| Parameter |
Value |
| Designation |
C/2020 U4 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-04-08T01:08:57.566400Z |
| Orbit solution date (soln_date, UTC) |
2024-10-05T23:12:23Z |
| Obs used |
921 |
| NEO |
- |
| M1 |
5.700 |
| K1 |
12.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2020-10-22T13:20:36.067200Z |
| Discovery magnitude (MPC) |
20.20 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-05-31.0000000 |
| e |
1.00130917 |
| q (au) |
5.353691 |
| a (au) |
-4089.389408 |
| i (deg) |
167.035866 |
| Ω (om, deg) |
120.013777 |
| ω (w, deg) |
69.541084 |
| M (ma, deg) |
0.000200 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.338 + 5.142\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.338 |
| n |
5.142 |
| gf |
0.996 |
| gb |
-0.733 |
| k |
0.800 |
| δ90 |
9.288 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2019-11-09 |
2021-01-18 |
+7.7107 |
-6.501 |
| 2021-01-18 |
2022-03-24 |
-6.4323 |
+4.665 |
| 2022-07-24 |
2024-09-11 |
-0.0039 |
+0.097 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
21:27:27.29 |
-11:09:05.9 |
HIP 105859 |
20.49 |
| 2026-06-01 12:00 |
21:27:20.86 |
-11:09:37.4 |
HIP 105859 |
19.76 |
| 2026-06-02 00:00 |
21:27:14.34 |
-11:10:09.4 |
HIP 105859 |
19.13 |
| 2026-06-02 12:00 |
21:27:07.73 |
-11:10:41.8 |
HIP 105859 |
18.63 |
| 2026-06-03 00:00 |
21:27:01.03 |
-11:11:14.7 |
HIP 105859 |
18.28 |
| 2026-06-03 12:00 |
21:26:54.25 |
-11:11:47.9 |
HIP 105859 |
18.08 |
| 2026-06-04 00:00 |
21:26:47.39 |
-11:12:21.7 |
HIP 105859 |
18.05 |
| 2026-06-04 12:00 |
21:26:40.43 |
-11:12:55.8 |
HIP 105859 |
18.20 |
| 2026-06-05 00:00 |
21:26:33.40 |
-11:13:30.4 |
HIP 105859 |
18.53 |
| 2026-06-05 12:00 |
21:26:26.27 |
-11:14:05.4 |
HIP 105859 |
19.04 |
| 2026-06-06 00:00 |
21:26:19.06 |
-11:14:40.9 |
HIP 105859 |
19.72 |
| 2026-06-06 12:00 |
21:26:11.77 |
-11:15:16.8 |
HIP 105859 |
20.55 |
| 2026-06-07 00:00 |
21:26:04.39 |
-11:15:53.1 |
HIP 105859 |
21.53 |
| 2026-06-07 12:00 |
21:25:56.93 |
-11:16:29.9 |
HIP 105859 |
22.64 |
| 2026-06-08 00:00 |
21:25:49.38 |
-11:17:07.1 |
HIP 105859 |
23.87 |
| 2026-06-08 12:00 |
21:25:41.75 |
-11:17:44.7 |
HIP 105859 |
25.21 |
| 2026-06-09 00:00 |
21:25:34.03 |
-11:18:22.8 |
HIP 105859 |
26.64 |
| 2026-06-09 12:00 |
21:25:26.23 |
-11:19:01.3 |
HIP 105859 |
28.16 |
| 2026-06-10 00:00 |
21:25:18.35 |
-11:19:40.2 |
HIP 105859 |
29.76 |
| 2026-06-10 12:00 |
21:25:10.39 |
-11:20:19.5 |
HIP 105859 |
31.42 |
| 2026-06-11 00:00 |
21:25:02.34 |
-11:20:59.3 |
HIP 105859 |
33.15 |
| 2026-06-11 12:00 |
21:24:54.21 |
-11:21:39.5 |
HIP 105859 |
34.93 |
| 2026-06-12 00:00 |
21:24:45.99 |
-11:22:20.2 |
HIP 105859 |
36.77 |
| 2026-06-12 12:00 |
21:24:37.70 |
-11:23:01.2 |
HIP 105859 |
38.66 |
| 2026-06-13 00:00 |
21:24:29.32 |
-11:23:42.7 |
HIP 105859 |
40.59 |
| 2026-06-13 12:00 |
21:24:20.86 |
-11:24:24.6 |
HIP 105633 |
40.34 |
| 2026-06-14 00:00 |
21:24:12.32 |
-11:25:06.9 |
HIP 105633 |
39.21 |
| 2026-06-14 12:00 |
21:24:03.70 |
-11:25:49.6 |
HIP 105451 |
37.64 |
| 2026-06-15 00:00 |
21:23:55.00 |
-11:26:32.8 |
HIP 105451 |
35.48 |
| 2026-06-15 12:00 |
21:23:46.22 |
-11:27:16.3 |
HIP 105451 |
33.32 |
| 2026-06-16 00:00 |
21:23:37.36 |
-11:28:00.3 |
HIP 105451 |
31.15 |
| 2026-06-16 12:00 |
21:23:28.42 |
-11:28:44.7 |
HIP 105451 |
28.98 |
| 2026-06-17 00:00 |
21:23:19.41 |
-11:29:29.5 |
HIP 105451 |
26.82 |
| 2026-06-17 12:00 |
21:23:10.31 |
-11:30:14.7 |
HIP 105451 |
24.67 |
| 2026-06-18 00:00 |
21:23:01.14 |
-11:31:00.3 |
HIP 105451 |
22.55 |
| 2026-06-18 12:00 |
21:22:51.89 |
-11:31:46.3 |
HIP 105451 |
20.46 |
| 2026-06-19 00:00 |
21:22:42.57 |
-11:32:32.7 |
HIP 105451 |
18.43 |
| 2026-06-19 12:00 |
21:22:33.17 |
-11:33:19.5 |
HIP 105451 |
16.48 |
| 2026-06-20 00:00 |
21:22:23.69 |
-11:34:06.7 |
HIP 105451 |
14.67 |
| 2026-06-20 12:00 |
21:22:14.14 |
-11:34:54.2 |
HIP 105451 |
13.06 |
| 2026-06-21 00:00 |
21:22:04.52 |
-11:35:42.2 |
HIP 105451 |
11.74 |
| 2026-06-21 12:00 |
21:21:54.82 |
-11:36:30.5 |
HIP 105451 |
10.84 |
| 2026-06-22 00:00 |
21:21:45.05 |
-11:37:19.3 |
HIP 105451 |
10.48 |