| Parameter |
Value |
| Designation |
C/2020 S4 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2023-02-09T07:08:52.416960Z |
| Orbit solution date (soln_date, UTC) |
2024-07-07T00:42:12Z |
| Obs used |
1527 |
| NEO |
- |
| M1 |
10.700 |
| K1 |
6.250 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-09-16T12:33:54.979200Z |
| Discovery magnitude (MPC) |
21.30 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-06-03.0000000 |
| e |
1.00061396 |
| q (au) |
3.369605 |
| a (au) |
-5488.353502 |
| i (deg) |
20.572607 |
| Ω (om, deg) |
117.721123 |
| ω (w, deg) |
21.002074 |
| M (ma, deg) |
-0.000609 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.434 + 2.232\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.434 |
| n |
2.232 |
| gf |
1.000 |
| gb |
-0.604 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2020-09-16 |
2022-04-14 |
+4.3248 |
-3.352 |
| 2022-04-14 |
2023-02-09 |
-3.8591 |
+1.947 |
| 2023-02-09 |
2024-02-12 |
+14.5140 |
-7.785 |
| 2024-02-12 |
2024-06-05 |
-10.6982 |
+9.545 |
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 |
16:50:32.62 |
-05:11:07.7 |
HIP 82301 |
26.31 |
| 2026-05-12 12:00 |
16:50:23.86 |
-05:10:44.8 |
HIP 82301 |
24.20 |
| 2026-05-13 00:00 |
16:50:15.05 |
-05:10:22.3 |
HIP 82301 |
22.11 |
| 2026-05-13 12:00 |
16:50:06.21 |
-05:10:00.1 |
HIP 82301 |
20.04 |
| 2026-05-14 00:00 |
16:49:57.32 |
-05:09:38.3 |
HIP 82301 |
18.01 |
| 2026-05-14 12:00 |
16:49:48.40 |
-05:09:16.9 |
HIP 82301 |
16.03 |
| 2026-05-15 00:00 |
16:49:39.44 |
-05:08:55.9 |
HIP 82301 |
14.13 |
| 2026-05-15 12:00 |
16:49:30.44 |
-05:08:35.2 |
HIP 82301 |
12.35 |
| 2026-05-16 00:00 |
16:49:21.41 |
-05:08:15.0 |
HIP 82301 |
10.76 |
| 2026-05-16 12:00 |
16:49:12.35 |
-05:07:55.1 |
HIP 82301 |
9.45 |
| 2026-05-17 00:00 |
16:49:03.25 |
-05:07:35.7 |
HIP 82301 |
8.56 |
| 2026-05-17 12:00 |
16:48:54.12 |
-05:07:16.7 |
HIP 82301 |
8.24 |
| 2026-05-18 00:00 |
16:48:44.96 |
-05:06:58.0 |
HIP 82301 |
8.56 |
| 2026-05-18 12:00 |
16:48:35.77 |
-05:06:39.8 |
HIP 82301 |
9.46 |
| 2026-05-19 00:00 |
16:48:26.55 |
-05:06:22.0 |
HIP 82301 |
10.79 |
| 2026-05-19 12:00 |
16:48:17.31 |
-05:06:04.6 |
HIP 82301 |
12.43 |
| 2026-05-20 00:00 |
16:48:08.04 |
-05:05:47.6 |
HIP 82301 |
14.26 |
| 2026-05-20 12:00 |
16:47:58.74 |
-05:05:31.0 |
HIP 82301 |
16.23 |
| 2026-05-21 00:00 |
16:47:49.43 |
-05:05:14.9 |
HIP 82301 |
18.30 |
| 2026-05-21 12:00 |
16:47:40.09 |
-05:04:59.2 |
HIP 82301 |
20.43 |
| 2026-05-22 00:00 |
16:47:30.72 |
-05:04:43.9 |
HIP 82301 |
22.60 |
| 2026-05-22 12:00 |
16:47:21.34 |
-05:04:29.0 |
HIP 82301 |
24.82 |
| 2026-05-23 00:00 |
16:47:11.94 |
-05:04:14.6 |
HIP 82301 |
27.06 |
| 2026-05-23 12:00 |
16:47:02.53 |
-05:04:00.6 |
HIP 82301 |
29.33 |
| 2026-05-24 00:00 |
16:46:53.09 |
-05:03:47.0 |
HIP 82301 |
31.61 |
| 2026-05-24 12:00 |
16:46:43.65 |
-05:03:33.9 |
HIP 82301 |
33.91 |
| 2026-05-25 00:00 |
16:46:34.18 |
-05:03:21.2 |
HIP 82301 |
36.22 |
| 2026-05-25 12:00 |
16:46:24.71 |
-05:03:09.0 |
HIP 82301 |
38.55 |
| 2026-05-26 00:00 |
16:46:15.22 |
-05:02:57.2 |
HIP 82301 |
40.88 |
| 2026-05-26 12:00 |
16:46:05.72 |
-05:02:45.8 |
HIP 82301 |
43.22 |
| 2026-05-27 00:00 |
16:45:56.21 |
-05:02:34.9 |
HIP 81952 |
44.62 |
| 2026-05-27 12:00 |
16:45:46.69 |
-05:02:24.4 |
HIP 81952 |
43.64 |
| 2026-05-28 00:00 |
16:45:37.17 |
-05:02:14.4 |
HIP 81952 |
42.76 |
| 2026-05-28 12:00 |
16:45:27.64 |
-05:02:04.8 |
HIP 81952 |
41.99 |
| 2026-05-29 00:00 |
16:45:18.10 |
-05:01:55.7 |
HIP 81952 |
41.34 |
| 2026-05-29 12:00 |
16:45:08.56 |
-05:01:47.1 |
HIP 81952 |
40.80 |
| 2026-05-30 00:00 |
16:44:59.01 |
-05:01:38.8 |
HIP 81952 |
40.40 |
| 2026-05-30 12:00 |
16:44:49.47 |
-05:01:31.1 |
HIP 81952 |
40.12 |
| 2026-05-31 00:00 |
16:44:39.92 |
-05:01:23.8 |
HIP 81952 |
39.97 |
| 2026-05-31 12:00 |
16:44:30.37 |
-05:01:17.0 |
HIP 81952 |
39.96 |
| 2026-06-01 00:00 |
16:44:20.82 |
-05:01:10.6 |
HIP 81952 |
40.08 |
| 2026-06-01 12:00 |
16:44:11.27 |
-05:01:04.7 |
HIP 81952 |
40.34 |
| 2026-06-02 00:00 |
16:44:01.73 |
-05:00:59.2 |
HIP 81952 |
40.72 |