C/2017 S6 (Catalina)
| 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) |
| 2026-02-03 00:00 |
13:03:03.09 |
-35:47:22.3 |
HIP 63589 |
24.27 |
| 2026-02-03 12:00 |
13:02:59.56 |
-35:47:42.8 |
HIP 63589 |
23.58 |
| 2026-02-04 00:00 |
13:02:55.99 |
-35:48:03.0 |
HIP 63589 |
22.89 |
| 2026-02-04 12:00 |
13:02:52.36 |
-35:48:22.7 |
HIP 63589 |
22.20 |
| 2026-02-05 00:00 |
13:02:48.67 |
-35:48:42.1 |
HIP 63589 |
21.53 |
| 2026-02-05 12:00 |
13:02:44.94 |
-35:49:01.0 |
HIP 63589 |
20.86 |
| 2026-02-06 00:00 |
13:02:41.15 |
-35:49:19.6 |
HIP 63589 |
20.20 |
| 2026-02-06 12:00 |
13:02:37.31 |
-35:49:37.7 |
HIP 63589 |
19.56 |
| 2026-02-07 00:00 |
13:02:33.41 |
-35:49:55.5 |
HIP 63589 |
18.94 |
| 2026-02-07 12:00 |
13:02:29.47 |
-35:50:12.8 |
HIP 63589 |
18.34 |
| 2026-02-08 00:00 |
13:02:25.47 |
-35:50:29.8 |
HIP 63589 |
17.75 |
| 2026-02-08 12:00 |
13:02:21.43 |
-35:50:46.3 |
HIP 63589 |
17.20 |
| 2026-02-09 00:00 |
13:02:17.33 |
-35:51:02.4 |
HIP 63589 |
16.67 |
| 2026-02-09 12:00 |
13:02:13.18 |
-35:51:18.1 |
HIP 63589 |
16.18 |
| 2026-02-10 00:00 |
13:02:08.98 |
-35:51:33.4 |
HIP 63589 |
15.72 |
| 2026-02-10 12:00 |
13:02:04.73 |
-35:51:48.3 |
HIP 63589 |
15.31 |
| 2026-02-11 00:00 |
13:02:00.43 |
-35:52:02.7 |
HIP 63589 |
14.94 |
| 2026-02-11 12:00 |
13:01:56.08 |
-35:52:16.7 |
HIP 63589 |
14.63 |
| 2026-02-12 00:00 |
13:01:51.68 |
-35:52:30.3 |
HIP 63589 |
14.38 |
| 2026-02-12 12:00 |
13:01:47.23 |
-35:52:43.5 |
HIP 63589 |
14.19 |
| 2026-02-13 00:00 |
13:01:42.74 |
-35:52:56.2 |
HIP 63589 |
14.07 |
| 2026-02-13 12:00 |
13:01:38.19 |
-35:53:08.5 |
HIP 63589 |
14.02 |
| 2026-02-14 00:00 |
13:01:33.59 |
-35:53:20.4 |
HIP 63589 |
14.04 |
| 2026-02-14 12:00 |
13:01:28.95 |
-35:53:31.8 |
HIP 63589 |
14.13 |
| 2026-02-15 00:00 |
13:01:24.26 |
-35:53:42.8 |
HIP 63589 |
14.30 |
| 2026-02-15 12:00 |
13:01:19.53 |
-35:53:53.4 |
HIP 63589 |
14.54 |
| 2026-02-16 00:00 |
13:01:14.74 |
-35:54:03.5 |
HIP 63589 |
14.85 |
| 2026-02-16 12:00 |
13:01:09.91 |
-35:54:13.2 |
HIP 63589 |
15.23 |
| 2026-02-17 00:00 |
13:01:05.03 |
-35:54:22.4 |
HIP 63589 |
15.68 |
| 2026-02-17 12:00 |
13:01:00.11 |
-35:54:31.2 |
HIP 63589 |
16.19 |
| 2026-02-18 00:00 |
13:00:55.14 |
-35:54:39.5 |
HIP 63589 |
16.75 |
| 2026-02-18 12:00 |
13:00:50.13 |
-35:54:47.3 |
HIP 63589 |
17.37 |
| 2026-02-19 00:00 |
13:00:45.07 |
-35:54:54.8 |
HIP 63589 |
18.03 |
| 2026-02-19 12:00 |
13:00:39.97 |
-35:55:01.7 |
HIP 63445 |
17.56 |
| 2026-02-20 00:00 |
13:00:34.82 |
-35:55:08.2 |
HIP 63445 |
17.05 |
| 2026-02-20 12:00 |
13:00:29.63 |
-35:55:14.3 |
HIP 63445 |
16.58 |
| 2026-02-21 00:00 |
13:00:24.40 |
-35:55:19.9 |
HIP 63445 |
16.18 |
| 2026-02-21 12:00 |
13:00:19.12 |
-35:55:25.0 |
HIP 63445 |
15.85 |
| 2026-02-22 00:00 |
13:00:13.81 |
-35:55:29.7 |
HIP 63445 |
15.58 |
| 2026-02-22 12:00 |
13:00:08.45 |
-35:55:33.9 |
HIP 63445 |
15.40 |
| 2026-02-23 00:00 |
13:00:03.05 |
-35:55:37.7 |
HIP 63445 |
15.30 |
| 2026-02-23 12:00 |
12:59:57.60 |
-35:55:41.0 |
HIP 63445 |
15.28 |
| 2026-02-24 00:00 |
12:59:52.12 |
-35:55:43.8 |
HIP 63445 |
15.36 |