| Parameter |
Value |
| Designation |
C/2017 W2 (Leonard) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-11-01T22:30:18.835200Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:38Z |
| Obs used |
169 |
| NEO |
- |
| M1 |
10.900 |
| K1 |
10.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-12-26.0000000 |
| e |
0.71125672 |
| q (au) |
3.957327 |
| a (au) |
13.705348 |
| i (deg) |
98.179291 |
| Ω (om, deg) |
312.809062 |
| ω (w, deg) |
169.157714 |
| M (ma, deg) |
1.050179 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.278 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.278 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.700 |
| 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) |
| 2026-05-12 00:00 |
23:44:59.89 |
-55:20:39.1 |
HIP 117297 |
17.59 |
| 2026-05-12 12:00 |
23:45:05.07 |
-55:21:27.1 |
HIP 117297 |
16.71 |
| 2026-05-13 00:00 |
23:45:10.17 |
-55:22:15.8 |
HIP 117297 |
15.86 |
| 2026-05-13 12:00 |
23:45:15.19 |
-55:23:05.1 |
HIP 117297 |
15.05 |
| 2026-05-14 00:00 |
23:45:20.13 |
-55:23:55.0 |
HIP 117297 |
14.29 |
| 2026-05-14 12:00 |
23:45:24.99 |
-55:24:45.6 |
HIP 117297 |
13.59 |
| 2026-05-15 00:00 |
23:45:29.77 |
-55:25:36.8 |
HIP 117297 |
12.95 |
| 2026-05-15 12:00 |
23:45:34.47 |
-55:26:28.7 |
HIP 117297 |
12.40 |
| 2026-05-16 00:00 |
23:45:39.08 |
-55:27:21.2 |
HIP 117297 |
11.93 |
| 2026-05-16 12:00 |
23:45:43.61 |
-55:28:14.3 |
HIP 117297 |
11.56 |
| 2026-05-17 00:00 |
23:45:48.06 |
-55:29:08.0 |
HIP 117297 |
11.30 |
| 2026-05-17 12:00 |
23:45:52.42 |
-55:30:02.3 |
HIP 117297 |
11.16 |
| 2026-05-18 00:00 |
23:45:56.69 |
-55:30:57.2 |
HIP 117297 |
11.14 |
| 2026-05-18 12:00 |
23:46:00.88 |
-55:31:52.8 |
HIP 117297 |
11.24 |
| 2026-05-19 00:00 |
23:46:04.99 |
-55:32:48.9 |
HIP 117297 |
11.47 |
| 2026-05-19 12:00 |
23:46:09.01 |
-55:33:45.7 |
HIP 117297 |
11.81 |
| 2026-05-20 00:00 |
23:46:12.93 |
-55:34:43.0 |
HIP 117297 |
12.26 |
| 2026-05-20 12:00 |
23:46:16.78 |
-55:35:40.9 |
HIP 117297 |
12.80 |
| 2026-05-21 00:00 |
23:46:20.53 |
-55:36:39.4 |
HIP 117276 |
12.67 |
| 2026-05-21 12:00 |
23:46:24.20 |
-55:37:38.5 |
HIP 117276 |
11.57 |
| 2026-05-22 00:00 |
23:46:27.77 |
-55:38:38.1 |
HIP 117276 |
10.47 |
| 2026-05-22 12:00 |
23:46:31.26 |
-55:39:38.3 |
HIP 117276 |
9.36 |
| 2026-05-23 00:00 |
23:46:34.65 |
-55:40:39.1 |
HIP 117276 |
8.25 |
| 2026-05-23 12:00 |
23:46:37.96 |
-55:41:40.4 |
HIP 117276 |
7.14 |
| 2026-05-24 00:00 |
23:46:41.17 |
-55:42:42.3 |
HIP 117276 |
6.03 |
| 2026-05-24 12:00 |
23:46:44.29 |
-55:43:44.7 |
HIP 117276 |
4.92 |
| 2026-05-25 00:00 |
23:46:47.32 |
-55:44:47.7 |
HIP 117276 |
3.81 |
| 2026-05-25 12:00 |
23:46:50.26 |
-55:45:51.2 |
HIP 117276 |
2.72 |
| 2026-05-26 00:00 |
23:46:53.10 |
-55:46:55.2 |
HIP 117276 |
1.67 |
| 2026-05-26 12:00 |
23:46:55.86 |
-55:47:59.8 |
HIP 117276 |
0.87 |
| 2026-05-27 00:00 |
23:46:58.51 |
-55:49:04.9 |
HIP 117276 |
1.15 |
| 2026-05-27 12:00 |
23:47:01.08 |
-55:50:10.5 |
HIP 117276 |
2.12 |
| 2026-05-28 00:00 |
23:47:03.55 |
-55:51:16.6 |
HIP 117276 |
3.22 |
| 2026-05-28 12:00 |
23:47:05.92 |
-55:52:23.2 |
HIP 117276 |
4.34 |
| 2026-05-29 00:00 |
23:47:08.20 |
-55:53:30.4 |
HIP 117276 |
5.48 |
| 2026-05-29 12:00 |
23:47:10.38 |
-55:54:38.0 |
HIP 117276 |
6.63 |
| 2026-05-30 00:00 |
23:47:12.47 |
-55:55:46.2 |
HIP 117276 |
7.79 |
| 2026-05-30 12:00 |
23:47:14.46 |
-55:56:54.8 |
HIP 117276 |
8.96 |
| 2026-05-31 00:00 |
23:47:16.35 |
-55:58:03.9 |
HIP 117276 |
10.13 |
| 2026-05-31 12:00 |
23:47:18.14 |
-55:59:13.5 |
HIP 117276 |
11.30 |
| 2026-06-01 00:00 |
23:47:19.84 |
-56:00:23.5 |
HIP 117276 |
12.49 |
| 2026-06-01 12:00 |
23:47:21.44 |
-56:01:34.1 |
HIP 117276 |
13.67 |
| 2026-06-02 00:00 |
23:47:22.94 |
-56:02:45.1 |
HIP 117276 |
14.86 |