| 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 |
2016-10-18 |
-4.8125 |
+3.659 |
| 2016-10-18 |
2018-04-08 |
-0.4026 |
+0.178 |
| 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) |
| 2026-05-12 00:00 |
15:54:46.26 |
+56:09:08.1 |
HIP 77989 |
21.11 |
| 2026-05-12 12:00 |
15:54:36.88 |
+56:09:26.1 |
HIP 77989 |
21.82 |
| 2026-05-13 00:00 |
15:54:27.49 |
+56:09:43.2 |
HIP 77989 |
22.58 |
| 2026-05-13 12:00 |
15:54:18.09 |
+56:09:59.6 |
HIP 77850 |
22.83 |
| 2026-05-14 00:00 |
15:54:08.68 |
+56:10:15.2 |
HIP 77850 |
22.37 |
| 2026-05-14 12:00 |
15:53:59.25 |
+56:10:30.0 |
HIP 77850 |
21.99 |
| 2026-05-15 00:00 |
15:53:49.82 |
+56:10:43.9 |
HIP 77850 |
21.70 |
| 2026-05-15 12:00 |
15:53:40.37 |
+56:10:57.1 |
HIP 77850 |
21.51 |
| 2026-05-16 00:00 |
15:53:30.92 |
+56:11:09.4 |
HIP 77850 |
21.40 |
| 2026-05-16 12:00 |
15:53:21.46 |
+56:11:21.0 |
HIP 77850 |
21.40 |
| 2026-05-17 00:00 |
15:53:11.99 |
+56:11:31.7 |
HIP 77850 |
21.48 |
| 2026-05-17 12:00 |
15:53:02.52 |
+56:11:41.6 |
HIP 77850 |
21.66 |
| 2026-05-18 00:00 |
15:52:53.04 |
+56:11:50.7 |
HIP 77850 |
21.94 |
| 2026-05-18 12:00 |
15:52:43.56 |
+56:11:59.0 |
HIP 77850 |
22.30 |
| 2026-05-19 00:00 |
15:52:34.08 |
+56:12:06.4 |
HIP 77738 |
22.64 |
| 2026-05-19 12:00 |
15:52:24.60 |
+56:12:13.1 |
HIP 77738 |
22.65 |
| 2026-05-20 00:00 |
15:52:15.11 |
+56:12:18.9 |
HIP 77738 |
22.72 |
| 2026-05-20 12:00 |
15:52:05.63 |
+56:12:24.0 |
HIP 77738 |
22.86 |
| 2026-05-21 00:00 |
15:51:56.15 |
+56:12:28.2 |
HIP 77484 |
22.22 |
| 2026-05-21 12:00 |
15:51:46.68 |
+56:12:31.6 |
HIP 77484 |
20.90 |
| 2026-05-22 00:00 |
15:51:37.20 |
+56:12:34.2 |
HIP 77484 |
19.59 |
| 2026-05-22 12:00 |
15:51:27.74 |
+56:12:36.0 |
HIP 77484 |
18.28 |
| 2026-05-23 00:00 |
15:51:18.28 |
+56:12:37.0 |
HIP 77484 |
16.96 |
| 2026-05-23 12:00 |
15:51:08.82 |
+56:12:37.2 |
HIP 77484 |
15.66 |
| 2026-05-24 00:00 |
15:50:59.37 |
+56:12:36.6 |
HIP 77484 |
14.35 |
| 2026-05-24 12:00 |
15:50:49.94 |
+56:12:35.1 |
HIP 77484 |
13.05 |
| 2026-05-25 00:00 |
15:50:40.51 |
+56:12:32.9 |
HIP 77484 |
11.76 |
| 2026-05-25 12:00 |
15:50:31.09 |
+56:12:29.9 |
HIP 77484 |
10.47 |
| 2026-05-26 00:00 |
15:50:21.69 |
+56:12:26.0 |
HIP 77484 |
9.19 |
| 2026-05-26 12:00 |
15:50:12.29 |
+56:12:21.4 |
HIP 77484 |
7.93 |
| 2026-05-27 00:00 |
15:50:02.91 |
+56:12:16.0 |
HIP 77484 |
6.70 |
| 2026-05-27 12:00 |
15:49:53.55 |
+56:12:09.7 |
HIP 77484 |
5.50 |
| 2026-05-28 00:00 |
15:49:44.20 |
+56:12:02.7 |
HIP 77484 |
4.38 |
| 2026-05-28 12:00 |
15:49:34.86 |
+56:11:54.9 |
HIP 77484 |
3.39 |
| 2026-05-29 00:00 |
15:49:25.54 |
+56:11:46.3 |
HIP 77484 |
2.71 |
| 2026-05-29 12:00 |
15:49:16.24 |
+56:11:36.9 |
HIP 77484 |
2.58 |
| 2026-05-30 00:00 |
15:49:06.96 |
+56:11:26.7 |
HIP 77484 |
3.06 |
| 2026-05-30 12:00 |
15:48:57.70 |
+56:11:15.7 |
HIP 77484 |
3.95 |
| 2026-05-31 00:00 |
15:48:48.46 |
+56:11:04.0 |
HIP 77484 |
5.02 |
| 2026-05-31 12:00 |
15:48:39.24 |
+56:10:51.4 |
HIP 77438 |
5.10 |
| 2026-06-01 00:00 |
15:48:30.04 |
+56:10:38.1 |
HIP 77438 |
4.70 |
| 2026-06-01 12:00 |
15:48:20.87 |
+56:10:24.0 |
HIP 77438 |
4.64 |
| 2026-06-02 00:00 |
15:48:11.72 |
+56:10:09.1 |
HIP 77438 |
4.91 |