| Parameter |
Value |
| Designation |
C/2018 O1 (ATLAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-08-31T13:40:52.855680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:46Z |
| Obs used |
331 |
| NEO |
- |
| M1 |
12.100 |
| K1 |
34.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-07-22T13:05:00.960000Z |
| Discovery magnitude (MPC) |
18.70 o |
| Discovery observatory (MPC) |
T08 · ATLAS-MLO, Mauna Loa |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-08-03.0000000 |
| e |
0.94409847 |
| q (au) |
1.558174 |
| a (au) |
27.873557 |
| i (deg) |
154.041045 |
| Ω (om, deg) |
87.619000 |
| ω (w, deg) |
162.502789 |
| M (ma, deg) |
359.808651 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.182 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.182 |
| n |
6.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
08:36:02.74 |
+00:50:41.1 |
HIP 42119 |
31.85 |
| 2026-09-20 12:00 |
08:36:05.83 |
+00:50:11.1 |
HIP 42119 |
31.74 |
| 2026-09-21 00:00 |
08:36:08.88 |
+00:49:41.1 |
HIP 42119 |
31.64 |
| 2026-09-21 12:00 |
08:36:11.90 |
+00:49:11.2 |
HIP 42119 |
31.57 |
| 2026-09-22 00:00 |
08:36:14.87 |
+00:48:41.2 |
HIP 42119 |
31.52 |
| 2026-09-22 12:00 |
08:36:17.81 |
+00:48:11.2 |
HIP 42370 |
31.39 |
| 2026-09-23 00:00 |
08:36:20.71 |
+00:47:41.2 |
HIP 42370 |
30.57 |
| 2026-09-23 12:00 |
08:36:23.58 |
+00:47:11.1 |
HIP 42370 |
29.77 |
| 2026-09-24 00:00 |
08:36:26.40 |
+00:46:41.1 |
HIP 42370 |
28.98 |
| 2026-09-24 12:00 |
08:36:29.19 |
+00:46:11.1 |
HIP 42370 |
28.21 |
| 2026-09-25 00:00 |
08:36:31.94 |
+00:45:41.1 |
HIP 42370 |
27.45 |
| 2026-09-25 12:00 |
08:36:34.65 |
+00:45:11.0 |
HIP 42370 |
26.71 |
| 2026-09-26 00:00 |
08:36:37.31 |
+00:44:41.0 |
HIP 42370 |
25.98 |
| 2026-09-26 12:00 |
08:36:39.94 |
+00:44:11.0 |
HIP 42370 |
25.27 |
| 2026-09-27 00:00 |
08:36:42.54 |
+00:43:41.0 |
HIP 42370 |
24.58 |
| 2026-09-27 12:00 |
08:36:45.09 |
+00:43:11.0 |
HIP 42370 |
23.90 |
| 2026-09-28 00:00 |
08:36:47.60 |
+00:42:41.0 |
HIP 42370 |
23.24 |
| 2026-09-28 12:00 |
08:36:50.07 |
+00:42:11.1 |
HIP 42370 |
22.61 |
| 2026-09-29 00:00 |
08:36:52.50 |
+00:41:41.1 |
HIP 42370 |
21.99 |
| 2026-09-29 12:00 |
08:36:54.88 |
+00:41:11.2 |
HIP 42370 |
21.39 |
| 2026-09-30 00:00 |
08:36:57.23 |
+00:40:41.3 |
HIP 42370 |
20.82 |
| 2026-09-30 12:00 |
08:36:59.54 |
+00:40:11.4 |
HIP 42370 |
20.27 |
| 2026-10-01 00:00 |
08:37:01.80 |
+00:39:41.5 |
HIP 42370 |
19.74 |
| 2026-10-01 12:00 |
08:37:04.02 |
+00:39:11.7 |
HIP 42370 |
19.24 |
| 2026-10-02 00:00 |
08:37:06.20 |
+00:38:41.9 |
HIP 42370 |
18.76 |
| 2026-10-02 12:00 |
08:37:08.34 |
+00:38:12.1 |
HIP 42370 |
18.32 |
| 2026-10-03 00:00 |
08:37:10.44 |
+00:37:42.4 |
HIP 42370 |
17.90 |
| 2026-10-03 12:00 |
08:37:12.49 |
+00:37:12.7 |
HIP 42370 |
17.51 |
| 2026-10-04 00:00 |
08:37:14.50 |
+00:36:43.0 |
HIP 42370 |
17.16 |
| 2026-10-04 12:00 |
08:37:16.46 |
+00:36:13.4 |
HIP 42370 |
16.83 |
| 2026-10-05 00:00 |
08:37:18.38 |
+00:35:43.8 |
HIP 42370 |
16.54 |
| 2026-10-05 12:00 |
08:37:20.26 |
+00:35:14.3 |
HIP 42370 |
16.28 |
| 2026-10-06 00:00 |
08:37:22.10 |
+00:34:44.8 |
HIP 42370 |
16.06 |
| 2026-10-06 12:00 |
08:37:23.88 |
+00:34:15.4 |
HIP 42370 |
15.87 |
| 2026-10-07 00:00 |
08:37:25.63 |
+00:33:46.0 |
HIP 42370 |
15.72 |
| 2026-10-07 12:00 |
08:37:27.33 |
+00:33:16.7 |
HIP 42370 |
15.60 |
| 2026-10-08 00:00 |
08:37:28.98 |
+00:32:47.5 |
HIP 42370 |
15.52 |
| 2026-10-08 12:00 |
08:37:30.59 |
+00:32:18.3 |
HIP 42370 |
15.47 |
| 2026-10-09 00:00 |
08:37:32.15 |
+00:31:49.2 |
HIP 42370 |
15.45 |
| 2026-10-09 12:00 |
08:37:33.67 |
+00:31:20.1 |
HIP 42370 |
15.47 |
| 2026-10-10 00:00 |
08:37:35.14 |
+00:30:51.2 |
HIP 42370 |
15.52 |
| 2026-10-10 12:00 |
08:37:36.57 |
+00:30:22.3 |
HIP 42370 |
15.60 |
| 2026-10-11 00:00 |
08:37:37.95 |
+00:29:53.4 |
HIP 42370 |
15.71 |