| Parameter |
Value |
| Designation |
C/2020 M5 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-08-19T21:12:41.952960Z |
| Orbit solution date (soln_date, UTC) |
2023-03-28T19:42:35Z |
| Obs used |
1605 |
| NEO |
- |
| M1 |
7.600 |
| K1 |
11.500 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2020-06-30T13:19:39.388800Z |
| Discovery magnitude (MPC) |
19.44 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-08-02.0000000 |
| e |
0.99994908 |
| q (au) |
3.004334 |
| a (au) |
59004.546918 |
| i (deg) |
93.222721 |
| Ω (om, deg) |
352.095028 |
| ω (w, deg) |
126.340033 |
| M (ma, deg) |
359.999999 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.967 + 5.727\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.967 |
| n |
5.727 |
| gf |
1.000 |
| gb |
-0.785 |
| 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 |
| 2019-08-10 |
2021-08-18 |
+1.0283 |
-0.456 |
| 2021-08-23 |
2022-02-06 |
-4.3432 |
+1.747 |
| 2022-02-06 |
2022-04-28 |
-5.1639 |
+2.582 |
| 2022-04-28 |
2023-02-27 |
-0.1853 |
-0.920 |
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 |
08:35:04.97 |
-54:04:36.2 |
HIP 42121 |
7.81 |
| 2026-09-20 12:00 |
08:35:11.26 |
-54:06:27.8 |
HIP 42121 |
5.91 |
| 2026-09-21 00:00 |
08:35:17.47 |
-54:08:19.9 |
HIP 42121 |
4.18 |
| 2026-09-21 12:00 |
08:35:23.59 |
-54:10:12.6 |
HIP 42121 |
2.93 |
| 2026-09-22 00:00 |
08:35:29.64 |
-54:12:05.7 |
HIP 42121 |
2.86 |
| 2026-09-22 12:00 |
08:35:35.60 |
-54:13:59.3 |
HIP 42121 |
4.06 |
| 2026-09-23 00:00 |
08:35:41.47 |
-54:15:53.4 |
HIP 42121 |
5.77 |
| 2026-09-23 12:00 |
08:35:47.26 |
-54:17:48.0 |
HIP 42121 |
7.67 |
| 2026-09-24 00:00 |
08:35:52.97 |
-54:19:43.0 |
HIP 42121 |
9.65 |
| 2026-09-24 12:00 |
08:35:58.59 |
-54:21:38.6 |
HIP 42121 |
11.66 |
| 2026-09-25 00:00 |
08:36:04.13 |
-54:23:34.6 |
HIP 42121 |
13.69 |
| 2026-09-25 12:00 |
08:36:09.58 |
-54:25:31.0 |
HIP 42121 |
15.74 |
| 2026-09-26 00:00 |
08:36:14.94 |
-54:27:27.9 |
HIP 42121 |
17.80 |
| 2026-09-26 12:00 |
08:36:20.21 |
-54:29:25.3 |
HIP 42061 |
19.87 |
| 2026-09-27 00:00 |
08:36:25.40 |
-54:31:23.1 |
HIP 42061 |
19.55 |
| 2026-09-27 12:00 |
08:36:30.49 |
-54:33:21.3 |
HIP 42061 |
19.45 |
| 2026-09-28 00:00 |
08:36:35.50 |
-54:35:20.0 |
HIP 42061 |
19.55 |
| 2026-09-28 12:00 |
08:36:40.41 |
-54:37:19.1 |
HIP 42061 |
19.87 |
| 2026-09-29 00:00 |
08:36:45.24 |
-54:39:18.6 |
HIP 42061 |
20.38 |
| 2026-09-29 12:00 |
08:36:49.97 |
-54:41:18.5 |
HIP 42323 |
19.88 |
| 2026-09-30 00:00 |
08:36:54.61 |
-54:43:18.8 |
HIP 42323 |
17.77 |
| 2026-09-30 12:00 |
08:36:59.16 |
-54:45:19.6 |
HIP 42323 |
15.66 |
| 2026-10-01 00:00 |
08:37:03.61 |
-54:47:20.7 |
HIP 42323 |
13.56 |
| 2026-10-01 12:00 |
08:37:07.97 |
-54:49:22.2 |
HIP 42323 |
11.46 |
| 2026-10-02 00:00 |
08:37:12.23 |
-54:51:24.1 |
HIP 42323 |
9.37 |
| 2026-10-02 12:00 |
08:37:16.40 |
-54:53:26.4 |
HIP 42323 |
7.30 |
| 2026-10-03 00:00 |
08:37:20.47 |
-54:55:29.1 |
HIP 42323 |
5.28 |
| 2026-10-03 12:00 |
08:37:24.44 |
-54:57:32.1 |
HIP 42323 |
3.40 |
| 2026-10-04 00:00 |
08:37:28.32 |
-54:59:35.5 |
HIP 42323 |
2.09 |
| 2026-10-04 12:00 |
08:37:32.10 |
-55:01:39.2 |
HIP 42323 |
2.52 |
| 2026-10-05 00:00 |
08:37:35.77 |
-55:03:43.3 |
HIP 42323 |
4.18 |
| 2026-10-05 12:00 |
08:37:39.35 |
-55:05:47.8 |
HIP 42323 |
6.15 |
| 2026-10-06 00:00 |
08:37:42.83 |
-55:07:52.5 |
HIP 42323 |
8.21 |
| 2026-10-06 12:00 |
08:37:46.20 |
-55:09:57.6 |
HIP 42323 |
10.30 |
| 2026-10-07 00:00 |
08:37:49.47 |
-55:12:03.0 |
HIP 42323 |
12.42 |
| 2026-10-07 12:00 |
08:37:52.64 |
-55:14:08.8 |
HIP 42323 |
14.54 |
| 2026-10-08 00:00 |
08:37:55.70 |
-55:16:14.8 |
HIP 42323 |
16.68 |
| 2026-10-08 12:00 |
08:37:58.66 |
-55:18:21.1 |
HIP 42323 |
18.82 |
| 2026-10-09 00:00 |
08:38:01.52 |
-55:20:27.7 |
HIP 42323 |
20.96 |
| 2026-10-09 12:00 |
08:38:04.27 |
-55:22:34.6 |
HIP 42323 |
23.11 |
| 2026-10-10 00:00 |
08:38:06.91 |
-55:24:41.8 |
HIP 42323 |
25.26 |
| 2026-10-10 12:00 |
08:38:09.44 |
-55:26:49.2 |
HIP 42323 |
27.41 |
| 2026-10-11 00:00 |
08:38:11.87 |
-55:28:56.9 |
HIP 42424 |
28.56 |