| 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) |
| 2026-09-20 00:00 |
06:28:24.48 |
+54:16:08.8 |
HIP 30817 |
7.08 |
| 2026-09-20 12:00 |
06:28:25.14 |
+54:16:33.1 |
HIP 30817 |
6.66 |
| 2026-09-21 00:00 |
06:28:25.76 |
+54:16:57.5 |
HIP 30817 |
6.25 |
| 2026-09-21 12:00 |
06:28:26.34 |
+54:17:22.0 |
HIP 30817 |
5.84 |
| 2026-09-22 00:00 |
06:28:26.87 |
+54:17:46.5 |
HIP 30817 |
5.43 |
| 2026-09-22 12:00 |
06:28:27.36 |
+54:18:11.1 |
HIP 30817 |
5.02 |
| 2026-09-23 00:00 |
06:28:27.80 |
+54:18:35.7 |
HIP 30817 |
4.60 |
| 2026-09-23 12:00 |
06:28:28.20 |
+54:19:00.4 |
HIP 30817 |
4.19 |
| 2026-09-24 00:00 |
06:28:28.56 |
+54:19:25.1 |
HIP 30817 |
3.78 |
| 2026-09-24 12:00 |
06:28:28.87 |
+54:19:49.8 |
HIP 30817 |
3.37 |
| 2026-09-25 00:00 |
06:28:29.14 |
+54:20:14.6 |
HIP 30817 |
2.96 |
| 2026-09-25 12:00 |
06:28:29.36 |
+54:20:39.4 |
HIP 30817 |
2.54 |
| 2026-09-26 00:00 |
06:28:29.54 |
+54:21:04.3 |
HIP 30817 |
2.13 |
| 2026-09-26 12:00 |
06:28:29.68 |
+54:21:29.2 |
HIP 30817 |
1.72 |
| 2026-09-27 00:00 |
06:28:29.77 |
+54:21:54.2 |
HIP 30817 |
1.31 |
| 2026-09-27 12:00 |
06:28:29.82 |
+54:22:19.1 |
HIP 30817 |
0.90 |
| 2026-09-28 00:00 |
06:28:29.82 |
+54:22:44.2 |
HIP 30817 |
0.50 |
| 2026-09-28 12:00 |
06:28:29.78 |
+54:23:09.2 |
HIP 30817 |
0.19 |
| 2026-09-29 00:00 |
06:28:29.69 |
+54:23:34.3 |
HIP 30817 |
0.41 |
| 2026-09-29 12:00 |
06:28:29.56 |
+54:23:59.4 |
HIP 30817 |
0.81 |
| 2026-09-30 00:00 |
06:28:29.38 |
+54:24:24.5 |
HIP 30817 |
1.22 |
| 2026-09-30 12:00 |
06:28:29.16 |
+54:24:49.6 |
HIP 30817 |
1.63 |
| 2026-10-01 00:00 |
06:28:28.90 |
+54:25:14.8 |
HIP 30817 |
2.05 |
| 2026-10-01 12:00 |
06:28:28.58 |
+54:25:40.0 |
HIP 30817 |
2.47 |
| 2026-10-02 00:00 |
06:28:28.23 |
+54:26:05.2 |
HIP 30817 |
2.89 |
| 2026-10-02 12:00 |
06:28:27.83 |
+54:26:30.4 |
HIP 30817 |
3.31 |
| 2026-10-03 00:00 |
06:28:27.38 |
+54:26:55.7 |
HIP 30817 |
3.73 |
| 2026-10-03 12:00 |
06:28:26.89 |
+54:27:20.9 |
HIP 30817 |
4.16 |
| 2026-10-04 00:00 |
06:28:26.35 |
+54:27:46.2 |
HIP 30817 |
4.58 |
| 2026-10-04 12:00 |
06:28:25.77 |
+54:28:11.5 |
HIP 30817 |
5.01 |
| 2026-10-05 00:00 |
06:28:25.14 |
+54:28:36.8 |
HIP 30817 |
5.44 |
| 2026-10-05 12:00 |
06:28:24.47 |
+54:29:02.1 |
HIP 30817 |
5.87 |
| 2026-10-06 00:00 |
06:28:23.75 |
+54:29:27.4 |
HIP 30817 |
6.30 |
| 2026-10-06 12:00 |
06:28:22.98 |
+54:29:52.7 |
HIP 30817 |
6.73 |
| 2026-10-07 00:00 |
06:28:22.17 |
+54:30:18.0 |
HIP 30817 |
7.16 |
| 2026-10-07 12:00 |
06:28:21.31 |
+54:30:43.3 |
HIP 30817 |
7.60 |
| 2026-10-08 00:00 |
06:28:20.41 |
+54:31:08.6 |
HIP 30817 |
8.03 |
| 2026-10-08 12:00 |
06:28:19.46 |
+54:31:33.9 |
HIP 30817 |
8.47 |
| 2026-10-09 00:00 |
06:28:18.47 |
+54:31:59.2 |
HIP 30899 |
8.76 |
| 2026-10-09 12:00 |
06:28:17.43 |
+54:32:24.5 |
HIP 30899 |
8.67 |
| 2026-10-10 00:00 |
06:28:16.35 |
+54:32:49.8 |
HIP 30899 |
8.61 |
| 2026-10-10 12:00 |
06:28:15.21 |
+54:33:15.0 |
HIP 30899 |
8.57 |
| 2026-10-11 00:00 |
06:28:14.04 |
+54:33:40.3 |
HIP 30899 |
8.57 |