| Parameter |
Value |
| Designation |
C/2020 O2 (Amaral) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-08-28T14:45:24.552000Z |
| Orbit solution date (soln_date, UTC) |
2024-05-14T12:42:17Z |
| Obs used |
1595 |
| NEO |
- |
| M1 |
5.900 |
| K1 |
10.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2020-07-23T23:20:29.184000Z |
| Discovery magnitude (MPC) |
18.10 R |
| Discovery observatory (MPC) |
X74 · Observatório Campo dos Amarais |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-02-27.0000000 |
| e |
1.00232543 |
| q (au) |
4.862254 |
| a (au) |
-2090.901073 |
| i (deg) |
71.750811 |
| Ω (om, deg) |
256.757254 |
| ω (w, deg) |
10.309432 |
| M (ma, deg) |
0.001880 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.977 + 4.155\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.977 |
| n |
4.155 |
| gf |
0.986 |
| gb |
-0.948 |
| k |
1.000 |
| δ90 |
9.957 |
| 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 |
| 2020-07-23 |
2021-08-28 |
+6.9479 |
-4.707 |
| 2021-08-29 |
2023-09-21 |
-0.9103 |
+0.615 |
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 |
00:05:46.48 |
+66:08:05.4 |
HIP 338 |
15.75 |
| 2026-05-12 12:00 |
00:06:04.75 |
+66:09:49.2 |
HIP 338 |
15.60 |
| 2026-05-13 00:00 |
00:06:22.92 |
+66:11:33.4 |
HIP 338 |
15.84 |
| 2026-05-13 12:00 |
00:06:41.00 |
+66:13:17.9 |
HIP 338 |
16.45 |
| 2026-05-14 00:00 |
00:06:58.98 |
+66:15:02.8 |
HIP 723 |
17.10 |
| 2026-05-14 12:00 |
00:07:16.86 |
+66:16:48.0 |
HIP 723 |
14.59 |
| 2026-05-15 00:00 |
00:07:34.65 |
+66:18:33.6 |
HIP 723 |
12.09 |
| 2026-05-15 12:00 |
00:07:52.33 |
+66:20:19.5 |
HIP 723 |
9.59 |
| 2026-05-16 00:00 |
00:08:09.91 |
+66:22:05.8 |
HIP 723 |
7.09 |
| 2026-05-16 12:00 |
00:08:27.40 |
+66:23:52.3 |
HIP 723 |
4.60 |
| 2026-05-17 00:00 |
00:08:44.78 |
+66:25:39.2 |
HIP 723 |
2.13 |
| 2026-05-17 12:00 |
00:09:02.06 |
+66:27:26.4 |
HIP 723 |
0.51 |
| 2026-05-18 00:00 |
00:09:19.23 |
+66:29:13.9 |
HIP 723 |
2.88 |
| 2026-05-18 12:00 |
00:09:36.30 |
+66:31:01.7 |
HIP 723 |
5.34 |
| 2026-05-19 00:00 |
00:09:53.27 |
+66:32:49.8 |
HIP 723 |
7.81 |
| 2026-05-19 12:00 |
00:10:10.13 |
+66:34:38.2 |
HIP 723 |
10.27 |
| 2026-05-20 00:00 |
00:10:26.88 |
+66:36:26.9 |
HIP 723 |
12.73 |
| 2026-05-20 12:00 |
00:10:43.52 |
+66:38:15.9 |
HIP 723 |
15.18 |
| 2026-05-21 00:00 |
00:11:00.05 |
+66:40:05.1 |
HIP 723 |
17.63 |
| 2026-05-21 12:00 |
00:11:16.48 |
+66:41:54.6 |
HIP 723 |
20.07 |
| 2026-05-22 00:00 |
00:11:32.79 |
+66:43:44.4 |
HIP 723 |
22.51 |
| 2026-05-22 12:00 |
00:11:49.00 |
+66:45:34.5 |
HIP 723 |
24.94 |
| 2026-05-23 00:00 |
00:12:05.09 |
+66:47:24.7 |
HIP 723 |
27.36 |
| 2026-05-23 12:00 |
00:12:21.07 |
+66:49:15.3 |
HIP 723 |
29.78 |
| 2026-05-24 00:00 |
00:12:36.94 |
+66:51:06.1 |
HIP 1036 |
31.85 |
| 2026-05-24 12:00 |
00:12:52.69 |
+66:52:57.1 |
HIP 1036 |
33.63 |
| 2026-05-25 00:00 |
00:13:08.33 |
+66:54:48.3 |
HIP 1036 |
35.49 |
| 2026-05-25 12:00 |
00:13:23.85 |
+66:56:39.8 |
HIP 1036 |
37.42 |
| 2026-05-26 00:00 |
00:13:39.26 |
+66:58:31.5 |
HIP 1557 |
39.38 |
| 2026-05-26 12:00 |
00:13:54.55 |
+67:00:23.5 |
HIP 1557 |
37.12 |
| 2026-05-27 00:00 |
00:14:09.72 |
+67:02:15.6 |
HIP 1557 |
34.89 |
| 2026-05-27 12:00 |
00:14:24.78 |
+67:04:08.0 |
HIP 1557 |
32.70 |
| 2026-05-28 00:00 |
00:14:39.71 |
+67:06:00.5 |
HIP 1557 |
30.54 |
| 2026-05-28 12:00 |
00:14:54.53 |
+67:07:53.3 |
HIP 1557 |
28.43 |
| 2026-05-29 00:00 |
00:15:09.22 |
+67:09:46.2 |
HIP 1557 |
26.38 |
| 2026-05-29 12:00 |
00:15:23.79 |
+67:11:39.3 |
HIP 1557 |
24.39 |
| 2026-05-30 00:00 |
00:15:38.25 |
+67:13:32.7 |
HIP 1557 |
22.49 |
| 2026-05-30 12:00 |
00:15:52.58 |
+67:15:26.2 |
HIP 1557 |
20.70 |
| 2026-05-31 00:00 |
00:16:06.78 |
+67:17:19.8 |
HIP 1557 |
19.05 |
| 2026-05-31 12:00 |
00:16:20.86 |
+67:19:13.7 |
HIP 1557 |
17.57 |
| 2026-06-01 00:00 |
00:16:34.82 |
+67:21:07.7 |
HIP 1557 |
16.30 |
| 2026-06-01 12:00 |
00:16:48.65 |
+67:23:01.9 |
HIP 1557 |
15.30 |
| 2026-06-02 00:00 |
00:17:02.35 |
+67:24:56.2 |
HIP 1557 |
14.62 |