| Parameter |
Value |
| Designation |
C/2020 J1 (SONEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-04-18T14:32:05.205120Z |
| Orbit solution date (soln_date, UTC) |
2023-05-24T21:12:29Z |
| Obs used |
1423 |
| NEO |
- |
| M1 |
8.000 |
| K1 |
7.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2020-05-01T06:33:40.896000Z |
| Discovery magnitude (MPC) |
17.00 R |
| Discovery observatory (MPC) |
Y00 · SONEAR Observatory, Oliveira |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-10-28.0000000 |
| e |
1.00036308 |
| q (au) |
3.355156 |
| a (au) |
-9240.744312 |
| i (deg) |
142.295628 |
| Ω (om, deg) |
226.582890 |
| ω (w, deg) |
341.755563 |
| M (ma, deg) |
0.000213 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.505 + 3.369\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.505 |
| n |
3.369 |
| gf |
0.833 |
| gb |
-0.500 |
| k |
0.921 |
| δ90 |
2.649 |
| 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 |
| 2020-04-19 |
2021-04-17 |
+0.2477 |
+0.184 |
| 2021-04-19 |
2021-12-01 |
-7.4917 |
+3.560 |
| 2021-12-01 |
2023-05-23 |
+6.0369 |
-4.382 |
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 |
08:34:07.60 |
+55:41:00.8 |
HIP 41835 |
21.13 |
| 2026-05-12 12:00 |
08:34:08.69 |
+55:39:45.3 |
HIP 41955 |
20.21 |
| 2026-05-13 00:00 |
08:34:09.90 |
+55:38:29.9 |
HIP 41955 |
19.16 |
| 2026-05-13 12:00 |
08:34:11.22 |
+55:37:14.5 |
HIP 41955 |
18.15 |
| 2026-05-14 00:00 |
08:34:12.65 |
+55:35:59.1 |
HIP 41955 |
17.18 |
| 2026-05-14 12:00 |
08:34:14.19 |
+55:34:43.9 |
HIP 41955 |
16.25 |
| 2026-05-15 00:00 |
08:34:15.84 |
+55:33:28.7 |
HIP 41955 |
15.40 |
| 2026-05-15 12:00 |
08:34:17.60 |
+55:32:13.6 |
HIP 41955 |
14.61 |
| 2026-05-16 00:00 |
08:34:19.48 |
+55:30:58.6 |
HIP 41955 |
13.91 |
| 2026-05-16 12:00 |
08:34:21.46 |
+55:29:43.7 |
HIP 41955 |
13.31 |
| 2026-05-17 00:00 |
08:34:23.54 |
+55:28:28.9 |
HIP 41955 |
12.82 |
| 2026-05-17 12:00 |
08:34:25.74 |
+55:27:14.1 |
HIP 41955 |
12.46 |
| 2026-05-18 00:00 |
08:34:28.04 |
+55:25:59.5 |
HIP 41955 |
12.24 |
| 2026-05-18 12:00 |
08:34:30.45 |
+55:24:45.1 |
HIP 41955 |
12.17 |
| 2026-05-19 00:00 |
08:34:32.96 |
+55:23:30.7 |
HIP 41955 |
12.25 |
| 2026-05-19 12:00 |
08:34:35.58 |
+55:22:16.4 |
HIP 41955 |
12.48 |
| 2026-05-20 00:00 |
08:34:38.29 |
+55:21:02.3 |
HIP 41955 |
12.85 |
| 2026-05-20 12:00 |
08:34:41.12 |
+55:19:48.3 |
HIP 41955 |
13.35 |
| 2026-05-21 00:00 |
08:34:44.04 |
+55:18:34.5 |
HIP 41955 |
13.97 |
| 2026-05-21 12:00 |
08:34:47.06 |
+55:17:20.8 |
HIP 42126 |
14.69 |
| 2026-05-22 00:00 |
08:34:50.18 |
+55:16:07.2 |
HIP 42126 |
13.39 |
| 2026-05-22 12:00 |
08:34:53.41 |
+55:14:53.8 |
HIP 42126 |
12.09 |
| 2026-05-23 00:00 |
08:34:56.73 |
+55:13:40.6 |
HIP 42126 |
10.79 |
| 2026-05-23 12:00 |
08:35:00.14 |
+55:12:27.5 |
HIP 42126 |
9.49 |
| 2026-05-24 00:00 |
08:35:03.66 |
+55:11:14.5 |
HIP 42126 |
8.20 |
| 2026-05-24 12:00 |
08:35:07.27 |
+55:10:01.8 |
HIP 42126 |
6.92 |
| 2026-05-25 00:00 |
08:35:10.97 |
+55:08:49.2 |
HIP 42126 |
5.66 |
| 2026-05-25 12:00 |
08:35:14.77 |
+55:07:36.8 |
HIP 42126 |
4.43 |
| 2026-05-26 00:00 |
08:35:18.67 |
+55:06:24.5 |
HIP 42126 |
3.29 |
| 2026-05-26 12:00 |
08:35:22.65 |
+55:05:12.5 |
HIP 42126 |
2.37 |
| 2026-05-27 00:00 |
08:35:26.73 |
+55:04:00.6 |
HIP 42126 |
1.99 |
| 2026-05-27 12:00 |
08:35:30.90 |
+55:02:48.9 |
HIP 42126 |
2.43 |
| 2026-05-28 00:00 |
08:35:35.16 |
+55:01:37.4 |
HIP 42126 |
3.39 |
| 2026-05-28 12:00 |
08:35:39.51 |
+55:00:26.1 |
HIP 42126 |
4.55 |
| 2026-05-29 00:00 |
08:35:43.95 |
+54:59:15.1 |
HIP 42126 |
5.80 |
| 2026-05-29 12:00 |
08:35:48.47 |
+54:58:04.2 |
HIP 42126 |
7.10 |
| 2026-05-30 00:00 |
08:35:53.09 |
+54:56:53.5 |
HIP 42126 |
8.41 |
| 2026-05-30 12:00 |
08:35:57.79 |
+54:55:43.0 |
HIP 42126 |
9.74 |
| 2026-05-31 00:00 |
08:36:02.58 |
+54:54:32.7 |
HIP 42126 |
11.08 |
| 2026-05-31 12:00 |
08:36:07.45 |
+54:53:22.7 |
HIP 42126 |
12.43 |
| 2026-06-01 00:00 |
08:36:12.41 |
+54:52:12.9 |
HIP 42126 |
13.79 |
| 2026-06-01 12:00 |
08:36:17.45 |
+54:51:03.3 |
HIP 42126 |
15.15 |
| 2026-06-02 00:00 |
08:36:22.57 |
+54:49:53.9 |
HIP 42126 |
16.52 |