| 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) |
| 2026-03-26 00:00 |
21:29:07.05 |
-11:00:02.5 |
HIP 106007 |
36.45 |
| 2026-03-26 12:00 |
21:29:11.20 |
-10:59:44.8 |
HIP 106007 |
37.10 |
| 2026-03-27 00:00 |
21:29:15.30 |
-10:59:27.4 |
HIP 106007 |
37.76 |
| 2026-03-27 12:00 |
21:29:19.34 |
-10:59:10.1 |
HIP 106007 |
38.43 |
| 2026-03-28 00:00 |
21:29:23.32 |
-10:58:53.1 |
HIP 106007 |
39.10 |
| 2026-03-28 12:00 |
21:29:27.24 |
-10:58:36.4 |
HIP 106087 |
39.21 |
| 2026-03-29 00:00 |
21:29:31.10 |
-10:58:19.8 |
HIP 106087 |
38.97 |
| 2026-03-29 12:00 |
21:29:34.90 |
-10:58:03.5 |
HIP 106087 |
38.76 |
| 2026-03-30 00:00 |
21:29:38.64 |
-10:57:47.4 |
HIP 106087 |
38.58 |
| 2026-03-30 12:00 |
21:29:42.33 |
-10:57:31.6 |
HIP 106087 |
38.42 |
| 2026-03-31 00:00 |
21:29:45.95 |
-10:57:16.0 |
HIP 106087 |
38.28 |
| 2026-03-31 12:00 |
21:29:49.51 |
-10:57:00.6 |
HIP 106087 |
38.17 |
| 2026-04-01 00:00 |
21:29:53.01 |
-10:56:45.5 |
HIP 106087 |
38.08 |
| 2026-04-01 12:00 |
21:29:56.44 |
-10:56:30.6 |
HIP 106087 |
38.02 |
| 2026-04-02 00:00 |
21:29:59.82 |
-10:56:16.0 |
HIP 106087 |
37.97 |
| 2026-04-02 12:00 |
21:30:03.13 |
-10:56:01.6 |
HIP 106087 |
37.94 |
| 2026-04-03 00:00 |
21:30:06.38 |
-10:55:47.5 |
HIP 106087 |
37.94 |
| 2026-04-03 12:00 |
21:30:09.56 |
-10:55:33.6 |
HIP 106087 |
37.95 |
| 2026-04-04 00:00 |
21:30:12.68 |
-10:55:20.0 |
HIP 106087 |
37.97 |
| 2026-04-04 12:00 |
21:30:15.74 |
-10:55:06.7 |
HIP 106087 |
38.01 |
| 2026-04-05 00:00 |
21:30:18.73 |
-10:54:53.6 |
HIP 106087 |
38.07 |
| 2026-04-05 12:00 |
21:30:21.65 |
-10:54:40.8 |
HIP 106087 |
38.14 |
| 2026-04-06 00:00 |
21:30:24.51 |
-10:54:28.3 |
HIP 106087 |
38.22 |
| 2026-04-06 12:00 |
21:30:27.30 |
-10:54:16.0 |
HIP 106365 |
38.11 |
| 2026-04-07 00:00 |
21:30:30.03 |
-10:54:04.1 |
HIP 106365 |
37.45 |
| 2026-04-07 12:00 |
21:30:32.69 |
-10:53:52.4 |
HIP 106365 |
36.80 |
| 2026-04-08 00:00 |
21:30:35.28 |
-10:53:40.9 |
HIP 106365 |
36.17 |
| 2026-04-08 12:00 |
21:30:37.80 |
-10:53:29.8 |
HIP 106365 |
35.56 |
| 2026-04-09 00:00 |
21:30:40.26 |
-10:53:19.0 |
HIP 106365 |
34.96 |
| 2026-04-09 12:00 |
21:30:42.65 |
-10:53:08.4 |
HIP 106365 |
34.38 |
| 2026-04-10 00:00 |
21:30:44.96 |
-10:52:58.1 |
HIP 106365 |
33.82 |
| 2026-04-10 12:00 |
21:30:47.21 |
-10:52:48.2 |
HIP 106365 |
33.28 |
| 2026-04-11 00:00 |
21:30:49.39 |
-10:52:38.5 |
HIP 106365 |
32.76 |
| 2026-04-11 12:00 |
21:30:51.49 |
-10:52:29.1 |
HIP 106365 |
32.25 |
| 2026-04-12 00:00 |
21:30:53.53 |
-10:52:20.1 |
HIP 106365 |
31.77 |
| 2026-04-12 12:00 |
21:30:55.49 |
-10:52:11.3 |
HIP 106365 |
31.30 |
| 2026-04-13 00:00 |
21:30:57.39 |
-10:52:02.9 |
HIP 106365 |
30.84 |
| 2026-04-13 12:00 |
21:30:59.21 |
-10:51:54.8 |
HIP 106365 |
30.41 |
| 2026-04-14 00:00 |
21:31:00.95 |
-10:51:47.0 |
HIP 106365 |
30.00 |
| 2026-04-14 12:00 |
21:31:02.63 |
-10:51:39.5 |
HIP 106365 |
29.60 |
| 2026-04-15 00:00 |
21:31:04.23 |
-10:51:32.3 |
HIP 106365 |
29.22 |
| 2026-04-15 12:00 |
21:31:05.75 |
-10:51:25.5 |
HIP 106365 |
28.86 |
| 2026-04-16 00:00 |
21:31:07.20 |
-10:51:18.9 |
HIP 106365 |
28.52 |