| 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) |
| 2026-05-12 00:00 |
07:20:45.17 |
+15:57:04.6 |
HIP 35551 |
14.21 |
| 2026-05-12 12:00 |
07:20:47.88 |
+15:57:01.7 |
HIP 35551 |
14.64 |
| 2026-05-13 00:00 |
07:20:50.61 |
+15:56:58.7 |
HIP 35551 |
15.10 |
| 2026-05-13 12:00 |
07:20:53.37 |
+15:56:55.6 |
HIP 35551 |
15.58 |
| 2026-05-14 00:00 |
07:20:56.17 |
+15:56:52.4 |
HIP 35551 |
16.08 |
| 2026-05-14 12:00 |
07:20:59.00 |
+15:56:49.1 |
HIP 35551 |
16.60 |
| 2026-05-15 00:00 |
07:21:01.86 |
+15:56:45.7 |
HIP 35551 |
17.14 |
| 2026-05-15 12:00 |
07:21:04.74 |
+15:56:42.2 |
HIP 35551 |
17.69 |
| 2026-05-16 00:00 |
07:21:07.66 |
+15:56:38.6 |
HIP 35551 |
18.26 |
| 2026-05-16 12:00 |
07:21:10.61 |
+15:56:34.9 |
HIP 35551 |
18.85 |
| 2026-05-17 00:00 |
07:21:13.59 |
+15:56:31.1 |
HIP 35551 |
19.45 |
| 2026-05-17 12:00 |
07:21:16.60 |
+15:56:27.1 |
HIP 35551 |
20.07 |
| 2026-05-18 00:00 |
07:21:19.64 |
+15:56:23.1 |
HIP 35551 |
20.69 |
| 2026-05-18 12:00 |
07:21:22.71 |
+15:56:19.0 |
HIP 35551 |
21.34 |
| 2026-05-19 00:00 |
07:21:25.81 |
+15:56:14.8 |
HIP 35551 |
21.99 |
| 2026-05-19 12:00 |
07:21:28.93 |
+15:56:10.5 |
HIP 35551 |
22.66 |
| 2026-05-20 00:00 |
07:21:32.09 |
+15:56:06.0 |
HIP 35551 |
23.34 |
| 2026-05-20 12:00 |
07:21:35.27 |
+15:56:01.5 |
HIP 35551 |
24.03 |
| 2026-05-21 00:00 |
07:21:38.48 |
+15:55:56.9 |
HIP 35818 |
23.79 |
| 2026-05-21 12:00 |
07:21:41.72 |
+15:55:52.2 |
HIP 35818 |
23.01 |
| 2026-05-22 00:00 |
07:21:44.99 |
+15:55:47.3 |
HIP 35818 |
22.23 |
| 2026-05-22 12:00 |
07:21:48.28 |
+15:55:42.4 |
HIP 35818 |
21.45 |
| 2026-05-23 00:00 |
07:21:51.60 |
+15:55:37.4 |
HIP 35818 |
20.66 |
| 2026-05-23 12:00 |
07:21:54.95 |
+15:55:32.3 |
HIP 35818 |
19.86 |
| 2026-05-24 00:00 |
07:21:58.32 |
+15:55:27.0 |
HIP 35818 |
19.06 |
| 2026-05-24 12:00 |
07:22:01.72 |
+15:55:21.7 |
HIP 35818 |
18.25 |
| 2026-05-25 00:00 |
07:22:05.14 |
+15:55:16.3 |
HIP 35818 |
17.44 |
| 2026-05-25 12:00 |
07:22:08.59 |
+15:55:10.8 |
HIP 35818 |
16.62 |
| 2026-05-26 00:00 |
07:22:12.07 |
+15:55:05.1 |
HIP 35818 |
15.80 |
| 2026-05-26 12:00 |
07:22:15.57 |
+15:54:59.4 |
HIP 35818 |
14.98 |
| 2026-05-27 00:00 |
07:22:19.10 |
+15:54:53.6 |
HIP 35818 |
14.15 |
| 2026-05-27 12:00 |
07:22:22.65 |
+15:54:47.7 |
HIP 35818 |
13.31 |
| 2026-05-28 00:00 |
07:22:26.22 |
+15:54:41.6 |
HIP 35818 |
12.48 |
| 2026-05-28 12:00 |
07:22:29.82 |
+15:54:35.5 |
HIP 35818 |
11.64 |
| 2026-05-29 00:00 |
07:22:33.44 |
+15:54:29.3 |
HIP 35818 |
10.81 |
| 2026-05-29 12:00 |
07:22:37.09 |
+15:54:23.0 |
HIP 35818 |
9.97 |
| 2026-05-30 00:00 |
07:22:40.76 |
+15:54:16.6 |
HIP 35818 |
9.14 |
| 2026-05-30 12:00 |
07:22:44.45 |
+15:54:10.1 |
HIP 35818 |
8.31 |
| 2026-05-31 00:00 |
07:22:48.17 |
+15:54:03.5 |
HIP 35818 |
7.50 |
| 2026-05-31 12:00 |
07:22:51.91 |
+15:53:56.7 |
HIP 35818 |
6.70 |
| 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 |