| Parameter |
Value |
| Designation |
C/2013 G7 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2014-03-18T16:01:39.025920Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:34Z |
| Obs used |
305 |
| NEO |
- |
| M1 |
6.000 |
| K1 |
12.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-07-23.0000000 |
| e |
0.99786135 |
| q (au) |
4.677407 |
| a (au) |
2187.083310 |
| i (deg) |
105.110084 |
| Ω (om, deg) |
48.402717 |
| ω (w, deg) |
218.263829 |
| M (ma, deg) |
359.997700 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.939 + 3.225\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.939 |
| n |
3.225 |
| gf |
1.000 |
| gb |
-0.866 |
| k |
0.999 |
| 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) |
| 2026-05-12 00:00 |
03:28:04.20 |
+07:25:26.1 |
HIP 16158 |
7.61 |
| 2026-05-12 12:00 |
03:28:08.20 |
+07:25:49.4 |
HIP 16158 |
7.77 |
| 2026-05-13 00:00 |
03:28:12.21 |
+07:26:12.6 |
HIP 16158 |
8.07 |
| 2026-05-13 12:00 |
03:28:16.21 |
+07:26:35.7 |
HIP 16158 |
8.49 |
| 2026-05-14 00:00 |
03:28:20.22 |
+07:26:58.6 |
HIP 16158 |
9.01 |
| 2026-05-14 12:00 |
03:28:24.23 |
+07:27:21.5 |
HIP 16158 |
9.62 |
| 2026-05-15 00:00 |
03:28:28.24 |
+07:27:44.2 |
HIP 16158 |
10.30 |
| 2026-05-15 12:00 |
03:28:32.25 |
+07:28:06.8 |
HIP 16158 |
11.05 |
| 2026-05-16 00:00 |
03:28:36.26 |
+07:28:29.3 |
HIP 16158 |
11.84 |
| 2026-05-16 12:00 |
03:28:40.26 |
+07:28:51.7 |
HIP 16158 |
12.66 |
| 2026-05-17 00:00 |
03:28:44.27 |
+07:29:14.0 |
HIP 16158 |
13.52 |
| 2026-05-17 12:00 |
03:28:48.28 |
+07:29:36.1 |
HIP 16158 |
14.41 |
| 2026-05-18 00:00 |
03:28:52.28 |
+07:29:58.1 |
HIP 16158 |
15.31 |
| 2026-05-18 12:00 |
03:28:56.29 |
+07:30:20.0 |
HIP 16158 |
16.23 |
| 2026-05-19 00:00 |
03:29:00.29 |
+07:30:41.8 |
HIP 16158 |
17.17 |
| 2026-05-19 12:00 |
03:29:04.28 |
+07:31:03.5 |
HIP 16158 |
18.11 |
| 2026-05-20 00:00 |
03:29:08.28 |
+07:31:25.0 |
HIP 16158 |
19.07 |
| 2026-05-20 12:00 |
03:29:12.27 |
+07:31:46.4 |
HIP 16158 |
20.03 |
| 2026-05-21 00:00 |
03:29:16.26 |
+07:32:07.7 |
HIP 16158 |
21.00 |
| 2026-05-21 12:00 |
03:29:20.25 |
+07:32:28.8 |
HIP 16158 |
21.98 |
| 2026-05-22 00:00 |
03:29:24.23 |
+07:32:49.9 |
HIP 16158 |
22.96 |
| 2026-05-22 12:00 |
03:29:28.21 |
+07:33:10.8 |
HIP 16158 |
23.94 |
| 2026-05-23 00:00 |
03:29:32.18 |
+07:33:31.6 |
HIP 16158 |
24.93 |
| 2026-05-23 12:00 |
03:29:36.15 |
+07:33:52.2 |
HIP 16158 |
25.92 |
| 2026-05-24 00:00 |
03:29:40.12 |
+07:34:12.7 |
HIP 16158 |
26.91 |
| 2026-05-24 12:00 |
03:29:44.07 |
+07:34:33.1 |
HIP 16158 |
27.90 |
| 2026-05-25 00:00 |
03:29:48.03 |
+07:34:53.4 |
HIP 16158 |
28.89 |
| 2026-05-25 12:00 |
03:29:51.98 |
+07:35:13.5 |
HIP 16380 |
29.00 |
| 2026-05-26 00:00 |
03:29:55.92 |
+07:35:33.5 |
HIP 16380 |
28.70 |
| 2026-05-26 12:00 |
03:29:59.85 |
+07:35:53.3 |
HIP 16380 |
28.44 |
| 2026-05-27 00:00 |
03:30:03.78 |
+07:36:13.1 |
HIP 16380 |
28.21 |
| 2026-05-27 12:00 |
03:30:07.71 |
+07:36:32.7 |
HIP 16380 |
28.02 |
| 2026-05-28 00:00 |
03:30:11.62 |
+07:36:52.1 |
HIP 16380 |
27.86 |
| 2026-05-28 12:00 |
03:30:15.53 |
+07:37:11.5 |
HIP 16464 |
27.08 |
| 2026-05-29 00:00 |
03:30:19.43 |
+07:37:30.6 |
HIP 16464 |
26.17 |
| 2026-05-29 12:00 |
03:30:23.32 |
+07:37:49.7 |
HIP 16464 |
25.26 |
| 2026-05-30 00:00 |
03:30:27.21 |
+07:38:08.6 |
HIP 16464 |
24.36 |
| 2026-05-30 12:00 |
03:30:31.09 |
+07:38:27.4 |
HIP 16464 |
23.47 |
| 2026-05-31 00:00 |
03:30:34.95 |
+07:38:46.0 |
HIP 16464 |
22.59 |
| 2026-05-31 12:00 |
03:30:38.81 |
+07:39:04.5 |
HIP 16464 |
21.73 |
| 2026-06-01 00:00 |
03:30:42.67 |
+07:39:22.9 |
HIP 16464 |
20.88 |
| 2026-06-01 12:00 |
03:30:46.51 |
+07:39:41.1 |
HIP 16464 |
20.04 |
| 2026-06-02 00:00 |
03:30:50.34 |
+07:39:59.2 |
HIP 16464 |
19.23 |