397P/Lemmon
| 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) |
| 2026-02-03 00:00 |
17:15:48.18 |
-31:43:07.2 |
HIP 84437 |
19.55 |
| 2026-02-03 12:00 |
17:16:17.22 |
-31:44:27.8 |
HIP 84437 |
19.36 |
| 2026-02-04 00:00 |
17:16:46.16 |
-31:45:48.2 |
HIP 84572 |
19.44 |
| 2026-02-04 12:00 |
17:17:15.00 |
-31:47:08.6 |
HIP 84572 |
16.82 |
| 2026-02-05 00:00 |
17:17:43.75 |
-31:48:29.0 |
HIP 84572 |
16.31 |
| 2026-02-05 12:00 |
17:18:12.39 |
-31:49:49.3 |
HIP 84751 |
16.46 |
| 2026-02-06 00:00 |
17:18:40.94 |
-31:51:09.5 |
HIP 84751 |
11.62 |
| 2026-02-06 12:00 |
17:19:09.39 |
-31:52:29.6 |
HIP 84751 |
8.74 |
| 2026-02-07 00:00 |
17:19:37.74 |
-31:53:49.7 |
HIP 84751 |
9.71 |
| 2026-02-07 12:00 |
17:20:05.98 |
-31:55:09.8 |
HIP 84751 |
13.71 |
| 2026-02-08 00:00 |
17:20:34.12 |
-31:56:29.8 |
HIP 84778 |
18.49 |
| 2026-02-08 12:00 |
17:21:02.15 |
-31:57:49.8 |
HIP 84778 |
23.39 |
| 2026-02-09 00:00 |
17:21:30.07 |
-31:59:09.7 |
HIP 84987 |
21.75 |
| 2026-02-09 12:00 |
17:21:57.89 |
-32:00:29.6 |
HIP 84987 |
21.28 |
| 2026-02-10 00:00 |
17:22:25.60 |
-32:01:49.5 |
HIP 85126 |
22.20 |
| 2026-02-10 12:00 |
17:22:53.19 |
-32:03:09.3 |
HIP 85126 |
16.91 |
| 2026-02-11 00:00 |
17:23:20.68 |
-32:04:29.1 |
HIP 85126 |
12.30 |
| 2026-02-11 12:00 |
17:23:48.05 |
-32:05:48.9 |
HIP 85126 |
9.37 |
| 2026-02-12 00:00 |
17:24:15.30 |
-32:07:08.6 |
HIP 85126 |
9.73 |
| 2026-02-12 12:00 |
17:24:42.44 |
-32:08:28.4 |
HIP 85126 |
13.08 |
| 2026-02-13 00:00 |
17:25:09.46 |
-32:09:48.1 |
HIP 85126 |
17.78 |
| 2026-02-13 12:00 |
17:25:36.36 |
-32:11:07.8 |
HIP 85126 |
22.99 |
| 2026-02-14 00:00 |
17:26:03.14 |
-32:12:27.5 |
HIP 85383 |
24.44 |
| 2026-02-14 12:00 |
17:26:29.80 |
-32:13:47.2 |
HIP 85383 |
21.52 |
| 2026-02-15 00:00 |
17:26:56.33 |
-32:15:06.9 |
HIP 85422 |
18.42 |
| 2026-02-15 12:00 |
17:27:22.74 |
-32:16:26.6 |
HIP 85422 |
16.35 |
| 2026-02-16 00:00 |
17:27:49.03 |
-32:17:46.3 |
HIP 85422 |
16.14 |
| 2026-02-16 12:00 |
17:28:15.18 |
-32:19:06.0 |
HIP 85422 |
17.84 |
| 2026-02-17 00:00 |
17:28:41.21 |
-32:20:25.7 |
HIP 85422 |
20.97 |
| 2026-02-17 12:00 |
17:29:07.10 |
-32:21:45.4 |
HIP 85422 |
24.97 |
| 2026-02-18 00:00 |
17:29:32.87 |
-32:23:05.1 |
HIP 85422 |
29.47 |
| 2026-02-18 12:00 |
17:29:58.50 |
-32:24:24.9 |
HIP 85752 |
31.86 |
| 2026-02-19 00:00 |
17:30:23.99 |
-32:25:44.7 |
HIP 85677 |
30.05 |
| 2026-02-19 12:00 |
17:30:49.35 |
-32:27:04.5 |
HIP 85677 |
28.92 |
| 2026-02-20 00:00 |
17:31:14.58 |
-32:28:24.4 |
HIP 85677 |
28.80 |
| 2026-02-20 12:00 |
17:31:39.66 |
-32:29:44.2 |
HIP 85677 |
29.70 |
| 2026-02-21 00:00 |
17:32:04.60 |
-32:31:04.2 |
HIP 85985 |
29.51 |
| 2026-02-21 12:00 |
17:32:29.41 |
-32:32:24.1 |
HIP 85985 |
24.36 |
| 2026-02-22 00:00 |
17:32:54.07 |
-32:33:44.1 |
HIP 85985 |
19.38 |
| 2026-02-22 12:00 |
17:33:18.58 |
-32:35:04.2 |
HIP 85985 |
14.70 |
| 2026-02-23 00:00 |
17:33:42.95 |
-32:36:24.3 |
HIP 85985 |
10.69 |
| 2026-02-23 12:00 |
17:34:07.18 |
-32:37:44.4 |
HIP 86011 |
7.96 |
| 2026-02-24 00:00 |
17:34:31.25 |
-32:39:04.6 |
HIP 86011 |
4.80 |