| 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) |
| 2026-07-29 00:00 |
01:25:01.63 |
-57:39:18.0 |
HIP 6485 |
17.06 |
| 2026-07-29 12:00 |
01:25:00.05 |
-57:40:04.6 |
HIP 6485 |
17.38 |
| 2026-07-30 00:00 |
01:24:58.41 |
-57:40:51.2 |
HIP 6485 |
17.73 |
| 2026-07-30 12:00 |
01:24:56.72 |
-57:41:37.7 |
HIP 6485 |
18.10 |
| 2026-07-31 00:00 |
01:24:54.99 |
-57:42:24.2 |
HIP 6485 |
18.49 |
| 2026-07-31 12:00 |
01:24:53.20 |
-57:43:10.7 |
HIP 6485 |
18.91 |
| 2026-08-01 00:00 |
01:24:51.37 |
-57:43:57.1 |
HIP 6485 |
19.35 |
| 2026-08-01 12:00 |
01:24:49.49 |
-57:44:43.5 |
HIP 6485 |
19.81 |
| 2026-08-02 00:00 |
01:24:47.56 |
-57:45:29.9 |
HIP 6485 |
20.28 |
| 2026-08-02 12:00 |
01:24:45.58 |
-57:46:16.1 |
HIP 6485 |
20.77 |
| 2026-08-03 00:00 |
01:24:43.55 |
-57:47:02.4 |
HIP 6485 |
21.28 |
| 2026-08-03 12:00 |
01:24:41.47 |
-57:47:48.5 |
HIP 6485 |
21.80 |
| 2026-08-04 00:00 |
01:24:39.34 |
-57:48:34.7 |
HIP 6485 |
22.34 |
| 2026-08-04 12:00 |
01:24:37.17 |
-57:49:20.7 |
HIP 6485 |
22.89 |
| 2026-08-05 00:00 |
01:24:34.94 |
-57:50:06.7 |
HIP 6375 |
22.66 |
| 2026-08-05 12:00 |
01:24:32.67 |
-57:50:52.6 |
HIP 6375 |
22.09 |
| 2026-08-06 00:00 |
01:24:30.35 |
-57:51:38.4 |
HIP 6375 |
21.54 |
| 2026-08-06 12:00 |
01:24:27.98 |
-57:52:24.2 |
HIP 6375 |
21.00 |
| 2026-08-07 00:00 |
01:24:25.56 |
-57:53:09.9 |
HIP 6375 |
20.47 |
| 2026-08-07 12:00 |
01:24:23.09 |
-57:53:55.5 |
HIP 6375 |
19.96 |
| 2026-08-08 00:00 |
01:24:20.57 |
-57:54:41.0 |
HIP 6375 |
19.46 |
| 2026-08-08 12:00 |
01:24:18.01 |
-57:55:26.4 |
HIP 6375 |
18.98 |
| 2026-08-09 00:00 |
01:24:15.40 |
-57:56:11.7 |
HIP 6375 |
18.52 |
| 2026-08-09 12:00 |
01:24:12.74 |
-57:56:56.9 |
HIP 6375 |
18.08 |
| 2026-08-10 00:00 |
01:24:10.03 |
-57:57:42.0 |
HIP 6375 |
17.67 |
| 2026-08-10 12:00 |
01:24:07.27 |
-57:58:27.0 |
HIP 6375 |
17.27 |
| 2026-08-11 00:00 |
01:24:04.47 |
-57:59:11.9 |
HIP 6375 |
16.90 |
| 2026-08-11 12:00 |
01:24:01.61 |
-57:59:56.7 |
HIP 6375 |
16.56 |
| 2026-08-12 00:00 |
01:23:58.71 |
-58:00:41.3 |
HIP 6375 |
16.25 |
| 2026-08-12 12:00 |
01:23:55.77 |
-58:01:25.8 |
HIP 6375 |
15.98 |
| 2026-08-13 00:00 |
01:23:52.77 |
-58:02:10.2 |
HIP 6375 |
15.73 |
| 2026-08-13 12:00 |
01:23:49.73 |
-58:02:54.5 |
HIP 6375 |
15.52 |
| 2026-08-14 00:00 |
01:23:46.64 |
-58:03:38.6 |
HIP 6375 |
15.35 |
| 2026-08-14 12:00 |
01:23:43.51 |
-58:04:22.6 |
HIP 6375 |
15.22 |
| 2026-08-15 00:00 |
01:23:40.33 |
-58:05:06.5 |
HIP 6375 |
15.12 |
| 2026-08-15 12:00 |
01:23:37.10 |
-58:05:50.2 |
HIP 6375 |
15.07 |
| 2026-08-16 00:00 |
01:23:33.83 |
-58:06:33.7 |
HIP 6375 |
15.05 |
| 2026-08-16 12:00 |
01:23:30.51 |
-58:07:17.1 |
HIP 6375 |
15.08 |
| 2026-08-17 00:00 |
01:23:27.15 |
-58:08:00.4 |
HIP 6375 |
15.15 |
| 2026-08-17 12:00 |
01:23:23.74 |
-58:08:43.5 |
HIP 6375 |
15.26 |
| 2026-08-18 00:00 |
01:23:20.28 |
-58:09:26.4 |
HIP 6375 |
15.41 |
| 2026-08-18 12:00 |
01:23:16.78 |
-58:10:09.1 |
HIP 6375 |
15.60 |
| 2026-08-19 00:00 |
01:23:13.24 |
-58:10:51.7 |
HIP 6375 |
15.82 |