| Parameter |
Value |
| Designation |
C/2017 S7 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-05-27T21:16:49.696320Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:36Z |
| Obs used |
157 |
| NEO |
- |
| M1 |
6.700 |
| K1 |
10.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-11-16.0000000 |
| e |
1.00249982 |
| q (au) |
7.614408 |
| a (au) |
-3045.987574 |
| i (deg) |
124.224743 |
| Ω (om, deg) |
262.788416 |
| ω (w, deg) |
187.747383 |
| M (ma, deg) |
0.001009 |
Magnitude
Scatter + Global Linear
$$
M_a = (1.282 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
1.282 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.505 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
23:48:20.28 |
-59:51:55.7 |
HIP 117275 |
11.88 |
| 2026-06-01 12:00 |
23:48:21.01 |
-59:53:09.7 |
HIP 117275 |
11.61 |
| 2026-06-02 00:00 |
23:48:21.66 |
-59:54:24.1 |
HIP 117275 |
11.45 |
| 2026-06-02 12:00 |
23:48:22.21 |
-59:55:38.8 |
HIP 117275 |
11.41 |
| 2026-06-03 00:00 |
23:48:22.68 |
-59:56:53.9 |
HIP 117486 |
10.51 |
| 2026-06-03 12:00 |
23:48:23.06 |
-59:58:09.3 |
HIP 117486 |
9.62 |
| 2026-06-04 00:00 |
23:48:23.35 |
-59:59:25.0 |
HIP 117486 |
8.82 |
| 2026-06-04 12:00 |
23:48:23.55 |
-60:00:41.1 |
HIP 117486 |
8.15 |
| 2026-06-05 00:00 |
23:48:23.65 |
-60:01:57.5 |
HIP 117486 |
7.64 |
| 2026-06-05 12:00 |
23:48:23.67 |
-60:03:14.3 |
HIP 117486 |
7.33 |
| 2026-06-06 00:00 |
23:48:23.59 |
-60:04:31.3 |
HIP 117486 |
7.25 |
| 2026-06-06 12:00 |
23:48:23.42 |
-60:05:48.7 |
HIP 117486 |
7.41 |
| 2026-06-07 00:00 |
23:48:23.16 |
-60:07:06.4 |
HIP 117486 |
7.79 |
| 2026-06-07 12:00 |
23:48:22.81 |
-60:08:24.3 |
HIP 117486 |
8.37 |
| 2026-06-08 00:00 |
23:48:22.36 |
-60:09:42.6 |
HIP 117486 |
9.11 |
| 2026-06-08 12:00 |
23:48:21.82 |
-60:11:01.2 |
HIP 117486 |
9.98 |
| 2026-06-09 00:00 |
23:48:21.19 |
-60:12:20.1 |
HIP 117486 |
10.95 |
| 2026-06-09 12:00 |
23:48:20.46 |
-60:13:39.2 |
HIP 117486 |
12.00 |
| 2026-06-10 00:00 |
23:48:19.64 |
-60:14:58.6 |
HIP 117486 |
13.11 |
| 2026-06-10 12:00 |
23:48:18.72 |
-60:16:18.3 |
HIP 117486 |
14.26 |
| 2026-06-11 00:00 |
23:48:17.71 |
-60:17:38.3 |
HIP 117486 |
15.46 |
| 2026-06-11 12:00 |
23:48:16.60 |
-60:18:58.5 |
HIP 117486 |
16.69 |
| 2026-06-12 00:00 |
23:48:15.39 |
-60:20:19.0 |
HIP 117486 |
17.94 |
| 2026-06-12 12:00 |
23:48:14.09 |
-60:21:39.8 |
HIP 117486 |
19.21 |
| 2026-06-13 00:00 |
23:48:12.69 |
-60:23:00.8 |
HIP 117486 |
20.50 |
| 2026-06-13 12:00 |
23:48:11.19 |
-60:24:22.0 |
HIP 117486 |
21.81 |
| 2026-06-14 00:00 |
23:48:09.59 |
-60:25:43.4 |
HIP 117470 |
21.40 |
| 2026-06-14 12:00 |
23:48:07.90 |
-60:27:05.1 |
HIP 117470 |
20.21 |
| 2026-06-15 00:00 |
23:48:06.11 |
-60:28:27.0 |
HIP 117470 |
19.04 |
| 2026-06-15 12:00 |
23:48:04.22 |
-60:29:49.1 |
HIP 117470 |
17.91 |
| 2026-06-16 00:00 |
23:48:02.23 |
-60:31:11.5 |
HIP 117470 |
16.82 |
| 2026-06-16 12:00 |
23:48:00.14 |
-60:32:34.0 |
HIP 117470 |
15.77 |
| 2026-06-17 00:00 |
23:47:57.95 |
-60:33:56.7 |
HIP 117470 |
14.80 |
| 2026-06-17 12:00 |
23:47:55.66 |
-60:35:19.6 |
HIP 117470 |
13.90 |
| 2026-06-18 00:00 |
23:47:53.27 |
-60:36:42.7 |
HIP 117264 |
12.94 |
| 2026-06-18 12:00 |
23:47:50.78 |
-60:38:05.9 |
HIP 117264 |
11.81 |
| 2026-06-19 00:00 |
23:47:48.19 |
-60:39:29.4 |
HIP 117264 |
10.73 |
| 2026-06-19 12:00 |
23:47:45.50 |
-60:40:53.0 |
HIP 117264 |
9.73 |
| 2026-06-20 00:00 |
23:47:42.71 |
-60:42:16.7 |
HIP 117264 |
8.83 |
| 2026-06-20 12:00 |
23:47:39.82 |
-60:43:40.6 |
HIP 117264 |
8.08 |
| 2026-06-21 00:00 |
23:47:36.82 |
-60:45:04.6 |
HIP 117264 |
7.52 |
| 2026-06-21 12:00 |
23:47:33.73 |
-60:46:28.8 |
HIP 117264 |
7.21 |
| 2026-06-22 00:00 |
23:47:30.53 |
-60:47:53.1 |
HIP 117264 |
7.17 |