| 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) |
| 2026-09-20 00:00 |
16:27:57.62 |
+20:39:05.9 |
HIP 80622 |
11.95 |
| 2026-09-20 12:00 |
16:27:58.83 |
+20:38:12.8 |
HIP 80622 |
12.87 |
| 2026-09-21 00:00 |
16:28:00.07 |
+20:37:19.8 |
HIP 80622 |
13.80 |
| 2026-09-21 12:00 |
16:28:01.36 |
+20:36:26.9 |
HIP 80622 |
14.74 |
| 2026-09-22 00:00 |
16:28:02.68 |
+20:35:34.1 |
HIP 80604 |
15.32 |
| 2026-09-22 12:00 |
16:28:04.05 |
+20:34:41.4 |
HIP 80604 |
14.75 |
| 2026-09-23 00:00 |
16:28:05.45 |
+20:33:48.8 |
HIP 80604 |
14.22 |
| 2026-09-23 12:00 |
16:28:06.89 |
+20:32:56.3 |
HIP 80604 |
13.75 |
| 2026-09-24 00:00 |
16:28:08.38 |
+20:32:03.9 |
HIP 80604 |
13.33 |
| 2026-09-24 12:00 |
16:28:09.90 |
+20:31:11.7 |
HIP 80604 |
12.98 |
| 2026-09-25 00:00 |
16:28:11.45 |
+20:30:19.6 |
HIP 80604 |
12.69 |
| 2026-09-25 12:00 |
16:28:13.05 |
+20:29:27.6 |
HIP 80604 |
12.48 |
| 2026-09-26 00:00 |
16:28:14.69 |
+20:28:35.7 |
HIP 80604 |
12.35 |
| 2026-09-26 12:00 |
16:28:16.36 |
+20:27:44.0 |
HIP 80604 |
12.29 |
| 2026-09-27 00:00 |
16:28:18.07 |
+20:26:52.4 |
HIP 80604 |
12.32 |
| 2026-09-27 12:00 |
16:28:19.82 |
+20:26:01.0 |
HIP 80604 |
12.43 |
| 2026-09-28 00:00 |
16:28:21.60 |
+20:25:09.6 |
HIP 80604 |
12.62 |
| 2026-09-28 12:00 |
16:28:23.42 |
+20:24:18.5 |
HIP 80604 |
12.89 |
| 2026-09-29 00:00 |
16:28:25.28 |
+20:23:27.5 |
HIP 80604 |
13.23 |
| 2026-09-29 12:00 |
16:28:27.18 |
+20:22:36.6 |
HIP 80604 |
13.63 |
| 2026-09-30 00:00 |
16:28:29.11 |
+20:21:45.9 |
HIP 80604 |
14.10 |
| 2026-09-30 12:00 |
16:28:31.08 |
+20:20:55.3 |
HIP 80604 |
14.63 |
| 2026-10-01 00:00 |
16:28:33.08 |
+20:20:04.9 |
HIP 80604 |
15.20 |
| 2026-10-01 12:00 |
16:28:35.13 |
+20:19:14.7 |
HIP 80604 |
15.82 |
| 2026-10-02 00:00 |
16:28:37.20 |
+20:18:24.6 |
HIP 80604 |
16.49 |
| 2026-10-02 12:00 |
16:28:39.32 |
+20:17:34.7 |
HIP 80604 |
17.18 |
| 2026-10-03 00:00 |
16:28:41.47 |
+20:16:44.9 |
HIP 80604 |
17.91 |
| 2026-10-03 12:00 |
16:28:43.65 |
+20:15:55.3 |
HIP 80604 |
18.67 |
| 2026-10-04 00:00 |
16:28:45.87 |
+20:15:05.9 |
HIP 80604 |
19.46 |
| 2026-10-04 12:00 |
16:28:48.13 |
+20:14:16.7 |
HIP 80604 |
20.27 |
| 2026-10-05 00:00 |
16:28:50.42 |
+20:13:27.7 |
HIP 80604 |
21.09 |
| 2026-10-05 12:00 |
16:28:52.74 |
+20:12:38.8 |
HIP 80604 |
21.94 |
| 2026-10-06 00:00 |
16:28:55.10 |
+20:11:50.2 |
HIP 80604 |
22.80 |
| 2026-10-06 12:00 |
16:28:57.49 |
+20:11:01.7 |
HIP 80845 |
22.83 |
| 2026-10-07 00:00 |
16:28:59.92 |
+20:10:13.4 |
HIP 80845 |
22.20 |
| 2026-10-07 12:00 |
16:29:02.38 |
+20:09:25.3 |
HIP 80845 |
21.58 |
| 2026-10-08 00:00 |
16:29:04.88 |
+20:08:37.5 |
HIP 80845 |
20.98 |
| 2026-10-08 12:00 |
16:29:07.41 |
+20:07:49.8 |
HIP 80845 |
20.41 |
| 2026-10-09 00:00 |
16:29:09.97 |
+20:07:02.3 |
HIP 80845 |
19.86 |
| 2026-10-09 12:00 |
16:29:12.57 |
+20:06:15.1 |
HIP 80845 |
19.34 |
| 2026-10-10 00:00 |
16:29:15.19 |
+20:05:28.0 |
HIP 80845 |
18.84 |
| 2026-10-10 12:00 |
16:29:17.85 |
+20:04:41.2 |
HIP 80845 |
18.38 |
| 2026-10-11 00:00 |
16:29:20.55 |
+20:03:54.6 |
HIP 80845 |
17.96 |