| Parameter |
Value |
| Designation |
C/2009 R1 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-07-02T16:16:32.168640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:34Z |
| Obs used |
751 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
6.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-04-11.0000000 |
| e |
1.00041320 |
| q (au) |
0.405087 |
| a (au) |
-980.359275 |
| i (deg) |
77.030765 |
| Ω (om, deg) |
322.622663 |
| ω (w, deg) |
130.693103 |
| M (ma, deg) |
-0.002655 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.751 + 4.546\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.751 |
| n |
4.546 |
| gf |
1.000 |
| gb |
-0.800 |
| k |
0.800 |
| 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 |
| 2009-07-20 |
2010-01-09 |
+20.6267 |
-13.127 |
| 2010-01-09 |
2010-06-05 |
-5.1168 |
-0.996 |
| 2010-06-05 |
2010-06-29 |
-1.4652 |
-1.713 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
23:08:53.07 |
-73:08:33.5 |
HIP 114080 |
15.27 |
| 2026-03-26 12:00 |
23:09:03.08 |
-73:08:40.2 |
HIP 114080 |
15.89 |
| 2026-03-27 00:00 |
23:09:13.07 |
-73:08:47.2 |
HIP 114080 |
16.52 |
| 2026-03-27 12:00 |
23:09:23.03 |
-73:08:54.6 |
HIP 114080 |
17.17 |
| 2026-03-28 00:00 |
23:09:32.97 |
-73:09:02.4 |
HIP 114080 |
17.82 |
| 2026-03-28 12:00 |
23:09:42.87 |
-73:09:10.5 |
HIP 114080 |
18.47 |
| 2026-03-29 00:00 |
23:09:52.75 |
-73:09:19.0 |
HIP 114701 |
18.41 |
| 2026-03-29 12:00 |
23:10:02.59 |
-73:09:27.8 |
HIP 114701 |
17.70 |
| 2026-03-30 00:00 |
23:10:12.40 |
-73:09:37.1 |
HIP 114701 |
17.00 |
| 2026-03-30 12:00 |
23:10:22.18 |
-73:09:46.7 |
HIP 114701 |
16.29 |
| 2026-03-31 00:00 |
23:10:31.93 |
-73:09:56.6 |
HIP 114701 |
15.59 |
| 2026-03-31 12:00 |
23:10:41.65 |
-73:10:07.0 |
HIP 114701 |
14.90 |
| 2026-04-01 00:00 |
23:10:51.34 |
-73:10:17.7 |
HIP 114701 |
14.22 |
| 2026-04-01 12:00 |
23:11:00.99 |
-73:10:28.7 |
HIP 114701 |
13.54 |
| 2026-04-02 00:00 |
23:11:10.60 |
-73:10:40.2 |
HIP 114701 |
12.87 |
| 2026-04-02 12:00 |
23:11:20.19 |
-73:10:51.9 |
HIP 114701 |
12.21 |
| 2026-04-03 00:00 |
23:11:29.74 |
-73:11:04.1 |
HIP 114701 |
11.56 |
| 2026-04-03 12:00 |
23:11:39.25 |
-73:11:16.6 |
HIP 114701 |
10.92 |
| 2026-04-04 00:00 |
23:11:48.73 |
-73:11:29.5 |
HIP 114701 |
10.30 |
| 2026-04-04 12:00 |
23:11:58.17 |
-73:11:42.7 |
HIP 114701 |
9.69 |
| 2026-04-05 00:00 |
23:12:07.57 |
-73:11:56.3 |
HIP 114701 |
9.11 |
| 2026-04-05 12:00 |
23:12:16.94 |
-73:12:10.2 |
HIP 114701 |
8.55 |
| 2026-04-06 00:00 |
23:12:26.27 |
-73:12:24.5 |
HIP 114701 |
8.03 |
| 2026-04-06 12:00 |
23:12:35.56 |
-73:12:39.2 |
HIP 114701 |
7.54 |
| 2026-04-07 00:00 |
23:12:44.81 |
-73:12:54.2 |
HIP 114701 |
7.09 |
| 2026-04-07 12:00 |
23:12:54.02 |
-73:13:09.6 |
HIP 114701 |
6.70 |
| 2026-04-08 00:00 |
23:13:03.20 |
-73:13:25.3 |
HIP 114701 |
6.37 |
| 2026-04-08 12:00 |
23:13:12.33 |
-73:13:41.4 |
HIP 114701 |
6.11 |
| 2026-04-09 00:00 |
23:13:21.42 |
-73:13:57.8 |
HIP 114701 |
5.93 |
| 2026-04-09 12:00 |
23:13:30.47 |
-73:14:14.6 |
HIP 114701 |
5.85 |
| 2026-04-10 00:00 |
23:13:39.47 |
-73:14:31.8 |
HIP 114701 |
5.85 |
| 2026-04-10 12:00 |
23:13:48.44 |
-73:14:49.2 |
HIP 114701 |
5.95 |
| 2026-04-11 00:00 |
23:13:57.36 |
-73:15:07.1 |
HIP 114701 |
6.13 |
| 2026-04-11 12:00 |
23:14:06.24 |
-73:15:25.3 |
HIP 114701 |
6.40 |
| 2026-04-12 00:00 |
23:14:15.07 |
-73:15:43.8 |
HIP 114701 |
6.73 |
| 2026-04-12 12:00 |
23:14:23.86 |
-73:16:02.7 |
HIP 114701 |
7.13 |
| 2026-04-13 00:00 |
23:14:32.60 |
-73:16:22.0 |
HIP 114701 |
7.57 |
| 2026-04-13 12:00 |
23:14:41.29 |
-73:16:41.5 |
HIP 114701 |
8.06 |
| 2026-04-14 00:00 |
23:14:49.94 |
-73:17:01.5 |
HIP 114701 |
8.58 |
| 2026-04-14 12:00 |
23:14:58.54 |
-73:17:21.7 |
HIP 114701 |
9.13 |
| 2026-04-15 00:00 |
23:15:07.10 |
-73:17:42.4 |
HIP 114701 |
9.71 |
| 2026-04-15 12:00 |
23:15:15.60 |
-73:18:03.3 |
HIP 114701 |
10.30 |
| 2026-04-16 00:00 |
23:15:24.06 |
-73:18:24.6 |
HIP 114701 |
10.91 |