| 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) |
| 2026-03-26 00:00 |
17:53:13.82 |
-34:03:00.6 |
HIP 87516 |
6.40 |
| 2026-03-26 12:00 |
17:53:26.20 |
-34:04:29.8 |
HIP 87516 |
8.02 |
| 2026-03-27 00:00 |
17:53:38.35 |
-34:05:59.2 |
HIP 87516 |
10.21 |
| 2026-03-27 12:00 |
17:53:50.26 |
-34:07:28.8 |
HIP 87516 |
12.65 |
| 2026-03-28 00:00 |
17:54:01.92 |
-34:08:58.6 |
HIP 87686 |
13.83 |
| 2026-03-28 12:00 |
17:54:13.35 |
-34:10:28.6 |
HIP 87686 |
14.08 |
| 2026-03-29 00:00 |
17:54:24.53 |
-34:11:58.8 |
HIP 87686 |
14.88 |
| 2026-03-29 12:00 |
17:54:35.46 |
-34:13:29.2 |
HIP 87671 |
14.62 |
| 2026-03-30 00:00 |
17:54:46.15 |
-34:14:59.8 |
HIP 87671 |
13.59 |
| 2026-03-30 12:00 |
17:54:56.60 |
-34:16:30.5 |
HIP 87785 |
12.33 |
| 2026-03-31 00:00 |
17:55:06.79 |
-34:18:01.5 |
HIP 87785 |
10.24 |
| 2026-03-31 12:00 |
17:55:16.74 |
-34:19:32.7 |
HIP 87785 |
8.48 |
| 2026-04-01 00:00 |
17:55:26.43 |
-34:21:04.0 |
HIP 87785 |
7.26 |
| 2026-04-01 12:00 |
17:55:35.87 |
-34:22:35.6 |
HIP 87785 |
6.83 |
| 2026-04-02 00:00 |
17:55:45.06 |
-34:24:07.3 |
HIP 87785 |
7.30 |
| 2026-04-02 12:00 |
17:55:53.99 |
-34:25:39.3 |
HIP 87785 |
8.47 |
| 2026-04-03 00:00 |
17:56:02.66 |
-34:27:11.4 |
HIP 87785 |
10.08 |
| 2026-04-03 12:00 |
17:56:11.07 |
-34:28:43.7 |
HIP 87785 |
11.93 |
| 2026-04-04 00:00 |
17:56:19.23 |
-34:30:16.1 |
HIP 87785 |
13.91 |
| 2026-04-04 12:00 |
17:56:27.12 |
-34:31:48.8 |
HIP 87785 |
15.95 |
| 2026-04-05 00:00 |
17:56:34.75 |
-34:33:21.6 |
HIP 87785 |
18.01 |
| 2026-04-05 12:00 |
17:56:42.12 |
-34:34:54.7 |
HIP 87785 |
20.09 |
| 2026-04-06 00:00 |
17:56:49.22 |
-34:36:27.8 |
HIP 87885 |
21.84 |
| 2026-04-06 12:00 |
17:56:56.05 |
-34:38:01.2 |
HIP 87885 |
23.15 |
| 2026-04-07 00:00 |
17:57:02.61 |
-34:39:34.7 |
HIP 87885 |
24.58 |
| 2026-04-07 12:00 |
17:57:08.90 |
-34:41:08.4 |
HIP 87798 |
25.13 |
| 2026-04-08 00:00 |
17:57:14.92 |
-34:42:42.2 |
HIP 87798 |
24.46 |
| 2026-04-08 12:00 |
17:57:20.66 |
-34:44:16.2 |
HIP 87993 |
23.83 |
| 2026-04-09 00:00 |
17:57:26.14 |
-34:45:50.4 |
HIP 87993 |
21.90 |
| 2026-04-09 12:00 |
17:57:31.33 |
-34:47:24.6 |
HIP 87993 |
20.00 |
| 2026-04-10 00:00 |
17:57:36.25 |
-34:48:59.1 |
HIP 87993 |
18.13 |
| 2026-04-10 12:00 |
17:57:40.88 |
-34:50:33.6 |
HIP 87993 |
16.29 |
| 2026-04-11 00:00 |
17:57:45.24 |
-34:52:08.3 |
HIP 87993 |
14.48 |
| 2026-04-11 12:00 |
17:57:49.31 |
-34:53:43.2 |
HIP 87993 |
12.71 |
| 2026-04-12 00:00 |
17:57:53.10 |
-34:55:18.1 |
HIP 87993 |
10.98 |
| 2026-04-12 12:00 |
17:57:56.61 |
-34:56:53.2 |
HIP 87993 |
9.29 |
| 2026-04-13 00:00 |
17:57:59.83 |
-34:58:28.4 |
HIP 87993 |
7.67 |
| 2026-04-13 12:00 |
17:58:02.76 |
-35:00:03.6 |
HIP 87993 |
6.15 |
| 2026-04-14 00:00 |
17:58:05.40 |
-35:01:39.0 |
HIP 87993 |
4.79 |
| 2026-04-14 12:00 |
17:58:07.76 |
-35:03:14.5 |
HIP 87993 |
3.77 |
| 2026-04-15 00:00 |
17:58:09.82 |
-35:04:50.0 |
HIP 87993 |
3.38 |
| 2026-04-15 12:00 |
17:58:11.59 |
-35:06:25.7 |
HIP 87993 |
3.79 |
| 2026-04-16 00:00 |
17:58:13.07 |
-35:08:01.3 |
HIP 87993 |
4.79 |