| 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) |
| 2026-07-29 00:00 |
16:29:52.23 |
+22:10:31.9 |
HIP 80898 |
18.84 |
| 2026-07-29 12:00 |
16:29:48.91 |
+22:09:48.0 |
HIP 80688 |
18.64 |
| 2026-07-30 00:00 |
16:29:45.63 |
+22:09:03.9 |
HIP 80688 |
17.86 |
| 2026-07-30 12:00 |
16:29:42.38 |
+22:08:19.4 |
HIP 80688 |
17.11 |
| 2026-07-31 00:00 |
16:29:39.18 |
+22:07:34.7 |
HIP 80688 |
16.41 |
| 2026-07-31 12:00 |
16:29:36.01 |
+22:06:49.8 |
HIP 80688 |
15.76 |
| 2026-08-01 00:00 |
16:29:32.89 |
+22:06:04.6 |
HIP 80688 |
15.17 |
| 2026-08-01 12:00 |
16:29:29.81 |
+22:05:19.1 |
HIP 80688 |
14.63 |
| 2026-08-02 00:00 |
16:29:26.77 |
+22:04:33.4 |
HIP 80688 |
14.16 |
| 2026-08-02 12:00 |
16:29:23.76 |
+22:03:47.5 |
HIP 80688 |
13.76 |
| 2026-08-03 00:00 |
16:29:20.80 |
+22:03:01.3 |
HIP 80688 |
13.44 |
| 2026-08-03 12:00 |
16:29:17.88 |
+22:02:14.9 |
HIP 80688 |
13.21 |
| 2026-08-04 00:00 |
16:29:15.00 |
+22:01:28.2 |
HIP 80688 |
13.06 |
| 2026-08-04 12:00 |
16:29:12.17 |
+22:00:41.3 |
HIP 80688 |
13.00 |
| 2026-08-05 00:00 |
16:29:09.37 |
+21:59:54.2 |
HIP 80688 |
13.03 |
| 2026-08-05 12:00 |
16:29:06.62 |
+21:59:06.8 |
HIP 80688 |
13.15 |
| 2026-08-06 00:00 |
16:29:03.90 |
+21:58:19.2 |
HIP 80688 |
13.35 |
| 2026-08-06 12:00 |
16:29:01.23 |
+21:57:31.4 |
HIP 80688 |
13.63 |
| 2026-08-07 00:00 |
16:28:58.60 |
+21:56:43.4 |
HIP 80688 |
13.99 |
| 2026-08-07 12:00 |
16:28:56.02 |
+21:55:55.2 |
HIP 80688 |
14.42 |
| 2026-08-08 00:00 |
16:28:53.47 |
+21:55:06.7 |
HIP 80688 |
14.91 |
| 2026-08-08 12:00 |
16:28:50.97 |
+21:54:18.1 |
HIP 80688 |
15.46 |
| 2026-08-09 00:00 |
16:28:48.51 |
+21:53:29.2 |
HIP 80688 |
16.05 |
| 2026-08-09 12:00 |
16:28:46.10 |
+21:52:40.1 |
HIP 80688 |
16.69 |
| 2026-08-10 00:00 |
16:28:43.72 |
+21:51:50.9 |
HIP 80639 |
17.14 |
| 2026-08-10 12:00 |
16:28:41.39 |
+21:51:01.4 |
HIP 80639 |
16.17 |
| 2026-08-11 00:00 |
16:28:39.10 |
+21:50:11.8 |
HIP 80639 |
15.20 |
| 2026-08-11 12:00 |
16:28:36.86 |
+21:49:22.0 |
HIP 80639 |
14.25 |
| 2026-08-12 00:00 |
16:28:34.66 |
+21:48:32.0 |
HIP 80639 |
13.29 |
| 2026-08-12 12:00 |
16:28:32.50 |
+21:47:41.8 |
HIP 80639 |
12.35 |
| 2026-08-13 00:00 |
16:28:30.39 |
+21:46:51.4 |
HIP 80639 |
11.42 |
| 2026-08-13 12:00 |
16:28:28.32 |
+21:46:00.9 |
HIP 80639 |
10.50 |
| 2026-08-14 00:00 |
16:28:26.29 |
+21:45:10.2 |
HIP 80639 |
9.60 |
| 2026-08-14 12:00 |
16:28:24.31 |
+21:44:19.3 |
HIP 80639 |
8.72 |
| 2026-08-15 00:00 |
16:28:22.37 |
+21:43:28.3 |
HIP 80639 |
7.87 |
| 2026-08-15 12:00 |
16:28:20.47 |
+21:42:37.1 |
HIP 80639 |
7.05 |
| 2026-08-16 00:00 |
16:28:18.62 |
+21:41:45.8 |
HIP 80639 |
6.28 |
| 2026-08-16 12:00 |
16:28:16.82 |
+21:40:54.3 |
HIP 80639 |
5.58 |
| 2026-08-17 00:00 |
16:28:15.05 |
+21:40:02.7 |
HIP 80639 |
4.97 |
| 2026-08-17 12:00 |
16:28:13.33 |
+21:39:10.9 |
HIP 80639 |
4.50 |
| 2026-08-18 00:00 |
16:28:11.66 |
+21:38:19.0 |
HIP 80639 |
4.20 |
| 2026-08-18 12:00 |
16:28:10.03 |
+21:37:27.0 |
HIP 80639 |
4.11 |
| 2026-08-19 00:00 |
16:28:08.44 |
+21:36:34.8 |
HIP 80639 |
4.25 |