| Parameter |
Value |
| Designation |
C/2020 S3 (Erasmus) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-12-12T16:07:52.118400Z |
| Orbit solution date (soln_date, UTC) |
2024-04-29T13:12:18Z |
| Obs used |
861 |
| NEO |
- |
| M1 |
13.000 |
| K1 |
4.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2020-09-17T14:40:43.536000Z |
| Discovery magnitude (MPC) |
18.48 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-03-11.0000000 |
| e |
0.99795482 |
| q (au) |
0.398469 |
| a (au) |
194.833484 |
| i (deg) |
19.861463 |
| Ω (om, deg) |
222.992545 |
| ω (w, deg) |
349.885700 |
| M (ma, deg) |
0.032012 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.351 + 5.209\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.351 |
| n |
5.209 |
| gf |
1.000 |
| gb |
-0.884 |
| k |
0.958 |
| 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 |
| 2020-09-17 |
2020-10-17 |
+19.9753 |
-1.996 |
| 2020-10-17 |
2020-11-05 |
-0.9153 |
-0.033 |
| 2020-11-05 |
2020-12-09 |
-2.1755 |
-0.819 |
| 2020-12-18 |
2020-12-28 |
+3.4304 |
+1.116 |
| 2020-12-28 |
2021-07-09 |
-1.2828 |
-0.363 |
| 2021-07-09 |
2021-09-12 |
+18.1671 |
-11.093 |
| 2021-09-12 |
2021-11-27 |
-10.8203 |
+6.847 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
00:53:32.00 |
+15:53:05.9 |
HIP 4387 |
41.20 |
| 2026-09-20 12:00 |
00:53:25.80 |
+15:52:32.2 |
HIP 4387 |
42.43 |
| 2026-09-21 00:00 |
00:53:19.58 |
+15:51:58.3 |
HIP 4387 |
43.69 |
| 2026-09-21 12:00 |
00:53:13.35 |
+15:51:24.1 |
HIP 4387 |
44.97 |
| 2026-09-22 00:00 |
00:53:07.10 |
+15:50:49.6 |
HIP 3931 |
44.17 |
| 2026-09-22 12:00 |
00:53:00.84 |
+15:50:14.9 |
HIP 3931 |
42.57 |
| 2026-09-23 00:00 |
00:52:54.56 |
+15:49:39.9 |
HIP 3931 |
40.97 |
| 2026-09-23 12:00 |
00:52:48.27 |
+15:49:04.7 |
HIP 3931 |
39.37 |
| 2026-09-24 00:00 |
00:52:41.96 |
+15:48:29.2 |
HIP 3931 |
37.76 |
| 2026-09-24 12:00 |
00:52:35.65 |
+15:47:53.5 |
HIP 3931 |
36.15 |
| 2026-09-25 00:00 |
00:52:29.32 |
+15:47:17.5 |
HIP 3931 |
34.54 |
| 2026-09-25 12:00 |
00:52:22.98 |
+15:46:41.3 |
HIP 3931 |
32.93 |
| 2026-09-26 00:00 |
00:52:16.62 |
+15:46:04.9 |
HIP 3931 |
31.31 |
| 2026-09-26 12:00 |
00:52:10.26 |
+15:45:28.2 |
HIP 3931 |
29.70 |
| 2026-09-27 00:00 |
00:52:03.89 |
+15:44:51.2 |
HIP 3931 |
28.08 |
| 2026-09-27 12:00 |
00:51:57.51 |
+15:44:14.1 |
HIP 3931 |
26.47 |
| 2026-09-28 00:00 |
00:51:51.12 |
+15:43:36.7 |
HIP 3931 |
24.85 |
| 2026-09-28 12:00 |
00:51:44.72 |
+15:42:59.1 |
HIP 3931 |
23.24 |
| 2026-09-29 00:00 |
00:51:38.31 |
+15:42:21.3 |
HIP 3931 |
21.63 |
| 2026-09-29 12:00 |
00:51:31.89 |
+15:41:43.2 |
HIP 3931 |
20.03 |
| 2026-09-30 00:00 |
00:51:25.47 |
+15:41:04.9 |
HIP 3931 |
18.43 |
| 2026-09-30 12:00 |
00:51:19.04 |
+15:40:26.5 |
HIP 3931 |
16.85 |
| 2026-10-01 00:00 |
00:51:12.61 |
+15:39:47.8 |
HIP 3931 |
15.28 |
| 2026-10-01 12:00 |
00:51:06.17 |
+15:39:08.9 |
HIP 3931 |
13.74 |
| 2026-10-02 00:00 |
00:50:59.73 |
+15:38:29.8 |
HIP 3931 |
12.23 |
| 2026-10-02 12:00 |
00:50:53.28 |
+15:37:50.5 |
HIP 3931 |
10.76 |
| 2026-10-03 00:00 |
00:50:46.83 |
+15:37:11.0 |
HIP 3931 |
9.37 |
| 2026-10-03 12:00 |
00:50:40.38 |
+15:36:31.3 |
HIP 3931 |
8.09 |
| 2026-10-04 00:00 |
00:50:33.92 |
+15:35:51.4 |
HIP 3931 |
6.98 |
| 2026-10-04 12:00 |
00:50:27.47 |
+15:35:11.3 |
HIP 3931 |
6.14 |
| 2026-10-05 00:00 |
00:50:21.01 |
+15:34:31.1 |
HIP 3931 |
5.68 |
| 2026-10-05 12:00 |
00:50:14.55 |
+15:33:50.6 |
HIP 3931 |
5.71 |
| 2026-10-06 00:00 |
00:50:08.09 |
+15:33:10.0 |
HIP 3931 |
6.22 |
| 2026-10-06 12:00 |
00:50:01.64 |
+15:32:29.2 |
HIP 3931 |
7.11 |
| 2026-10-07 00:00 |
00:49:55.18 |
+15:31:48.3 |
HIP 3931 |
8.25 |
| 2026-10-07 12:00 |
00:49:48.73 |
+15:31:07.1 |
HIP 3931 |
9.56 |
| 2026-10-08 00:00 |
00:49:42.28 |
+15:30:25.8 |
HIP 3931 |
10.98 |
| 2026-10-08 12:00 |
00:49:35.83 |
+15:29:44.4 |
HIP 3931 |
12.46 |
| 2026-10-09 00:00 |
00:49:29.38 |
+15:29:02.8 |
HIP 3931 |
14.00 |
| 2026-10-09 12:00 |
00:49:22.95 |
+15:28:21.0 |
HIP 3931 |
15.56 |
| 2026-10-10 00:00 |
00:49:16.51 |
+15:27:39.1 |
HIP 3931 |
17.16 |
| 2026-10-10 12:00 |
00:49:10.08 |
+15:26:57.1 |
HIP 3931 |
18.77 |
| 2026-10-11 00:00 |
00:49:03.66 |
+15:26:14.9 |
HIP 3931 |
20.39 |