| Parameter |
Value |
| Designation |
C/2013 U1 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-11-18T17:23:35.376000Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:41Z |
| Obs used |
137 |
| NEO |
- |
| M1 |
13.900 |
| K1 |
10.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-10-31.0000000 |
| e |
0.79716890 |
| q (au) |
2.418807 |
| a (au) |
11.925225 |
| i (deg) |
23.941661 |
| Ω (om, deg) |
211.251432 |
| ω (w, deg) |
143.142203 |
| M (ma, deg) |
359.551854 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.975 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.975 |
| n |
6.000 |
| gf |
0.999 |
| gb |
-0.998 |
| k |
1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
10:34:42.53 |
-09:43:46.0 |
HIP 51741 |
11.82 |
| 2026-09-20 12:00 |
10:34:48.29 |
-09:44:25.9 |
HIP 51741 |
12.07 |
| 2026-09-21 00:00 |
10:34:54.04 |
-09:45:05.9 |
HIP 51741 |
12.51 |
| 2026-09-21 12:00 |
10:34:59.78 |
-09:45:46.0 |
HIP 51741 |
13.11 |
| 2026-09-22 00:00 |
10:35:05.49 |
-09:46:26.3 |
HIP 51741 |
13.87 |
| 2026-09-22 12:00 |
10:35:11.19 |
-09:47:06.7 |
HIP 51741 |
14.74 |
| 2026-09-23 00:00 |
10:35:16.88 |
-09:47:47.2 |
HIP 51741 |
15.72 |
| 2026-09-23 12:00 |
10:35:22.54 |
-09:48:27.8 |
HIP 51741 |
16.78 |
| 2026-09-24 00:00 |
10:35:28.19 |
-09:49:08.5 |
HIP 51741 |
17.90 |
| 2026-09-24 12:00 |
10:35:33.82 |
-09:49:49.4 |
HIP 51741 |
19.08 |
| 2026-09-25 00:00 |
10:35:39.44 |
-09:50:30.3 |
HIP 51741 |
20.31 |
| 2026-09-25 12:00 |
10:35:45.03 |
-09:51:11.4 |
HIP 51944 |
20.12 |
| 2026-09-26 00:00 |
10:35:50.61 |
-09:51:52.6 |
HIP 51944 |
19.68 |
| 2026-09-26 12:00 |
10:35:56.17 |
-09:52:33.9 |
HIP 51944 |
19.37 |
| 2026-09-27 00:00 |
10:36:01.71 |
-09:53:15.3 |
HIP 51944 |
19.17 |
| 2026-09-27 12:00 |
10:36:07.23 |
-09:53:56.8 |
HIP 51944 |
19.10 |
| 2026-09-28 00:00 |
10:36:12.73 |
-09:54:38.4 |
HIP 51944 |
19.15 |
| 2026-09-28 12:00 |
10:36:18.21 |
-09:55:20.1 |
HIP 51944 |
19.33 |
| 2026-09-29 00:00 |
10:36:23.67 |
-09:56:01.9 |
HIP 51944 |
19.62 |
| 2026-09-29 12:00 |
10:36:29.11 |
-09:56:43.7 |
HIP 51944 |
20.03 |
| 2026-09-30 00:00 |
10:36:34.53 |
-09:57:25.7 |
HIP 51944 |
20.55 |
| 2026-09-30 12:00 |
10:36:39.93 |
-09:58:07.8 |
HIP 52017 |
20.79 |
| 2026-10-01 00:00 |
10:36:45.31 |
-09:58:49.9 |
HIP 52017 |
20.43 |
| 2026-10-01 12:00 |
10:36:50.67 |
-09:59:32.2 |
HIP 52017 |
20.19 |
| 2026-10-02 00:00 |
10:36:56.00 |
-10:00:14.5 |
HIP 52017 |
20.05 |
| 2026-10-02 12:00 |
10:37:01.31 |
-10:00:56.9 |
HIP 52017 |
20.03 |
| 2026-10-03 00:00 |
10:37:06.60 |
-10:01:39.4 |
HIP 52017 |
20.13 |
| 2026-10-03 12:00 |
10:37:11.87 |
-10:02:21.9 |
HIP 52017 |
20.33 |
| 2026-10-04 00:00 |
10:37:17.11 |
-10:03:04.5 |
HIP 52017 |
20.64 |
| 2026-10-04 12:00 |
10:37:22.33 |
-10:03:47.2 |
HIP 52017 |
21.06 |
| 2026-10-05 00:00 |
10:37:27.52 |
-10:04:30.0 |
HIP 52017 |
21.56 |
| 2026-10-05 12:00 |
10:37:32.69 |
-10:05:12.8 |
HIP 52121 |
20.58 |
| 2026-10-06 00:00 |
10:37:37.84 |
-10:05:55.7 |
HIP 52121 |
19.21 |
| 2026-10-06 12:00 |
10:37:42.96 |
-10:06:38.6 |
HIP 52121 |
17.86 |
| 2026-10-07 00:00 |
10:37:48.05 |
-10:07:21.6 |
HIP 52121 |
16.52 |
| 2026-10-07 12:00 |
10:37:53.12 |
-10:08:04.7 |
HIP 52121 |
15.22 |
| 2026-10-08 00:00 |
10:37:58.17 |
-10:08:47.8 |
HIP 52121 |
13.95 |
| 2026-10-08 12:00 |
10:38:03.18 |
-10:09:30.9 |
HIP 52121 |
12.72 |
| 2026-10-09 00:00 |
10:38:08.17 |
-10:10:14.1 |
HIP 52121 |
11.55 |
| 2026-10-09 12:00 |
10:38:13.14 |
-10:10:57.4 |
HIP 52121 |
10.44 |
| 2026-10-10 00:00 |
10:38:18.07 |
-10:11:40.6 |
HIP 52121 |
9.42 |
| 2026-10-10 12:00 |
10:38:22.98 |
-10:12:24.0 |
HIP 52121 |
8.52 |
| 2026-10-11 00:00 |
10:38:27.86 |
-10:13:07.3 |
HIP 52121 |
7.79 |