| 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 · University of Arizona 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) |
| 2026-09-20 00:00 |
18:02:49.86 |
+15:52:01.0 |
HIP 88315 |
11.24 |
| 2026-09-20 12:00 |
18:02:51.11 |
+15:50:38.5 |
HIP 88315 |
12.26 |
| 2026-09-21 00:00 |
18:02:52.43 |
+15:49:16.0 |
HIP 88315 |
13.37 |
| 2026-09-21 12:00 |
18:02:53.82 |
+15:47:53.7 |
HIP 88315 |
14.54 |
| 2026-09-22 00:00 |
18:02:55.29 |
+15:46:31.4 |
HIP 88315 |
15.77 |
| 2026-09-22 12:00 |
18:02:56.84 |
+15:45:09.3 |
HIP 88315 |
17.03 |
| 2026-09-23 00:00 |
18:02:58.46 |
+15:43:47.2 |
HIP 88315 |
18.33 |
| 2026-09-23 12:00 |
18:03:00.15 |
+15:42:25.3 |
HIP 88315 |
19.65 |
| 2026-09-24 00:00 |
18:03:01.92 |
+15:41:03.5 |
HIP 88315 |
21.00 |
| 2026-09-24 12:00 |
18:03:03.76 |
+15:39:41.8 |
HIP 88315 |
22.36 |
| 2026-09-25 00:00 |
18:03:05.68 |
+15:38:20.2 |
HIP 88315 |
23.74 |
| 2026-09-25 12:00 |
18:03:07.67 |
+15:36:58.7 |
HIP 88315 |
25.14 |
| 2026-09-26 00:00 |
18:03:09.73 |
+15:35:37.4 |
HIP 88315 |
26.55 |
| 2026-09-26 12:00 |
18:03:11.87 |
+15:34:16.3 |
HIP 88315 |
27.96 |
| 2026-09-27 00:00 |
18:03:14.08 |
+15:32:55.2 |
HIP 88315 |
29.39 |
| 2026-09-27 12:00 |
18:03:16.37 |
+15:31:34.3 |
HIP 88590 |
30.33 |
| 2026-09-28 00:00 |
18:03:18.72 |
+15:30:13.6 |
HIP 88590 |
30.13 |
| 2026-09-28 12:00 |
18:03:21.15 |
+15:28:53.0 |
HIP 88394 |
29.18 |
| 2026-09-29 00:00 |
18:03:23.65 |
+15:27:32.6 |
HIP 88394 |
27.97 |
| 2026-09-29 12:00 |
18:03:26.23 |
+15:26:12.4 |
HIP 88394 |
26.80 |
| 2026-09-30 00:00 |
18:03:28.88 |
+15:24:52.4 |
HIP 88394 |
25.67 |
| 2026-09-30 12:00 |
18:03:31.59 |
+15:23:32.5 |
HIP 88394 |
24.58 |
| 2026-10-01 00:00 |
18:03:34.38 |
+15:22:12.8 |
HIP 88394 |
23.55 |
| 2026-10-01 12:00 |
18:03:37.25 |
+15:20:53.3 |
HIP 88394 |
22.57 |
| 2026-10-02 00:00 |
18:03:40.18 |
+15:19:34.0 |
HIP 88394 |
21.67 |
| 2026-10-02 12:00 |
18:03:43.18 |
+15:18:14.9 |
HIP 88394 |
20.85 |
| 2026-10-03 00:00 |
18:03:46.26 |
+15:16:56.0 |
HIP 88394 |
20.11 |
| 2026-10-03 12:00 |
18:03:49.41 |
+15:15:37.3 |
HIP 88394 |
19.48 |
| 2026-10-04 00:00 |
18:03:52.62 |
+15:14:18.8 |
HIP 88394 |
18.97 |
| 2026-10-04 12:00 |
18:03:55.91 |
+15:13:00.5 |
HIP 88394 |
18.58 |
| 2026-10-05 00:00 |
18:03:59.27 |
+15:11:42.5 |
HIP 88394 |
18.33 |
| 2026-10-05 12:00 |
18:04:02.70 |
+15:10:24.7 |
HIP 88394 |
18.21 |
| 2026-10-06 00:00 |
18:04:06.20 |
+15:09:07.1 |
HIP 88394 |
18.25 |
| 2026-10-06 12:00 |
18:04:09.77 |
+15:07:49.8 |
HIP 88394 |
18.43 |
| 2026-10-07 00:00 |
18:04:13.40 |
+15:06:32.8 |
HIP 88394 |
18.76 |
| 2026-10-07 12:00 |
18:04:17.11 |
+15:05:15.9 |
HIP 88493 |
18.48 |
| 2026-10-08 00:00 |
18:04:20.89 |
+15:03:59.4 |
HIP 88493 |
17.32 |
| 2026-10-08 12:00 |
18:04:24.73 |
+15:02:43.1 |
HIP 88493 |
16.25 |
| 2026-10-09 00:00 |
18:04:28.64 |
+15:01:27.1 |
HIP 88493 |
15.27 |
| 2026-10-09 12:00 |
18:04:32.63 |
+15:00:11.3 |
HIP 88493 |
14.41 |
| 2026-10-10 00:00 |
18:04:36.68 |
+14:58:55.8 |
HIP 88493 |
13.69 |
| 2026-10-10 12:00 |
18:04:40.79 |
+14:57:40.6 |
HIP 88493 |
13.13 |
| 2026-10-11 00:00 |
18:04:44.98 |
+14:56:25.8 |
HIP 88493 |
12.77 |