| Parameter |
Value |
| Designation |
C/2005 S4 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2007-07-18T15:31:21.316800Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:53Z |
| Obs used |
580 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2007-06-06.0000000 |
| e |
0.99897119 |
| q (au) |
5.850108 |
| a (au) |
5686.269098 |
| i (deg) |
107.958958 |
| Ω (om, deg) |
318.290291 |
| ω (w, deg) |
31.453945 |
| M (ma, deg) |
359.999902 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.966 + 3.745\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.966 |
| n |
3.745 |
| gf |
0.995 |
| gb |
-0.897 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2005-07-27 |
2007-07-16 |
-1.0253 |
+0.679 |
| 2007-07-19 |
2008-10-06 |
+18.7523 |
-14.647 |
| 2008-10-06 |
2009-07-23 |
+4.6293 |
-3.301 |
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 |
10:04:04.24 |
+28:12:57.2 |
HIP 49356 |
23.04 |
| 2026-07-29 12:00 |
10:04:07.19 |
+28:12:33.3 |
HIP 49356 |
22.48 |
| 2026-07-30 00:00 |
10:04:10.14 |
+28:12:09.6 |
HIP 49356 |
21.94 |
| 2026-07-30 12:00 |
10:04:13.11 |
+28:11:45.8 |
HIP 49356 |
21.41 |
| 2026-07-31 00:00 |
10:04:16.09 |
+28:11:22.1 |
HIP 49356 |
20.89 |
| 2026-07-31 12:00 |
10:04:19.08 |
+28:10:58.5 |
HIP 49356 |
20.39 |
| 2026-08-01 00:00 |
10:04:22.08 |
+28:10:35.0 |
HIP 49356 |
19.91 |
| 2026-08-01 12:00 |
10:04:25.08 |
+28:10:11.5 |
HIP 49356 |
19.45 |
| 2026-08-02 00:00 |
10:04:28.10 |
+28:09:48.0 |
HIP 49356 |
19.00 |
| 2026-08-02 12:00 |
10:04:31.12 |
+28:09:24.6 |
HIP 49356 |
18.58 |
| 2026-08-03 00:00 |
10:04:34.16 |
+28:09:01.3 |
HIP 49356 |
18.19 |
| 2026-08-03 12:00 |
10:04:37.20 |
+28:08:38.1 |
HIP 49356 |
17.82 |
| 2026-08-04 00:00 |
10:04:40.25 |
+28:08:14.9 |
HIP 49356 |
17.48 |
| 2026-08-04 12:00 |
10:04:43.30 |
+28:07:51.8 |
HIP 49356 |
17.17 |
| 2026-08-05 00:00 |
10:04:46.37 |
+28:07:28.7 |
HIP 49356 |
16.89 |
| 2026-08-05 12:00 |
10:04:49.44 |
+28:07:05.8 |
HIP 49356 |
16.64 |
| 2026-08-06 00:00 |
10:04:52.52 |
+28:06:42.8 |
HIP 49356 |
16.43 |
| 2026-08-06 12:00 |
10:04:55.61 |
+28:06:20.0 |
HIP 49356 |
16.25 |
| 2026-08-07 00:00 |
10:04:58.70 |
+28:05:57.2 |
HIP 49356 |
16.11 |
| 2026-08-07 12:00 |
10:05:01.81 |
+28:05:34.6 |
HIP 49356 |
16.02 |
| 2026-08-08 00:00 |
10:05:04.91 |
+28:05:11.9 |
HIP 49356 |
15.96 |
| 2026-08-08 12:00 |
10:05:08.03 |
+28:04:49.4 |
HIP 49356 |
15.94 |
| 2026-08-09 00:00 |
10:05:11.15 |
+28:04:27.0 |
HIP 49356 |
15.96 |
| 2026-08-09 12:00 |
10:05:14.28 |
+28:04:04.6 |
HIP 49356 |
16.02 |
| 2026-08-10 00:00 |
10:05:17.41 |
+28:03:42.3 |
HIP 49356 |
16.12 |
| 2026-08-10 12:00 |
10:05:20.54 |
+28:03:20.1 |
HIP 49356 |
16.26 |
| 2026-08-11 00:00 |
10:05:23.69 |
+28:02:57.9 |
HIP 49356 |
16.44 |
| 2026-08-11 12:00 |
10:05:26.83 |
+28:02:35.9 |
HIP 49356 |
16.65 |
| 2026-08-12 00:00 |
10:05:29.99 |
+28:02:13.9 |
HIP 49356 |
16.90 |
| 2026-08-12 12:00 |
10:05:33.14 |
+28:01:52.1 |
HIP 49356 |
17.19 |
| 2026-08-13 00:00 |
10:05:36.31 |
+28:01:30.3 |
HIP 49356 |
17.51 |
| 2026-08-13 12:00 |
10:05:39.47 |
+28:01:08.6 |
HIP 49356 |
17.85 |
| 2026-08-14 00:00 |
10:05:42.64 |
+28:00:47.0 |
HIP 49356 |
18.23 |
| 2026-08-14 12:00 |
10:05:45.81 |
+28:00:25.5 |
HIP 49356 |
18.64 |
| 2026-08-15 00:00 |
10:05:48.99 |
+28:00:04.1 |
HIP 49356 |
19.07 |
| 2026-08-15 12:00 |
10:05:52.17 |
+27:59:42.8 |
HIP 49356 |
19.52 |
| 2026-08-16 00:00 |
10:05:55.35 |
+27:59:21.6 |
HIP 49356 |
20.00 |
| 2026-08-16 12:00 |
10:05:58.53 |
+27:59:00.4 |
HIP 49356 |
20.49 |
| 2026-08-17 00:00 |
10:06:01.72 |
+27:58:39.4 |
HIP 49356 |
21.01 |
| 2026-08-17 12:00 |
10:06:04.91 |
+27:58:18.5 |
HIP 49356 |
21.54 |
| 2026-08-18 00:00 |
10:06:08.10 |
+27:57:57.7 |
HIP 49356 |
22.09 |
| 2026-08-18 12:00 |
10:06:11.29 |
+27:57:36.9 |
HIP 49356 |
22.65 |
| 2026-08-19 00:00 |
10:06:14.48 |
+27:57:16.3 |
HIP 49356 |
23.23 |