| Parameter |
Value |
| Designation |
C/2009 Y1 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-01-28T21:38:30.526080Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:38Z |
| Obs used |
1677 |
| NEO |
- |
| M1 |
6.400 |
| K1 |
14.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-01-30.0000000 |
| e |
0.99328974 |
| q (au) |
2.520495 |
| a (au) |
375.617800 |
| i (deg) |
107.316562 |
| Ω (om, deg) |
160.277046 |
| ω (w, deg) |
127.391328 |
| M (ma, deg) |
0.000149 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.100 + 5.550\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.100 |
| n |
5.550 |
| gf |
0.975 |
| gb |
-0.618 |
| k |
0.800 |
| δ90 |
8.562 |
| 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 |
| 2009-12-17 |
2010-03-31 |
-6.0824 |
+4.086 |
| 2010-03-31 |
2010-08-16 |
+4.8977 |
-2.662 |
| 2010-08-16 |
2011-01-28 |
-4.5465 |
+1.824 |
| 2011-01-29 |
2011-07-12 |
+1.5201 |
-0.975 |
| 2011-07-12 |
2011-12-23 |
-8.7975 |
+4.473 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
09:01:46.67 |
-77:16:26.7 |
HIP 44355 |
22.78 |
| 2026-03-26 12:00 |
09:01:37.08 |
-77:15:39.7 |
HIP 44355 |
22.01 |
| 2026-03-27 00:00 |
09:01:27.63 |
-77:14:52.3 |
HIP 44355 |
21.26 |
| 2026-03-27 12:00 |
09:01:18.31 |
-77:14:04.7 |
HIP 44355 |
20.52 |
| 2026-03-28 00:00 |
09:01:09.12 |
-77:13:16.8 |
HIP 44355 |
19.79 |
| 2026-03-28 12:00 |
09:01:00.07 |
-77:12:28.5 |
HIP 44355 |
19.07 |
| 2026-03-29 00:00 |
09:00:51.15 |
-77:11:39.9 |
HIP 44355 |
18.37 |
| 2026-03-29 12:00 |
09:00:42.36 |
-77:10:51.1 |
HIP 44355 |
17.68 |
| 2026-03-30 00:00 |
09:00:33.70 |
-77:10:01.9 |
HIP 44355 |
17.02 |
| 2026-03-30 12:00 |
09:00:25.18 |
-77:09:12.5 |
HIP 44355 |
16.37 |
| 2026-03-31 00:00 |
09:00:16.80 |
-77:08:22.7 |
HIP 44355 |
15.75 |
| 2026-03-31 12:00 |
09:00:08.54 |
-77:07:32.7 |
HIP 44355 |
15.16 |
| 2026-04-01 00:00 |
09:00:00.43 |
-77:06:42.4 |
HIP 44355 |
14.60 |
| 2026-04-01 12:00 |
08:59:52.45 |
-77:05:51.8 |
HIP 44355 |
14.07 |
| 2026-04-02 00:00 |
08:59:44.60 |
-77:05:01.0 |
HIP 44355 |
13.58 |
| 2026-04-02 12:00 |
08:59:36.89 |
-77:04:09.9 |
HIP 44355 |
13.14 |
| 2026-04-03 00:00 |
08:59:29.31 |
-77:03:18.5 |
HIP 44355 |
12.75 |
| 2026-04-03 12:00 |
08:59:21.87 |
-77:02:26.9 |
HIP 44355 |
12.41 |
| 2026-04-04 00:00 |
08:59:14.57 |
-77:01:35.0 |
HIP 44355 |
12.12 |
| 2026-04-04 12:00 |
08:59:07.40 |
-77:00:42.8 |
HIP 44355 |
11.90 |
| 2026-04-05 00:00 |
08:59:00.37 |
-76:59:50.5 |
HIP 44355 |
11.75 |
| 2026-04-05 12:00 |
08:58:53.48 |
-76:58:57.8 |
HIP 44355 |
11.66 |
| 2026-04-06 00:00 |
08:58:46.72 |
-76:58:05.0 |
HIP 44355 |
11.65 |
| 2026-04-06 12:00 |
08:58:40.10 |
-76:57:11.9 |
HIP 44355 |
11.71 |
| 2026-04-07 00:00 |
08:58:33.62 |
-76:56:18.6 |
HIP 44355 |
11.83 |
| 2026-04-07 12:00 |
08:58:27.28 |
-76:55:25.0 |
HIP 44355 |
12.03 |
| 2026-04-08 00:00 |
08:58:21.07 |
-76:54:31.3 |
HIP 44355 |
12.29 |
| 2026-04-08 12:00 |
08:58:15.00 |
-76:53:37.3 |
HIP 44355 |
12.61 |
| 2026-04-09 00:00 |
08:58:09.07 |
-76:52:43.1 |
HIP 44355 |
12.99 |
| 2026-04-09 12:00 |
08:58:03.27 |
-76:51:48.7 |
HIP 44355 |
13.42 |
| 2026-04-10 00:00 |
08:57:57.62 |
-76:50:54.1 |
HIP 44355 |
13.90 |
| 2026-04-10 12:00 |
08:57:52.10 |
-76:49:59.3 |
HIP 44355 |
14.42 |
| 2026-04-11 00:00 |
08:57:46.72 |
-76:49:04.3 |
HIP 44355 |
14.98 |
| 2026-04-11 12:00 |
08:57:41.48 |
-76:48:09.1 |
HIP 44355 |
15.58 |
| 2026-04-12 00:00 |
08:57:36.38 |
-76:47:13.7 |
HIP 44355 |
16.20 |
| 2026-04-12 12:00 |
08:57:31.41 |
-76:46:18.2 |
HIP 44355 |
16.85 |
| 2026-04-13 00:00 |
08:57:26.59 |
-76:45:22.5 |
HIP 44355 |
17.53 |
| 2026-04-13 12:00 |
08:57:21.90 |
-76:44:26.6 |
HIP 44355 |
18.22 |
| 2026-04-14 00:00 |
08:57:17.35 |
-76:43:30.5 |
HIP 44355 |
18.94 |
| 2026-04-14 12:00 |
08:57:12.94 |
-76:42:34.2 |
HIP 43888 |
19.33 |
| 2026-04-15 00:00 |
08:57:08.66 |
-76:41:37.9 |
HIP 43888 |
18.36 |
| 2026-04-15 12:00 |
08:57:04.53 |
-76:40:41.3 |
HIP 43888 |
17.40 |
| 2026-04-16 00:00 |
08:57:00.53 |
-76:39:44.6 |
HIP 43888 |
16.43 |