| Parameter |
Value |
| Designation |
C/2017 S6 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-02-26T22:22:53.693760Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:35Z |
| Obs used |
247 |
| NEO |
- |
| M1 |
15.300 |
| K1 |
4.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-11-15.0000000 |
| e |
1.00140730 |
| q (au) |
1.542930 |
| a (au) |
-1096.375698 |
| i (deg) |
152.826812 |
| Ω (om, deg) |
130.873122 |
| ω (w, deg) |
134.685410 |
| M (ma, deg) |
-0.002822 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.010 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.010 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.676 |
| k |
0.800 |
| 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 |
| 2017-02-16 |
2017-10-28 |
+4.8973 |
-2.493 |
| 2017-10-28 |
2018-02-05 |
+7.2164 |
-2.343 |
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 |
12:53:27.35 |
-35:44:16.0 |
HIP 62813 |
18.67 |
| 2026-03-26 12:00 |
12:53:20.34 |
-35:43:50.4 |
HIP 62813 |
17.89 |
| 2026-03-27 00:00 |
12:53:13.32 |
-35:43:24.4 |
HIP 62813 |
17.20 |
| 2026-03-27 12:00 |
12:53:06.29 |
-35:42:58.0 |
HIP 62813 |
16.63 |
| 2026-03-28 00:00 |
12:52:59.26 |
-35:42:31.2 |
HIP 62813 |
16.18 |
| 2026-03-28 12:00 |
12:52:52.22 |
-35:42:03.9 |
HIP 62813 |
15.86 |
| 2026-03-29 00:00 |
12:52:45.18 |
-35:41:36.2 |
HIP 62813 |
15.68 |
| 2026-03-29 12:00 |
12:52:38.13 |
-35:41:08.1 |
HIP 62813 |
15.66 |
| 2026-03-30 00:00 |
12:52:31.08 |
-35:40:39.5 |
HIP 62813 |
15.78 |
| 2026-03-30 12:00 |
12:52:24.02 |
-35:40:10.6 |
HIP 62813 |
16.05 |
| 2026-03-31 00:00 |
12:52:16.96 |
-35:39:41.2 |
HIP 62813 |
16.47 |
| 2026-03-31 12:00 |
12:52:09.90 |
-35:39:11.4 |
HIP 62692 |
16.89 |
| 2026-04-01 00:00 |
12:52:02.84 |
-35:38:41.2 |
HIP 62692 |
15.43 |
| 2026-04-01 12:00 |
12:51:55.77 |
-35:38:10.5 |
HIP 62692 |
13.98 |
| 2026-04-02 00:00 |
12:51:48.71 |
-35:37:39.5 |
HIP 62692 |
12.55 |
| 2026-04-02 12:00 |
12:51:41.64 |
-35:37:08.1 |
HIP 62692 |
11.15 |
| 2026-04-03 00:00 |
12:51:34.57 |
-35:36:36.2 |
HIP 62692 |
9.78 |
| 2026-04-03 12:00 |
12:51:27.51 |
-35:36:04.0 |
HIP 62692 |
8.48 |
| 2026-04-04 00:00 |
12:51:20.45 |
-35:35:31.3 |
HIP 62692 |
7.26 |
| 2026-04-04 12:00 |
12:51:13.38 |
-35:34:58.3 |
HIP 62692 |
6.20 |
| 2026-04-05 00:00 |
12:51:06.33 |
-35:34:24.8 |
HIP 62692 |
5.37 |
| 2026-04-05 12:00 |
12:50:59.27 |
-35:33:51.0 |
HIP 62692 |
4.90 |
| 2026-04-06 00:00 |
12:50:52.22 |
-35:33:16.7 |
HIP 62692 |
4.90 |
| 2026-04-06 12:00 |
12:50:45.17 |
-35:32:42.1 |
HIP 62692 |
5.37 |
| 2026-04-07 00:00 |
12:50:38.12 |
-35:32:07.1 |
HIP 62692 |
6.21 |
| 2026-04-07 12:00 |
12:50:31.09 |
-35:31:31.7 |
HIP 62692 |
7.29 |
| 2026-04-08 00:00 |
12:50:24.05 |
-35:30:56.0 |
HIP 62692 |
8.52 |
| 2026-04-08 12:00 |
12:50:17.03 |
-35:30:19.8 |
HIP 62692 |
9.84 |
| 2026-04-09 00:00 |
12:50:10.01 |
-35:29:43.3 |
HIP 62692 |
11.23 |
| 2026-04-09 12:00 |
12:50:03.00 |
-35:29:06.5 |
HIP 62692 |
12.66 |
| 2026-04-10 00:00 |
12:49:55.99 |
-35:28:29.2 |
HIP 62692 |
14.11 |
| 2026-04-10 12:00 |
12:49:49.00 |
-35:27:51.6 |
HIP 62692 |
15.59 |
| 2026-04-11 00:00 |
12:49:42.01 |
-35:27:13.6 |
HIP 62692 |
17.09 |
| 2026-04-11 12:00 |
12:49:35.04 |
-35:26:35.3 |
HIP 62692 |
18.60 |
| 2026-04-12 00:00 |
12:49:28.07 |
-35:25:56.6 |
HIP 62692 |
20.11 |
| 2026-04-12 12:00 |
12:49:21.12 |
-35:25:17.5 |
HIP 62692 |
21.64 |
| 2026-04-13 00:00 |
12:49:14.18 |
-35:24:38.1 |
HIP 62467 |
22.33 |
| 2026-04-13 12:00 |
12:49:07.25 |
-35:23:58.4 |
HIP 62467 |
22.04 |
| 2026-04-14 00:00 |
12:49:00.33 |
-35:23:18.3 |
HIP 62467 |
21.85 |
| 2026-04-14 12:00 |
12:48:53.42 |
-35:22:37.8 |
HIP 62467 |
21.79 |
| 2026-04-15 00:00 |
12:48:46.53 |
-35:21:57.1 |
HIP 62467 |
21.84 |
| 2026-04-15 12:00 |
12:48:39.66 |
-35:21:16.0 |
HIP 62467 |
22.00 |
| 2026-04-16 00:00 |
12:48:32.79 |
-35:20:34.5 |
HIP 62467 |
22.28 |