| 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) |
| 2026-07-29 00:00 |
08:28:09.16 |
+01:34:40.5 |
HIP 41428 |
17.58 |
| 2026-07-29 12:00 |
08:28:14.38 |
+01:34:24.0 |
HIP 41428 |
18.90 |
| 2026-07-30 00:00 |
08:28:19.59 |
+01:34:07.2 |
HIP 41573 |
19.70 |
| 2026-07-30 12:00 |
08:28:24.79 |
+01:33:50.3 |
HIP 41573 |
19.19 |
| 2026-07-31 00:00 |
08:28:30.00 |
+01:33:33.2 |
HIP 41573 |
18.76 |
| 2026-07-31 12:00 |
08:28:35.19 |
+01:33:15.9 |
HIP 41573 |
18.41 |
| 2026-08-01 00:00 |
08:28:40.39 |
+01:32:58.3 |
HIP 41573 |
18.15 |
| 2026-08-01 12:00 |
08:28:45.58 |
+01:32:40.5 |
HIP 41573 |
17.98 |
| 2026-08-02 00:00 |
08:28:50.77 |
+01:32:22.6 |
HIP 41573 |
17.91 |
| 2026-08-02 12:00 |
08:28:55.95 |
+01:32:04.4 |
HIP 41573 |
17.93 |
| 2026-08-03 00:00 |
08:29:01.13 |
+01:31:46.0 |
HIP 41573 |
18.04 |
| 2026-08-03 12:00 |
08:29:06.31 |
+01:31:27.4 |
HIP 41573 |
18.25 |
| 2026-08-04 00:00 |
08:29:11.47 |
+01:31:08.6 |
HIP 41573 |
18.54 |
| 2026-08-04 12:00 |
08:29:16.63 |
+01:30:49.7 |
HIP 41573 |
18.93 |
| 2026-08-05 00:00 |
08:29:21.79 |
+01:30:30.5 |
HIP 41573 |
19.39 |
| 2026-08-05 12:00 |
08:29:26.94 |
+01:30:11.1 |
HIP 41573 |
19.92 |
| 2026-08-06 00:00 |
08:29:32.08 |
+01:29:51.5 |
HIP 41573 |
20.53 |
| 2026-08-06 12:00 |
08:29:37.21 |
+01:29:31.7 |
HIP 41573 |
21.19 |
| 2026-08-07 00:00 |
08:29:42.34 |
+01:29:11.8 |
HIP 41573 |
21.92 |
| 2026-08-07 12:00 |
08:29:47.46 |
+01:28:51.6 |
HIP 41766 |
20.66 |
| 2026-08-08 00:00 |
08:29:52.57 |
+01:28:31.2 |
HIP 41766 |
19.36 |
| 2026-08-08 12:00 |
08:29:57.67 |
+01:28:10.7 |
HIP 41766 |
18.06 |
| 2026-08-09 00:00 |
08:30:02.76 |
+01:27:50.0 |
HIP 41766 |
16.77 |
| 2026-08-09 12:00 |
08:30:07.84 |
+01:27:29.0 |
HIP 41766 |
15.48 |
| 2026-08-10 00:00 |
08:30:12.91 |
+01:27:07.9 |
HIP 41766 |
14.20 |
| 2026-08-10 12:00 |
08:30:17.98 |
+01:26:46.6 |
HIP 41766 |
12.93 |
| 2026-08-11 00:00 |
08:30:23.03 |
+01:26:25.2 |
HIP 41766 |
11.66 |
| 2026-08-11 12:00 |
08:30:28.07 |
+01:26:03.5 |
HIP 41766 |
10.41 |
| 2026-08-12 00:00 |
08:30:33.10 |
+01:25:41.7 |
HIP 41766 |
9.17 |
| 2026-08-12 12:00 |
08:30:38.11 |
+01:25:19.7 |
HIP 41766 |
7.96 |
| 2026-08-13 00:00 |
08:30:43.12 |
+01:24:57.5 |
HIP 41766 |
6.78 |
| 2026-08-13 12:00 |
08:30:48.11 |
+01:24:35.1 |
HIP 41766 |
5.66 |
| 2026-08-14 00:00 |
08:30:53.09 |
+01:24:12.6 |
HIP 41766 |
4.63 |
| 2026-08-14 12:00 |
08:30:58.06 |
+01:23:49.9 |
HIP 41766 |
3.77 |
| 2026-08-15 00:00 |
08:31:03.01 |
+01:23:27.0 |
HIP 41766 |
3.21 |
| 2026-08-15 12:00 |
08:31:07.95 |
+01:23:04.0 |
HIP 41766 |
3.13 |
| 2026-08-16 00:00 |
08:31:12.88 |
+01:22:40.8 |
HIP 41766 |
3.54 |
| 2026-08-16 12:00 |
08:31:17.79 |
+01:22:17.4 |
HIP 41766 |
4.31 |
| 2026-08-17 00:00 |
08:31:22.68 |
+01:21:53.9 |
HIP 41766 |
5.29 |
| 2026-08-17 12:00 |
08:31:27.56 |
+01:21:30.2 |
HIP 41766 |
6.37 |
| 2026-08-18 00:00 |
08:31:32.42 |
+01:21:06.4 |
HIP 41766 |
7.51 |
| 2026-08-18 12:00 |
08:31:37.27 |
+01:20:42.4 |
HIP 41766 |
8.68 |
| 2026-08-19 00:00 |
08:31:42.10 |
+01:20:18.3 |
HIP 41766 |
9.87 |