| 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) |
| 2026-09-20 00:00 |
05:05:43.60 |
+01:13:16.2 |
HIP 23680 |
5.61 |
| 2026-09-20 12:00 |
05:05:42.74 |
+01:12:36.1 |
HIP 23680 |
5.14 |
| 2026-09-21 00:00 |
05:05:41.84 |
+01:11:56.0 |
HIP 23680 |
4.71 |
| 2026-09-21 12:00 |
05:05:40.89 |
+01:11:15.8 |
HIP 23680 |
4.33 |
| 2026-09-22 00:00 |
05:05:39.88 |
+01:10:35.6 |
HIP 23680 |
4.04 |
| 2026-09-22 12:00 |
05:05:38.83 |
+01:09:55.3 |
HIP 23680 |
3.85 |
| 2026-09-23 00:00 |
05:05:37.73 |
+01:09:15.1 |
HIP 23680 |
3.78 |
| 2026-09-23 12:00 |
05:05:36.58 |
+01:08:34.8 |
HIP 23680 |
3.83 |
| 2026-09-24 00:00 |
05:05:35.38 |
+01:07:54.5 |
HIP 23680 |
4.01 |
| 2026-09-24 12:00 |
05:05:34.13 |
+01:07:14.2 |
HIP 23680 |
4.30 |
| 2026-09-25 00:00 |
05:05:32.83 |
+01:06:33.8 |
HIP 23680 |
4.69 |
| 2026-09-25 12:00 |
05:05:31.48 |
+01:05:53.4 |
HIP 23680 |
5.15 |
| 2026-09-26 00:00 |
05:05:30.09 |
+01:05:13.1 |
HIP 23680 |
5.67 |
| 2026-09-26 12:00 |
05:05:28.64 |
+01:04:32.7 |
HIP 23680 |
6.24 |
| 2026-09-27 00:00 |
05:05:27.15 |
+01:03:52.3 |
HIP 23680 |
6.84 |
| 2026-09-27 12:00 |
05:05:25.61 |
+01:03:11.9 |
HIP 23680 |
7.48 |
| 2026-09-28 00:00 |
05:05:24.02 |
+01:02:31.5 |
HIP 23680 |
8.13 |
| 2026-09-28 12:00 |
05:05:22.38 |
+01:01:51.1 |
HIP 23680 |
8.81 |
| 2026-09-29 00:00 |
05:05:20.69 |
+01:01:10.7 |
HIP 23680 |
9.51 |
| 2026-09-29 12:00 |
05:05:18.95 |
+01:00:30.3 |
HIP 23680 |
10.22 |
| 2026-09-30 00:00 |
05:05:17.16 |
+00:59:49.9 |
HIP 23680 |
10.95 |
| 2026-09-30 12:00 |
05:05:15.33 |
+00:59:09.5 |
HIP 23680 |
11.69 |
| 2026-10-01 00:00 |
05:05:13.45 |
+00:58:29.1 |
HIP 23680 |
12.44 |
| 2026-10-01 12:00 |
05:05:11.52 |
+00:57:48.7 |
HIP 23680 |
13.20 |
| 2026-10-02 00:00 |
05:05:09.54 |
+00:57:08.4 |
HIP 23680 |
13.98 |
| 2026-10-02 12:00 |
05:05:07.51 |
+00:56:28.0 |
HIP 23680 |
14.76 |
| 2026-10-03 00:00 |
05:05:05.44 |
+00:55:47.7 |
HIP 23680 |
15.55 |
| 2026-10-03 12:00 |
05:05:03.31 |
+00:55:07.5 |
HIP 23680 |
16.35 |
| 2026-10-04 00:00 |
05:05:01.14 |
+00:54:27.2 |
HIP 23680 |
17.16 |
| 2026-10-04 12:00 |
05:04:58.93 |
+00:53:47.0 |
HIP 23680 |
17.98 |
| 2026-10-05 00:00 |
05:04:56.66 |
+00:53:06.8 |
HIP 23680 |
18.80 |
| 2026-10-05 12:00 |
05:04:54.35 |
+00:52:26.6 |
HIP 23680 |
19.64 |
| 2026-10-06 00:00 |
05:04:51.99 |
+00:51:46.5 |
HIP 23680 |
20.48 |
| 2026-10-06 12:00 |
05:04:49.58 |
+00:51:06.4 |
HIP 23680 |
21.33 |
| 2026-10-07 00:00 |
05:04:47.12 |
+00:50:26.4 |
HIP 23680 |
22.19 |
| 2026-10-07 12:00 |
05:04:44.62 |
+00:49:46.4 |
HIP 23680 |
23.06 |
| 2026-10-08 00:00 |
05:04:42.07 |
+00:49:06.4 |
HIP 23680 |
23.93 |
| 2026-10-08 12:00 |
05:04:39.47 |
+00:48:26.5 |
HIP 23680 |
24.82 |
| 2026-10-09 00:00 |
05:04:36.83 |
+00:47:46.7 |
HIP 23680 |
25.71 |
| 2026-10-09 12:00 |
05:04:34.14 |
+00:47:06.9 |
HIP 23680 |
26.60 |
| 2026-10-10 00:00 |
05:04:31.41 |
+00:46:27.2 |
HIP 23680 |
27.51 |
| 2026-10-10 12:00 |
05:04:28.63 |
+00:45:47.6 |
HIP 23680 |
28.42 |
| 2026-10-11 00:00 |
05:04:25.80 |
+00:45:08.0 |
HIP 23680 |
29.34 |