| Parameter |
Value |
| Designation |
C/2018 M1 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-07-10T00:35:11.529600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:44Z |
| Obs used |
171 |
| NEO |
- |
| M1 |
16.600 |
| K1 |
5.250 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-06-25T10:26:00.672000Z |
| Discovery magnitude (MPC) |
17.60 G |
| Discovery observatory (MPC) |
703 · University of Arizona Catalina Sky Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-08-16.0000000 |
| e |
0.93870003 |
| q (au) |
1.303480 |
| a (au) |
21.263951 |
| i (deg) |
37.257024 |
| Ω (om, deg) |
339.463309 |
| ω (w, deg) |
14.132786 |
| M (ma, deg) |
0.371666 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.433 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.433 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.965 |
| δ90 |
1.000 |
| 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 |
10:30:33.92 |
+14:33:28.8 |
HIP 51392 |
27.20 |
| 2026-09-20 12:00 |
10:30:39.42 |
+14:32:55.6 |
HIP 51392 |
27.28 |
| 2026-09-21 00:00 |
10:30:44.90 |
+14:32:22.6 |
HIP 51392 |
27.43 |
| 2026-09-21 12:00 |
10:30:50.37 |
+14:31:49.7 |
HIP 51392 |
27.66 |
| 2026-09-22 00:00 |
10:30:55.81 |
+14:31:17.0 |
HIP 51392 |
27.96 |
| 2026-09-22 12:00 |
10:31:01.24 |
+14:30:44.4 |
HIP 51627 |
26.88 |
| 2026-09-23 00:00 |
10:31:06.64 |
+14:30:12.0 |
HIP 51627 |
25.76 |
| 2026-09-23 12:00 |
10:31:12.03 |
+14:29:39.8 |
HIP 51627 |
24.67 |
| 2026-09-24 00:00 |
10:31:17.40 |
+14:29:07.7 |
HIP 51627 |
23.61 |
| 2026-09-24 12:00 |
10:31:22.75 |
+14:28:35.8 |
HIP 51627 |
22.60 |
| 2026-09-25 00:00 |
10:31:28.08 |
+14:28:04.1 |
HIP 51627 |
21.64 |
| 2026-09-25 12:00 |
10:31:33.39 |
+14:27:32.5 |
HIP 51627 |
20.72 |
| 2026-09-26 00:00 |
10:31:38.68 |
+14:27:01.1 |
HIP 51627 |
19.86 |
| 2026-09-26 12:00 |
10:31:43.95 |
+14:26:29.8 |
HIP 51627 |
19.07 |
| 2026-09-27 00:00 |
10:31:49.20 |
+14:25:58.8 |
HIP 51627 |
18.35 |
| 2026-09-27 12:00 |
10:31:54.42 |
+14:25:27.9 |
HIP 51627 |
17.71 |
| 2026-09-28 00:00 |
10:31:59.62 |
+14:24:57.1 |
HIP 51585 |
16.98 |
| 2026-09-28 12:00 |
10:32:04.81 |
+14:24:26.6 |
HIP 51585 |
16.30 |
| 2026-09-29 00:00 |
10:32:09.97 |
+14:23:56.2 |
HIP 51585 |
15.71 |
| 2026-09-29 12:00 |
10:32:15.10 |
+14:23:26.0 |
HIP 51585 |
15.22 |
| 2026-09-30 00:00 |
10:32:20.22 |
+14:22:56.0 |
HIP 51585 |
14.84 |
| 2026-09-30 12:00 |
10:32:25.31 |
+14:22:26.2 |
HIP 51585 |
14.58 |
| 2026-10-01 00:00 |
10:32:30.37 |
+14:21:56.6 |
HIP 51585 |
14.43 |
| 2026-10-01 12:00 |
10:32:35.42 |
+14:21:27.1 |
HIP 51585 |
14.41 |
| 2026-10-02 00:00 |
10:32:40.44 |
+14:20:57.9 |
HIP 51585 |
14.50 |
| 2026-10-02 12:00 |
10:32:45.43 |
+14:20:28.8 |
HIP 51585 |
14.71 |
| 2026-10-03 00:00 |
10:32:50.40 |
+14:20:00.0 |
HIP 51585 |
15.03 |
| 2026-10-03 12:00 |
10:32:55.34 |
+14:19:31.3 |
HIP 51585 |
15.45 |
| 2026-10-04 00:00 |
10:33:00.26 |
+14:19:02.8 |
HIP 51585 |
15.96 |
| 2026-10-04 12:00 |
10:33:05.16 |
+14:18:34.5 |
HIP 51585 |
16.56 |
| 2026-10-05 00:00 |
10:33:10.02 |
+14:18:06.4 |
HIP 51585 |
17.22 |
| 2026-10-05 12:00 |
10:33:14.86 |
+14:17:38.5 |
HIP 51585 |
17.95 |
| 2026-10-06 00:00 |
10:33:19.67 |
+14:17:10.9 |
HIP 51585 |
18.73 |
| 2026-10-06 12:00 |
10:33:24.46 |
+14:16:43.4 |
HIP 51585 |
19.55 |
| 2026-10-07 00:00 |
10:33:29.22 |
+14:16:16.1 |
HIP 51585 |
20.41 |
| 2026-10-07 12:00 |
10:33:33.95 |
+14:15:49.1 |
HIP 51585 |
21.31 |
| 2026-10-08 00:00 |
10:33:38.65 |
+14:15:22.2 |
HIP 51585 |
22.23 |
| 2026-10-08 12:00 |
10:33:43.32 |
+14:14:55.6 |
HIP 51585 |
23.17 |
| 2026-10-09 00:00 |
10:33:47.97 |
+14:14:29.2 |
HIP 51585 |
24.13 |
| 2026-10-09 12:00 |
10:33:52.58 |
+14:14:03.0 |
HIP 51585 |
25.11 |
| 2026-10-10 00:00 |
10:33:57.17 |
+14:13:37.0 |
HIP 51585 |
26.10 |
| 2026-10-10 12:00 |
10:34:01.72 |
+14:13:11.2 |
HIP 51585 |
27.10 |
| 2026-10-11 00:00 |
10:34:06.25 |
+14:12:45.7 |
HIP 51585 |
28.11 |