| 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) |
| 2026-07-29 00:00 |
10:20:22.42 |
+15:40:04.4 |
HIP 50560 |
11.25 |
| 2026-07-29 12:00 |
10:20:27.82 |
+15:39:25.8 |
HIP 50560 |
12.70 |
| 2026-07-30 00:00 |
10:20:33.24 |
+15:38:47.2 |
HIP 50560 |
14.15 |
| 2026-07-30 12:00 |
10:20:38.68 |
+15:38:08.5 |
HIP 50560 |
15.61 |
| 2026-07-31 00:00 |
10:20:44.14 |
+15:37:29.8 |
HIP 50750 |
16.10 |
| 2026-07-31 12:00 |
10:20:49.62 |
+15:36:51.0 |
HIP 50750 |
14.64 |
| 2026-08-01 00:00 |
10:20:55.11 |
+15:36:12.2 |
HIP 50750 |
13.18 |
| 2026-08-01 12:00 |
10:21:00.62 |
+15:35:33.4 |
HIP 50750 |
11.72 |
| 2026-08-02 00:00 |
10:21:06.14 |
+15:34:54.5 |
HIP 50750 |
10.26 |
| 2026-08-02 12:00 |
10:21:11.68 |
+15:34:15.6 |
HIP 50750 |
8.80 |
| 2026-08-03 00:00 |
10:21:17.24 |
+15:33:36.7 |
HIP 50750 |
7.35 |
| 2026-08-03 12:00 |
10:21:22.82 |
+15:32:57.7 |
HIP 50750 |
5.91 |
| 2026-08-04 00:00 |
10:21:28.41 |
+15:32:18.7 |
HIP 50750 |
4.50 |
| 2026-08-04 12:00 |
10:21:34.01 |
+15:31:39.6 |
HIP 50750 |
3.17 |
| 2026-08-05 00:00 |
10:21:39.63 |
+15:31:00.5 |
HIP 50750 |
2.08 |
| 2026-08-05 12:00 |
10:21:45.26 |
+15:30:21.4 |
HIP 50750 |
1.76 |
| 2026-08-06 00:00 |
10:21:50.91 |
+15:29:42.3 |
HIP 50750 |
2.53 |
| 2026-08-06 12:00 |
10:21:56.57 |
+15:29:03.2 |
HIP 50750 |
3.78 |
| 2026-08-07 00:00 |
10:22:02.25 |
+15:28:24.0 |
HIP 50750 |
5.17 |
| 2026-08-07 12:00 |
10:22:07.93 |
+15:27:44.8 |
HIP 50750 |
6.62 |
| 2026-08-08 00:00 |
10:22:13.63 |
+15:27:05.7 |
HIP 50750 |
8.10 |
| 2026-08-08 12:00 |
10:22:19.35 |
+15:26:26.4 |
HIP 50829 |
8.27 |
| 2026-08-09 00:00 |
10:22:25.07 |
+15:25:47.2 |
HIP 50829 |
6.84 |
| 2026-08-09 12:00 |
10:22:30.81 |
+15:25:08.0 |
HIP 50829 |
5.47 |
| 2026-08-10 00:00 |
10:22:36.56 |
+15:24:28.7 |
HIP 50829 |
4.20 |
| 2026-08-10 12:00 |
10:22:42.32 |
+15:23:49.5 |
HIP 50829 |
3.17 |
| 2026-08-11 00:00 |
10:22:48.09 |
+15:23:10.2 |
HIP 50829 |
2.69 |
| 2026-08-11 12:00 |
10:22:53.87 |
+15:22:31.0 |
HIP 50829 |
3.02 |
| 2026-08-12 00:00 |
10:22:59.66 |
+15:21:51.7 |
HIP 50829 |
3.97 |
| 2026-08-12 12:00 |
10:23:05.46 |
+15:21:12.5 |
HIP 50829 |
5.21 |
| 2026-08-13 00:00 |
10:23:11.28 |
+15:20:33.2 |
HIP 50829 |
6.59 |
| 2026-08-13 12:00 |
10:23:17.09 |
+15:19:54.0 |
HIP 50829 |
8.03 |
| 2026-08-14 00:00 |
10:23:22.92 |
+15:19:14.8 |
HIP 50829 |
9.50 |
| 2026-08-14 12:00 |
10:23:28.76 |
+15:18:35.5 |
HIP 50829 |
11.00 |
| 2026-08-15 00:00 |
10:23:34.60 |
+15:17:56.3 |
HIP 50829 |
12.51 |
| 2026-08-15 12:00 |
10:23:40.45 |
+15:17:17.1 |
HIP 50829 |
14.04 |
| 2026-08-16 00:00 |
10:23:46.31 |
+15:16:37.9 |
HIP 50829 |
15.57 |
| 2026-08-16 12:00 |
10:23:52.18 |
+15:15:58.8 |
HIP 50829 |
17.11 |
| 2026-08-17 00:00 |
10:23:58.05 |
+15:15:19.6 |
HIP 50829 |
18.65 |
| 2026-08-17 12:00 |
10:24:03.93 |
+15:14:40.5 |
HIP 50829 |
20.20 |
| 2026-08-18 00:00 |
10:24:09.81 |
+15:14:01.4 |
HIP 50829 |
21.75 |
| 2026-08-18 12:00 |
10:24:15.70 |
+15:13:22.4 |
HIP 50829 |
23.30 |
| 2026-08-19 00:00 |
10:24:21.59 |
+15:12:43.3 |
HIP 50911 |
24.81 |