| 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 · 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) |
| 2026-03-26 00:00 |
16:43:48.82 |
+24:46:18.1 |
HIP 81871 |
23.09 |
| 2026-03-26 12:00 |
16:43:46.11 |
+24:47:43.0 |
HIP 81871 |
21.56 |
| 2026-03-27 00:00 |
16:43:43.34 |
+24:49:07.8 |
HIP 81871 |
20.03 |
| 2026-03-27 12:00 |
16:43:40.51 |
+24:50:32.5 |
HIP 81871 |
18.51 |
| 2026-03-28 00:00 |
16:43:37.61 |
+24:51:56.9 |
HIP 81871 |
16.98 |
| 2026-03-28 12:00 |
16:43:34.65 |
+24:53:21.2 |
HIP 81871 |
15.47 |
| 2026-03-29 00:00 |
16:43:31.62 |
+24:54:45.3 |
HIP 81871 |
13.96 |
| 2026-03-29 12:00 |
16:43:28.54 |
+24:56:09.2 |
HIP 81871 |
12.46 |
| 2026-03-30 00:00 |
16:43:25.39 |
+24:57:32.9 |
HIP 81871 |
10.99 |
| 2026-03-30 12:00 |
16:43:22.18 |
+24:58:56.3 |
HIP 81871 |
9.55 |
| 2026-03-31 00:00 |
16:43:18.91 |
+25:00:19.6 |
HIP 81871 |
8.16 |
| 2026-03-31 12:00 |
16:43:15.58 |
+25:01:42.6 |
HIP 81871 |
6.86 |
| 2026-04-01 00:00 |
16:43:12.19 |
+25:03:05.5 |
HIP 81871 |
5.71 |
| 2026-04-01 12:00 |
16:43:08.73 |
+25:04:28.0 |
HIP 81871 |
4.81 |
| 2026-04-02 00:00 |
16:43:05.22 |
+25:05:50.4 |
HIP 81871 |
4.34 |
| 2026-04-02 12:00 |
16:43:01.64 |
+25:07:12.5 |
HIP 81871 |
4.44 |
| 2026-04-03 00:00 |
16:42:58.01 |
+25:08:34.4 |
HIP 81871 |
5.08 |
| 2026-04-03 12:00 |
16:42:54.31 |
+25:09:56.0 |
HIP 81871 |
6.09 |
| 2026-04-04 00:00 |
16:42:50.56 |
+25:11:17.3 |
HIP 81871 |
7.32 |
| 2026-04-04 12:00 |
16:42:46.74 |
+25:12:38.4 |
HIP 81871 |
8.69 |
| 2026-04-05 00:00 |
16:42:42.87 |
+25:13:59.2 |
HIP 81871 |
10.13 |
| 2026-04-05 12:00 |
16:42:38.94 |
+25:15:19.8 |
HIP 81871 |
11.62 |
| 2026-04-06 00:00 |
16:42:34.95 |
+25:16:40.0 |
HIP 81781 |
10.47 |
| 2026-04-06 12:00 |
16:42:30.90 |
+25:18:00.0 |
HIP 81781 |
8.87 |
| 2026-04-07 00:00 |
16:42:26.79 |
+25:19:19.7 |
HIP 81777 |
7.27 |
| 2026-04-07 12:00 |
16:42:22.63 |
+25:20:39.0 |
HIP 81777 |
5.65 |
| 2026-04-08 00:00 |
16:42:18.41 |
+25:21:58.1 |
HIP 81777 |
4.05 |
| 2026-04-08 12:00 |
16:42:14.13 |
+25:23:16.8 |
HIP 81777 |
2.47 |
| 2026-04-09 00:00 |
16:42:09.79 |
+25:24:35.3 |
HIP 81777 |
1.06 |
| 2026-04-09 12:00 |
16:42:05.40 |
+25:25:53.4 |
HIP 81777 |
1.24 |
| 2026-04-10 00:00 |
16:42:00.95 |
+25:27:11.1 |
HIP 81777 |
2.71 |
| 2026-04-10 12:00 |
16:41:56.45 |
+25:28:28.6 |
HIP 81777 |
4.31 |
| 2026-04-11 00:00 |
16:41:51.89 |
+25:29:45.7 |
HIP 81777 |
5.94 |
| 2026-04-11 12:00 |
16:41:47.27 |
+25:31:02.4 |
HIP 81777 |
7.58 |
| 2026-04-12 00:00 |
16:41:42.60 |
+25:32:18.8 |
HIP 81777 |
9.22 |
| 2026-04-12 12:00 |
16:41:37.88 |
+25:33:34.8 |
HIP 81777 |
10.88 |
| 2026-04-13 00:00 |
16:41:33.10 |
+25:34:50.5 |
HIP 81777 |
12.53 |
| 2026-04-13 12:00 |
16:41:28.27 |
+25:36:05.8 |
HIP 81777 |
14.20 |
| 2026-04-14 00:00 |
16:41:23.38 |
+25:37:20.7 |
HIP 81777 |
15.86 |
| 2026-04-14 12:00 |
16:41:18.44 |
+25:38:35.2 |
HIP 81777 |
17.53 |
| 2026-04-15 00:00 |
16:41:13.45 |
+25:39:49.3 |
HIP 81607 |
18.13 |
| 2026-04-15 12:00 |
16:41:08.41 |
+25:41:03.0 |
HIP 81607 |
17.69 |
| 2026-04-16 00:00 |
16:41:03.31 |
+25:42:16.4 |
HIP 81607 |
17.40 |