| 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) |
| 2026-03-26 00:00 |
01:57:22.42 |
-10:15:24.7 |
HIP 9094 |
3.23 |
| 2026-03-26 12:00 |
01:57:29.30 |
-10:14:34.4 |
HIP 9094 |
4.79 |
| 2026-03-27 00:00 |
01:57:36.20 |
-10:13:44.4 |
HIP 9094 |
6.53 |
| 2026-03-27 12:00 |
01:57:43.12 |
-10:12:54.5 |
HIP 9094 |
8.35 |
| 2026-03-28 00:00 |
01:57:50.06 |
-10:12:04.8 |
HIP 9094 |
10.19 |
| 2026-03-28 12:00 |
01:57:57.02 |
-10:11:15.3 |
HIP 9094 |
12.06 |
| 2026-03-29 00:00 |
01:58:04.00 |
-10:10:26.1 |
HIP 9094 |
13.94 |
| 2026-03-29 12:00 |
01:58:11.00 |
-10:09:37.0 |
HIP 9271 |
14.28 |
| 2026-03-30 00:00 |
01:58:18.03 |
-10:08:48.2 |
HIP 9271 |
12.68 |
| 2026-03-30 12:00 |
01:58:25.07 |
-10:07:59.6 |
HIP 9271 |
11.19 |
| 2026-03-31 00:00 |
01:58:32.13 |
-10:07:11.2 |
HIP 9271 |
9.83 |
| 2026-03-31 12:00 |
01:58:39.20 |
-10:06:23.1 |
HIP 9271 |
8.67 |
| 2026-04-01 00:00 |
01:58:46.30 |
-10:05:35.2 |
HIP 9271 |
7.82 |
| 2026-04-01 12:00 |
01:58:53.41 |
-10:04:47.5 |
HIP 9271 |
7.37 |
| 2026-04-02 00:00 |
01:59:00.55 |
-10:04:00.0 |
HIP 9271 |
7.41 |
| 2026-04-02 12:00 |
01:59:07.69 |
-10:03:12.8 |
HIP 9271 |
7.92 |
| 2026-04-03 00:00 |
01:59:14.86 |
-10:02:25.8 |
HIP 9271 |
8.83 |
| 2026-04-03 12:00 |
01:59:22.04 |
-10:01:39.0 |
HIP 9271 |
10.04 |
| 2026-04-04 00:00 |
01:59:29.24 |
-10:00:52.5 |
HIP 9271 |
11.44 |
| 2026-04-04 12:00 |
01:59:36.45 |
-10:00:06.2 |
HIP 9271 |
12.97 |
| 2026-04-05 00:00 |
01:59:43.68 |
-09:59:20.2 |
HIP 9271 |
14.60 |
| 2026-04-05 12:00 |
01:59:50.92 |
-09:58:34.4 |
HIP 9271 |
16.30 |
| 2026-04-06 00:00 |
01:59:58.18 |
-09:57:48.9 |
HIP 9271 |
18.05 |
| 2026-04-06 12:00 |
02:00:05.45 |
-09:57:03.6 |
HIP 9271 |
19.83 |
| 2026-04-07 00:00 |
02:00:12.73 |
-09:56:18.6 |
HIP 9271 |
21.64 |
| 2026-04-07 12:00 |
02:00:20.03 |
-09:55:33.8 |
HIP 9399 |
20.76 |
| 2026-04-08 00:00 |
02:00:27.34 |
-09:54:49.3 |
HIP 9399 |
19.53 |
| 2026-04-08 12:00 |
02:00:34.66 |
-09:54:05.0 |
HIP 9399 |
18.43 |
| 2026-04-09 00:00 |
02:00:42.00 |
-09:53:21.1 |
HIP 9399 |
17.48 |
| 2026-04-09 12:00 |
02:00:49.34 |
-09:52:37.4 |
HIP 9399 |
16.71 |
| 2026-04-10 00:00 |
02:00:56.70 |
-09:51:53.9 |
HIP 9399 |
16.15 |
| 2026-04-10 12:00 |
02:01:04.07 |
-09:51:10.8 |
HIP 9399 |
15.81 |
| 2026-04-11 00:00 |
02:01:11.45 |
-09:50:27.9 |
HIP 9399 |
15.71 |
| 2026-04-11 12:00 |
02:01:18.84 |
-09:49:45.3 |
HIP 9399 |
15.86 |
| 2026-04-12 00:00 |
02:01:26.24 |
-09:49:02.9 |
HIP 9399 |
16.26 |
| 2026-04-12 12:00 |
02:01:33.65 |
-09:48:20.9 |
HIP 9399 |
16.87 |
| 2026-04-13 00:00 |
02:01:41.06 |
-09:47:39.1 |
HIP 9399 |
17.69 |
| 2026-04-13 12:00 |
02:01:48.49 |
-09:46:57.7 |
HIP 9399 |
18.68 |
| 2026-04-14 00:00 |
02:01:55.92 |
-09:46:16.5 |
HIP 9399 |
19.82 |
| 2026-04-14 12:00 |
02:02:03.37 |
-09:45:35.6 |
HIP 9399 |
21.09 |
| 2026-04-15 00:00 |
02:02:10.81 |
-09:44:55.0 |
HIP 9399 |
22.46 |
| 2026-04-15 12:00 |
02:02:18.27 |
-09:44:14.7 |
HIP 9399 |
23.91 |
| 2026-04-16 00:00 |
02:02:25.73 |
-09:43:34.7 |
HIP 9616 |
23.39 |