C/2018 O1 (ATLAS)
| 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) |
| 2026-02-03 00:00 |
08:28:59.83 |
-00:44:30.9 |
HIP 41645 |
15.17 |
| 2026-02-03 12:00 |
08:28:52.65 |
-00:43:56.5 |
HIP 41645 |
16.62 |
| 2026-02-04 00:00 |
08:28:45.49 |
-00:43:21.9 |
HIP 41645 |
18.15 |
| 2026-02-04 12:00 |
08:28:38.34 |
-00:42:47.0 |
HIP 41645 |
19.74 |
| 2026-02-05 00:00 |
08:28:31.21 |
-00:42:11.8 |
HIP 41645 |
21.38 |
| 2026-02-05 12:00 |
08:28:24.08 |
-00:41:36.4 |
HIP 41645 |
23.06 |
| 2026-02-06 00:00 |
08:28:16.97 |
-00:41:00.7 |
HIP 41645 |
24.77 |
| 2026-02-06 12:00 |
08:28:09.88 |
-00:40:24.8 |
HIP 41645 |
26.49 |
| 2026-02-07 00:00 |
08:28:02.80 |
-00:39:48.6 |
HIP 41425 |
25.26 |
| 2026-02-07 12:00 |
08:27:55.73 |
-00:39:12.2 |
HIP 41425 |
23.67 |
| 2026-02-08 00:00 |
08:27:48.69 |
-00:38:35.6 |
HIP 41425 |
22.13 |
| 2026-02-08 12:00 |
08:27:41.66 |
-00:37:58.8 |
HIP 41425 |
20.65 |
| 2026-02-09 00:00 |
08:27:34.64 |
-00:37:21.7 |
HIP 41425 |
19.22 |
| 2026-02-09 12:00 |
08:27:27.65 |
-00:36:44.3 |
HIP 41425 |
17.88 |
| 2026-02-10 00:00 |
08:27:20.67 |
-00:36:06.8 |
HIP 41425 |
16.63 |
| 2026-02-10 12:00 |
08:27:13.72 |
-00:35:29.0 |
HIP 41425 |
15.50 |
| 2026-02-11 00:00 |
08:27:06.78 |
-00:34:51.0 |
HIP 41425 |
14.52 |
| 2026-02-11 12:00 |
08:26:59.86 |
-00:34:12.8 |
HIP 41425 |
13.72 |
| 2026-02-12 00:00 |
08:26:52.97 |
-00:33:34.4 |
HIP 41425 |
13.12 |
| 2026-02-12 12:00 |
08:26:46.09 |
-00:32:55.8 |
HIP 41425 |
12.75 |
| 2026-02-13 00:00 |
08:26:39.24 |
-00:32:17.0 |
HIP 41425 |
12.64 |
| 2026-02-13 12:00 |
08:26:32.41 |
-00:31:38.0 |
HIP 41425 |
12.78 |
| 2026-02-14 00:00 |
08:26:25.61 |
-00:30:58.7 |
HIP 120004 |
11.26 |
| 2026-02-14 12:00 |
08:26:18.82 |
-00:30:19.3 |
HIP 120004 |
9.50 |
| 2026-02-15 00:00 |
08:26:12.07 |
-00:29:39.7 |
HIP 120004 |
7.77 |
| 2026-02-15 12:00 |
08:26:05.33 |
-00:28:59.9 |
HIP 120004 |
6.10 |
| 2026-02-16 00:00 |
08:25:58.63 |
-00:28:19.9 |
HIP 120004 |
4.52 |
| 2026-02-16 12:00 |
08:25:51.95 |
-00:27:39.7 |
HIP 120004 |
3.19 |
| 2026-02-17 00:00 |
08:25:45.29 |
-00:26:59.4 |
HIP 41313 |
2.30 |
| 2026-02-17 12:00 |
08:25:38.67 |
-00:26:18.8 |
HIP 41313 |
2.45 |
| 2026-02-18 00:00 |
08:25:32.07 |
-00:25:38.1 |
HIP 41313 |
3.61 |
| 2026-02-18 12:00 |
08:25:25.50 |
-00:24:57.3 |
HIP 41313 |
5.14 |
| 2026-02-19 00:00 |
08:25:18.96 |
-00:24:16.2 |
HIP 41313 |
6.78 |
| 2026-02-19 12:00 |
08:25:12.44 |
-00:23:35.1 |
HIP 41313 |
8.47 |
| 2026-02-20 00:00 |
08:25:05.96 |
-00:22:53.7 |
HIP 41313 |
10.18 |
| 2026-02-20 12:00 |
08:24:59.51 |
-00:22:12.2 |
HIP 41313 |
11.89 |
| 2026-02-21 00:00 |
08:24:53.09 |
-00:21:30.5 |
HIP 41230 |
13.17 |
| 2026-02-21 12:00 |
08:24:46.70 |
-00:20:48.8 |
HIP 41230 |
12.43 |
| 2026-02-22 00:00 |
08:24:40.34 |
-00:20:06.8 |
HIP 41230 |
11.90 |
| 2026-02-22 12:00 |
08:24:34.02 |
-00:19:24.7 |
HIP 41230 |
11.60 |
| 2026-02-23 00:00 |
08:24:27.73 |
-00:18:42.5 |
HIP 41230 |
11.56 |
| 2026-02-23 12:00 |
08:24:21.47 |
-00:18:00.2 |
HIP 41230 |
11.76 |
| 2026-02-24 00:00 |
08:24:15.25 |
-00:17:17.7 |
HIP 41230 |
12.19 |