| Parameter |
Value |
| Designation |
P/2017 Y3 (Leonard) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2018-02-11T06:14:12.742080Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:39Z |
| Obs used |
93 |
| NEO |
Yes |
| M1 |
16.500 |
| K1 |
11.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-02-20.0000000 |
| e |
0.87071088 |
| q (au) |
1.275381 |
| a (au) |
9.864564 |
| i (deg) |
27.585652 |
| Ω (om, deg) |
153.873913 |
| ω (w, deg) |
67.528786 |
| M (ma, deg) |
0.278039 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.771 + 4.270\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.771 |
| n |
4.270 |
| gf |
1.000 |
| gb |
-1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
02:17:01.35 |
-11:22:48.9 |
HIP 10645 |
7.63 |
| 2026-09-20 12:00 |
02:16:56.23 |
-11:23:45.9 |
HIP 10645 |
8.74 |
| 2026-09-21 00:00 |
02:16:51.06 |
-11:24:42.8 |
HIP 10645 |
9.97 |
| 2026-09-21 12:00 |
02:16:45.85 |
-11:25:39.6 |
HIP 10645 |
11.29 |
| 2026-09-22 00:00 |
02:16:40.60 |
-11:26:36.2 |
HIP 10645 |
12.67 |
| 2026-09-22 12:00 |
02:16:35.30 |
-11:27:32.7 |
HIP 10645 |
14.10 |
| 2026-09-23 00:00 |
02:16:29.96 |
-11:28:29.1 |
HIP 10645 |
15.57 |
| 2026-09-23 12:00 |
02:16:24.59 |
-11:29:25.2 |
HIP 10645 |
17.07 |
| 2026-09-24 00:00 |
02:16:19.17 |
-11:30:21.3 |
HIP 10645 |
18.59 |
| 2026-09-24 12:00 |
02:16:13.71 |
-11:31:17.2 |
HIP 10645 |
20.13 |
| 2026-09-25 00:00 |
02:16:08.22 |
-11:32:12.9 |
HIP 10645 |
21.69 |
| 2026-09-25 12:00 |
02:16:02.68 |
-11:33:08.4 |
HIP 10645 |
23.26 |
| 2026-09-26 00:00 |
02:15:57.11 |
-11:34:03.8 |
HIP 10645 |
24.85 |
| 2026-09-26 12:00 |
02:15:51.50 |
-11:34:59.0 |
HIP 10645 |
26.44 |
| 2026-09-27 00:00 |
02:15:45.85 |
-11:35:54.0 |
HIP 10645 |
28.05 |
| 2026-09-27 12:00 |
02:15:40.17 |
-11:36:48.8 |
HIP 10484 |
27.20 |
| 2026-09-28 00:00 |
02:15:34.44 |
-11:37:43.4 |
HIP 10484 |
25.99 |
| 2026-09-28 12:00 |
02:15:28.69 |
-11:38:37.8 |
HIP 10484 |
24.83 |
| 2026-09-29 00:00 |
02:15:22.89 |
-11:39:32.1 |
HIP 10484 |
23.74 |
| 2026-09-29 12:00 |
02:15:17.06 |
-11:40:26.1 |
HIP 10484 |
22.72 |
| 2026-09-30 00:00 |
02:15:11.20 |
-11:41:19.9 |
HIP 10484 |
21.79 |
| 2026-09-30 12:00 |
02:15:05.31 |
-11:42:13.4 |
HIP 10484 |
20.96 |
| 2026-10-01 00:00 |
02:14:59.38 |
-11:43:06.8 |
HIP 10484 |
20.24 |
| 2026-10-01 12:00 |
02:14:53.41 |
-11:44:00.0 |
HIP 10484 |
19.65 |
| 2026-10-02 00:00 |
02:14:47.42 |
-11:44:52.8 |
HIP 10484 |
19.20 |
| 2026-10-02 12:00 |
02:14:41.39 |
-11:45:45.5 |
HIP 10484 |
18.90 |
| 2026-10-03 00:00 |
02:14:35.33 |
-11:46:37.9 |
HIP 10484 |
18.76 |
| 2026-10-03 12:00 |
02:14:29.24 |
-11:47:30.1 |
HIP 10484 |
18.78 |
| 2026-10-04 00:00 |
02:14:23.12 |
-11:48:22.0 |
HIP 10484 |
18.97 |
| 2026-10-04 12:00 |
02:14:16.97 |
-11:49:13.7 |
HIP 10484 |
19.32 |
| 2026-10-05 00:00 |
02:14:10.79 |
-11:50:05.1 |
HIP 10484 |
19.83 |
| 2026-10-05 12:00 |
02:14:04.58 |
-11:50:56.2 |
HIP 10484 |
20.48 |
| 2026-10-06 00:00 |
02:13:58.34 |
-11:51:47.1 |
HIP 10484 |
21.26 |
| 2026-10-06 12:00 |
02:13:52.08 |
-11:52:37.6 |
HIP 10484 |
22.16 |
| 2026-10-07 00:00 |
02:13:45.78 |
-11:53:27.9 |
HIP 10484 |
23.17 |
| 2026-10-07 12:00 |
02:13:39.47 |
-11:54:17.9 |
HIP 10484 |
24.26 |
| 2026-10-08 00:00 |
02:13:33.12 |
-11:55:07.6 |
HIP 10484 |
25.44 |
| 2026-10-08 12:00 |
02:13:26.75 |
-11:55:57.1 |
HIP 10484 |
26.69 |
| 2026-10-09 00:00 |
02:13:20.36 |
-11:56:46.2 |
HIP 10484 |
28.00 |
| 2026-10-09 12:00 |
02:13:13.94 |
-11:57:35.0 |
HIP 10484 |
29.37 |
| 2026-10-10 00:00 |
02:13:07.50 |
-11:58:23.4 |
HIP 10484 |
30.78 |
| 2026-10-10 12:00 |
02:13:01.04 |
-11:59:11.6 |
HIP 10484 |
32.24 |
| 2026-10-11 00:00 |
02:12:54.56 |
-11:59:59.5 |
HIP 10484 |
33.73 |