| 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) |
| 2026-05-12 00:00 |
08:17:46.42 |
+01:23:59.3 |
HIP 40624 |
15.47 |
| 2026-05-12 12:00 |
08:17:47.90 |
+01:24:25.2 |
HIP 40624 |
15.96 |
| 2026-05-13 00:00 |
08:17:49.44 |
+01:24:50.9 |
HIP 40624 |
16.46 |
| 2026-05-13 12:00 |
08:17:51.01 |
+01:25:16.3 |
HIP 40624 |
16.96 |
| 2026-05-14 00:00 |
08:17:52.64 |
+01:25:41.5 |
HIP 40624 |
17.46 |
| 2026-05-14 12:00 |
08:17:54.31 |
+01:26:06.3 |
HIP 40624 |
17.97 |
| 2026-05-15 00:00 |
08:17:56.03 |
+01:26:30.9 |
HIP 40624 |
18.48 |
| 2026-05-15 12:00 |
08:17:57.80 |
+01:26:55.2 |
HIP 40624 |
18.99 |
| 2026-05-16 00:00 |
08:17:59.61 |
+01:27:19.2 |
HIP 40624 |
19.51 |
| 2026-05-16 12:00 |
08:18:01.46 |
+01:27:43.0 |
HIP 40624 |
20.03 |
| 2026-05-17 00:00 |
08:18:03.37 |
+01:28:06.5 |
HIP 40774 |
20.47 |
| 2026-05-17 12:00 |
08:18:05.31 |
+01:28:29.7 |
HIP 40774 |
20.17 |
| 2026-05-18 00:00 |
08:18:07.31 |
+01:28:52.6 |
HIP 40774 |
19.88 |
| 2026-05-18 12:00 |
08:18:09.34 |
+01:29:15.3 |
HIP 40774 |
19.59 |
| 2026-05-19 00:00 |
08:18:11.42 |
+01:29:37.6 |
HIP 40774 |
19.31 |
| 2026-05-19 12:00 |
08:18:13.55 |
+01:29:59.7 |
HIP 40774 |
19.03 |
| 2026-05-20 00:00 |
08:18:15.72 |
+01:30:21.5 |
HIP 40783 |
18.47 |
| 2026-05-20 12:00 |
08:18:17.93 |
+01:30:43.0 |
HIP 40783 |
17.84 |
| 2026-05-21 00:00 |
08:18:20.19 |
+01:31:04.2 |
HIP 40783 |
17.19 |
| 2026-05-21 12:00 |
08:18:22.48 |
+01:31:25.2 |
HIP 40783 |
16.54 |
| 2026-05-22 00:00 |
08:18:24.82 |
+01:31:45.8 |
HIP 40783 |
15.88 |
| 2026-05-22 12:00 |
08:18:27.21 |
+01:32:06.2 |
HIP 40783 |
15.22 |
| 2026-05-23 00:00 |
08:18:29.63 |
+01:32:26.3 |
HIP 40783 |
14.54 |
| 2026-05-23 12:00 |
08:18:32.10 |
+01:32:46.1 |
HIP 40783 |
13.86 |
| 2026-05-24 00:00 |
08:18:34.61 |
+01:33:05.6 |
HIP 40783 |
13.18 |
| 2026-05-24 12:00 |
08:18:37.16 |
+01:33:24.9 |
HIP 40783 |
12.48 |
| 2026-05-25 00:00 |
08:18:39.75 |
+01:33:43.8 |
HIP 40783 |
11.79 |
| 2026-05-25 12:00 |
08:18:42.38 |
+01:34:02.5 |
HIP 40783 |
11.08 |
| 2026-05-26 00:00 |
08:18:45.05 |
+01:34:20.9 |
HIP 40783 |
10.37 |
| 2026-05-26 12:00 |
08:18:47.76 |
+01:34:38.9 |
HIP 40783 |
9.65 |
| 2026-05-27 00:00 |
08:18:50.51 |
+01:34:56.7 |
HIP 40783 |
8.92 |
| 2026-05-27 12:00 |
08:18:53.30 |
+01:35:14.3 |
HIP 40783 |
8.20 |
| 2026-05-28 00:00 |
08:18:56.13 |
+01:35:31.5 |
HIP 40783 |
7.46 |
| 2026-05-28 12:00 |
08:18:58.99 |
+01:35:48.4 |
HIP 40783 |
6.73 |
| 2026-05-29 00:00 |
08:19:01.90 |
+01:36:05.1 |
HIP 40783 |
5.99 |
| 2026-05-29 12:00 |
08:19:04.84 |
+01:36:21.4 |
HIP 40783 |
5.26 |
| 2026-05-30 00:00 |
08:19:07.82 |
+01:36:37.5 |
HIP 40783 |
4.53 |
| 2026-05-30 12:00 |
08:19:10.84 |
+01:36:53.3 |
HIP 40783 |
3.82 |
| 2026-05-31 00:00 |
08:19:13.90 |
+01:37:08.8 |
HIP 40783 |
3.15 |
| 2026-05-31 12:00 |
08:19:17.00 |
+01:37:24.0 |
HIP 40783 |
2.54 |
| 2026-06-01 00:00 |
08:19:20.13 |
+01:37:38.9 |
HIP 40783 |
2.06 |
| 2026-06-01 12:00 |
08:19:23.29 |
+01:37:53.6 |
HIP 40783 |
1.84 |
| 2026-06-02 00:00 |
08:19:26.50 |
+01:38:07.9 |
HIP 40783 |
1.96 |