| Parameter |
Value |
| Designation |
P/2020 A4 (PANSTARRS-Lemmon) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2019-11-22T17:20:48.589440Z |
| Orbit solution date (soln_date, UTC) |
2022-08-07T20:12:03Z |
| Obs used |
106 |
| NEO |
- |
| M1 |
15.600 |
| K1 |
8.750 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-01-01T12:06:58.176000Z |
| Discovery magnitude (MPC) |
21.40 w |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-02-03.0000000 |
| e |
0.65370445 |
| q (au) |
2.842514 |
| a (au) |
8.208347 |
| i (deg) |
24.990302 |
| Ω (om, deg) |
312.429623 |
| ω (w, deg) |
144.883054 |
| M (ma, deg) |
3.029158 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.586 + 3.081\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.586 |
| n |
3.081 |
| gf |
1.000 |
| gb |
-0.590 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
16:26:44.72 |
-42:36:22.6 |
HIP 80581 |
9.55 |
| 2026-09-20 12:00 |
16:26:51.66 |
-42:35:39.5 |
HIP 80581 |
8.33 |
| 2026-09-21 00:00 |
16:26:58.70 |
-42:34:56.9 |
HIP 80581 |
7.20 |
| 2026-09-21 12:00 |
16:27:05.83 |
-42:34:14.5 |
HIP 80581 |
6.21 |
| 2026-09-22 00:00 |
16:27:13.05 |
-42:33:32.6 |
HIP 80581 |
5.47 |
| 2026-09-22 12:00 |
16:27:20.36 |
-42:32:50.9 |
HIP 80581 |
5.09 |
| 2026-09-23 00:00 |
16:27:27.76 |
-42:32:09.7 |
HIP 80581 |
5.17 |
| 2026-09-23 12:00 |
16:27:35.26 |
-42:31:28.8 |
HIP 80581 |
5.69 |
| 2026-09-24 00:00 |
16:27:42.84 |
-42:30:48.2 |
HIP 80581 |
6.55 |
| 2026-09-24 12:00 |
16:27:50.52 |
-42:30:08.1 |
HIP 80581 |
7.66 |
| 2026-09-25 00:00 |
16:27:58.28 |
-42:29:28.2 |
HIP 80581 |
8.92 |
| 2026-09-25 12:00 |
16:28:06.13 |
-42:28:48.8 |
HIP 80581 |
10.28 |
| 2026-09-26 00:00 |
16:28:14.08 |
-42:28:09.7 |
HIP 80581 |
11.72 |
| 2026-09-26 12:00 |
16:28:22.11 |
-42:27:31.0 |
HIP 80581 |
13.22 |
| 2026-09-27 00:00 |
16:28:30.22 |
-42:26:52.6 |
HIP 80581 |
14.75 |
| 2026-09-27 12:00 |
16:28:38.43 |
-42:26:14.6 |
HIP 80581 |
16.32 |
| 2026-09-28 00:00 |
16:28:46.72 |
-42:25:36.9 |
HIP 80581 |
17.92 |
| 2026-09-28 12:00 |
16:28:55.09 |
-42:24:59.7 |
HIP 80581 |
19.54 |
| 2026-09-29 00:00 |
16:29:03.55 |
-42:24:22.7 |
HIP 80581 |
21.19 |
| 2026-09-29 12:00 |
16:29:12.10 |
-42:23:46.2 |
HIP 80759 |
21.83 |
| 2026-09-30 00:00 |
16:29:20.73 |
-42:23:10.0 |
HIP 80759 |
21.17 |
| 2026-09-30 12:00 |
16:29:29.45 |
-42:22:34.2 |
HIP 80759 |
20.64 |
| 2026-10-01 00:00 |
16:29:38.25 |
-42:21:58.8 |
HIP 80759 |
20.25 |
| 2026-10-01 12:00 |
16:29:47.13 |
-42:21:23.7 |
HIP 80759 |
20.01 |
| 2026-10-02 00:00 |
16:29:56.09 |
-42:20:49.0 |
HIP 80759 |
19.93 |
| 2026-10-02 12:00 |
16:30:05.14 |
-42:20:14.6 |
HIP 80759 |
20.02 |
| 2026-10-03 00:00 |
16:30:14.27 |
-42:19:40.6 |
HIP 80759 |
20.28 |
| 2026-10-03 12:00 |
16:30:23.48 |
-42:19:07.0 |
HIP 80759 |
20.70 |
| 2026-10-04 00:00 |
16:30:32.77 |
-42:18:33.8 |
HIP 80759 |
21.28 |
| 2026-10-04 12:00 |
16:30:42.14 |
-42:18:00.9 |
HIP 80759 |
22.01 |
| 2026-10-05 00:00 |
16:30:51.59 |
-42:17:28.4 |
HIP 80759 |
22.88 |
| 2026-10-05 12:00 |
16:31:01.13 |
-42:16:56.3 |
HIP 80759 |
23.87 |
| 2026-10-06 00:00 |
16:31:10.74 |
-42:16:24.5 |
HIP 80759 |
24.98 |
| 2026-10-06 12:00 |
16:31:20.42 |
-42:15:53.2 |
HIP 80759 |
26.19 |
| 2026-10-07 00:00 |
16:31:30.19 |
-42:15:22.1 |
HIP 80945 |
26.43 |
| 2026-10-07 12:00 |
16:31:40.04 |
-42:14:51.5 |
HIP 80945 |
25.83 |
| 2026-10-08 00:00 |
16:31:49.96 |
-42:14:21.2 |
HIP 80945 |
25.37 |
| 2026-10-08 12:00 |
16:31:59.95 |
-42:13:51.4 |
HIP 80945 |
25.06 |
| 2026-10-09 00:00 |
16:32:10.03 |
-42:13:21.8 |
HIP 80945 |
24.89 |
| 2026-10-09 12:00 |
16:32:20.17 |
-42:12:52.7 |
HIP 80945 |
24.89 |
| 2026-10-10 00:00 |
16:32:30.40 |
-42:12:23.9 |
HIP 80945 |
25.05 |
| 2026-10-10 12:00 |
16:32:40.69 |
-42:11:55.5 |
HIP 80945 |
25.38 |
| 2026-10-11 00:00 |
16:32:51.06 |
-42:11:27.5 |
HIP 80945 |
25.86 |