| Parameter |
Value |
| Designation |
C/2016 X1 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-04-29T21:10:40.776960Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:28Z |
| Obs used |
289 |
| NEO |
- |
| M1 |
6.600 |
| K1 |
9.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-09-28.0000000 |
| e |
0.99625285 |
| q (au) |
7.564181 |
| a (au) |
2018.648757 |
| i (deg) |
26.455050 |
| Ω (om, deg) |
256.425245 |
| ω (w, deg) |
224.569464 |
| M (ma, deg) |
359.997676 |
Magnitude
Scatter + Global Linear
$$
M_a = (0.331 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
0.331 |
| n |
6.000 |
| gf |
0.995 |
| gb |
-0.734 |
| 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) |
| 2026-05-12 00:00 |
13:54:19.84 |
-31:00:27.2 |
HIP 67798 |
18.88 |
| 2026-05-12 12:00 |
13:54:14.20 |
-30:59:39.5 |
HIP 67798 |
17.47 |
| 2026-05-13 00:00 |
13:54:08.60 |
-30:58:51.5 |
HIP 67798 |
16.08 |
| 2026-05-13 12:00 |
13:54:03.02 |
-30:58:03.4 |
HIP 67798 |
14.70 |
| 2026-05-14 00:00 |
13:53:57.47 |
-30:57:15.1 |
HIP 67798 |
13.33 |
| 2026-05-14 12:00 |
13:53:51.95 |
-30:56:26.7 |
HIP 67798 |
11.98 |
| 2026-05-15 00:00 |
13:53:46.47 |
-30:55:38.1 |
HIP 67798 |
10.65 |
| 2026-05-15 12:00 |
13:53:41.01 |
-30:54:49.3 |
HIP 67798 |
9.36 |
| 2026-05-16 00:00 |
13:53:35.59 |
-30:54:00.4 |
HIP 67798 |
8.11 |
| 2026-05-16 12:00 |
13:53:30.21 |
-30:53:11.3 |
HIP 67798 |
6.92 |
| 2026-05-17 00:00 |
13:53:24.85 |
-30:52:22.1 |
HIP 67798 |
5.83 |
| 2026-05-17 12:00 |
13:53:19.54 |
-30:51:32.8 |
HIP 67798 |
4.91 |
| 2026-05-18 00:00 |
13:53:14.25 |
-30:50:43.3 |
HIP 67798 |
4.27 |
| 2026-05-18 12:00 |
13:53:09.01 |
-30:49:53.7 |
HIP 67798 |
4.02 |
| 2026-05-19 00:00 |
13:53:03.80 |
-30:49:04.0 |
HIP 67798 |
4.23 |
| 2026-05-19 12:00 |
13:52:58.63 |
-30:48:14.2 |
HIP 67798 |
4.85 |
| 2026-05-20 00:00 |
13:52:53.49 |
-30:47:24.3 |
HIP 67798 |
5.73 |
| 2026-05-20 12:00 |
13:52:48.39 |
-30:46:34.2 |
HIP 67798 |
6.77 |
| 2026-05-21 00:00 |
13:52:43.34 |
-30:45:44.1 |
HIP 67798 |
7.91 |
| 2026-05-21 12:00 |
13:52:38.32 |
-30:44:53.8 |
HIP 67798 |
9.10 |
| 2026-05-22 00:00 |
13:52:33.34 |
-30:44:03.5 |
HIP 67798 |
10.33 |
| 2026-05-22 12:00 |
13:52:28.40 |
-30:43:13.1 |
HIP 67798 |
11.58 |
| 2026-05-23 00:00 |
13:52:23.51 |
-30:42:22.6 |
HIP 67798 |
12.85 |
| 2026-05-23 12:00 |
13:52:18.65 |
-30:41:32.0 |
HIP 67798 |
14.12 |
| 2026-05-24 00:00 |
13:52:13.84 |
-30:40:41.3 |
HIP 67798 |
15.39 |
| 2026-05-24 12:00 |
13:52:09.07 |
-30:39:50.6 |
HIP 67604 |
14.21 |
| 2026-05-25 00:00 |
13:52:04.34 |
-30:38:59.8 |
HIP 67604 |
12.94 |
| 2026-05-25 12:00 |
13:51:59.65 |
-30:38:09.0 |
HIP 67604 |
11.69 |
| 2026-05-26 00:00 |
13:51:55.01 |
-30:37:18.1 |
HIP 67604 |
10.46 |
| 2026-05-26 12:00 |
13:51:50.41 |
-30:36:27.1 |
HIP 67604 |
9.26 |
| 2026-05-27 00:00 |
13:51:45.86 |
-30:35:36.1 |
HIP 67604 |
8.11 |
| 2026-05-27 12:00 |
13:51:41.35 |
-30:34:45.1 |
HIP 67604 |
7.02 |
| 2026-05-28 00:00 |
13:51:36.89 |
-30:33:54.0 |
HIP 67604 |
6.01 |
| 2026-05-28 12:00 |
13:51:32.47 |
-30:33:02.9 |
HIP 67604 |
5.14 |
| 2026-05-29 00:00 |
13:51:28.10 |
-30:32:11.8 |
HIP 67604 |
4.48 |
| 2026-05-29 12:00 |
13:51:23.77 |
-30:31:20.7 |
HIP 67604 |
4.13 |
| 2026-05-30 00:00 |
13:51:19.49 |
-30:30:29.5 |
HIP 67604 |
4.14 |
| 2026-05-30 12:00 |
13:51:15.26 |
-30:29:38.3 |
HIP 67604 |
4.53 |
| 2026-05-31 00:00 |
13:51:11.08 |
-30:28:47.1 |
HIP 67604 |
5.19 |
| 2026-05-31 12:00 |
13:51:06.94 |
-30:27:55.9 |
HIP 67604 |
6.04 |
| 2026-06-01 00:00 |
13:51:02.86 |
-30:27:04.7 |
HIP 67604 |
7.01 |
| 2026-06-01 12:00 |
13:50:58.82 |
-30:26:13.5 |
HIP 67604 |
8.04 |
| 2026-06-02 00:00 |
13:50:54.83 |
-30:25:22.3 |
HIP 67550 |
8.00 |