| 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 |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| δ90 |
10.000 |
| 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) |
| 2026-05-12 00:00 |
10:16:37.67 |
-09:23:55.7 |
HIP 50363 |
22.13 |
| 2026-05-12 12:00 |
10:16:37.19 |
-09:23:19.2 |
HIP 50363 |
21.57 |
| 2026-05-13 00:00 |
10:16:36.76 |
-09:22:43.0 |
HIP 50363 |
21.02 |
| 2026-05-13 12:00 |
10:16:36.37 |
-09:22:07.0 |
HIP 50363 |
20.47 |
| 2026-05-14 00:00 |
10:16:36.04 |
-09:21:31.2 |
HIP 50363 |
19.93 |
| 2026-05-14 12:00 |
10:16:35.76 |
-09:20:55.7 |
HIP 50363 |
19.38 |
| 2026-05-15 00:00 |
10:16:35.52 |
-09:20:20.5 |
HIP 50363 |
18.85 |
| 2026-05-15 12:00 |
10:16:35.34 |
-09:19:45.5 |
HIP 50363 |
18.31 |
| 2026-05-16 00:00 |
10:16:35.21 |
-09:19:10.8 |
HIP 50363 |
17.78 |
| 2026-05-16 12:00 |
10:16:35.13 |
-09:18:36.3 |
HIP 50363 |
17.25 |
| 2026-05-17 00:00 |
10:16:35.09 |
-09:18:02.1 |
HIP 50363 |
16.72 |
| 2026-05-17 12:00 |
10:16:35.11 |
-09:17:28.2 |
HIP 50363 |
16.20 |
| 2026-05-18 00:00 |
10:16:35.18 |
-09:16:54.5 |
HIP 50363 |
15.67 |
| 2026-05-18 12:00 |
10:16:35.30 |
-09:16:21.1 |
HIP 50363 |
15.15 |
| 2026-05-19 00:00 |
10:16:35.46 |
-09:15:48.0 |
HIP 50363 |
14.63 |
| 2026-05-19 12:00 |
10:16:35.68 |
-09:15:15.2 |
HIP 50363 |
14.11 |
| 2026-05-20 00:00 |
10:16:35.95 |
-09:14:42.6 |
HIP 50363 |
13.60 |
| 2026-05-20 12:00 |
10:16:36.26 |
-09:14:10.4 |
HIP 50363 |
13.08 |
| 2026-05-21 00:00 |
10:16:36.63 |
-09:13:38.4 |
HIP 50363 |
12.57 |
| 2026-05-21 12:00 |
10:16:37.05 |
-09:13:06.7 |
HIP 50363 |
12.05 |
| 2026-05-22 00:00 |
10:16:37.51 |
-09:12:35.2 |
HIP 50363 |
11.54 |
| 2026-05-22 12:00 |
10:16:38.02 |
-09:12:04.1 |
HIP 50363 |
11.02 |
| 2026-05-23 00:00 |
10:16:38.59 |
-09:11:33.3 |
HIP 50363 |
10.51 |
| 2026-05-23 12:00 |
10:16:39.20 |
-09:11:02.7 |
HIP 50363 |
10.00 |
| 2026-05-24 00:00 |
10:16:39.86 |
-09:10:32.5 |
HIP 50363 |
9.48 |
| 2026-05-24 12:00 |
10:16:40.57 |
-09:10:02.5 |
HIP 50363 |
8.97 |
| 2026-05-25 00:00 |
10:16:41.33 |
-09:09:32.8 |
HIP 50363 |
8.45 |
| 2026-05-25 12:00 |
10:16:42.14 |
-09:09:03.5 |
HIP 50363 |
7.93 |
| 2026-05-26 00:00 |
10:16:43.00 |
-09:08:34.4 |
HIP 50363 |
7.41 |
| 2026-05-26 12:00 |
10:16:43.90 |
-09:08:05.6 |
HIP 50363 |
6.89 |
| 2026-05-27 00:00 |
10:16:44.85 |
-09:07:37.2 |
HIP 50363 |
6.37 |
| 2026-05-27 12:00 |
10:16:45.86 |
-09:07:09.0 |
HIP 50363 |
5.85 |
| 2026-05-28 00:00 |
10:16:46.90 |
-09:06:41.2 |
HIP 50363 |
5.32 |
| 2026-05-28 12:00 |
10:16:48.00 |
-09:06:13.6 |
HIP 50363 |
4.80 |
| 2026-05-29 00:00 |
10:16:49.15 |
-09:05:46.4 |
HIP 50363 |
4.27 |
| 2026-05-29 12:00 |
10:16:50.34 |
-09:05:19.4 |
HIP 50363 |
3.73 |
| 2026-05-30 00:00 |
10:16:51.58 |
-09:04:52.8 |
HIP 50363 |
3.20 |
| 2026-05-30 12:00 |
10:16:52.87 |
-09:04:26.5 |
HIP 50363 |
2.66 |
| 2026-05-31 00:00 |
10:16:54.20 |
-09:04:00.5 |
HIP 50363 |
2.12 |
| 2026-05-31 12:00 |
10:16:55.58 |
-09:03:34.8 |
HIP 50363 |
1.58 |
| 2026-06-01 00:00 |
10:16:57.01 |
-09:03:09.5 |
HIP 50363 |
1.04 |
| 2026-06-01 12:00 |
10:16:58.49 |
-09:02:44.4 |
HIP 50363 |
0.50 |
| 2026-06-02 00:00 |
10:17:00.01 |
-09:02:19.7 |
HIP 50363 |
0.20 |