| 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 |
1.000 |
| gb |
-0.948 |
| k |
1.000 |
| 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 |
| 2020-07-23 |
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) |
| 2026-07-29 00:00 |
00:25:35.64 |
+70:53:40.7 |
HIP 1606 |
26.99 |
| 2026-07-29 12:00 |
00:25:29.42 |
+70:55:10.6 |
HIP 1733 |
26.11 |
| 2026-07-30 00:00 |
00:25:23.00 |
+70:56:40.0 |
HIP 1733 |
24.65 |
| 2026-07-30 12:00 |
00:25:16.38 |
+70:58:08.7 |
HIP 1733 |
23.21 |
| 2026-07-31 00:00 |
00:25:09.56 |
+70:59:36.7 |
HIP 1733 |
21.78 |
| 2026-07-31 12:00 |
00:25:02.55 |
+71:01:04.1 |
HIP 1733 |
20.37 |
| 2026-08-01 00:00 |
00:24:55.33 |
+71:02:30.8 |
HIP 1733 |
18.97 |
| 2026-08-01 12:00 |
00:24:47.91 |
+71:03:56.8 |
HIP 1733 |
17.60 |
| 2026-08-02 00:00 |
00:24:40.30 |
+71:05:22.1 |
HIP 1733 |
16.26 |
| 2026-08-02 12:00 |
00:24:32.48 |
+71:06:46.8 |
HIP 1733 |
14.95 |
| 2026-08-03 00:00 |
00:24:24.47 |
+71:08:10.7 |
HIP 1733 |
13.69 |
| 2026-08-03 12:00 |
00:24:16.26 |
+71:09:34.0 |
HIP 1733 |
12.48 |
| 2026-08-04 00:00 |
00:24:07.86 |
+71:10:56.5 |
HIP 1733 |
11.33 |
| 2026-08-04 12:00 |
00:23:59.25 |
+71:12:18.3 |
HIP 1733 |
10.28 |
| 2026-08-05 00:00 |
00:23:50.45 |
+71:13:39.3 |
HIP 1733 |
9.35 |
| 2026-08-05 12:00 |
00:23:41.45 |
+71:14:59.6 |
HIP 1733 |
8.57 |
| 2026-08-06 00:00 |
00:23:32.26 |
+71:16:19.2 |
HIP 1733 |
8.00 |
| 2026-08-06 12:00 |
00:23:22.87 |
+71:17:37.9 |
HIP 1733 |
7.67 |
| 2026-08-07 00:00 |
00:23:13.29 |
+71:18:56.0 |
HIP 1733 |
7.61 |
| 2026-08-07 12:00 |
00:23:03.51 |
+71:20:13.2 |
HIP 1733 |
7.83 |
| 2026-08-08 00:00 |
00:22:53.53 |
+71:21:29.7 |
HIP 1733 |
8.30 |
| 2026-08-08 12:00 |
00:22:43.37 |
+71:22:45.3 |
HIP 1756 |
8.07 |
| 2026-08-09 00:00 |
00:22:33.01 |
+71:24:00.2 |
HIP 1756 |
6.65 |
| 2026-08-09 12:00 |
00:22:22.46 |
+71:25:14.2 |
HIP 1756 |
5.29 |
| 2026-08-10 00:00 |
00:22:11.71 |
+71:26:27.4 |
HIP 1756 |
4.04 |
| 2026-08-10 12:00 |
00:22:00.78 |
+71:27:39.8 |
HIP 1756 |
3.02 |
| 2026-08-11 00:00 |
00:21:49.66 |
+71:28:51.3 |
HIP 1756 |
2.55 |
| 2026-08-11 12:00 |
00:21:38.35 |
+71:30:02.0 |
HIP 1756 |
2.89 |
| 2026-08-12 00:00 |
00:21:26.85 |
+71:31:11.8 |
HIP 1756 |
3.83 |
| 2026-08-12 12:00 |
00:21:15.17 |
+71:32:20.8 |
HIP 1756 |
5.04 |
| 2026-08-13 00:00 |
00:21:03.30 |
+71:33:28.9 |
HIP 1756 |
6.37 |
| 2026-08-13 12:00 |
00:20:51.24 |
+71:34:36.1 |
HIP 1756 |
7.75 |
| 2026-08-14 00:00 |
00:20:39.01 |
+71:35:42.4 |
HIP 1756 |
9.17 |
| 2026-08-14 12:00 |
00:20:26.59 |
+71:36:47.8 |
HIP 1756 |
10.60 |
| 2026-08-15 00:00 |
00:20:13.99 |
+71:37:52.2 |
HIP 1756 |
12.04 |
| 2026-08-15 12:00 |
00:20:01.22 |
+71:38:55.8 |
HIP 1756 |
13.48 |
| 2026-08-16 00:00 |
00:19:48.26 |
+71:39:58.5 |
HIP 1756 |
14.93 |
| 2026-08-16 12:00 |
00:19:35.14 |
+71:41:00.2 |
HIP 1756 |
16.38 |
| 2026-08-17 00:00 |
00:19:21.83 |
+71:42:01.0 |
HIP 1756 |
17.83 |
| 2026-08-17 12:00 |
00:19:08.36 |
+71:43:00.8 |
HIP 1300 |
18.33 |
| 2026-08-18 00:00 |
00:18:54.71 |
+71:43:59.7 |
HIP 1300 |
16.88 |
| 2026-08-18 12:00 |
00:18:40.89 |
+71:44:57.6 |
HIP 1300 |
15.43 |
| 2026-08-19 00:00 |
00:18:26.91 |
+71:45:54.6 |
HIP 1300 |
13.98 |