| Parameter |
Value |
| Designation |
C/2018 B1 (Lemmon) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-03-30T10:39:55.339200Z |
| Orbit solution date (soln_date, UTC) |
2022-07-19T01:12:15Z |
| Obs used |
316 |
| NEO |
- |
| M1 |
12.300 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-10-22.0000000 |
| e |
1.00296934 |
| q (au) |
5.116718 |
| a (au) |
-1723.183540 |
| i (deg) |
162.423569 |
| Ω (om, deg) |
133.168875 |
| ω (w, deg) |
68.349093 |
| M (ma, deg) |
0.002832 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.479 + 2.127\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.479 |
| n |
2.127 |
| gf |
0.999 |
| gb |
-0.810 |
| k |
0.800 |
| 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 |
| 2017-01-16 |
2018-03-03 |
+44.9933 |
-31.597 |
| 2018-08-17 |
2019-10-31 |
+3.0484 |
-2.392 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
20:55:00.79 |
-19:10:52.3 |
HIP 103166 |
17.08 |
| 2026-05-12 12:00 |
20:54:58.74 |
-19:11:08.5 |
HIP 103166 |
16.89 |
| 2026-05-13 00:00 |
20:54:56.64 |
-19:11:25.0 |
HIP 103166 |
16.72 |
| 2026-05-13 12:00 |
20:54:54.47 |
-19:11:41.8 |
HIP 103166 |
16.55 |
| 2026-05-14 00:00 |
20:54:52.26 |
-19:11:58.7 |
HIP 103166 |
16.40 |
| 2026-05-14 12:00 |
20:54:49.98 |
-19:12:15.9 |
HIP 103166 |
16.26 |
| 2026-05-15 00:00 |
20:54:47.66 |
-19:12:33.2 |
HIP 103166 |
16.14 |
| 2026-05-15 12:00 |
20:54:45.27 |
-19:12:50.8 |
HIP 103166 |
16.04 |
| 2026-05-16 00:00 |
20:54:42.84 |
-19:13:08.7 |
HIP 103166 |
15.96 |
| 2026-05-16 12:00 |
20:54:40.35 |
-19:13:26.7 |
HIP 103166 |
15.90 |
| 2026-05-17 00:00 |
20:54:37.80 |
-19:13:45.0 |
HIP 103166 |
15.87 |
| 2026-05-17 12:00 |
20:54:35.20 |
-19:14:03.4 |
HIP 103166 |
15.86 |
| 2026-05-18 00:00 |
20:54:32.54 |
-19:14:22.1 |
HIP 103166 |
15.88 |
| 2026-05-18 12:00 |
20:54:29.83 |
-19:14:41.0 |
HIP 103114 |
15.72 |
| 2026-05-19 00:00 |
20:54:27.06 |
-19:15:00.2 |
HIP 103114 |
15.33 |
| 2026-05-19 12:00 |
20:54:24.24 |
-19:15:19.5 |
HIP 103114 |
14.95 |
| 2026-05-20 00:00 |
20:54:21.37 |
-19:15:39.0 |
HIP 103114 |
14.59 |
| 2026-05-20 12:00 |
20:54:18.44 |
-19:15:58.8 |
HIP 103114 |
14.25 |
| 2026-05-21 00:00 |
20:54:15.46 |
-19:16:18.8 |
HIP 103114 |
13.95 |
| 2026-05-21 12:00 |
20:54:12.42 |
-19:16:39.0 |
HIP 103114 |
13.67 |
| 2026-05-22 00:00 |
20:54:09.33 |
-19:16:59.3 |
HIP 103114 |
13.43 |
| 2026-05-22 12:00 |
20:54:06.19 |
-19:17:19.9 |
HIP 103114 |
13.23 |
| 2026-05-23 00:00 |
20:54:02.99 |
-19:17:40.8 |
HIP 103114 |
13.07 |
| 2026-05-23 12:00 |
20:53:59.75 |
-19:18:01.8 |
HIP 103114 |
12.96 |
| 2026-05-24 00:00 |
20:53:56.44 |
-19:18:23.0 |
HIP 103114 |
12.90 |
| 2026-05-24 12:00 |
20:53:53.09 |
-19:18:44.4 |
HIP 103114 |
12.90 |
| 2026-05-25 00:00 |
20:53:49.68 |
-19:19:06.0 |
HIP 103114 |
12.95 |
| 2026-05-25 12:00 |
20:53:46.22 |
-19:19:27.8 |
HIP 103114 |
13.07 |
| 2026-05-26 00:00 |
20:53:42.71 |
-19:19:49.9 |
HIP 103114 |
13.24 |
| 2026-05-26 12:00 |
20:53:39.14 |
-19:20:12.1 |
HIP 103114 |
13.48 |
| 2026-05-27 00:00 |
20:53:35.53 |
-19:20:34.5 |
HIP 103114 |
13.77 |
| 2026-05-27 12:00 |
20:53:31.86 |
-19:20:57.1 |
HIP 103114 |
14.13 |
| 2026-05-28 00:00 |
20:53:28.14 |
-19:21:19.9 |
HIP 103114 |
14.54 |
| 2026-05-28 12:00 |
20:53:24.36 |
-19:21:42.9 |
HIP 103114 |
15.01 |
| 2026-05-29 00:00 |
20:53:20.54 |
-19:22:06.1 |
HIP 103114 |
15.52 |
| 2026-05-29 12:00 |
20:53:16.67 |
-19:22:29.5 |
HIP 103032 |
14.86 |
| 2026-05-30 00:00 |
20:53:12.74 |
-19:22:53.1 |
HIP 103032 |
13.90 |
| 2026-05-30 12:00 |
20:53:08.77 |
-19:23:16.8 |
HIP 103032 |
12.93 |
| 2026-05-31 00:00 |
20:53:04.74 |
-19:23:40.8 |
HIP 103032 |
11.95 |
| 2026-05-31 12:00 |
20:53:00.66 |
-19:24:04.9 |
HIP 103032 |
10.98 |
| 2026-06-01 00:00 |
20:52:56.53 |
-19:24:29.3 |
HIP 103032 |
10.01 |
| 2026-06-01 12:00 |
20:52:52.36 |
-19:24:53.8 |
HIP 103032 |
9.05 |
| 2026-06-02 00:00 |
20:52:48.13 |
-19:25:18.5 |
HIP 103032 |
8.11 |