| 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
$$
M_a = (10.751 + 4.547\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.751 |
| n |
4.547 |
| 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 |
-5.1167 |
-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) |
| 2026-09-20 00:00 |
22:55:17.52 |
-76:02:42.2 |
HIP 113344 |
19.69 |
| 2026-09-20 12:00 |
22:55:05.14 |
-76:02:34.9 |
HIP 113344 |
19.87 |
| 2026-09-21 00:00 |
22:54:52.80 |
-76:02:27.1 |
HIP 113344 |
20.07 |
| 2026-09-21 12:00 |
22:54:40.50 |
-76:02:18.9 |
HIP 113344 |
20.29 |
| 2026-09-22 00:00 |
22:54:28.24 |
-76:02:10.2 |
HIP 113344 |
20.52 |
| 2026-09-22 12:00 |
22:54:16.01 |
-76:02:01.1 |
HIP 113344 |
20.78 |
| 2026-09-23 00:00 |
22:54:03.83 |
-76:01:51.6 |
HIP 113344 |
21.05 |
| 2026-09-23 12:00 |
22:53:51.69 |
-76:01:41.6 |
HIP 113344 |
21.34 |
| 2026-09-24 00:00 |
22:53:39.59 |
-76:01:31.2 |
HIP 113344 |
21.64 |
| 2026-09-24 12:00 |
22:53:27.53 |
-76:01:20.4 |
HIP 113344 |
21.96 |
| 2026-09-25 00:00 |
22:53:15.52 |
-76:01:09.2 |
HIP 113344 |
22.29 |
| 2026-09-25 12:00 |
22:53:03.56 |
-76:00:57.5 |
HIP 113344 |
22.64 |
| 2026-09-26 00:00 |
22:52:51.64 |
-76:00:45.4 |
HIP 113344 |
23.00 |
| 2026-09-26 12:00 |
22:52:39.77 |
-76:00:32.9 |
HIP 112732 |
22.89 |
| 2026-09-27 00:00 |
22:52:27.95 |
-76:00:20.0 |
HIP 112732 |
22.78 |
| 2026-09-27 12:00 |
22:52:16.18 |
-76:00:06.6 |
HIP 112732 |
22.70 |
| 2026-09-28 00:00 |
22:52:04.46 |
-75:59:52.9 |
HIP 112732 |
22.65 |
| 2026-09-28 12:00 |
22:51:52.80 |
-75:59:38.7 |
HIP 112732 |
22.63 |
| 2026-09-29 00:00 |
22:51:41.18 |
-75:59:24.1 |
HIP 112732 |
22.64 |
| 2026-09-29 12:00 |
22:51:29.63 |
-75:59:09.0 |
HIP 112732 |
22.68 |
| 2026-09-30 00:00 |
22:51:18.12 |
-75:58:53.6 |
HIP 112732 |
22.76 |
| 2026-09-30 12:00 |
22:51:06.68 |
-75:58:37.8 |
HIP 112732 |
22.86 |
| 2026-10-01 00:00 |
22:50:55.29 |
-75:58:21.5 |
HIP 112732 |
23.00 |
| 2026-10-01 12:00 |
22:50:43.96 |
-75:58:04.8 |
HIP 112732 |
23.16 |
| 2026-10-02 00:00 |
22:50:32.69 |
-75:57:47.7 |
HIP 112732 |
23.35 |
| 2026-10-02 12:00 |
22:50:21.48 |
-75:57:30.3 |
HIP 112732 |
23.57 |
| 2026-10-03 00:00 |
22:50:10.33 |
-75:57:12.4 |
HIP 112732 |
23.82 |
| 2026-10-03 12:00 |
22:49:59.25 |
-75:56:54.1 |
HIP 112732 |
24.10 |
| 2026-10-04 00:00 |
22:49:48.23 |
-75:56:35.4 |
HIP 112732 |
24.40 |
| 2026-10-04 12:00 |
22:49:37.27 |
-75:56:16.2 |
HIP 112732 |
24.73 |
| 2026-10-05 00:00 |
22:49:26.38 |
-75:55:56.7 |
HIP 112732 |
25.07 |
| 2026-10-05 12:00 |
22:49:15.55 |
-75:55:36.8 |
HIP 112732 |
25.45 |
| 2026-10-06 00:00 |
22:49:04.80 |
-75:55:16.5 |
HIP 112732 |
25.84 |
| 2026-10-06 12:00 |
22:48:54.11 |
-75:54:55.9 |
HIP 112732 |
26.25 |
| 2026-10-07 00:00 |
22:48:43.49 |
-75:54:34.8 |
HIP 112732 |
26.68 |
| 2026-10-07 12:00 |
22:48:32.95 |
-75:54:13.3 |
HIP 112732 |
27.13 |
| 2026-10-08 00:00 |
22:48:22.47 |
-75:53:51.4 |
HIP 112732 |
27.60 |
| 2026-10-08 12:00 |
22:48:12.07 |
-75:53:29.2 |
HIP 112732 |
28.09 |
| 2026-10-09 00:00 |
22:48:01.75 |
-75:53:06.5 |
HIP 112429 |
28.44 |
| 2026-10-09 12:00 |
22:47:51.49 |
-75:52:43.5 |
HIP 112429 |
27.93 |
| 2026-10-10 00:00 |
22:47:41.32 |
-75:52:20.1 |
HIP 112429 |
27.43 |
| 2026-10-10 12:00 |
22:47:31.22 |
-75:51:56.3 |
HIP 112429 |
26.94 |
| 2026-10-11 00:00 |
22:47:21.19 |
-75:51:32.2 |
HIP 112429 |
26.45 |