| Parameter |
Value |
| Designation |
C/2019 U6 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2020-06-18T19:43:24.988800Z |
| Orbit solution date (soln_date, UTC) |
2022-04-16T22:12:22Z |
| Obs used |
1144 |
| NEO |
- |
| M1 |
13.200 |
| K1 |
7.750 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2019-10-31T10:24:29.952000Z |
| Discovery magnitude (MPC) |
20.50 G |
| Discovery observatory (MPC) |
G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-04-28.0000000 |
| e |
0.99790319 |
| q (au) |
0.914264 |
| a (au) |
436.025928 |
| i (deg) |
61.001339 |
| Ω (om, deg) |
235.705755 |
| ω (w, deg) |
329.659058 |
| M (ma, deg) |
359.994390 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.998 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.998 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2018-11-06 |
2020-01-26 |
-9.9490 |
+4.967 |
| 2020-01-26 |
2020-04-22 |
+11.1473 |
-3.130 |
| 2020-04-22 |
2020-06-18 |
-1.0370 |
-2.413 |
| 2020-06-18 |
2020-07-26 |
+16.3476 |
-0.540 |
| 2020-07-26 |
2020-11-28 |
-5.2648 |
+1.320 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
23:32:59.89 |
+51:55:46.7 |
HIP 116169 |
6.82 |
| 2026-09-20 12:00 |
23:32:50.72 |
+51:55:13.5 |
HIP 116169 |
5.34 |
| 2026-09-21 00:00 |
23:32:41.55 |
+51:54:39.6 |
HIP 116169 |
3.88 |
| 2026-09-21 12:00 |
23:32:32.40 |
+51:54:05.0 |
HIP 116169 |
2.51 |
| 2026-09-22 00:00 |
23:32:23.26 |
+51:53:29.6 |
HIP 116169 |
1.47 |
| 2026-09-22 12:00 |
23:32:14.13 |
+51:52:53.5 |
HIP 116169 |
1.66 |
| 2026-09-23 00:00 |
23:32:05.02 |
+51:52:16.7 |
HIP 116169 |
2.85 |
| 2026-09-23 12:00 |
23:31:55.93 |
+51:51:39.2 |
HIP 116169 |
4.26 |
| 2026-09-24 00:00 |
23:31:46.85 |
+51:51:01.0 |
HIP 116169 |
5.75 |
| 2026-09-24 12:00 |
23:31:37.79 |
+51:50:22.1 |
HIP 116169 |
7.26 |
| 2026-09-25 00:00 |
23:31:28.75 |
+51:49:42.4 |
HIP 116046 |
8.35 |
| 2026-09-25 12:00 |
23:31:19.73 |
+51:49:02.1 |
HIP 116046 |
7.94 |
| 2026-09-26 00:00 |
23:31:10.73 |
+51:48:21.1 |
HIP 116046 |
7.83 |
| 2026-09-26 12:00 |
23:31:01.75 |
+51:47:39.3 |
HIP 116046 |
8.04 |
| 2026-09-27 00:00 |
23:30:52.79 |
+51:46:56.9 |
HIP 116046 |
8.54 |
| 2026-09-27 12:00 |
23:30:43.86 |
+51:46:13.8 |
HIP 116046 |
9.28 |
| 2026-09-28 00:00 |
23:30:34.94 |
+51:45:30.0 |
HIP 116046 |
10.22 |
| 2026-09-28 12:00 |
23:30:26.06 |
+51:44:45.5 |
HIP 115952 |
9.24 |
| 2026-09-29 00:00 |
23:30:17.19 |
+51:44:00.3 |
HIP 115952 |
7.68 |
| 2026-09-29 12:00 |
23:30:08.36 |
+51:43:14.4 |
HIP 115952 |
6.13 |
| 2026-09-30 00:00 |
23:29:59.55 |
+51:42:27.9 |
HIP 115952 |
4.59 |
| 2026-09-30 12:00 |
23:29:50.77 |
+51:41:40.7 |
HIP 115952 |
3.08 |
| 2026-10-01 00:00 |
23:29:42.01 |
+51:40:52.9 |
HIP 115952 |
1.68 |
| 2026-10-01 12:00 |
23:29:33.29 |
+51:40:04.3 |
HIP 115952 |
1.09 |
| 2026-10-02 00:00 |
23:29:24.60 |
+51:39:15.1 |
HIP 115952 |
2.13 |
| 2026-10-02 12:00 |
23:29:15.94 |
+51:38:25.3 |
HIP 115952 |
3.59 |
| 2026-10-03 00:00 |
23:29:07.31 |
+51:37:34.8 |
HIP 115952 |
5.13 |
| 2026-10-03 12:00 |
23:28:58.71 |
+51:36:43.6 |
HIP 115952 |
6.69 |
| 2026-10-04 00:00 |
23:28:50.15 |
+51:35:51.8 |
HIP 115952 |
8.26 |
| 2026-10-04 12:00 |
23:28:41.62 |
+51:34:59.4 |
HIP 115952 |
9.84 |
| 2026-10-05 00:00 |
23:28:33.12 |
+51:34:06.3 |
HIP 115952 |
11.42 |
| 2026-10-05 12:00 |
23:28:24.67 |
+51:33:12.6 |
HIP 115952 |
13.01 |
| 2026-10-06 00:00 |
23:28:16.25 |
+51:32:18.3 |
HIP 115952 |
14.60 |
| 2026-10-06 12:00 |
23:28:07.86 |
+51:31:23.3 |
HIP 115952 |
16.19 |
| 2026-10-07 00:00 |
23:27:59.52 |
+51:30:27.8 |
HIP 115952 |
17.79 |
| 2026-10-07 12:00 |
23:27:51.22 |
+51:29:31.6 |
HIP 115952 |
19.38 |
| 2026-10-08 00:00 |
23:27:42.95 |
+51:28:34.8 |
HIP 115952 |
20.98 |
| 2026-10-08 12:00 |
23:27:34.73 |
+51:27:37.3 |
HIP 115952 |
22.58 |
| 2026-10-09 00:00 |
23:27:26.55 |
+51:26:39.3 |
HIP 115952 |
24.18 |
| 2026-10-09 12:00 |
23:27:18.42 |
+51:25:40.7 |
HIP 115873 |
24.82 |
| 2026-10-10 00:00 |
23:27:10.33 |
+51:24:41.5 |
HIP 115873 |
24.60 |
| 2026-10-10 12:00 |
23:27:02.28 |
+51:23:41.8 |
HIP 115873 |
24.47 |
| 2026-10-11 00:00 |
23:26:54.28 |
+51:22:41.4 |
HIP 115873 |
24.44 |