| 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 |
-1.7758 |
+1.105 |
| 2017-09-21 |
2017-12-30 |
+16.2248 |
-5.376 |
| 2018-01-05 |
2019-02-14 |
+1.6842 |
-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) |
| 2026-09-20 00:00 |
13:39:13.15 |
+51:11:47.7 |
HIP 66516 |
17.89 |
| 2026-09-20 12:00 |
13:39:20.63 |
+51:10:58.8 |
HIP 66516 |
18.02 |
| 2026-09-21 00:00 |
13:39:28.14 |
+51:10:10.3 |
HIP 66516 |
18.27 |
| 2026-09-21 12:00 |
13:39:35.67 |
+51:09:22.3 |
HIP 66516 |
18.63 |
| 2026-09-22 00:00 |
13:39:43.23 |
+51:08:34.8 |
HIP 66516 |
19.10 |
| 2026-09-22 12:00 |
13:39:50.82 |
+51:07:47.7 |
HIP 66516 |
19.67 |
| 2026-09-23 00:00 |
13:39:58.43 |
+51:07:01.0 |
HIP 66734 |
19.95 |
| 2026-09-23 12:00 |
13:40:06.07 |
+51:06:14.8 |
HIP 66734 |
18.83 |
| 2026-09-24 00:00 |
13:40:13.73 |
+51:05:29.0 |
HIP 66734 |
17.75 |
| 2026-09-24 12:00 |
13:40:21.41 |
+51:04:43.7 |
HIP 66734 |
16.74 |
| 2026-09-25 00:00 |
13:40:29.12 |
+51:03:58.8 |
HIP 66734 |
15.80 |
| 2026-09-25 12:00 |
13:40:36.85 |
+51:03:14.4 |
HIP 66734 |
14.95 |
| 2026-09-26 00:00 |
13:40:44.60 |
+51:02:30.4 |
HIP 66843 |
14.08 |
| 2026-09-26 12:00 |
13:40:52.38 |
+51:01:47.0 |
HIP 66843 |
12.67 |
| 2026-09-27 00:00 |
13:41:00.18 |
+51:01:03.9 |
HIP 66843 |
11.26 |
| 2026-09-27 12:00 |
13:41:08.00 |
+51:00:21.4 |
HIP 66843 |
9.86 |
| 2026-09-28 00:00 |
13:41:15.84 |
+50:59:39.3 |
HIP 66843 |
8.47 |
| 2026-09-28 12:00 |
13:41:23.70 |
+50:58:57.7 |
HIP 66843 |
7.09 |
| 2026-09-29 00:00 |
13:41:31.58 |
+50:58:16.6 |
HIP 66843 |
5.73 |
| 2026-09-29 12:00 |
13:41:39.48 |
+50:57:35.9 |
HIP 66843 |
4.41 |
| 2026-09-30 00:00 |
13:41:47.40 |
+50:56:55.7 |
HIP 66843 |
3.19 |
| 2026-09-30 12:00 |
13:41:55.34 |
+50:56:16.0 |
HIP 66843 |
2.22 |
| 2026-10-01 00:00 |
13:42:03.30 |
+50:55:36.8 |
HIP 66843 |
1.93 |
| 2026-10-01 12:00 |
13:42:11.28 |
+50:54:58.0 |
HIP 66843 |
2.56 |
| 2026-10-02 00:00 |
13:42:19.28 |
+50:54:19.8 |
HIP 66843 |
3.66 |
| 2026-10-02 12:00 |
13:42:27.29 |
+50:53:42.0 |
HIP 66843 |
4.93 |
| 2026-10-03 00:00 |
13:42:35.32 |
+50:53:04.8 |
HIP 66843 |
6.26 |
| 2026-10-03 12:00 |
13:42:43.37 |
+50:52:28.0 |
HIP 66843 |
7.62 |
| 2026-10-04 00:00 |
13:42:51.43 |
+50:51:51.7 |
HIP 66843 |
9.00 |
| 2026-10-04 12:00 |
13:42:59.51 |
+50:51:15.9 |
HIP 66843 |
10.38 |
| 2026-10-05 00:00 |
13:43:07.61 |
+50:50:40.7 |
HIP 66843 |
11.77 |
| 2026-10-05 12:00 |
13:43:15.72 |
+50:50:05.9 |
HIP 66843 |
13.17 |
| 2026-10-06 00:00 |
13:43:23.84 |
+50:49:31.6 |
HIP 66843 |
14.56 |
| 2026-10-06 12:00 |
13:43:31.98 |
+50:48:57.9 |
HIP 66843 |
15.96 |
| 2026-10-07 00:00 |
13:43:40.14 |
+50:48:24.7 |
HIP 66843 |
17.36 |
| 2026-10-07 12:00 |
13:43:48.30 |
+50:47:51.9 |
HIP 66843 |
18.76 |
| 2026-10-08 00:00 |
13:43:56.48 |
+50:47:19.7 |
HIP 66843 |
20.16 |
| 2026-10-08 12:00 |
13:44:04.68 |
+50:46:48.1 |
HIP 66843 |
21.55 |
| 2026-10-09 00:00 |
13:44:12.88 |
+50:46:16.9 |
HIP 66843 |
22.95 |
| 2026-10-09 12:00 |
13:44:21.09 |
+50:45:46.3 |
HIP 66843 |
24.34 |
| 2026-10-10 00:00 |
13:44:29.32 |
+50:45:16.2 |
HIP 67258 |
25.37 |
| 2026-10-10 12:00 |
13:44:37.56 |
+50:44:46.6 |
HIP 67258 |
24.12 |
| 2026-10-11 00:00 |
13:44:45.80 |
+50:44:17.5 |
HIP 67258 |
22.87 |