P/2017 Y3 (Leonard)
| 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) |
| 2026-02-03 00:00 |
01:48:48.85 |
-11:48:45.9 |
HIP 8411 |
4.71 |
| 2026-02-03 12:00 |
01:48:51.47 |
-11:47:52.6 |
HIP 8411 |
5.22 |
| 2026-02-04 00:00 |
01:48:54.14 |
-11:46:59.0 |
HIP 8411 |
5.92 |
| 2026-02-04 12:00 |
01:48:56.88 |
-11:46:05.3 |
HIP 8411 |
6.74 |
| 2026-02-05 00:00 |
01:48:59.67 |
-11:45:11.5 |
HIP 8411 |
7.65 |
| 2026-02-05 12:00 |
01:49:02.52 |
-11:44:17.5 |
HIP 8411 |
8.62 |
| 2026-02-06 00:00 |
01:49:05.43 |
-11:43:23.4 |
HIP 8411 |
9.65 |
| 2026-02-06 12:00 |
01:49:08.39 |
-11:42:29.1 |
HIP 8411 |
10.71 |
| 2026-02-07 00:00 |
01:49:11.41 |
-11:41:34.7 |
HIP 8411 |
11.81 |
| 2026-02-07 12:00 |
01:49:14.49 |
-11:40:40.2 |
HIP 8411 |
12.93 |
| 2026-02-08 00:00 |
01:49:17.62 |
-11:39:45.5 |
HIP 8411 |
14.07 |
| 2026-02-08 12:00 |
01:49:20.81 |
-11:38:50.8 |
HIP 8411 |
15.23 |
| 2026-02-09 00:00 |
01:49:24.05 |
-11:37:55.9 |
HIP 8411 |
16.41 |
| 2026-02-09 12:00 |
01:49:27.35 |
-11:37:00.9 |
HIP 8411 |
17.61 |
| 2026-02-10 00:00 |
01:49:30.70 |
-11:36:05.7 |
HIP 8411 |
18.82 |
| 2026-02-10 12:00 |
01:49:34.11 |
-11:35:10.5 |
HIP 8411 |
20.05 |
| 2026-02-11 00:00 |
01:49:37.58 |
-11:34:15.2 |
HIP 8411 |
21.29 |
| 2026-02-11 12:00 |
01:49:41.09 |
-11:33:19.8 |
HIP 8411 |
22.54 |
| 2026-02-12 00:00 |
01:49:44.67 |
-11:32:24.2 |
HIP 8411 |
23.80 |
| 2026-02-12 12:00 |
01:49:48.29 |
-11:31:28.6 |
HIP 8411 |
25.08 |
| 2026-02-13 00:00 |
01:49:51.97 |
-11:30:32.9 |
HIP 8411 |
26.37 |
| 2026-02-13 12:00 |
01:49:55.70 |
-11:29:37.1 |
HIP 8411 |
27.67 |
| 2026-02-14 00:00 |
01:49:59.49 |
-11:28:41.3 |
HIP 8411 |
28.98 |
| 2026-02-14 12:00 |
01:50:03.32 |
-11:27:45.3 |
HIP 8411 |
30.30 |
| 2026-02-15 00:00 |
01:50:07.21 |
-11:26:49.3 |
HIP 8411 |
31.63 |
| 2026-02-15 12:00 |
01:50:11.16 |
-11:25:53.2 |
HIP 8411 |
32.97 |
| 2026-02-16 00:00 |
01:50:15.15 |
-11:24:57.1 |
HIP 8411 |
34.33 |
| 2026-02-16 12:00 |
01:50:19.19 |
-11:24:00.9 |
HIP 8411 |
35.69 |
| 2026-02-17 00:00 |
01:50:23.29 |
-11:23:04.6 |
HIP 8411 |
37.06 |
| 2026-02-17 12:00 |
01:50:27.44 |
-11:22:08.3 |
HIP 8411 |
38.44 |
| 2026-02-18 00:00 |
01:50:31.63 |
-11:21:11.9 |
HIP 8691 |
38.05 |
| 2026-02-18 12:00 |
01:50:35.88 |
-11:20:15.5 |
HIP 8691 |
36.72 |
| 2026-02-19 00:00 |
01:50:40.18 |
-11:19:19.1 |
HIP 8691 |
35.39 |
| 2026-02-19 12:00 |
01:50:44.52 |
-11:18:22.6 |
HIP 8691 |
34.06 |
| 2026-02-20 00:00 |
01:50:48.92 |
-11:17:26.1 |
HIP 8691 |
32.73 |
| 2026-02-20 12:00 |
01:50:53.36 |
-11:16:29.6 |
HIP 8691 |
31.41 |
| 2026-02-21 00:00 |
01:50:57.85 |
-11:15:33.0 |
HIP 8691 |
30.09 |
| 2026-02-21 12:00 |
01:51:02.39 |
-11:14:36.4 |
HIP 8691 |
28.78 |
| 2026-02-22 00:00 |
01:51:06.98 |
-11:13:39.9 |
HIP 8691 |
27.48 |
| 2026-02-22 12:00 |
01:51:11.61 |
-11:12:43.3 |
HIP 8691 |
26.19 |
| 2026-02-23 00:00 |
01:51:16.29 |
-11:11:46.7 |
HIP 8691 |
24.92 |
| 2026-02-23 12:00 |
01:51:21.02 |
-11:10:50.0 |
HIP 8691 |
23.67 |
| 2026-02-24 00:00 |
01:51:25.79 |
-11:09:53.4 |
HIP 8691 |
22.45 |