:33:07.1 |
HIP 85923 |
6.42 |
| 2026-02-21 12:00 |
17:32:46.49 |
+57:34:07.1 |
HIP 85923 |
6.08 |
| 2026-02-22 00:00 |
17:32:49.14 |
+57:35:07.2 |
HIP 85923 |
5.91 |
| 2026-02-22 12:00 |
17:32:51.72 |
+57:36:07.6 |
HIP 85923 |
5.95 |
| 2026-02-23 00:00 |
17:32:54.24 |
+57:37:08.1 |
HIP 85923 |
6.17 |
| 2026-02-23 12:00 |
17:32:56.71 |
+57:38:08.8 |
HIP 85923 |
6.58 |
| 2026-02-24 00:00 |
17:32:59.11 |
+57:39:09.6 |
HIP 85923 |
7.12 |