| 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) |
| 2026-03-26 00:00 |
16:06:19.65 |
+54:47:52.9 |
HIP 79241 |
35.38 |
| 2026-03-26 12:00 |
16:06:15.31 |
+54:49:11.7 |
HIP 79241 |
36.31 |
| 2026-03-27 00:00 |
16:06:10.89 |
+54:50:30.1 |
HIP 78942 |
36.34 |
| 2026-03-27 12:00 |
16:06:06.39 |
+54:51:48.0 |
HIP 78942 |
35.19 |
| 2026-03-28 00:00 |
16:06:01.80 |
+54:53:05.5 |
HIP 78942 |
34.07 |
| 2026-03-28 12:00 |
16:05:57.13 |
+54:54:22.7 |
HIP 78942 |
32.99 |
| 2026-03-29 00:00 |
16:05:52.38 |
+54:55:39.3 |
HIP 78942 |
31.94 |
| 2026-03-29 12:00 |
16:05:47.55 |
+54:56:55.6 |
HIP 78942 |
30.94 |
| 2026-03-30 00:00 |
16:05:42.64 |
+54:58:11.3 |
HIP 78942 |
29.99 |
| 2026-03-30 12:00 |
16:05:37.65 |
+54:59:26.7 |
HIP 78942 |
29.09 |
| 2026-03-31 00:00 |
16:05:32.58 |
+55:00:41.5 |
HIP 78942 |
28.25 |
| 2026-03-31 12:00 |
16:05:27.43 |
+55:01:55.9 |
HIP 78942 |
27.47 |
| 2026-04-01 00:00 |
16:05:22.21 |
+55:03:09.9 |
HIP 78942 |
26.75 |
| 2026-04-01 12:00 |
16:05:16.90 |
+55:04:23.3 |
HIP 78942 |
26.11 |
| 2026-04-02 00:00 |
16:05:11.52 |
+55:05:36.3 |
HIP 78942 |
25.54 |
| 2026-04-02 12:00 |
16:05:06.06 |
+55:06:48.8 |
HIP 78942 |
25.06 |
| 2026-04-03 00:00 |
16:05:00.53 |
+55:08:00.8 |
HIP 78548 |
24.20 |
| 2026-04-03 12:00 |
16:04:54.92 |
+55:09:12.3 |
HIP 78548 |
23.30 |
| 2026-04-04 00:00 |
16:04:49.23 |
+55:10:23.2 |
HIP 78548 |
22.45 |
| 2026-04-04 12:00 |
16:04:43.47 |
+55:11:33.7 |
HIP 78548 |
21.65 |
| 2026-04-05 00:00 |
16:04:37.63 |
+55:12:43.7 |
HIP 78548 |
20.90 |
| 2026-04-05 12:00 |
16:04:31.72 |
+55:13:53.1 |
HIP 78548 |
20.22 |
| 2026-04-06 00:00 |
16:04:25.74 |
+55:15:02.0 |
HIP 78548 |
19.61 |
| 2026-04-06 12:00 |
16:04:19.68 |
+55:16:10.4 |
HIP 78548 |
19.08 |
| 2026-04-07 00:00 |
16:04:13.55 |
+55:17:18.2 |
HIP 78548 |
18.62 |
| 2026-04-07 12:00 |
16:04:07.35 |
+55:18:25.5 |
HIP 78548 |
18.26 |
| 2026-04-08 00:00 |
16:04:01.08 |
+55:19:32.2 |
HIP 78548 |
17.99 |
| 2026-04-08 12:00 |
16:03:54.73 |
+55:20:38.3 |
HIP 78548 |
17.82 |
| 2026-04-09 00:00 |
16:03:48.32 |
+55:21:44.0 |
HIP 78548 |
17.74 |
| 2026-04-09 12:00 |
16:03:41.83 |
+55:22:49.0 |
HIP 78548 |
17.77 |
| 2026-04-10 00:00 |
16:03:35.28 |
+55:23:53.4 |
HIP 78548 |
17.90 |
| 2026-04-10 12:00 |
16:03:28.66 |
+55:24:57.3 |
HIP 78548 |
18.13 |
| 2026-04-11 00:00 |
16:03:21.97 |
+55:26:00.6 |
HIP 78492 |
17.33 |
| 2026-04-11 12:00 |
16:03:15.21 |
+55:27:03.3 |
HIP 78492 |
16.11 |
| 2026-04-12 00:00 |
16:03:08.38 |
+55:28:05.4 |
HIP 78492 |
14.92 |
| 2026-04-12 12:00 |
16:03:01.49 |
+55:29:06.9 |
HIP 78492 |
13.77 |
| 2026-04-13 00:00 |
16:02:54.54 |
+55:30:07.8 |
HIP 78492 |
12.67 |
| 2026-04-13 12:00 |
16:02:47.52 |
+55:31:08.1 |
HIP 78492 |
11.62 |
| 2026-04-14 00:00 |
16:02:40.43 |
+55:32:07.7 |
HIP 78492 |
10.65 |
| 2026-04-14 12:00 |
16:02:33.28 |
+55:33:06.8 |
HIP 78492 |
9.77 |
| 2026-04-15 00:00 |
16:02:26.07 |
+55:34:05.2 |
HIP 78492 |
9.03 |
| 2026-04-15 12:00 |
16:02:18.80 |
+55:35:02.9 |
HIP 78492 |
8.44 |
| 2026-04-16 00:00 |
16:02:11.46 |
+55:36:00.0 |
HIP 78492 |
8.04 |