| Parameter |
Value |
| Designation |
C/2018 W1 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-05-11T20:28:13.800000Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:48Z |
| Obs used |
287 |
| NEO |
- |
| M1 |
14.000 |
| K1 |
10.000 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-11-16T04:47:27.168000Z |
| Discovery magnitude (MPC) |
19.80 G |
| Discovery observatory (MPC) |
703 · University of Arizona Catalina Sky Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-01-26.0000000 |
| e |
0.93766329 |
| q (au) |
1.360177 |
| a (au) |
21.819838 |
| i (deg) |
83.278879 |
| Ω (om, deg) |
233.589579 |
| ω (w, deg) |
251.248066 |
| M (ma, deg) |
358.976401 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.588 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.588 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.941 |
| k |
0.999 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2018-11-16 |
2019-03-08 |
-1.4661 |
+0.573 |
| 2019-05-26 |
2020-05-21 |
+6.2919 |
-4.653 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
16:18:41.43 |
+24:31:37.0 |
HIP 79930 |
3.93 |
| 2026-09-20 12:00 |
16:18:44.31 |
+24:30:36.2 |
HIP 79930 |
2.73 |
| 2026-09-21 00:00 |
16:18:47.24 |
+24:29:35.4 |
HIP 79930 |
1.52 |
| 2026-09-21 12:00 |
16:18:50.23 |
+24:28:34.9 |
HIP 79930 |
0.33 |
| 2026-09-22 00:00 |
16:18:53.27 |
+24:27:34.5 |
HIP 79930 |
0.94 |
| 2026-09-22 12:00 |
16:18:56.36 |
+24:26:34.3 |
HIP 79930 |
2.15 |
| 2026-09-23 00:00 |
16:18:59.51 |
+24:25:34.3 |
HIP 79930 |
3.38 |
| 2026-09-23 12:00 |
16:19:02.70 |
+24:24:34.5 |
HIP 79930 |
4.61 |
| 2026-09-24 00:00 |
16:19:05.95 |
+24:23:34.9 |
HIP 79930 |
5.85 |
| 2026-09-24 12:00 |
16:19:09.25 |
+24:22:35.4 |
HIP 79930 |
7.09 |
| 2026-09-25 00:00 |
16:19:12.60 |
+24:21:36.2 |
HIP 79930 |
8.34 |
| 2026-09-25 12:00 |
16:19:16.00 |
+24:20:37.2 |
HIP 79930 |
9.59 |
| 2026-09-26 00:00 |
16:19:19.45 |
+24:19:38.4 |
HIP 79930 |
10.84 |
| 2026-09-26 12:00 |
16:19:22.95 |
+24:18:39.8 |
HIP 79930 |
12.10 |
| 2026-09-27 00:00 |
16:19:26.50 |
+24:17:41.4 |
HIP 79930 |
13.37 |
| 2026-09-27 12:00 |
16:19:30.10 |
+24:16:43.2 |
HIP 79930 |
14.63 |
| 2026-09-28 00:00 |
16:19:33.75 |
+24:15:45.2 |
HIP 79930 |
15.91 |
| 2026-09-28 12:00 |
16:19:37.45 |
+24:14:47.5 |
HIP 79930 |
17.18 |
| 2026-09-29 00:00 |
16:19:41.20 |
+24:13:50.0 |
HIP 79930 |
18.46 |
| 2026-09-29 12:00 |
16:19:44.99 |
+24:12:52.7 |
HIP 79930 |
19.75 |
| 2026-09-30 00:00 |
16:19:48.84 |
+24:11:55.7 |
HIP 79930 |
21.04 |
| 2026-09-30 12:00 |
16:19:52.73 |
+24:10:58.9 |
HIP 79930 |
22.33 |
| 2026-10-01 00:00 |
16:19:56.68 |
+24:10:02.4 |
HIP 79930 |
23.63 |
| 2026-10-01 12:00 |
16:20:00.66 |
+24:09:06.1 |
HIP 79930 |
24.93 |
| 2026-10-02 00:00 |
16:20:04.70 |
+24:08:10.1 |
HIP 79930 |
26.24 |
| 2026-10-02 12:00 |
16:20:08.78 |
+24:07:14.3 |
HIP 80006 |
26.56 |
| 2026-10-03 00:00 |
16:20:12.92 |
+24:06:18.8 |
HIP 80006 |
25.80 |
| 2026-10-03 12:00 |
16:20:17.09 |
+24:05:23.5 |
HIP 80006 |
25.09 |
| 2026-10-04 00:00 |
16:20:21.32 |
+24:04:28.5 |
HIP 80006 |
24.44 |
| 2026-10-04 12:00 |
16:20:25.59 |
+24:03:33.8 |
HIP 80006 |
23.85 |
| 2026-10-05 00:00 |
16:20:29.90 |
+24:02:39.4 |
HIP 80006 |
23.33 |
| 2026-10-05 12:00 |
16:20:34.27 |
+24:01:45.2 |
HIP 80006 |
22.89 |
| 2026-10-06 00:00 |
16:20:38.67 |
+24:00:51.4 |
HIP 80006 |
22.53 |
| 2026-10-06 12:00 |
16:20:43.13 |
+23:59:57.8 |
HIP 80006 |
22.26 |
| 2026-10-07 00:00 |
16:20:47.62 |
+23:59:04.6 |
HIP 80103 |
21.39 |
| 2026-10-07 12:00 |
16:20:52.16 |
+23:58:11.6 |
HIP 80103 |
20.34 |
| 2026-10-08 00:00 |
16:20:56.75 |
+23:57:18.9 |
HIP 80103 |
19.33 |
| 2026-10-08 12:00 |
16:21:01.38 |
+23:56:26.5 |
HIP 80103 |
18.37 |
| 2026-10-09 00:00 |
16:21:06.05 |
+23:55:34.5 |
HIP 80103 |
17.47 |
| 2026-10-09 12:00 |
16:21:10.77 |
+23:54:42.8 |
HIP 80103 |
16.64 |
| 2026-10-10 00:00 |
16:21:15.53 |
+23:53:51.4 |
HIP 80103 |
15.89 |
| 2026-10-10 12:00 |
16:21:20.33 |
+23:53:00.3 |
HIP 80103 |
15.24 |
| 2026-10-11 00:00 |
16:21:25.17 |
+23:52:09.5 |
HIP 80103 |
14.70 |