| 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) |
| 2026-09-20 00:00 |
17:08:52.98 |
-33:53:54.0 |
HIP 83861 |
6.92 |
| 2026-09-20 12:00 |
17:09:15.45 |
-33:53:01.8 |
HIP 83861 |
11.36 |
| 2026-09-21 00:00 |
17:09:38.17 |
-33:52:10.0 |
HIP 83861 |
16.02 |
| 2026-09-21 12:00 |
17:10:01.13 |
-33:51:18.6 |
HIP 83861 |
20.79 |
| 2026-09-22 00:00 |
17:10:24.33 |
-33:50:27.4 |
HIP 84134 |
24.19 |
| 2026-09-22 12:00 |
17:10:47.78 |
-33:49:36.7 |
HIP 84134 |
19.82 |
| 2026-09-23 00:00 |
17:11:11.47 |
-33:48:46.3 |
HIP 84134 |
15.77 |
| 2026-09-23 12:00 |
17:11:35.40 |
-33:47:56.2 |
HIP 84134 |
12.41 |
| 2026-09-24 00:00 |
17:11:59.56 |
-33:47:06.4 |
HIP 84134 |
10.51 |
| 2026-09-24 12:00 |
17:12:23.96 |
-33:46:16.9 |
HIP 84240 |
10.58 |
| 2026-09-25 00:00 |
17:12:48.60 |
-33:45:27.8 |
HIP 84240 |
6.95 |
| 2026-09-25 12:00 |
17:13:13.47 |
-33:44:39.0 |
HIP 84240 |
6.19 |
| 2026-09-26 00:00 |
17:13:38.57 |
-33:43:50.4 |
HIP 84240 |
9.14 |
| 2026-09-26 12:00 |
17:14:03.91 |
-33:43:02.2 |
HIP 84240 |
13.62 |
| 2026-09-27 00:00 |
17:14:29.47 |
-33:42:14.3 |
HIP 84401 |
13.95 |
| 2026-09-27 12:00 |
17:14:55.26 |
-33:41:26.6 |
HIP 84401 |
9.89 |
| 2026-09-28 00:00 |
17:15:21.28 |
-33:40:39.2 |
HIP 84435 |
5.09 |
| 2026-09-28 12:00 |
17:15:47.52 |
-33:39:52.1 |
HIP 84435 |
0.67 |
| 2026-09-29 00:00 |
17:16:13.99 |
-33:39:05.2 |
HIP 84435 |
6.03 |
| 2026-09-29 12:00 |
17:16:40.68 |
-33:38:18.6 |
HIP 84435 |
11.63 |
| 2026-09-30 00:00 |
17:17:07.60 |
-33:37:32.2 |
HIP 84435 |
17.28 |
| 2026-09-30 12:00 |
17:17:34.73 |
-33:36:46.1 |
HIP 84685 |
17.70 |
| 2026-10-01 00:00 |
17:18:02.09 |
-33:36:00.2 |
HIP 84685 |
12.90 |
| 2026-10-01 12:00 |
17:18:29.67 |
-33:35:14.5 |
HIP 84685 |
9.24 |
| 2026-10-02 00:00 |
17:18:57.46 |
-33:34:29.1 |
HIP 84685 |
8.47 |
| 2026-10-02 12:00 |
17:19:25.47 |
-33:33:43.8 |
HIP 84685 |
11.29 |
| 2026-10-03 00:00 |
17:19:53.70 |
-33:32:58.8 |
HIP 84685 |
15.93 |
| 2026-10-03 12:00 |
17:20:22.14 |
-33:32:14.0 |
HIP 84685 |
21.27 |
| 2026-10-04 00:00 |
17:20:50.80 |
-33:31:29.3 |
HIP 84966 |
15.53 |
| 2026-10-04 12:00 |
17:21:19.67 |
-33:30:44.9 |
HIP 84966 |
9.95 |
| 2026-10-05 00:00 |
17:21:48.75 |
-33:30:00.6 |
HIP 84966 |
5.50 |
| 2026-10-05 12:00 |
17:22:18.04 |
-33:29:16.5 |
HIP 84966 |
6.05 |
| 2026-10-06 00:00 |
17:22:47.54 |
-33:28:32.5 |
HIP 84966 |
10.93 |
| 2026-10-06 12:00 |
17:23:17.25 |
-33:27:48.8 |
HIP 85056 |
15.83 |
| 2026-10-07 00:00 |
17:23:47.16 |
-33:27:05.1 |
HIP 85056 |
17.86 |
| 2026-10-07 12:00 |
17:24:17.29 |
-33:26:21.6 |
HIP 85056 |
21.63 |
| 2026-10-08 00:00 |
17:24:47.62 |
-33:25:38.3 |
HIP 85056 |
26.44 |
| 2026-10-08 12:00 |
17:25:18.15 |
-33:24:55.1 |
HIP 85375 |
29.64 |
| 2026-10-09 00:00 |
17:25:48.88 |
-33:24:11.9 |
HIP 85375 |
27.02 |
| 2026-10-09 12:00 |
17:26:19.82 |
-33:23:29.0 |
HIP 85360 |
25.52 |
| 2026-10-10 00:00 |
17:26:50.95 |
-33:22:46.1 |
HIP 85360 |
24.83 |
| 2026-10-10 12:00 |
17:27:22.29 |
-33:22:03.3 |
HIP 85360 |
25.87 |
| 2026-10-11 00:00 |
17:27:53.82 |
-33:21:20.6 |
HIP 85360 |
28.46 |