| Parameter |
Value |
| Designation |
C/2009 O2 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2010-03-24T09:57:09.682560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:31Z |
| Obs used |
281 |
| NEO |
- |
| M1 |
12.900 |
| K1 |
7.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-10-31.0000000 |
| e |
0.99749905 |
| q (au) |
0.695547 |
| a (au) |
278.112822 |
| i (deg) |
107.960453 |
| Ω (om, deg) |
310.232085 |
| ω (w, deg) |
133.397136 |
| M (ma, deg) |
359.969311 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.631 + 3.055\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.631 |
| n |
3.055 |
| gf |
0.800 |
| gb |
-0.619 |
| k |
0.800 |
| δ90 |
9.999 |
| 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 |
| 2009-03-10 |
2009-07-30 |
-77.4381 |
+43.845 |
| 2009-07-30 |
2009-12-03 |
+12.4136 |
-6.726 |
| 2009-12-03 |
2010-03-24 |
-7.2272 |
-1.412 |
| 2010-03-26 |
2010-04-16 |
-88.5728 |
-12.010 |
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 |
01:19:59.23 |
-56:06:23.8 |
HIP 6345 |
12.83 |
| 2026-05-12 12:00 |
01:20:03.91 |
-56:06:38.6 |
HIP 6345 |
12.15 |
| 2026-05-13 00:00 |
01:20:08.56 |
-56:06:53.8 |
HIP 6345 |
11.48 |
| 2026-05-13 12:00 |
01:20:13.19 |
-56:07:09.3 |
HIP 6345 |
10.81 |
| 2026-05-14 00:00 |
01:20:17.79 |
-56:07:25.2 |
HIP 6345 |
10.15 |
| 2026-05-14 12:00 |
01:20:22.38 |
-56:07:41.5 |
HIP 6345 |
9.50 |
| 2026-05-15 00:00 |
01:20:26.94 |
-56:07:58.1 |
HIP 6345 |
8.85 |
| 2026-05-15 12:00 |
01:20:31.48 |
-56:08:15.0 |
HIP 6345 |
8.22 |
| 2026-05-16 00:00 |
01:20:35.99 |
-56:08:32.4 |
HIP 6345 |
7.60 |
| 2026-05-16 12:00 |
01:20:40.48 |
-56:08:50.0 |
HIP 6345 |
7.00 |
| 2026-05-17 00:00 |
01:20:44.94 |
-56:09:08.1 |
HIP 6345 |
6.43 |
| 2026-05-17 12:00 |
01:20:49.38 |
-56:09:26.5 |
HIP 6345 |
5.88 |
| 2026-05-18 00:00 |
01:20:53.80 |
-56:09:45.2 |
HIP 6345 |
5.37 |
| 2026-05-18 12:00 |
01:20:58.18 |
-56:10:04.3 |
HIP 6345 |
4.91 |
| 2026-05-19 00:00 |
01:21:02.55 |
-56:10:23.7 |
HIP 6345 |
4.51 |
| 2026-05-19 12:00 |
01:21:06.88 |
-56:10:43.5 |
HIP 6345 |
4.20 |
| 2026-05-20 00:00 |
01:21:11.19 |
-56:11:03.7 |
HIP 6345 |
3.99 |
| 2026-05-20 12:00 |
01:21:15.48 |
-56:11:24.2 |
HIP 6345 |
3.90 |
| 2026-05-21 00:00 |
01:21:19.73 |
-56:11:45.0 |
HIP 6345 |
3.93 |
| 2026-05-21 12:00 |
01:21:23.96 |
-56:12:06.2 |
HIP 6345 |
4.09 |
| 2026-05-22 00:00 |
01:21:28.16 |
-56:12:27.7 |
HIP 6345 |
4.36 |
| 2026-05-22 12:00 |
01:21:32.34 |
-56:12:49.5 |
HIP 6345 |
4.72 |
| 2026-05-23 00:00 |
01:21:36.48 |
-56:13:11.7 |
HIP 6345 |
5.15 |
| 2026-05-23 12:00 |
01:21:40.60 |
-56:13:34.2 |
HIP 6345 |
5.64 |
| 2026-05-24 00:00 |
01:21:44.68 |
-56:13:57.1 |
HIP 6345 |
6.17 |
| 2026-05-24 12:00 |
01:21:48.74 |
-56:14:20.3 |
HIP 6345 |
6.72 |
| 2026-05-25 00:00 |
01:21:52.77 |
-56:14:43.8 |
HIP 6345 |
7.31 |
| 2026-05-25 12:00 |
01:21:56.77 |
-56:15:07.6 |
HIP 6345 |
7.91 |
| 2026-05-26 00:00 |
01:22:00.74 |
-56:15:31.8 |
HIP 6345 |
8.53 |
| 2026-05-26 12:00 |
01:22:04.68 |
-56:15:56.3 |
HIP 6345 |
9.16 |
| 2026-05-27 00:00 |
01:22:08.59 |
-56:16:21.1 |
HIP 6345 |
9.80 |
| 2026-05-27 12:00 |
01:22:12.47 |
-56:16:46.3 |
HIP 6345 |
10.44 |
| 2026-05-28 00:00 |
01:22:16.32 |
-56:17:11.7 |
HIP 6345 |
11.10 |
| 2026-05-28 12:00 |
01:22:20.13 |
-56:17:37.5 |
HIP 6345 |
11.75 |
| 2026-05-29 00:00 |
01:22:23.92 |
-56:18:03.6 |
HIP 6345 |
12.42 |
| 2026-05-29 12:00 |
01:22:27.67 |
-56:18:30.1 |
HIP 6345 |
13.08 |
| 2026-05-30 00:00 |
01:22:31.39 |
-56:18:56.8 |
HIP 6345 |
13.75 |
| 2026-05-30 12:00 |
01:22:35.08 |
-56:19:23.8 |
HIP 6345 |
14.42 |
| 2026-05-31 00:00 |
01:22:38.74 |
-56:19:51.2 |
HIP 6345 |
15.09 |
| 2026-05-31 12:00 |
01:22:42.36 |
-56:20:18.9 |
HIP 6345 |
15.77 |
| 2026-06-01 00:00 |
01:22:45.96 |
-56:20:46.8 |
HIP 6345 |
16.45 |
| 2026-06-01 12:00 |
01:22:49.51 |
-56:21:15.1 |
HIP 6345 |
17.12 |
| 2026-06-02 00:00 |
01:22:53.04 |
-56:21:43.7 |
HIP 6345 |
17.80 |