C/2021 U5 (Catalina)
| Parameter |
Value |
| Designation |
C/2021 U5 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-01-26T14:41:49.295040Z |
| Orbit solution date (soln_date, UTC) |
2022-11-29T21:43:26Z |
| Obs used |
463 |
| NEO |
- |
| M1 |
4.800 |
| K1 |
28.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2021-10-29T11:47:30.652800Z |
| Discovery magnitude (MPC) |
19.16 G |
| Discovery observatory (MPC) |
703 · Catalina Sky Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-02-19.0000000 |
| e |
0.98911516 |
| q (au) |
2.363288 |
| a (au) |
217.117490 |
| i (deg) |
39.049400 |
| Ω (om, deg) |
182.755199 |
| ω (w, deg) |
321.471259 |
| M (ma, deg) |
0.007205 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.219 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.219 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.744 |
| k |
0.800 |
| 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) |
| 2026-02-03 00:00 |
18:20:17.80 |
+13:33:32.2 |
HIP 89939 |
18.91 |
| 2026-02-03 12:00 |
18:20:26.82 |
+13:34:30.3 |
HIP 89939 |
16.91 |
| 2026-02-04 00:00 |
18:20:35.79 |
+13:35:28.9 |
HIP 89939 |
15.01 |
| 2026-02-04 12:00 |
18:20:44.71 |
+13:36:28.1 |
HIP 89939 |
13.27 |
| 2026-02-05 00:00 |
18:20:53.58 |
+13:37:27.8 |
HIP 89939 |
11.75 |
| 2026-02-05 12:00 |
18:21:02.40 |
+13:38:28.0 |
HIP 89939 |
10.54 |
| 2026-02-06 00:00 |
18:21:11.16 |
+13:39:28.8 |
HIP 89939 |
9.76 |
| 2026-02-06 12:00 |
18:21:19.87 |
+13:40:30.0 |
HIP 89939 |
9.49 |
| 2026-02-07 00:00 |
18:21:28.53 |
+13:41:31.8 |
HIP 89939 |
9.78 |
| 2026-02-07 12:00 |
18:21:37.14 |
+13:42:34.1 |
HIP 89939 |
10.58 |
| 2026-02-08 00:00 |
18:21:45.69 |
+13:43:36.9 |
HIP 89939 |
11.78 |
| 2026-02-08 12:00 |
18:21:54.18 |
+13:44:40.2 |
HIP 89939 |
13.26 |
| 2026-02-09 00:00 |
18:22:02.63 |
+13:45:44.0 |
HIP 89939 |
14.94 |
| 2026-02-09 12:00 |
18:22:11.01 |
+13:46:48.3 |
HIP 89939 |
16.76 |
| 2026-02-10 00:00 |
18:22:19.34 |
+13:47:53.1 |
HIP 89939 |
18.67 |
| 2026-02-10 12:00 |
18:22:27.61 |
+13:48:58.4 |
HIP 89939 |
20.64 |
| 2026-02-11 00:00 |
18:22:35.83 |
+13:50:04.2 |
HIP 89939 |
22.66 |
| 2026-02-11 12:00 |
18:22:43.99 |
+13:51:10.5 |
HIP 89939 |
24.71 |
| 2026-02-12 00:00 |
18:22:52.09 |
+13:52:17.3 |
HIP 90221 |
26.08 |
| 2026-02-12 12:00 |
18:23:00.13 |
+13:53:24.5 |
HIP 90221 |
24.76 |
| 2026-02-13 00:00 |
18:23:08.11 |
+13:54:32.2 |
HIP 90221 |
23.60 |
| 2026-02-13 12:00 |
18:23:16.03 |
+13:55:40.4 |
HIP 90221 |
22.62 |
| 2026-02-14 00:00 |
18:23:23.89 |
+13:56:49.0 |
HIP 90221 |
21.84 |
| 2026-02-14 12:00 |
18:23:31.70 |
+13:57:58.1 |
HIP 90221 |
21.28 |
| 2026-02-15 00:00 |
18:23:39.44 |
+13:59:07.6 |
HIP 90221 |
20.96 |
| 2026-02-15 12:00 |
18:23:47.12 |
+14:00:17.6 |
HIP 90263 |
20.22 |
| 2026-02-16 00:00 |
18:23:54.74 |
+14:01:28.1 |
HIP 90263 |
18.05 |
| 2026-02-16 12:00 |
18:24:02.29 |
+14:02:39.0 |
HIP 90263 |
15.90 |
| 2026-02-17 00:00 |
18:24:09.78 |
+14:03:50.3 |
HIP 90263 |
13.78 |
| 2026-02-17 12:00 |
18:24:17.21 |
+14:05:02.1 |
HIP 90263 |
11.68 |
| 2026-02-18 00:00 |
18:24:24.58 |
+14:06:14.3 |
HIP 90263 |
9.62 |
| 2026-02-18 12:00 |
18:24:31.88 |
+14:07:26.9 |
HIP 90263 |
7.63 |
| 2026-02-19 00:00 |
18:24:39.12 |
+14:08:40.0 |
HIP 90263 |
5.78 |
| 2026-02-19 12:00 |
18:24:46.29 |
+14:09:53.4 |
HIP 90263 |
4.21 |
| 2026-02-20 00:00 |
18:24:53.40 |
+14:11:07.3 |
HIP 90263 |
3.35 |
| 2026-02-20 12:00 |
18:25:00.44 |
+14:12:21.6 |
HIP 90263 |
3.71 |
| 2026-02-21 00:00 |
18:25:07.41 |
+14:13:36.2 |
HIP 90263 |
5.02 |
| 2026-02-21 12:00 |
18:25:14.32 |
+14:14:51.3 |
HIP 90263 |
6.74 |
| 2026-02-22 00:00 |
18:25:21.16 |
+14:16:06.8 |
HIP 90263 |
8.63 |
| 2026-02-22 12:00 |
18:25:27.94 |
+14:17:22.6 |
HIP 90263 |
10.58 |
| 2026-02-23 00:00 |
18:25:34.64 |
+14:18:38.8 |
HIP 90263 |
12.57 |
| 2026-02-23 12:00 |
18:25:41.28 |
+14:19:55.4 |
HIP 90263 |
14.57 |
| 2026-02-24 00:00 |
18:25:47.85 |
+14:21:12.4 |
HIP 90263 |
16.58 |