| Parameter |
Value |
| Designation |
C/2013 F3 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-05-25T06:10:32.957760Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:32Z |
| Obs used |
301 |
| NEO |
- |
| M1 |
15.400 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-06-20.0000000 |
| e |
0.99704135 |
| q (au) |
2.252615 |
| a (au) |
761.365596 |
| i (deg) |
85.444578 |
| Ω (om, deg) |
266.108702 |
| ω (w, deg) |
18.757634 |
| M (ma, deg) |
0.001208 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.685 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.685 |
| n |
2.000 |
| gf |
0.979 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.839 |
| 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 |
| 2013-05-31 |
2015-04-15 |
-19.7567 |
+7.281 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
05:42:10.56 |
+36:10:42.0 |
HIP 26889 |
4.36 |
| 2026-07-29 12:00 |
05:42:14.25 |
+36:10:47.5 |
HIP 26889 |
3.62 |
| 2026-07-30 00:00 |
05:42:17.92 |
+36:10:53.1 |
HIP 26889 |
2.90 |
| 2026-07-30 12:00 |
05:42:21.56 |
+36:10:58.7 |
HIP 26889 |
2.19 |
| 2026-07-31 00:00 |
05:42:25.18 |
+36:11:04.4 |
HIP 26889 |
1.53 |
| 2026-07-31 12:00 |
05:42:28.77 |
+36:11:10.2 |
HIP 26889 |
0.97 |
| 2026-08-01 00:00 |
05:42:32.34 |
+36:11:16.0 |
HIP 26889 |
0.78 |
| 2026-08-01 12:00 |
05:42:35.88 |
+36:11:21.9 |
HIP 26889 |
1.15 |
| 2026-08-02 00:00 |
05:42:39.39 |
+36:11:27.9 |
HIP 26889 |
1.75 |
| 2026-08-02 12:00 |
05:42:42.88 |
+36:11:33.9 |
HIP 26889 |
2.41 |
| 2026-08-03 00:00 |
05:42:46.34 |
+36:11:40.0 |
HIP 26902 |
2.85 |
| 2026-08-03 12:00 |
05:42:49.77 |
+36:11:46.1 |
HIP 26902 |
3.24 |
| 2026-08-04 00:00 |
05:42:53.17 |
+36:11:52.3 |
HIP 26902 |
3.72 |
| 2026-08-04 12:00 |
05:42:56.55 |
+36:11:58.6 |
HIP 26902 |
4.26 |
| 2026-08-05 00:00 |
05:42:59.90 |
+36:12:05.0 |
HIP 26902 |
4.83 |
| 2026-08-05 12:00 |
05:43:03.22 |
+36:12:11.4 |
HIP 26902 |
5.43 |
| 2026-08-06 00:00 |
05:43:06.51 |
+36:12:17.8 |
HIP 26902 |
6.04 |
| 2026-08-06 12:00 |
05:43:09.77 |
+36:12:24.4 |
HIP 26902 |
6.65 |
| 2026-08-07 00:00 |
05:43:13.00 |
+36:12:31.0 |
HIP 26902 |
7.27 |
| 2026-08-07 12:00 |
05:43:16.20 |
+36:12:37.6 |
HIP 26902 |
7.89 |
| 2026-08-08 00:00 |
05:43:19.38 |
+36:12:44.3 |
HIP 26902 |
8.52 |
| 2026-08-08 12:00 |
05:43:22.52 |
+36:12:51.1 |
HIP 26902 |
9.14 |
| 2026-08-09 00:00 |
05:43:25.64 |
+36:12:57.9 |
HIP 26902 |
9.76 |
| 2026-08-09 12:00 |
05:43:28.72 |
+36:13:04.8 |
HIP 26902 |
10.37 |
| 2026-08-10 00:00 |
05:43:31.77 |
+36:13:11.7 |
HIP 26902 |
10.98 |
| 2026-08-10 12:00 |
05:43:34.79 |
+36:13:18.7 |
HIP 26902 |
11.59 |
| 2026-08-11 00:00 |
05:43:37.78 |
+36:13:25.8 |
HIP 26902 |
12.20 |
| 2026-08-11 12:00 |
05:43:40.74 |
+36:13:32.9 |
HIP 26902 |
12.80 |
| 2026-08-12 00:00 |
05:43:43.67 |
+36:13:40.1 |
HIP 26902 |
13.39 |
| 2026-08-12 12:00 |
05:43:46.56 |
+36:13:47.3 |
HIP 26902 |
13.98 |
| 2026-08-13 00:00 |
05:43:49.43 |
+36:13:54.6 |
HIP 26902 |
14.57 |
| 2026-08-13 12:00 |
05:43:52.26 |
+36:14:01.9 |
HIP 26902 |
15.14 |
| 2026-08-14 00:00 |
05:43:55.06 |
+36:14:09.3 |
HIP 26902 |
15.72 |
| 2026-08-14 12:00 |
05:43:57.82 |
+36:14:16.7 |
HIP 26902 |
16.29 |
| 2026-08-15 00:00 |
05:44:00.55 |
+36:14:24.2 |
HIP 26902 |
16.85 |
| 2026-08-15 12:00 |
05:44:03.25 |
+36:14:31.7 |
HIP 26902 |
17.40 |
| 2026-08-16 00:00 |
05:44:05.92 |
+36:14:39.3 |
HIP 26902 |
17.95 |
| 2026-08-16 12:00 |
05:44:08.55 |
+36:14:46.9 |
HIP 26902 |
18.50 |
| 2026-08-17 00:00 |
05:44:11.15 |
+36:14:54.6 |
HIP 26902 |
19.03 |
| 2026-08-17 12:00 |
05:44:13.71 |
+36:15:02.3 |
HIP 26902 |
19.57 |
| 2026-08-18 00:00 |
05:44:16.24 |
+36:15:10.1 |
HIP 26902 |
20.09 |
| 2026-08-18 12:00 |
05:44:18.74 |
+36:15:17.9 |
HIP 26902 |
20.61 |
| 2026-08-19 00:00 |
05:44:21.20 |
+36:15:25.8 |
HIP 26902 |
21.12 |