C/2009 R1 (McNaught)
| 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
$$
M_a = (10.729 + 4.483\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.729 |
| n |
4.483 |
| gf |
0.979 |
| gb |
-0.784 |
| 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 |
+19.9786 |
-12.794 |
| 2010-01-09 |
2010-06-05 |
-5.1146 |
-0.989 |
| 2010-06-05 |
2010-06-29 |
-1.2896 |
-1.690 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
22:51:13.63 |
-73:29:25.3 |
HIP 112834 |
11.00 |
| 2026-02-03 12:00 |
22:51:23.34 |
-73:28:55.7 |
HIP 112834 |
10.57 |
| 2026-02-04 00:00 |
22:51:33.08 |
-73:28:26.3 |
HIP 112834 |
10.21 |
| 2026-02-04 12:00 |
22:51:42.86 |
-73:27:57.3 |
HIP 112834 |
9.91 |
| 2026-02-05 00:00 |
22:51:52.67 |
-73:27:28.5 |
HIP 112834 |
9.69 |
| 2026-02-05 12:00 |
22:52:02.51 |
-73:27:00.1 |
HIP 112834 |
9.54 |
| 2026-02-06 00:00 |
22:52:12.38 |
-73:26:32.0 |
HIP 112834 |
9.47 |
| 2026-02-06 12:00 |
22:52:22.29 |
-73:26:04.2 |
HIP 112834 |
9.48 |
| 2026-02-07 00:00 |
22:52:32.22 |
-73:25:36.7 |
HIP 112834 |
9.57 |
| 2026-02-07 12:00 |
22:52:42.18 |
-73:25:09.5 |
HIP 112834 |
9.74 |
| 2026-02-08 00:00 |
22:52:52.18 |
-73:24:42.7 |
HIP 112834 |
9.99 |
| 2026-02-08 12:00 |
22:53:02.20 |
-73:24:16.1 |
HIP 112834 |
10.30 |
| 2026-02-09 00:00 |
22:53:12.25 |
-73:23:49.9 |
HIP 112834 |
10.68 |
| 2026-02-09 12:00 |
22:53:22.33 |
-73:23:24.0 |
HIP 112834 |
11.11 |
| 2026-02-10 00:00 |
22:53:32.43 |
-73:22:58.4 |
HIP 112834 |
11.59 |
| 2026-02-10 12:00 |
22:53:42.57 |
-73:22:33.1 |
HIP 112834 |
12.12 |
| 2026-02-11 00:00 |
22:53:52.72 |
-73:22:08.2 |
HIP 112834 |
12.68 |
| 2026-02-11 12:00 |
22:54:02.90 |
-73:21:43.6 |
HIP 112834 |
13.27 |
| 2026-02-12 00:00 |
22:54:13.11 |
-73:21:19.3 |
HIP 112834 |
13.90 |
| 2026-02-12 12:00 |
22:54:23.34 |
-73:20:55.4 |
HIP 112834 |
14.55 |
| 2026-02-13 00:00 |
22:54:33.59 |
-73:20:31.8 |
HIP 112834 |
15.21 |
| 2026-02-13 12:00 |
22:54:43.87 |
-73:20:08.5 |
HIP 112834 |
15.90 |
| 2026-02-14 00:00 |
22:54:54.16 |
-73:19:45.5 |
HIP 113182 |
15.63 |
| 2026-02-14 12:00 |
22:55:04.48 |
-73:19:22.9 |
HIP 113182 |
15.22 |
| 2026-02-15 00:00 |
22:55:14.82 |
-73:19:00.7 |
HIP 113182 |
14.85 |
| 2026-02-15 12:00 |
22:55:25.18 |
-73:18:38.7 |
HIP 113182 |
14.52 |
| 2026-02-16 00:00 |
22:55:35.56 |
-73:18:17.1 |
HIP 113182 |
14.24 |
| 2026-02-16 12:00 |
22:55:45.95 |
-73:17:55.9 |
HIP 113182 |
14.01 |
| 2026-02-17 00:00 |
22:55:56.37 |
-73:17:35.0 |
HIP 113182 |
13.84 |
| 2026-02-17 12:00 |
22:56:06.80 |
-73:17:14.4 |
HIP 113182 |
13.71 |
| 2026-02-18 00:00 |
22:56:17.25 |
-73:16:54.2 |
HIP 113182 |
13.65 |
| 2026-02-18 12:00 |
22:56:27.71 |
-73:16:34.4 |
HIP 113182 |
13.64 |
| 2026-02-19 00:00 |
22:56:38.19 |
-73:16:14.8 |
HIP 113182 |
13.68 |
| 2026-02-19 12:00 |
22:56:48.68 |
-73:15:55.7 |
HIP 113182 |
13.78 |
| 2026-02-20 00:00 |
22:56:59.19 |
-73:15:36.9 |
HIP 113182 |
13.94 |
| 2026-02-20 12:00 |
22:57:09.71 |
-73:15:18.4 |
HIP 113182 |
14.14 |
| 2026-02-21 00:00 |
22:57:20.24 |
-73:15:00.3 |
HIP 113182 |
14.40 |
| 2026-02-21 12:00 |
22:57:30.79 |
-73:14:42.5 |
HIP 113182 |
14.70 |
| 2026-02-22 00:00 |
22:57:41.34 |
-73:14:25.1 |
HIP 113182 |
15.04 |
| 2026-02-22 12:00 |
22:57:51.91 |
-73:14:08.1 |
HIP 113182 |
15.43 |
| 2026-02-23 00:00 |
22:58:02.48 |
-73:13:51.4 |
HIP 113182 |
15.85 |
| 2026-02-23 12:00 |
22:58:13.07 |
-73:13:35.0 |
HIP 113182 |
16.31 |
| 2026-02-24 00:00 |
22:58:23.66 |
-73:13:19.1 |
HIP 113182 |
16.79 |