| Parameter |
Value |
| Designation |
C/2014 A4 (SONEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-09-05T20:45:05.630400Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:46Z |
| Obs used |
2742 |
| NEO |
- |
| M1 |
9.500 |
| K1 |
5.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-10-28.0000000 |
| e |
1.00085476 |
| q (au) |
4.180180 |
| a (au) |
-4890.464363 |
| i (deg) |
121.359968 |
| Ω (om, deg) |
29.727220 |
| ω (w, deg) |
356.788414 |
| M (ma, deg) |
0.000150 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.149 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.149 |
| n |
2.000 |
| gf |
0.830 |
| gb |
-0.500 |
| k |
0.927 |
| δ90 |
1.000 |
| 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 |
| 2014-01-12 |
2014-10-21 |
+6.8415 |
-5.586 |
| 2014-10-21 |
2015-09-01 |
-9.4186 |
+6.023 |
| 2015-09-06 |
2016-12-24 |
-2.1233 |
+1.498 |
| 2016-12-24 |
2017-09-17 |
+16.6300 |
-12.756 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
16:50:16.22 |
+21:47:56.6 |
HIP 82368 |
9.50 |
| 2026-03-26 12:00 |
16:50:13.69 |
+21:48:43.8 |
HIP 82368 |
9.77 |
| 2026-03-27 00:00 |
16:50:11.12 |
+21:49:30.8 |
HIP 82368 |
10.12 |
| 2026-03-27 12:00 |
16:50:08.50 |
+21:50:17.7 |
HIP 82368 |
10.55 |
| 2026-03-28 00:00 |
16:50:05.84 |
+21:51:04.6 |
HIP 82368 |
11.04 |
| 2026-03-28 12:00 |
16:50:03.14 |
+21:51:51.2 |
HIP 82368 |
11.60 |
| 2026-03-29 00:00 |
16:50:00.39 |
+21:52:37.8 |
HIP 82368 |
12.21 |
| 2026-03-29 12:00 |
16:49:57.60 |
+21:53:24.2 |
HIP 82368 |
12.86 |
| 2026-03-30 00:00 |
16:49:54.76 |
+21:54:10.6 |
HIP 82368 |
13.55 |
| 2026-03-30 12:00 |
16:49:51.88 |
+21:54:56.7 |
HIP 82368 |
14.29 |
| 2026-03-31 00:00 |
16:49:48.96 |
+21:55:42.7 |
HIP 82368 |
15.05 |
| 2026-03-31 12:00 |
16:49:45.99 |
+21:56:28.6 |
HIP 82368 |
15.84 |
| 2026-04-01 00:00 |
16:49:42.98 |
+21:57:14.4 |
HIP 82368 |
16.65 |
| 2026-04-01 12:00 |
16:49:39.93 |
+21:58:00.0 |
HIP 82368 |
17.49 |
| 2026-04-02 00:00 |
16:49:36.83 |
+21:58:45.4 |
HIP 82368 |
18.34 |
| 2026-04-02 12:00 |
16:49:33.69 |
+21:59:30.7 |
HIP 82368 |
19.22 |
| 2026-04-03 00:00 |
16:49:30.51 |
+22:00:15.8 |
HIP 82368 |
20.11 |
| 2026-04-03 12:00 |
16:49:27.29 |
+22:01:00.7 |
HIP 82398 |
20.61 |
| 2026-04-04 00:00 |
16:49:24.02 |
+22:01:45.5 |
HIP 82398 |
20.36 |
| 2026-04-04 12:00 |
16:49:20.71 |
+22:02:30.1 |
HIP 82398 |
20.18 |
| 2026-04-05 00:00 |
16:49:17.36 |
+22:03:14.5 |
HIP 82398 |
20.06 |
| 2026-04-05 12:00 |
16:49:13.97 |
+22:03:58.7 |
HIP 82398 |
20.00 |
| 2026-04-06 00:00 |
16:49:10.54 |
+22:04:42.8 |
HIP 82398 |
20.01 |
| 2026-04-06 12:00 |
16:49:07.07 |
+22:05:26.6 |
HIP 82398 |
20.09 |
| 2026-04-07 00:00 |
16:49:03.55 |
+22:06:10.3 |
HIP 82398 |
20.24 |
| 2026-04-07 12:00 |
16:49:00.00 |
+22:06:53.8 |
HIP 82398 |
20.45 |
| 2026-04-08 00:00 |
16:48:56.40 |
+22:07:37.0 |
HIP 82398 |
20.73 |
| 2026-04-08 12:00 |
16:48:52.77 |
+22:08:20.1 |
HIP 82398 |
21.07 |
| 2026-04-09 00:00 |
16:48:49.09 |
+22:09:02.9 |
HIP 82398 |
21.47 |
| 2026-04-09 12:00 |
16:48:45.38 |
+22:09:45.6 |
HIP 82398 |
21.93 |
| 2026-04-10 00:00 |
16:48:41.62 |
+22:10:28.0 |
HIP 82398 |
22.45 |
| 2026-04-10 12:00 |
16:48:37.82 |
+22:11:10.2 |
HIP 82398 |
23.02 |
| 2026-04-11 00:00 |
16:48:33.99 |
+22:11:52.2 |
HIP 82398 |
23.64 |
| 2026-04-11 12:00 |
16:48:30.12 |
+22:12:33.9 |
HIP 82398 |
24.31 |
| 2026-04-12 00:00 |
16:48:26.21 |
+22:13:15.4 |
HIP 82398 |
25.02 |
| 2026-04-12 12:00 |
16:48:22.26 |
+22:13:56.7 |
HIP 82398 |
25.77 |
| 2026-04-13 00:00 |
16:48:18.27 |
+22:14:37.7 |
HIP 82398 |
26.55 |
| 2026-04-13 12:00 |
16:48:14.24 |
+22:15:18.5 |
HIP 82398 |
27.37 |
| 2026-04-14 00:00 |
16:48:10.18 |
+22:15:59.1 |
HIP 82398 |
28.23 |
| 2026-04-14 12:00 |
16:48:06.07 |
+22:16:39.3 |
HIP 82398 |
29.11 |
| 2026-04-15 00:00 |
16:48:01.94 |
+22:17:19.4 |
HIP 82398 |
30.02 |
| 2026-04-15 12:00 |
16:47:57.76 |
+22:17:59.1 |
HIP 82398 |
30.96 |
| 2026-04-16 00:00 |
16:47:53.55 |
+22:18:38.6 |
HIP 82398 |
31.92 |