C/2018 E1 (ATLAS)
| Parameter |
Value |
| Designation |
C/2018 E1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-04-17T07:44:27.119040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:40Z |
| Obs used |
227 |
| NEO |
- |
| M1 |
11.400 |
| K1 |
8.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-03-10T05:26:27.744000Z |
| Discovery magnitude (MPC) |
16.80 T |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-04-14.0000000 |
| e |
0.95034655 |
| q (au) |
2.705441 |
| a (au) |
54.486472 |
| i (deg) |
72.479572 |
| Ω (om, deg) |
146.840866 |
| ω (w, deg) |
299.471840 |
| M (ma, deg) |
359.991858 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.403 + 3.492\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.403 |
| n |
3.492 |
| 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 |
| 2015-08-11 |
2016-09-27 |
-5.2884 |
+4.083 |
| 2016-09-27 |
2018-04-08 |
-0.4722 |
+0.207 |
| 2018-04-19 |
2019-04-23 |
+9.1428 |
-5.069 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
16:05:56.56 |
+52:19:35.6 |
HIP 78894 |
3.60 |
| 2026-02-03 12:00 |
16:06:01.19 |
+52:20:58.9 |
HIP 78894 |
3.42 |
| 2026-02-04 00:00 |
16:06:05.73 |
+52:22:22.5 |
HIP 78894 |
3.92 |
| 2026-02-04 12:00 |
16:06:10.20 |
+52:23:46.4 |
HIP 78894 |
4.90 |
| 2026-02-05 00:00 |
16:06:14.59 |
+52:25:10.6 |
HIP 78894 |
6.13 |
| 2026-02-05 12:00 |
16:06:18.89 |
+52:26:35.1 |
HIP 78894 |
7.48 |
| 2026-02-06 00:00 |
16:06:23.12 |
+52:27:59.8 |
HIP 78894 |
8.91 |
| 2026-02-06 12:00 |
16:06:27.26 |
+52:29:24.8 |
HIP 78894 |
10.37 |
| 2026-02-07 00:00 |
16:06:31.32 |
+52:30:50.1 |
HIP 78894 |
11.86 |
| 2026-02-07 12:00 |
16:06:35.30 |
+52:32:15.7 |
HIP 78894 |
13.37 |
| 2026-02-08 00:00 |
16:06:39.20 |
+52:33:41.5 |
HIP 78894 |
14.88 |
| 2026-02-08 12:00 |
16:06:43.01 |
+52:35:07.6 |
HIP 78894 |
16.41 |
| 2026-02-09 00:00 |
16:06:46.74 |
+52:36:33.9 |
HIP 78894 |
17.94 |
| 2026-02-09 12:00 |
16:06:50.39 |
+52:38:00.4 |
HIP 78894 |
19.47 |
| 2026-02-10 00:00 |
16:06:53.96 |
+52:39:27.2 |
HIP 78894 |
21.00 |
| 2026-02-10 12:00 |
16:06:57.44 |
+52:40:54.1 |
HIP 78894 |
22.54 |
| 2026-02-11 00:00 |
16:07:00.83 |
+52:42:21.4 |
HIP 79126 |
23.32 |
| 2026-02-11 12:00 |
16:07:04.14 |
+52:43:48.8 |
HIP 79126 |
22.05 |
| 2026-02-12 00:00 |
16:07:07.37 |
+52:45:16.4 |
HIP 79126 |
20.82 |
| 2026-02-12 12:00 |
16:07:10.51 |
+52:46:44.2 |
HIP 79126 |
19.64 |
| 2026-02-13 00:00 |
16:07:13.56 |
+52:48:12.2 |
HIP 79126 |
18.53 |
| 2026-02-13 12:00 |
16:07:16.53 |
+52:49:40.4 |
HIP 79126 |
17.49 |
| 2026-02-14 00:00 |
16:07:19.41 |
+52:51:08.8 |
HIP 79126 |
16.55 |
| 2026-02-14 12:00 |
16:07:22.21 |
+52:52:37.3 |
HIP 79126 |
15.71 |
| 2026-02-15 00:00 |
16:07:24.92 |
+52:54:06.0 |
HIP 79126 |
14.99 |
| 2026-02-15 12:00 |
16:07:27.54 |
+52:55:34.9 |
HIP 79126 |
14.41 |
| 2026-02-16 00:00 |
16:07:30.07 |
+52:57:03.9 |
HIP 79126 |
14.00 |
| 2026-02-16 12:00 |
16:07:32.52 |
+52:58:33.0 |
HIP 79126 |
13.75 |
| 2026-02-17 00:00 |
16:07:34.88 |
+53:00:02.3 |
HIP 79126 |
13.69 |
| 2026-02-17 12:00 |
16:07:37.15 |
+53:01:31.7 |
HIP 79126 |
13.81 |
| 2026-02-18 00:00 |
16:07:39.33 |
+53:03:01.2 |
HIP 79126 |
14.11 |
| 2026-02-18 12:00 |
16:07:41.42 |
+53:04:30.9 |
HIP 79126 |
14.58 |
| 2026-02-19 00:00 |
16:07:43.42 |
+53:06:00.6 |
HIP 79126 |
15.20 |
| 2026-02-19 12:00 |
16:07:45.34 |
+53:07:30.5 |
HIP 79126 |
15.96 |
| 2026-02-20 00:00 |
16:07:47.16 |
+53:09:00.4 |
HIP 79126 |
16.82 |
| 2026-02-20 12:00 |
16:07:48.90 |
+53:10:30.4 |
HIP 79126 |
17.79 |
| 2026-02-21 00:00 |
16:07:50.55 |
+53:12:00.5 |
HIP 79126 |
18.84 |
| 2026-02-21 12:00 |
16:07:52.10 |
+53:13:30.6 |
HIP 79126 |
19.96 |
| 2026-02-22 00:00 |
16:07:53.57 |
+53:15:00.8 |
HIP 79126 |
21.13 |
| 2026-02-22 12:00 |
16:07:54.95 |
+53:16:31.1 |
HIP 78892 |
20.26 |
| 2026-02-23 00:00 |
16:07:56.23 |
+53:18:01.4 |
HIP 78892 |
19.36 |
| 2026-02-23 12:00 |
16:07:57.43 |
+53:19:31.7 |
HIP 78892 |
18.53 |
| 2026-02-24 00:00 |
16:07:58.54 |
+53:21:02.1 |
HIP 78892 |
17.78 |