| 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 |
-0.503 |
| 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) |
| 2026-07-29 00:00 |
16:56:43.65 |
-36:04:24.0 |
HIP 82735 |
26.78 |
| 2026-07-29 12:00 |
16:56:33.69 |
-36:02:57.3 |
HIP 82735 |
25.47 |
| 2026-07-30 00:00 |
16:56:24.05 |
-36:01:30.3 |
HIP 82735 |
24.39 |
| 2026-07-30 12:00 |
16:56:14.74 |
-36:00:03.3 |
HIP 82735 |
23.57 |
| 2026-07-31 00:00 |
16:56:05.75 |
-35:58:36.1 |
HIP 82735 |
23.02 |
| 2026-07-31 12:00 |
16:55:57.09 |
-35:57:08.9 |
HIP 82735 |
22.74 |
| 2026-08-01 00:00 |
16:55:48.76 |
-35:55:41.6 |
HIP 82735 |
22.73 |
| 2026-08-01 12:00 |
16:55:40.76 |
-35:54:14.2 |
HIP 82735 |
22.97 |
| 2026-08-02 00:00 |
16:55:33.08 |
-35:52:46.8 |
HIP 82735 |
23.45 |
| 2026-08-02 12:00 |
16:55:25.73 |
-35:51:19.3 |
HIP 82735 |
24.12 |
| 2026-08-03 00:00 |
16:55:18.72 |
-35:49:51.9 |
HIP 82885 |
24.14 |
| 2026-08-03 12:00 |
16:55:12.03 |
-35:48:24.4 |
HIP 82885 |
23.64 |
| 2026-08-04 00:00 |
16:55:05.67 |
-35:46:57.0 |
HIP 82885 |
23.26 |
| 2026-08-04 12:00 |
16:54:59.65 |
-35:45:29.6 |
HIP 82885 |
22.98 |
| 2026-08-05 00:00 |
16:54:53.96 |
-35:44:02.3 |
HIP 82885 |
22.82 |
| 2026-08-05 12:00 |
16:54:48.59 |
-35:42:35.0 |
HIP 82885 |
22.75 |
| 2026-08-06 00:00 |
16:54:43.57 |
-35:41:07.8 |
HIP 82885 |
22.77 |
| 2026-08-06 12:00 |
16:54:38.87 |
-35:39:40.7 |
HIP 82885 |
22.87 |
| 2026-08-07 00:00 |
16:54:34.51 |
-35:38:13.8 |
HIP 82885 |
23.04 |
| 2026-08-07 12:00 |
16:54:30.48 |
-35:36:46.9 |
HIP 82885 |
23.27 |
| 2026-08-08 00:00 |
16:54:26.79 |
-35:35:20.2 |
HIP 82739 |
22.04 |
| 2026-08-08 12:00 |
16:54:23.43 |
-35:33:53.6 |
HIP 82739 |
20.71 |
| 2026-08-09 00:00 |
16:54:20.41 |
-35:32:27.3 |
HIP 82739 |
19.42 |
| 2026-08-09 12:00 |
16:54:17.72 |
-35:31:01.1 |
HIP 82739 |
18.15 |
| 2026-08-10 00:00 |
16:54:15.37 |
-35:29:35.0 |
HIP 82739 |
16.91 |
| 2026-08-10 12:00 |
16:54:13.35 |
-35:28:09.2 |
HIP 82739 |
15.69 |
| 2026-08-11 00:00 |
16:54:11.67 |
-35:26:43.7 |
HIP 82739 |
14.51 |
| 2026-08-11 12:00 |
16:54:10.33 |
-35:25:18.3 |
HIP 82739 |
13.35 |
| 2026-08-12 00:00 |
16:54:09.31 |
-35:23:53.2 |
HIP 82739 |
12.21 |
| 2026-08-12 12:00 |
16:54:08.64 |
-35:22:28.3 |
HIP 82739 |
11.12 |
| 2026-08-13 00:00 |
16:54:08.30 |
-35:21:03.8 |
HIP 82739 |
10.06 |
| 2026-08-13 12:00 |
16:54:08.29 |
-35:19:39.5 |
HIP 82739 |
9.05 |
| 2026-08-14 00:00 |
16:54:08.62 |
-35:18:15.4 |
HIP 82739 |
8.10 |
| 2026-08-14 12:00 |
16:54:09.29 |
-35:16:51.7 |
HIP 82739 |
7.25 |
| 2026-08-15 00:00 |
16:54:10.28 |
-35:15:28.3 |
HIP 82739 |
6.52 |
| 2026-08-15 12:00 |
16:54:11.61 |
-35:14:05.2 |
HIP 82739 |
5.97 |
| 2026-08-16 00:00 |
16:54:13.27 |
-35:12:42.5 |
HIP 82739 |
5.65 |
| 2026-08-16 12:00 |
16:54:15.27 |
-35:11:20.0 |
HIP 82739 |
5.62 |
| 2026-08-17 00:00 |
16:54:17.59 |
-35:09:58.0 |
HIP 82739 |
5.89 |
| 2026-08-17 12:00 |
16:54:20.24 |
-35:08:36.3 |
HIP 82739 |
6.42 |
| 2026-08-18 00:00 |
16:54:23.23 |
-35:07:14.9 |
HIP 82739 |
7.19 |
| 2026-08-18 12:00 |
16:54:26.54 |
-35:05:53.9 |
HIP 82739 |
8.12 |
| 2026-08-19 00:00 |
16:54:30.18 |
-35:04:33.3 |
HIP 82739 |
9.18 |