| Parameter |
Value |
| Designation |
397P/Lemmon |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2020-06-19T12:25:57.619200Z |
| Orbit solution date (soln_date, UTC) |
2025-04-09T14:01:58Z |
| Obs used |
484 |
| NEO |
- |
| M1 |
15.500 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-09-17.0000000 |
| e |
0.40063396 |
| q (au) |
2.313559 |
| a (au) |
3.860010 |
| i (deg) |
11.022023 |
| Ω (om, deg) |
8.973574 |
| ω (w, deg) |
12.487247 |
| M (ma, deg) |
229.189372 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.384 + 4.751\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.384 |
| n |
4.751 |
| gf |
0.999 |
| gb |
-0.738 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
17:52:34.42 |
-36:28:13.8 |
HIP 87580 |
11.40 |
| 2026-05-12 12:00 |
17:52:19.93 |
-36:29:36.8 |
HIP 87580 |
14.11 |
| 2026-05-13 00:00 |
17:52:05.14 |
-36:30:59.2 |
HIP 87580 |
17.06 |
| 2026-05-13 12:00 |
17:51:50.07 |
-36:32:20.9 |
HIP 87580 |
20.16 |
| 2026-05-14 00:00 |
17:51:34.72 |
-36:33:41.9 |
HIP 87509 |
23.37 |
| 2026-05-14 12:00 |
17:51:19.07 |
-36:35:02.3 |
HIP 87509 |
26.41 |
| 2026-05-15 00:00 |
17:51:03.15 |
-36:36:21.8 |
HIP 87218 |
23.65 |
| 2026-05-15 12:00 |
17:50:46.94 |
-36:37:40.7 |
HIP 87218 |
20.84 |
| 2026-05-16 00:00 |
17:50:30.46 |
-36:38:58.8 |
HIP 87218 |
18.21 |
| 2026-05-16 12:00 |
17:50:13.70 |
-36:40:16.1 |
HIP 87218 |
15.89 |
| 2026-05-17 00:00 |
17:49:56.66 |
-36:41:32.6 |
HIP 87218 |
14.08 |
| 2026-05-17 12:00 |
17:49:39.35 |
-36:42:48.2 |
HIP 87218 |
13.03 |
| 2026-05-18 00:00 |
17:49:21.77 |
-36:44:03.0 |
HIP 87218 |
12.95 |
| 2026-05-18 12:00 |
17:49:03.93 |
-36:45:17.0 |
HIP 87139 |
9.98 |
| 2026-05-19 00:00 |
17:48:45.82 |
-36:46:30.1 |
HIP 87139 |
6.79 |
| 2026-05-19 12:00 |
17:48:27.45 |
-36:47:42.2 |
HIP 87139 |
4.64 |
| 2026-05-20 00:00 |
17:48:08.83 |
-36:48:53.5 |
HIP 87139 |
5.19 |
| 2026-05-20 12:00 |
17:47:49.95 |
-36:50:03.8 |
HIP 87139 |
7.95 |
| 2026-05-21 00:00 |
17:47:30.81 |
-36:51:13.2 |
HIP 87139 |
11.47 |
| 2026-05-21 12:00 |
17:47:11.43 |
-36:52:21.6 |
HIP 87139 |
15.26 |
| 2026-05-22 00:00 |
17:46:51.80 |
-36:53:29.0 |
HIP 86951 |
16.75 |
| 2026-05-22 12:00 |
17:46:31.93 |
-36:54:35.4 |
HIP 86951 |
15.95 |
| 2026-05-23 00:00 |
17:46:11.82 |
-36:55:40.7 |
HIP 86922 |
14.90 |
| 2026-05-23 12:00 |
17:45:51.48 |
-36:56:45.0 |
HIP 86922 |
14.68 |
| 2026-05-24 00:00 |
17:45:30.90 |
-36:57:48.3 |
HIP 86922 |
15.62 |
| 2026-05-24 12:00 |
17:45:10.09 |
-36:58:50.4 |
HIP 86922 |
17.57 |
| 2026-05-25 00:00 |
17:44:49.06 |
-36:59:51.5 |
HIP 86922 |
20.26 |
| 2026-05-25 12:00 |
17:44:27.81 |
-37:00:51.5 |
HIP 86698 |
19.75 |
| 2026-05-26 00:00 |
17:44:06.33 |
-37:01:50.3 |
HIP 86698 |
15.87 |
| 2026-05-26 12:00 |
17:43:44.64 |
-37:02:48.0 |
HIP 86698 |
12.29 |
| 2026-05-27 00:00 |
17:43:22.74 |
-37:03:44.5 |
HIP 86698 |
9.44 |
| 2026-05-27 12:00 |
17:43:00.63 |
-37:04:39.8 |
HIP 86698 |
8.16 |
| 2026-05-28 00:00 |
17:42:38.32 |
-37:05:33.9 |
HIP 86698 |
9.20 |
| 2026-05-28 12:00 |
17:42:15.80 |
-37:06:26.8 |
HIP 86698 |
12.00 |
| 2026-05-29 00:00 |
17:41:53.09 |
-37:07:18.5 |
HIP 86698 |
15.68 |
| 2026-05-29 12:00 |
17:41:30.19 |
-37:08:09.0 |
HIP 86484 |
13.69 |
| 2026-05-30 00:00 |
17:41:07.10 |
-37:08:58.1 |
HIP 86484 |
9.29 |
| 2026-05-30 12:00 |
17:40:43.82 |
-37:09:46.0 |
HIP 86484 |
5.33 |
| 2026-05-31 00:00 |
17:40:20.36 |
-37:10:32.6 |
HIP 86484 |
3.85 |
| 2026-05-31 12:00 |
17:39:56.72 |
-37:11:18.0 |
HIP 86461 |
2.97 |
| 2026-06-01 00:00 |
17:39:32.91 |
-37:12:01.9 |
HIP 86461 |
5.37 |
| 2026-06-01 12:00 |
17:39:08.94 |
-37:12:44.6 |
HIP 86461 |
9.78 |
| 2026-06-02 00:00 |
17:38:44.80 |
-37:13:25.9 |
HIP 86418 |
12.17 |