| Parameter |
Value |
| Designation |
C/2018 L2 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-12-02T13:55:55.485120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:44Z |
| Obs used |
731 |
| NEO |
- |
| M1 |
9.500 |
| K1 |
10.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-06-06T07:58:35.040000Z |
| Discovery magnitude (MPC) |
15.60 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-12-29.0000000 |
| e |
0.99298130 |
| q (au) |
1.711711 |
| a (au) |
243.878556 |
| i (deg) |
67.423590 |
| Ω (om, deg) |
243.018259 |
| ω (w, deg) |
56.230818 |
| M (ma, deg) |
0.006837 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.836 + 4.978\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.836 |
| n |
4.978 |
| gf |
1.000 |
| gb |
-0.767 |
| k |
0.985 |
| 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 |
| 2018-06-04 |
2018-09-08 |
+4.1202 |
-1.557 |
| 2018-09-08 |
2018-12-01 |
+25.5943 |
-7.920 |
| 2018-12-03 |
2020-01-20 |
+2.8927 |
-2.045 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
04:52:39.66 |
+02:33:07.0 |
HIP 22730 |
11.08 |
| 2026-06-01 12:00 |
04:52:45.52 |
+02:33:11.1 |
HIP 22730 |
9.68 |
| 2026-06-02 00:00 |
04:52:51.39 |
+02:33:15.0 |
HIP 22730 |
8.30 |
| 2026-06-02 12:00 |
04:52:57.25 |
+02:33:18.7 |
HIP 22730 |
6.96 |
| 2026-06-03 00:00 |
04:53:03.12 |
+02:33:22.1 |
HIP 22730 |
5.68 |
| 2026-06-03 12:00 |
04:53:08.99 |
+02:33:25.3 |
HIP 22730 |
4.51 |
| 2026-06-04 00:00 |
04:53:14.85 |
+02:33:28.2 |
HIP 22730 |
3.57 |
| 2026-06-04 12:00 |
04:53:20.72 |
+02:33:30.9 |
HIP 22730 |
3.06 |
| 2026-06-05 00:00 |
04:53:26.59 |
+02:33:33.3 |
HIP 22730 |
3.21 |
| 2026-06-05 12:00 |
04:53:32.46 |
+02:33:35.5 |
HIP 22730 |
3.93 |
| 2026-06-06 00:00 |
04:53:38.32 |
+02:33:37.5 |
HIP 22730 |
4.99 |
| 2026-06-06 12:00 |
04:53:44.19 |
+02:33:39.2 |
HIP 22730 |
6.21 |
| 2026-06-07 00:00 |
04:53:50.05 |
+02:33:40.6 |
HIP 22730 |
7.52 |
| 2026-06-07 12:00 |
04:53:55.91 |
+02:33:41.9 |
HIP 22797 |
8.70 |
| 2026-06-08 00:00 |
04:54:01.77 |
+02:33:42.8 |
HIP 22797 |
8.00 |
| 2026-06-08 12:00 |
04:54:07.63 |
+02:33:43.5 |
HIP 22797 |
7.52 |
| 2026-06-09 00:00 |
04:54:13.48 |
+02:33:44.0 |
HIP 22797 |
7.30 |
| 2026-06-09 12:00 |
04:54:19.33 |
+02:33:44.2 |
HIP 22797 |
7.37 |
| 2026-06-10 00:00 |
04:54:25.18 |
+02:33:44.2 |
HIP 22797 |
7.72 |
| 2026-06-10 12:00 |
04:54:31.02 |
+02:33:43.9 |
HIP 22797 |
8.31 |
| 2026-06-11 00:00 |
04:54:36.86 |
+02:33:43.4 |
HIP 22797 |
9.09 |
| 2026-06-11 12:00 |
04:54:42.69 |
+02:33:42.6 |
HIP 22797 |
10.02 |
| 2026-06-12 00:00 |
04:54:48.52 |
+02:33:41.6 |
HIP 22797 |
11.06 |
| 2026-06-12 12:00 |
04:54:54.35 |
+02:33:40.3 |
HIP 22797 |
12.18 |
| 2026-06-13 00:00 |
04:55:00.17 |
+02:33:38.7 |
HIP 22797 |
13.37 |
| 2026-06-13 12:00 |
04:55:05.98 |
+02:33:37.0 |
HIP 22797 |
14.59 |
| 2026-06-14 00:00 |
04:55:11.78 |
+02:33:34.9 |
HIP 22797 |
15.86 |
| 2026-06-14 12:00 |
04:55:17.58 |
+02:33:32.6 |
HIP 22797 |
17.15 |
| 2026-06-15 00:00 |
04:55:23.37 |
+02:33:30.0 |
HIP 22797 |
18.46 |
| 2026-06-15 12:00 |
04:55:29.16 |
+02:33:27.2 |
HIP 22797 |
19.78 |
| 2026-06-16 00:00 |
04:55:34.93 |
+02:33:24.1 |
HIP 22797 |
21.12 |
| 2026-06-16 12:00 |
04:55:40.70 |
+02:33:20.8 |
HIP 22797 |
22.47 |
| 2026-06-17 00:00 |
04:55:46.46 |
+02:33:17.2 |
HIP 22940 |
23.59 |
| 2026-06-17 12:00 |
04:55:52.21 |
+02:33:13.4 |
HIP 22940 |
23.33 |
| 2026-06-18 00:00 |
04:55:57.95 |
+02:33:09.3 |
HIP 22940 |
23.16 |
| 2026-06-18 12:00 |
04:56:03.68 |
+02:33:04.9 |
HIP 22940 |
23.08 |
| 2026-06-19 00:00 |
04:56:09.40 |
+02:33:00.3 |
HIP 22940 |
23.09 |
| 2026-06-19 12:00 |
04:56:15.11 |
+02:32:55.5 |
HIP 22940 |
23.20 |
| 2026-06-20 00:00 |
04:56:20.81 |
+02:32:50.3 |
HIP 22940 |
23.39 |
| 2026-06-20 12:00 |
04:56:26.50 |
+02:32:45.0 |
HIP 22940 |
23.68 |
| 2026-06-21 00:00 |
04:56:32.17 |
+02:32:39.3 |
HIP 22940 |
24.05 |
| 2026-06-21 12:00 |
04:56:37.84 |
+02:32:33.4 |
HIP 22940 |
24.50 |
| 2026-06-22 00:00 |
04:56:43.49 |
+02:32:27.3 |
HIP 22940 |
25.02 |