| Parameter |
Value |
| Designation |
C/2007 T1 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2007-12-12T12:43:02.167680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:12Z |
| Obs used |
321 |
| NEO |
- |
| M1 |
11.100 |
| K1 |
15.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2007-12-03.0000000 |
| e |
0.99975973 |
| q (au) |
0.968503 |
| a (au) |
4030.976593 |
| i (deg) |
117.642445 |
| Ω (om, deg) |
111.433284 |
| ω (w, deg) |
233.755132 |
| M (ma, deg) |
359.999963 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.423 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.423 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.980 |
| 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 |
| 2007-10-09 |
2007-11-17 |
+26.4957 |
-3.984 |
| 2007-12-28 |
2008-03-01 |
+0.7702 |
-2.913 |
| 2008-03-01 |
2008-04-10 |
+33.3065 |
-10.740 |
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 |
06:23:42.76 |
+53:42:44.3 |
HIP 30404 |
15.29 |
| 2026-07-29 12:00 |
06:23:46.96 |
+53:42:56.0 |
HIP 30404 |
15.15 |
| 2026-07-30 00:00 |
06:23:51.14 |
+53:43:07.8 |
HIP 30404 |
15.04 |
| 2026-07-30 12:00 |
06:23:55.30 |
+53:43:19.8 |
HIP 30404 |
14.96 |
| 2026-07-31 00:00 |
06:23:59.44 |
+53:43:32.0 |
HIP 30404 |
14.90 |
| 2026-07-31 12:00 |
06:24:03.56 |
+53:43:44.3 |
HIP 30404 |
14.86 |
| 2026-08-01 00:00 |
06:24:07.66 |
+53:43:56.8 |
HIP 30404 |
14.84 |
| 2026-08-01 12:00 |
06:24:11.74 |
+53:44:09.5 |
HIP 30404 |
14.85 |
| 2026-08-02 00:00 |
06:24:15.79 |
+53:44:22.3 |
HIP 30404 |
14.89 |
| 2026-08-02 12:00 |
06:24:19.82 |
+53:44:35.3 |
HIP 30610 |
14.66 |
| 2026-08-03 00:00 |
06:24:23.83 |
+53:44:48.4 |
HIP 30610 |
14.07 |
| 2026-08-03 12:00 |
06:24:27.82 |
+53:45:01.7 |
HIP 30610 |
13.48 |
| 2026-08-04 00:00 |
06:24:31.78 |
+53:45:15.1 |
HIP 30610 |
12.90 |
| 2026-08-04 12:00 |
06:24:35.72 |
+53:45:28.8 |
HIP 30610 |
12.32 |
| 2026-08-05 00:00 |
06:24:39.63 |
+53:45:42.5 |
HIP 30610 |
11.76 |
| 2026-08-05 12:00 |
06:24:43.53 |
+53:45:56.4 |
HIP 30610 |
11.21 |
| 2026-08-06 00:00 |
06:24:47.39 |
+53:46:10.5 |
HIP 30610 |
10.66 |
| 2026-08-06 12:00 |
06:24:51.24 |
+53:46:24.7 |
HIP 30610 |
10.13 |
| 2026-08-07 00:00 |
06:24:55.05 |
+53:46:39.1 |
HIP 30610 |
9.62 |
| 2026-08-07 12:00 |
06:24:58.85 |
+53:46:53.7 |
HIP 30610 |
9.12 |
| 2026-08-08 00:00 |
06:25:02.62 |
+53:47:08.4 |
HIP 30610 |
8.64 |
| 2026-08-08 12:00 |
06:25:06.36 |
+53:47:23.2 |
HIP 30610 |
8.18 |
| 2026-08-09 00:00 |
06:25:10.07 |
+53:47:38.2 |
HIP 30610 |
7.74 |
| 2026-08-09 12:00 |
06:25:13.76 |
+53:47:53.4 |
HIP 30610 |
7.33 |
| 2026-08-10 00:00 |
06:25:17.43 |
+53:48:08.7 |
HIP 30610 |
6.96 |
| 2026-08-10 12:00 |
06:25:21.07 |
+53:48:24.1 |
HIP 30610 |
6.63 |
| 2026-08-11 00:00 |
06:25:24.67 |
+53:48:39.7 |
HIP 30610 |
6.33 |
| 2026-08-11 12:00 |
06:25:28.26 |
+53:48:55.5 |
HIP 30610 |
6.09 |
| 2026-08-12 00:00 |
06:25:31.81 |
+53:49:11.4 |
HIP 30610 |
5.90 |
| 2026-08-12 12:00 |
06:25:35.34 |
+53:49:27.4 |
HIP 30610 |
5.77 |
| 2026-08-13 00:00 |
06:25:38.84 |
+53:49:43.6 |
HIP 30610 |
5.70 |
| 2026-08-13 12:00 |
06:25:42.30 |
+53:50:00.0 |
HIP 30610 |
5.70 |
| 2026-08-14 00:00 |
06:25:45.74 |
+53:50:16.4 |
HIP 30610 |
5.75 |
| 2026-08-14 12:00 |
06:25:49.16 |
+53:50:33.1 |
HIP 30610 |
5.87 |
| 2026-08-15 00:00 |
06:25:52.54 |
+53:50:49.8 |
HIP 30610 |
6.04 |
| 2026-08-15 12:00 |
06:25:55.89 |
+53:51:06.8 |
HIP 30610 |
6.27 |
| 2026-08-16 00:00 |
06:25:59.21 |
+53:51:23.8 |
HIP 30610 |
6.53 |
| 2026-08-16 12:00 |
06:26:02.50 |
+53:51:41.0 |
HIP 30610 |
6.84 |
| 2026-08-17 00:00 |
06:26:05.77 |
+53:51:58.4 |
HIP 30610 |
7.18 |
| 2026-08-17 12:00 |
06:26:09.00 |
+53:52:15.8 |
HIP 30610 |
7.55 |
| 2026-08-18 00:00 |
06:26:12.20 |
+53:52:33.4 |
HIP 30610 |
7.94 |
| 2026-08-18 12:00 |
06:26:15.37 |
+53:52:51.2 |
HIP 30610 |
8.35 |
| 2026-08-19 00:00 |
06:26:18.50 |
+53:53:09.1 |
HIP 30610 |
8.77 |