| 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) |
| 2026-05-12 00:00 |
23:21:23.31 |
-73:43:58.4 |
HIP 115354 |
2.68 |
| 2026-05-12 12:00 |
23:21:28.44 |
-73:44:35.2 |
HIP 115354 |
2.82 |
| 2026-05-13 00:00 |
23:21:33.50 |
-73:45:12.2 |
HIP 115354 |
3.13 |
| 2026-05-13 12:00 |
23:21:38.48 |
-73:45:49.5 |
HIP 115354 |
3.57 |
| 2026-05-14 00:00 |
23:21:43.39 |
-73:46:27.0 |
HIP 115354 |
4.08 |
| 2026-05-14 12:00 |
23:21:48.22 |
-73:47:04.8 |
HIP 115354 |
4.66 |
| 2026-05-15 00:00 |
23:21:52.97 |
-73:47:42.7 |
HIP 115354 |
5.27 |
| 2026-05-15 12:00 |
23:21:57.64 |
-73:48:20.9 |
HIP 115354 |
5.91 |
| 2026-05-16 00:00 |
23:22:02.24 |
-73:48:59.4 |
HIP 115354 |
6.57 |
| 2026-05-16 12:00 |
23:22:06.75 |
-73:49:38.0 |
HIP 115354 |
7.24 |
| 2026-05-17 00:00 |
23:22:11.18 |
-73:50:16.9 |
HIP 115354 |
7.92 |
| 2026-05-17 12:00 |
23:22:15.54 |
-73:50:55.9 |
HIP 115354 |
8.61 |
| 2026-05-18 00:00 |
23:22:19.81 |
-73:51:35.2 |
HIP 115354 |
9.31 |
| 2026-05-18 12:00 |
23:22:24.01 |
-73:52:14.7 |
HIP 115354 |
10.02 |
| 2026-05-19 00:00 |
23:22:28.12 |
-73:52:54.4 |
HIP 115354 |
10.72 |
| 2026-05-19 12:00 |
23:22:32.15 |
-73:53:34.4 |
HIP 115354 |
11.43 |
| 2026-05-20 00:00 |
23:22:36.09 |
-73:54:14.5 |
HIP 115354 |
12.15 |
| 2026-05-20 12:00 |
23:22:39.96 |
-73:54:54.8 |
HIP 115354 |
12.86 |
| 2026-05-21 00:00 |
23:22:43.74 |
-73:55:35.3 |
HIP 115354 |
13.58 |
| 2026-05-21 12:00 |
23:22:47.44 |
-73:56:16.0 |
HIP 115354 |
14.30 |
| 2026-05-22 00:00 |
23:22:51.05 |
-73:56:56.8 |
HIP 115354 |
15.03 |
| 2026-05-22 12:00 |
23:22:54.58 |
-73:57:37.9 |
HIP 115354 |
15.75 |
| 2026-05-23 00:00 |
23:22:58.03 |
-73:58:19.2 |
HIP 115354 |
16.48 |
| 2026-05-23 12:00 |
23:23:01.39 |
-73:59:00.6 |
HIP 115354 |
17.21 |
| 2026-05-24 00:00 |
23:23:04.66 |
-73:59:42.2 |
HIP 115354 |
17.93 |
| 2026-05-24 12:00 |
23:23:07.85 |
-74:00:24.0 |
HIP 115354 |
18.66 |
| 2026-05-25 00:00 |
23:23:10.95 |
-74:01:05.9 |
HIP 115739 |
18.94 |
| 2026-05-25 12:00 |
23:23:13.97 |
-74:01:48.0 |
HIP 115739 |
19.18 |
| 2026-05-26 00:00 |
23:23:16.90 |
-74:02:30.3 |
HIP 115739 |
19.45 |
| 2026-05-26 12:00 |
23:23:19.75 |
-74:03:12.8 |
HIP 115739 |
19.76 |
| 2026-05-27 00:00 |
23:23:22.50 |
-74:03:55.4 |
HIP 115739 |
20.09 |
| 2026-05-27 12:00 |
23:23:25.17 |
-74:04:38.1 |
HIP 115739 |
20.45 |
| 2026-05-28 00:00 |
23:23:27.76 |
-74:05:21.0 |
HIP 115739 |
20.83 |
| 2026-05-28 12:00 |
23:23:30.25 |
-74:06:04.1 |
HIP 115739 |
21.24 |
| 2026-05-29 00:00 |
23:23:32.65 |
-74:06:47.3 |
HIP 115739 |
21.68 |
| 2026-05-29 12:00 |
23:23:34.97 |
-74:07:30.6 |
HIP 115739 |
22.13 |
| 2026-05-30 00:00 |
23:23:37.20 |
-74:08:14.1 |
HIP 115739 |
22.61 |
| 2026-05-30 12:00 |
23:23:39.33 |
-74:08:57.8 |
HIP 115739 |
23.10 |
| 2026-05-31 00:00 |
23:23:41.38 |
-74:09:41.5 |
HIP 115739 |
23.62 |
| 2026-05-31 12:00 |
23:23:43.34 |
-74:10:25.4 |
HIP 115739 |
24.15 |
| 2026-06-01 00:00 |
23:23:45.21 |
-74:11:09.5 |
HIP 115739 |
24.69 |
| 2026-06-01 12:00 |
23:23:46.98 |
-74:11:53.6 |
HIP 115739 |
25.26 |
| 2026-06-02 00:00 |
23:23:48.67 |
-74:12:37.9 |
HIP 115739 |
25.83 |