C/2020 S4 (PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
16:52:14.03 |
-06:56:32.8 |
HIP 82699 |
33.73 |
| 2026-02-03 12:00 |
16:52:22.96 |
-06:56:17.5 |
HIP 82699 |
31.61 |
| 2026-02-04 00:00 |
16:52:31.82 |
-06:56:01.8 |
HIP 82699 |
29.52 |
| 2026-02-04 12:00 |
16:52:40.59 |
-06:55:45.6 |
HIP 82699 |
27.46 |
| 2026-02-05 00:00 |
16:52:49.27 |
-06:55:29.1 |
HIP 82699 |
25.45 |
| 2026-02-05 12:00 |
16:52:57.87 |
-06:55:12.2 |
HIP 82699 |
23.48 |
| 2026-02-06 00:00 |
16:53:06.38 |
-06:54:55.0 |
HIP 82699 |
21.55 |
| 2026-02-06 12:00 |
16:53:14.81 |
-06:54:37.3 |
HIP 82699 |
19.68 |
| 2026-02-07 00:00 |
16:53:23.15 |
-06:54:19.3 |
HIP 82699 |
17.88 |
| 2026-02-07 12:00 |
16:53:31.40 |
-06:54:00.9 |
HIP 82699 |
16.16 |
| 2026-02-08 00:00 |
16:53:39.56 |
-06:53:42.1 |
HIP 82699 |
14.55 |
| 2026-02-08 12:00 |
16:53:47.63 |
-06:53:22.9 |
HIP 82699 |
13.06 |
| 2026-02-09 00:00 |
16:53:55.62 |
-06:53:03.4 |
HIP 82699 |
11.74 |
| 2026-02-09 12:00 |
16:54:03.51 |
-06:52:43.5 |
HIP 82699 |
10.64 |
| 2026-02-10 00:00 |
16:54:11.32 |
-06:52:23.3 |
HIP 82699 |
9.82 |
| 2026-02-10 12:00 |
16:54:19.03 |
-06:52:02.6 |
HIP 82699 |
9.34 |
| 2026-02-11 00:00 |
16:54:26.66 |
-06:51:41.7 |
HIP 82699 |
9.24 |
| 2026-02-11 12:00 |
16:54:34.19 |
-06:51:20.3 |
HIP 82699 |
9.53 |
| 2026-02-12 00:00 |
16:54:41.63 |
-06:50:58.6 |
HIP 82699 |
10.15 |
| 2026-02-12 12:00 |
16:54:48.97 |
-06:50:36.6 |
HIP 82699 |
11.04 |
| 2026-02-13 00:00 |
16:54:56.23 |
-06:50:14.2 |
HIP 82790 |
11.55 |
| 2026-02-13 12:00 |
16:55:03.39 |
-06:49:51.5 |
HIP 82790 |
10.86 |
| 2026-02-14 00:00 |
16:55:10.46 |
-06:49:28.4 |
HIP 82790 |
10.44 |
| 2026-02-14 12:00 |
16:55:17.43 |
-06:49:05.0 |
HIP 82790 |
10.30 |
| 2026-02-15 00:00 |
16:55:24.31 |
-06:48:41.2 |
HIP 82790 |
10.46 |
| 2026-02-15 12:00 |
16:55:31.09 |
-06:48:17.1 |
HIP 82790 |
10.88 |
| 2026-02-16 00:00 |
16:55:37.78 |
-06:47:52.7 |
HIP 82790 |
11.52 |
| 2026-02-16 12:00 |
16:55:44.37 |
-06:47:27.9 |
HIP 82790 |
12.35 |
| 2026-02-17 00:00 |
16:55:50.86 |
-06:47:02.8 |
HIP 82790 |
13.33 |
| 2026-02-17 12:00 |
16:55:57.26 |
-06:46:37.4 |
HIP 82790 |
14.40 |
| 2026-02-18 00:00 |
16:56:03.56 |
-06:46:11.7 |
HIP 82790 |
15.55 |
| 2026-02-18 12:00 |
16:56:09.77 |
-06:45:45.6 |
HIP 82790 |
16.76 |
| 2026-02-19 00:00 |
16:56:15.87 |
-06:45:19.2 |
HIP 82790 |
18.00 |
| 2026-02-19 12:00 |
16:56:21.88 |
-06:44:52.6 |
HIP 82790 |
19.27 |
| 2026-02-20 00:00 |
16:56:27.79 |
-06:44:25.6 |
HIP 82790 |
20.55 |
| 2026-02-20 12:00 |
16:56:33.60 |
-06:43:58.3 |
HIP 82790 |
21.84 |
| 2026-02-21 00:00 |
16:56:39.31 |
-06:43:30.7 |
HIP 82790 |
23.13 |
| 2026-02-21 12:00 |
16:56:44.92 |
-06:43:02.9 |
HIP 82790 |
24.41 |
| 2026-02-22 00:00 |
16:56:50.43 |
-06:42:34.7 |
HIP 82790 |
25.70 |
| 2026-02-22 12:00 |
16:56:55.84 |
-06:42:06.2 |
HIP 82790 |
26.97 |
| 2026-02-23 00:00 |
16:57:01.15 |
-06:41:37.5 |
HIP 82790 |
28.23 |
| 2026-02-23 12:00 |
16:57:06.36 |
-06:41:08.5 |
HIP 82790 |
29.49 |
| 2026-02-24 00:00 |
16:57:11.47 |
-06:40:39.1 |
HIP 82790 |
30.72 |