| 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) |
| 2026-07-29 00:00 |
10:24:12.40 |
-08:52:52.8 |
HIP 50827 |
38.09 |
| 2026-07-29 12:00 |
10:24:17.91 |
-08:53:07.5 |
HIP 50827 |
38.71 |
| 2026-07-30 00:00 |
10:24:23.45 |
-08:53:22.5 |
HIP 50827 |
39.37 |
| 2026-07-30 12:00 |
10:24:29.00 |
-08:53:37.8 |
HIP 50827 |
40.06 |
| 2026-07-31 00:00 |
10:24:34.57 |
-08:53:53.5 |
HIP 50827 |
40.79 |
| 2026-07-31 12:00 |
10:24:40.16 |
-08:54:09.4 |
HIP 51165 |
40.40 |
| 2026-08-01 00:00 |
10:24:45.77 |
-08:54:25.7 |
HIP 51165 |
39.06 |
| 2026-08-01 12:00 |
10:24:51.40 |
-08:54:42.3 |
HIP 51165 |
37.71 |
| 2026-08-02 00:00 |
10:24:57.04 |
-08:54:59.1 |
HIP 51165 |
36.36 |
| 2026-08-02 12:00 |
10:25:02.70 |
-08:55:16.3 |
HIP 51165 |
35.01 |
| 2026-08-03 00:00 |
10:25:08.38 |
-08:55:33.8 |
HIP 51165 |
33.67 |
| 2026-08-03 12:00 |
10:25:14.07 |
-08:55:51.7 |
HIP 51165 |
32.32 |
| 2026-08-04 00:00 |
10:25:19.78 |
-08:56:09.8 |
HIP 51165 |
30.98 |
| 2026-08-04 12:00 |
10:25:25.51 |
-08:56:28.2 |
HIP 51165 |
29.64 |
| 2026-08-05 00:00 |
10:25:31.25 |
-08:56:46.9 |
HIP 51165 |
28.30 |
| 2026-08-05 12:00 |
10:25:37.01 |
-08:57:06.0 |
HIP 51165 |
26.97 |
| 2026-08-06 00:00 |
10:25:42.78 |
-08:57:25.3 |
HIP 51165 |
25.64 |
| 2026-08-06 12:00 |
10:25:48.57 |
-08:57:44.9 |
HIP 51165 |
24.33 |
| 2026-08-07 00:00 |
10:25:54.37 |
-08:58:04.9 |
HIP 51165 |
23.03 |
| 2026-08-07 12:00 |
10:26:00.18 |
-08:58:25.1 |
HIP 51165 |
21.74 |
| 2026-08-08 00:00 |
10:26:06.01 |
-08:58:45.6 |
HIP 51165 |
20.48 |
| 2026-08-08 12:00 |
10:26:11.85 |
-08:59:06.5 |
HIP 51165 |
19.23 |
| 2026-08-09 00:00 |
10:26:17.71 |
-08:59:27.6 |
HIP 51165 |
18.02 |
| 2026-08-09 12:00 |
10:26:23.58 |
-08:59:49.0 |
HIP 51165 |
16.85 |
| 2026-08-10 00:00 |
10:26:29.46 |
-09:00:10.7 |
HIP 51165 |
15.73 |
| 2026-08-10 12:00 |
10:26:35.35 |
-09:00:32.8 |
HIP 51165 |
14.66 |
| 2026-08-11 00:00 |
10:26:41.26 |
-09:00:55.1 |
HIP 51165 |
13.68 |
| 2026-08-11 12:00 |
10:26:47.17 |
-09:01:17.6 |
HIP 51165 |
12.79 |
| 2026-08-12 00:00 |
10:26:53.10 |
-09:01:40.5 |
HIP 51165 |
12.01 |
| 2026-08-12 12:00 |
10:26:59.04 |
-09:02:03.7 |
HIP 51165 |
11.38 |
| 2026-08-13 00:00 |
10:27:04.99 |
-09:02:27.1 |
HIP 51165 |
10.93 |
| 2026-08-13 12:00 |
10:27:10.95 |
-09:02:50.9 |
HIP 51165 |
10.66 |
| 2026-08-14 00:00 |
10:27:16.92 |
-09:03:14.9 |
HIP 51165 |
10.61 |
| 2026-08-14 12:00 |
10:27:22.89 |
-09:03:39.2 |
HIP 51165 |
10.77 |
| 2026-08-15 00:00 |
10:27:28.88 |
-09:04:03.7 |
HIP 51165 |
11.14 |
| 2026-08-15 12:00 |
10:27:34.88 |
-09:04:28.6 |
HIP 51165 |
11.70 |
| 2026-08-16 00:00 |
10:27:40.88 |
-09:04:53.7 |
HIP 51165 |
12.42 |
| 2026-08-16 12:00 |
10:27:46.89 |
-09:05:19.1 |
HIP 51165 |
13.28 |
| 2026-08-17 00:00 |
10:27:52.91 |
-09:05:44.8 |
HIP 51165 |
14.26 |
| 2026-08-17 12:00 |
10:27:58.94 |
-09:06:10.7 |
HIP 51296 |
14.93 |
| 2026-08-18 00:00 |
10:28:04.97 |
-09:06:36.9 |
HIP 51296 |
14.22 |
| 2026-08-18 12:00 |
10:28:11.01 |
-09:07:03.4 |
HIP 51296 |
13.65 |
| 2026-08-19 00:00 |
10:28:17.06 |
-09:07:30.1 |
HIP 51296 |
13.25 |