| 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
$$
M_a = (8.341 + 5.142\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.341 |
| n |
5.142 |
| gf |
0.955 |
| gb |
-0.733 |
| k |
0.800 |
| δ90 |
9.550 |
| 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 |
+7.7109 |
-6.501 |
| 2021-01-18 |
2022-03-24 |
-6.4322 |
+4.665 |
| 2022-07-24 |
2024-09-11 |
-0.0037 |
+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) |
| 2026-05-12 00:00 |
21:30:32.50 |
-10:54:07.9 |
HIP 106365 |
36.98 |
| 2026-05-12 12:00 |
21:30:29.60 |
-10:54:21.7 |
HIP 106365 |
37.70 |
| 2026-05-13 00:00 |
21:30:26.61 |
-10:54:36.0 |
HIP 106365 |
38.44 |
| 2026-05-13 12:00 |
21:30:23.53 |
-10:54:50.8 |
HIP 106087 |
38.47 |
| 2026-05-14 00:00 |
21:30:20.37 |
-10:55:05.9 |
HIP 106087 |
38.41 |
| 2026-05-14 12:00 |
21:30:17.11 |
-10:55:21.5 |
HIP 106087 |
38.36 |
| 2026-05-15 00:00 |
21:30:13.77 |
-10:55:37.5 |
HIP 106087 |
38.33 |
| 2026-05-15 12:00 |
21:30:10.34 |
-10:55:54.0 |
HIP 106087 |
38.33 |
| 2026-05-16 00:00 |
21:30:06.82 |
-10:56:10.9 |
HIP 106087 |
38.34 |
| 2026-05-16 12:00 |
21:30:03.21 |
-10:56:28.3 |
HIP 106087 |
38.38 |
| 2026-05-17 00:00 |
21:29:59.51 |
-10:56:46.1 |
HIP 106087 |
38.44 |
| 2026-05-17 12:00 |
21:29:55.72 |
-10:57:04.3 |
HIP 106087 |
38.53 |
| 2026-05-18 00:00 |
21:29:51.85 |
-10:57:23.0 |
HIP 106087 |
38.64 |
| 2026-05-18 12:00 |
21:29:47.88 |
-10:57:42.1 |
HIP 106087 |
38.79 |
| 2026-05-19 00:00 |
21:29:43.83 |
-10:58:01.6 |
HIP 106087 |
38.96 |
| 2026-05-19 12:00 |
21:29:39.68 |
-10:58:21.6 |
HIP 106087 |
39.17 |
| 2026-05-20 00:00 |
21:29:35.45 |
-10:58:42.1 |
HIP 106087 |
39.41 |
| 2026-05-20 12:00 |
21:29:31.13 |
-10:59:02.9 |
HIP 106087 |
39.69 |
| 2026-05-21 00:00 |
21:29:26.72 |
-10:59:24.3 |
HIP 106007 |
39.01 |
| 2026-05-21 12:00 |
21:29:22.21 |
-10:59:46.1 |
HIP 106007 |
38.19 |
| 2026-05-22 00:00 |
21:29:17.63 |
-11:00:08.3 |
HIP 106007 |
37.37 |
| 2026-05-22 12:00 |
21:29:12.95 |
-11:00:30.9 |
HIP 106007 |
36.56 |
| 2026-05-23 00:00 |
21:29:08.18 |
-11:00:54.1 |
HIP 106007 |
35.75 |
| 2026-05-23 12:00 |
21:29:03.32 |
-11:01:17.6 |
HIP 106007 |
34.96 |
| 2026-05-24 00:00 |
21:28:58.38 |
-11:01:41.6 |
HIP 106007 |
34.18 |
| 2026-05-24 12:00 |
21:28:53.35 |
-11:02:06.1 |
HIP 106007 |
33.42 |
| 2026-05-25 00:00 |
21:28:48.22 |
-11:02:30.9 |
HIP 106007 |
32.67 |
| 2026-05-25 12:00 |
21:28:43.01 |
-11:02:56.3 |
HIP 106007 |
31.96 |
| 2026-05-26 00:00 |
21:28:37.72 |
-11:03:22.1 |
HIP 106007 |
31.27 |
| 2026-05-26 12:00 |
21:28:32.33 |
-11:03:48.3 |
HIP 106007 |
30.62 |
| 2026-05-27 00:00 |
21:28:26.86 |
-11:04:14.9 |
HIP 106007 |
30.01 |
| 2026-05-27 12:00 |
21:28:21.29 |
-11:04:42.0 |
HIP 106007 |
29.44 |
| 2026-05-28 00:00 |
21:28:15.64 |
-11:05:09.6 |
HIP 105859 |
28.63 |
| 2026-05-28 12:00 |
21:28:09.91 |
-11:05:37.6 |
HIP 105859 |
27.50 |
| 2026-05-29 00:00 |
21:28:04.08 |
-11:06:06.0 |
HIP 105859 |
26.38 |
| 2026-05-29 12:00 |
21:27:58.17 |
-11:06:34.9 |
HIP 105859 |
25.28 |
| 2026-05-30 00:00 |
21:27:52.17 |
-11:07:04.2 |
HIP 105859 |
24.22 |
| 2026-05-30 12:00 |
21:27:46.08 |
-11:07:34.0 |
HIP 105859 |
23.20 |
| 2026-05-31 00:00 |
21:27:39.90 |
-11:08:04.2 |
HIP 105859 |
22.23 |
| 2026-05-31 12:00 |
21:27:33.64 |
-11:08:34.8 |
HIP 105859 |
21.32 |
| 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 |