| Parameter |
Value |
| Designation |
C/2017 K6 (Jacques) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-01-03T03:16:30.506880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:34Z |
| Obs used |
475 |
| NEO |
- |
| M1 |
12.100 |
| K1 |
6.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-02-05.0000000 |
| e |
0.99822114 |
| q (au) |
2.002756 |
| a (au) |
1125.867222 |
| i (deg) |
57.251183 |
| Ω (om, deg) |
85.054187 |
| ω (w, deg) |
303.838384 |
| M (ma, deg) |
0.000857 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.455 + 4.414\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.455 |
| n |
4.414 |
| gf |
1.000 |
| gb |
-0.891 |
| k |
0.984 |
| 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 |
| 2017-05-29 |
2017-09-21 |
-1.7754 |
+1.104 |
| 2017-09-21 |
2017-12-30 |
+16.2254 |
-5.376 |
| 2018-01-05 |
2019-02-14 |
+1.6841 |
-1.364 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
13:37:23.34 |
+55:44:13.5 |
HIP 66584 |
14.00 |
| 2026-05-12 12:00 |
13:37:15.73 |
+55:43:47.7 |
HIP 66584 |
14.88 |
| 2026-05-13 00:00 |
13:37:08.17 |
+55:43:21.3 |
HIP 66584 |
15.80 |
| 2026-05-13 12:00 |
13:37:00.64 |
+55:42:54.3 |
HIP 66584 |
16.74 |
| 2026-05-14 00:00 |
13:36:53.16 |
+55:42:26.6 |
HIP 66584 |
17.70 |
| 2026-05-14 12:00 |
13:36:45.72 |
+55:41:58.2 |
HIP 66584 |
18.67 |
| 2026-05-15 00:00 |
13:36:38.32 |
+55:41:29.3 |
HIP 66584 |
19.65 |
| 2026-05-15 12:00 |
13:36:30.97 |
+55:40:59.7 |
HIP 66584 |
20.64 |
| 2026-05-16 00:00 |
13:36:23.66 |
+55:40:29.4 |
HIP 66584 |
21.65 |
| 2026-05-16 12:00 |
13:36:16.40 |
+55:39:58.6 |
HIP 66584 |
22.66 |
| 2026-05-17 00:00 |
13:36:09.18 |
+55:39:27.1 |
HIP 66584 |
23.68 |
| 2026-05-17 12:00 |
13:36:02.01 |
+55:38:55.0 |
HIP 66198 |
24.25 |
| 2026-05-18 00:00 |
13:35:54.89 |
+55:38:22.2 |
HIP 66198 |
23.17 |
| 2026-05-18 12:00 |
13:35:47.81 |
+55:37:48.9 |
HIP 66198 |
22.10 |
| 2026-05-19 00:00 |
13:35:40.79 |
+55:37:14.9 |
HIP 66198 |
21.03 |
| 2026-05-19 12:00 |
13:35:33.81 |
+55:36:40.4 |
HIP 66198 |
19.97 |
| 2026-05-20 00:00 |
13:35:26.88 |
+55:36:05.2 |
HIP 66198 |
18.91 |
| 2026-05-20 12:00 |
13:35:20.01 |
+55:35:29.4 |
HIP 66198 |
17.85 |
| 2026-05-21 00:00 |
13:35:13.18 |
+55:34:53.1 |
HIP 66198 |
16.81 |
| 2026-05-21 12:00 |
13:35:06.41 |
+55:34:16.1 |
HIP 66198 |
15.77 |
| 2026-05-22 00:00 |
13:34:59.69 |
+55:33:38.6 |
HIP 66198 |
14.74 |
| 2026-05-22 12:00 |
13:34:53.02 |
+55:33:00.4 |
HIP 66198 |
13.73 |
| 2026-05-23 00:00 |
13:34:46.40 |
+55:32:21.7 |
HIP 66198 |
12.72 |
| 2026-05-23 12:00 |
13:34:39.84 |
+55:31:42.4 |
HIP 66198 |
11.74 |
| 2026-05-24 00:00 |
13:34:33.33 |
+55:31:02.6 |
HIP 66198 |
10.79 |
| 2026-05-24 12:00 |
13:34:26.88 |
+55:30:22.2 |
HIP 66198 |
9.86 |
| 2026-05-25 00:00 |
13:34:20.48 |
+55:29:41.2 |
HIP 66198 |
8.98 |
| 2026-05-25 12:00 |
13:34:14.14 |
+55:28:59.6 |
HIP 66198 |
8.14 |
| 2026-05-26 00:00 |
13:34:07.85 |
+55:28:17.5 |
HIP 66198 |
7.39 |
| 2026-05-26 12:00 |
13:34:01.62 |
+55:27:34.9 |
HIP 66198 |
6.72 |
| 2026-05-27 00:00 |
13:33:55.44 |
+55:26:51.7 |
HIP 66198 |
6.19 |
| 2026-05-27 12:00 |
13:33:49.32 |
+55:26:07.9 |
HIP 66198 |
5.82 |
| 2026-05-28 00:00 |
13:33:43.27 |
+55:25:23.6 |
HIP 66198 |
5.64 |
| 2026-05-28 12:00 |
13:33:37.26 |
+55:24:38.8 |
HIP 66198 |
5.68 |
| 2026-05-29 00:00 |
13:33:31.32 |
+55:23:53.4 |
HIP 66198 |
5.92 |
| 2026-05-29 12:00 |
13:33:25.44 |
+55:23:07.6 |
HIP 66198 |
6.35 |
| 2026-05-30 00:00 |
13:33:19.61 |
+55:22:21.2 |
HIP 66198 |
6.93 |
| 2026-05-30 12:00 |
13:33:13.84 |
+55:21:34.2 |
HIP 66198 |
7.63 |
| 2026-05-31 00:00 |
13:33:08.14 |
+55:20:46.8 |
HIP 66198 |
8.41 |
| 2026-05-31 12:00 |
13:33:02.49 |
+55:19:58.9 |
HIP 66130 |
8.83 |
| 2026-06-01 00:00 |
13:32:56.91 |
+55:19:10.4 |
HIP 66130 |
8.43 |
| 2026-06-01 12:00 |
13:32:51.38 |
+55:18:21.4 |
HIP 66130 |
8.15 |
| 2026-06-02 00:00 |
13:32:45.92 |
+55:17:32.0 |
HIP 66130 |
8.01 |