| 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) |
| 2026-07-29 00:00 |
07:31:33.02 |
+15:31:02.6 |
HIP 36564 |
16.43 |
| 2026-07-29 12:00 |
07:31:37.54 |
+15:30:46.9 |
HIP 36564 |
16.47 |
| 2026-07-30 00:00 |
07:31:42.05 |
+15:30:31.2 |
HIP 36564 |
16.59 |
| 2026-07-30 12:00 |
07:31:46.54 |
+15:30:15.5 |
HIP 36564 |
16.78 |
| 2026-07-31 00:00 |
07:31:51.03 |
+15:29:59.7 |
HIP 36564 |
17.04 |
| 2026-07-31 12:00 |
07:31:55.50 |
+15:29:43.8 |
HIP 36564 |
17.36 |
| 2026-08-01 00:00 |
07:31:59.96 |
+15:29:28.0 |
HIP 36564 |
17.74 |
| 2026-08-01 12:00 |
07:32:04.42 |
+15:29:12.0 |
HIP 36564 |
18.19 |
| 2026-08-02 00:00 |
07:32:08.86 |
+15:28:56.1 |
HIP 36564 |
18.68 |
| 2026-08-02 12:00 |
07:32:13.29 |
+15:28:40.1 |
HIP 36564 |
19.22 |
| 2026-08-03 00:00 |
07:32:17.70 |
+15:28:24.1 |
HIP 36739 |
18.94 |
| 2026-08-03 12:00 |
07:32:22.11 |
+15:28:08.0 |
HIP 36739 |
18.20 |
| 2026-08-04 00:00 |
07:32:26.50 |
+15:27:51.9 |
HIP 36739 |
17.49 |
| 2026-08-04 12:00 |
07:32:30.88 |
+15:27:35.8 |
HIP 36739 |
16.83 |
| 2026-08-05 00:00 |
07:32:35.24 |
+15:27:19.6 |
HIP 36739 |
16.22 |
| 2026-08-05 12:00 |
07:32:39.60 |
+15:27:03.4 |
HIP 36739 |
15.66 |
| 2026-08-06 00:00 |
07:32:43.94 |
+15:26:47.2 |
HIP 36739 |
15.16 |
| 2026-08-06 12:00 |
07:32:48.26 |
+15:26:30.9 |
HIP 36739 |
14.72 |
| 2026-08-07 00:00 |
07:32:52.57 |
+15:26:14.6 |
HIP 36739 |
14.36 |
| 2026-08-07 12:00 |
07:32:56.87 |
+15:25:58.3 |
HIP 36739 |
14.07 |
| 2026-08-08 00:00 |
07:33:01.15 |
+15:25:42.0 |
HIP 36739 |
13.86 |
| 2026-08-08 12:00 |
07:33:05.42 |
+15:25:25.6 |
HIP 36739 |
13.73 |
| 2026-08-09 00:00 |
07:33:09.67 |
+15:25:09.2 |
HIP 36739 |
13.68 |
| 2026-08-09 12:00 |
07:33:13.91 |
+15:24:52.7 |
HIP 36739 |
13.72 |
| 2026-08-10 00:00 |
07:33:18.13 |
+15:24:36.3 |
HIP 36739 |
13.83 |
| 2026-08-10 12:00 |
07:33:22.33 |
+15:24:19.8 |
HIP 36739 |
14.03 |
| 2026-08-11 00:00 |
07:33:26.52 |
+15:24:03.3 |
HIP 36739 |
14.30 |
| 2026-08-11 12:00 |
07:33:30.69 |
+15:23:46.7 |
HIP 36739 |
14.64 |
| 2026-08-12 00:00 |
07:33:34.85 |
+15:23:30.2 |
HIP 36739 |
15.05 |
| 2026-08-12 12:00 |
07:33:38.99 |
+15:23:13.6 |
HIP 36739 |
15.51 |
| 2026-08-13 00:00 |
07:33:43.10 |
+15:22:57.0 |
HIP 36739 |
16.03 |
| 2026-08-13 12:00 |
07:33:47.21 |
+15:22:40.4 |
HIP 36739 |
16.59 |
| 2026-08-14 00:00 |
07:33:51.29 |
+15:22:23.7 |
HIP 36739 |
17.20 |
| 2026-08-14 12:00 |
07:33:55.35 |
+15:22:07.1 |
HIP 36739 |
17.84 |
| 2026-08-15 00:00 |
07:33:59.40 |
+15:21:50.4 |
HIP 36739 |
18.51 |
| 2026-08-15 12:00 |
07:34:03.43 |
+15:21:33.7 |
HIP 36739 |
19.21 |
| 2026-08-16 00:00 |
07:34:07.44 |
+15:21:17.0 |
HIP 36739 |
19.94 |
| 2026-08-16 12:00 |
07:34:11.42 |
+15:21:00.3 |
HIP 36739 |
20.68 |
| 2026-08-17 00:00 |
07:34:15.39 |
+15:20:43.6 |
HIP 36739 |
21.45 |
| 2026-08-17 12:00 |
07:34:19.34 |
+15:20:26.8 |
HIP 36739 |
22.23 |
| 2026-08-18 00:00 |
07:34:23.27 |
+15:20:10.1 |
HIP 36739 |
23.02 |
| 2026-08-18 12:00 |
07:34:27.18 |
+15:19:53.3 |
HIP 36739 |
23.83 |
| 2026-08-19 00:00 |
07:34:31.07 |
+15:19:36.5 |
HIP 36739 |
24.64 |