| Parameter |
Value |
| Designation |
C/2020 P3 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-04-20T20:06:04.121280Z |
| Orbit solution date (soln_date, UTC) |
2024-04-29T13:12:18Z |
| Obs used |
698 |
| NEO |
- |
| M1 |
5.800 |
| K1 |
10.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2020-08-09T13:40:41.433600Z |
| Discovery magnitude (MPC) |
19.01 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-07-14.0000000 |
| e |
0.99914404 |
| q (au) |
6.812376 |
| a (au) |
7958.786111 |
| i (deg) |
61.884995 |
| Ω (om, deg) |
19.484342 |
| ω (w, deg) |
82.246067 |
| M (ma, deg) |
0.000117 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.781 + 5.487\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.781 |
| n |
5.487 |
| gf |
1.000 |
| gb |
-0.906 |
| 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 |
| 2021-05-24 |
2024-04-12 |
+10.1462 |
-9.061 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
13:11:34.65 |
+03:33:20.7 |
HIP 64350 |
23.37 |
| 2026-03-26 12:00 |
13:11:26.03 |
+03:33:39.0 |
HIP 64350 |
23.54 |
| 2026-03-27 00:00 |
13:11:17.38 |
+03:33:57.2 |
HIP 64350 |
23.91 |
| 2026-03-27 12:00 |
13:11:08.72 |
+03:34:15.2 |
HIP 64350 |
24.47 |
| 2026-03-28 00:00 |
13:11:00.04 |
+03:34:33.1 |
HIP 64350 |
25.21 |
| 2026-03-28 12:00 |
13:10:51.35 |
+03:34:50.9 |
HIP 64350 |
26.10 |
| 2026-03-29 00:00 |
13:10:42.64 |
+03:35:08.5 |
HIP 64350 |
27.15 |
| 2026-03-29 12:00 |
13:10:33.92 |
+03:35:25.9 |
HIP 64350 |
28.32 |
| 2026-03-30 00:00 |
13:10:25.18 |
+03:35:43.2 |
HIP 64350 |
29.61 |
| 2026-03-30 12:00 |
13:10:16.44 |
+03:36:00.3 |
HIP 64350 |
31.00 |
| 2026-03-31 00:00 |
13:10:07.68 |
+03:36:17.2 |
HIP 64103 |
30.34 |
| 2026-03-31 12:00 |
13:09:58.91 |
+03:36:34.0 |
HIP 64103 |
28.20 |
| 2026-04-01 00:00 |
13:09:50.14 |
+03:36:50.6 |
HIP 64103 |
26.06 |
| 2026-04-01 12:00 |
13:09:41.35 |
+03:37:06.9 |
HIP 64103 |
23.93 |
| 2026-04-02 00:00 |
13:09:32.56 |
+03:37:23.2 |
HIP 64103 |
21.82 |
| 2026-04-02 12:00 |
13:09:23.76 |
+03:37:39.2 |
HIP 64103 |
19.73 |
| 2026-04-03 00:00 |
13:09:14.96 |
+03:37:55.0 |
HIP 64103 |
17.67 |
| 2026-04-03 12:00 |
13:09:06.15 |
+03:38:10.6 |
HIP 64103 |
15.65 |
| 2026-04-04 00:00 |
13:08:57.33 |
+03:38:26.0 |
HIP 64103 |
13.70 |
| 2026-04-04 12:00 |
13:08:48.51 |
+03:38:41.2 |
HIP 64103 |
11.83 |
| 2026-04-05 00:00 |
13:08:39.69 |
+03:38:56.2 |
HIP 64103 |
10.11 |
| 2026-04-05 12:00 |
13:08:30.87 |
+03:39:10.9 |
HIP 64103 |
8.63 |
| 2026-04-06 00:00 |
13:08:22.04 |
+03:39:25.5 |
HIP 64103 |
7.51 |
| 2026-04-06 12:00 |
13:08:13.22 |
+03:39:39.8 |
HIP 64103 |
6.95 |
| 2026-04-07 00:00 |
13:08:04.39 |
+03:39:53.9 |
HIP 64103 |
7.08 |
| 2026-04-07 12:00 |
13:07:55.57 |
+03:40:07.8 |
HIP 64103 |
7.86 |
| 2026-04-08 00:00 |
13:07:46.74 |
+03:40:21.4 |
HIP 64103 |
9.12 |
| 2026-04-08 12:00 |
13:07:37.93 |
+03:40:34.7 |
HIP 64103 |
10.70 |
| 2026-04-09 00:00 |
13:07:29.11 |
+03:40:47.9 |
HIP 64103 |
12.47 |
| 2026-04-09 12:00 |
13:07:20.30 |
+03:41:00.7 |
HIP 64103 |
14.37 |
| 2026-04-10 00:00 |
13:07:11.49 |
+03:41:13.4 |
HIP 64041 |
15.73 |
| 2026-04-10 12:00 |
13:07:02.69 |
+03:41:25.7 |
HIP 64041 |
16.34 |
| 2026-04-11 00:00 |
13:06:53.90 |
+03:41:37.8 |
HIP 64041 |
17.21 |
| 2026-04-11 12:00 |
13:06:45.11 |
+03:41:49.7 |
HIP 63939 |
16.86 |
| 2026-04-12 00:00 |
13:06:36.34 |
+03:42:01.2 |
HIP 63939 |
15.79 |
| 2026-04-12 12:00 |
13:06:27.57 |
+03:42:12.5 |
HIP 63939 |
14.98 |
| 2026-04-13 00:00 |
13:06:18.81 |
+03:42:23.5 |
HIP 63939 |
14.46 |
| 2026-04-13 12:00 |
13:06:10.06 |
+03:42:34.2 |
HIP 63939 |
14.26 |
| 2026-04-14 00:00 |
13:06:01.33 |
+03:42:44.7 |
HIP 63939 |
14.41 |
| 2026-04-14 12:00 |
13:05:52.61 |
+03:42:54.8 |
HIP 63939 |
14.88 |
| 2026-04-15 00:00 |
13:05:43.90 |
+03:43:04.7 |
HIP 63939 |
15.65 |
| 2026-04-15 12:00 |
13:05:35.20 |
+03:43:14.2 |
HIP 63939 |
16.67 |
| 2026-04-16 00:00 |
13:05:26.53 |
+03:43:23.4 |
HIP 63939 |
17.90 |