| Parameter |
Value |
| Designation |
C/2015 F4 (Jacques) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-08-10T20:42:31.959360Z |
| Orbit solution date (soln_date, UTC) |
2022-06-07T21:44:08Z |
| Obs used |
2837 |
| NEO |
- |
| M1 |
11.300 |
| K1 |
9.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-08-22.0000000 |
| e |
0.98587145 |
| q (au) |
1.643925 |
| a (au) |
116.354874 |
| i (deg) |
48.704931 |
| Ω (om, deg) |
285.958058 |
| ω (w, deg) |
36.346505 |
| M (ma, deg) |
0.008746 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.073 + 3.298\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.073 |
| n |
3.298 |
| gf |
1.000 |
| gb |
-0.617 |
| 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 |
| 2015-03-27 |
2015-08-10 |
-1.7959 |
+0.136 |
| 2015-08-10 |
2015-10-17 |
+11.1365 |
-2.891 |
| 2015-10-17 |
2016-11-06 |
-3.6108 |
+1.480 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
07:22:55.67 |
+15:53:49.9 |
HIP 35818 |
5.92 |
| 2026-06-01 12:00 |
07:22:59.45 |
+15:53:43.0 |
HIP 35818 |
5.19 |
| 2026-06-02 00:00 |
07:23:03.26 |
+15:53:36.0 |
HIP 35818 |
4.52 |
| 2026-06-02 12:00 |
07:23:07.09 |
+15:53:28.9 |
HIP 35818 |
3.95 |
| 2026-06-03 00:00 |
07:23:10.93 |
+15:53:21.8 |
HIP 35818 |
3.53 |
| 2026-06-03 12:00 |
07:23:14.80 |
+15:53:14.5 |
HIP 35818 |
3.32 |
| 2026-06-04 00:00 |
07:23:18.69 |
+15:53:07.1 |
HIP 35818 |
3.38 |
| 2026-06-04 12:00 |
07:23:22.61 |
+15:52:59.6 |
HIP 35818 |
3.68 |
| 2026-06-05 00:00 |
07:23:26.54 |
+15:52:52.0 |
HIP 35818 |
4.19 |
| 2026-06-05 12:00 |
07:23:30.49 |
+15:52:44.4 |
HIP 35818 |
4.83 |
| 2026-06-06 00:00 |
07:23:34.46 |
+15:52:36.6 |
HIP 35818 |
5.57 |
| 2026-06-06 12:00 |
07:23:38.46 |
+15:52:28.7 |
HIP 35818 |
6.38 |
| 2026-06-07 00:00 |
07:23:42.47 |
+15:52:20.8 |
HIP 35818 |
7.22 |
| 2026-06-07 12:00 |
07:23:46.50 |
+15:52:12.7 |
HIP 35818 |
8.10 |
| 2026-06-08 00:00 |
07:23:50.55 |
+15:52:04.6 |
HIP 35818 |
9.01 |
| 2026-06-08 12:00 |
07:23:54.62 |
+15:51:56.3 |
HIP 35818 |
9.93 |
| 2026-06-09 00:00 |
07:23:58.71 |
+15:51:48.0 |
HIP 35818 |
10.87 |
| 2026-06-09 12:00 |
07:24:02.81 |
+15:51:39.5 |
HIP 35818 |
11.83 |
| 2026-06-10 00:00 |
07:24:06.94 |
+15:51:31.0 |
HIP 35818 |
12.79 |
| 2026-06-10 12:00 |
07:24:11.08 |
+15:51:22.4 |
HIP 35818 |
13.76 |
| 2026-06-11 00:00 |
07:24:15.24 |
+15:51:13.7 |
HIP 35818 |
14.74 |
| 2026-06-11 12:00 |
07:24:19.41 |
+15:51:04.9 |
HIP 35818 |
15.73 |
| 2026-06-12 00:00 |
07:24:23.61 |
+15:50:56.0 |
HIP 35818 |
16.73 |
| 2026-06-12 12:00 |
07:24:27.82 |
+15:50:47.0 |
HIP 35818 |
17.73 |
| 2026-06-13 00:00 |
07:24:32.04 |
+15:50:37.9 |
HIP 35818 |
18.74 |
| 2026-06-13 12:00 |
07:24:36.29 |
+15:50:28.7 |
HIP 35933 |
19.56 |
| 2026-06-14 00:00 |
07:24:40.55 |
+15:50:19.4 |
HIP 35933 |
19.54 |
| 2026-06-14 12:00 |
07:24:44.82 |
+15:50:10.0 |
HIP 35933 |
19.58 |
| 2026-06-15 00:00 |
07:24:49.11 |
+15:50:00.6 |
HIP 35933 |
19.67 |
| 2026-06-15 12:00 |
07:24:53.41 |
+15:49:51.0 |
HIP 35933 |
19.81 |
| 2026-06-16 00:00 |
07:24:57.73 |
+15:49:41.4 |
HIP 35933 |
20.01 |
| 2026-06-16 12:00 |
07:25:02.07 |
+15:49:31.6 |
HIP 35933 |
20.27 |
| 2026-06-17 00:00 |
07:25:06.41 |
+15:49:21.8 |
HIP 35933 |
20.57 |
| 2026-06-17 12:00 |
07:25:10.78 |
+15:49:11.9 |
HIP 35933 |
20.92 |
| 2026-06-18 00:00 |
07:25:15.15 |
+15:49:01.9 |
HIP 35933 |
21.32 |
| 2026-06-18 12:00 |
07:25:19.54 |
+15:48:51.8 |
HIP 35933 |
21.77 |
| 2026-06-19 00:00 |
07:25:23.94 |
+15:48:41.6 |
HIP 35933 |
22.26 |
| 2026-06-19 12:00 |
07:25:28.35 |
+15:48:31.3 |
HIP 35933 |
22.79 |
| 2026-06-20 00:00 |
07:25:32.78 |
+15:48:21.0 |
HIP 35933 |
23.36 |
| 2026-06-20 12:00 |
07:25:37.22 |
+15:48:10.5 |
HIP 35933 |
23.97 |
| 2026-06-21 00:00 |
07:25:41.67 |
+15:48:00.0 |
HIP 35933 |
24.60 |
| 2026-06-21 12:00 |
07:25:46.13 |
+15:47:49.4 |
HIP 36209 |
24.99 |
| 2026-06-22 00:00 |
07:25:50.60 |
+15:47:38.7 |
HIP 36209 |
23.92 |