| Parameter |
Value |
| Designation |
C/2018 A6 (Gibbs) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-07-14T07:12:03.481920Z |
| Orbit solution date (soln_date, UTC) |
2024-05-30T01:12:17Z |
| Obs used |
915 |
| NEO |
- |
| M1 |
9.700 |
| K1 |
7.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-12-10.0000000 |
| e |
0.80342745 |
| q (au) |
3.017827 |
| a (au) |
15.352231 |
| i (deg) |
76.954875 |
| Ω (om, deg) |
340.386138 |
| ω (w, deg) |
264.536453 |
| M (ma, deg) |
2.436451 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.874 + 3.973\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.874 |
| n |
3.973 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| 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 |
| 2017-04-03 |
2018-02-13 |
-4.4374 |
+4.270 |
| 2018-02-13 |
2019-07-08 |
+5.4711 |
-3.199 |
| 2019-07-20 |
2020-06-07 |
+11.2381 |
-6.514 |
| 2020-06-07 |
2021-10-03 |
-7.5580 |
+5.191 |
| 2021-10-03 |
2023-10-19 |
-7.6929 |
+5.633 |
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 |
22:03:30.08 |
+41:29:49.8 |
HIP 108861 |
6.52 |
| 2026-09-20 12:00 |
22:03:20.81 |
+41:28:57.1 |
HIP 108861 |
4.93 |
| 2026-09-21 00:00 |
22:03:11.59 |
+41:28:03.7 |
HIP 108861 |
3.70 |
| 2026-09-21 12:00 |
22:03:02.42 |
+41:27:09.7 |
HIP 108861 |
3.24 |
| 2026-09-22 00:00 |
22:02:53.30 |
+41:26:15.0 |
HIP 108861 |
3.84 |
| 2026-09-22 12:00 |
22:02:44.24 |
+41:25:19.6 |
HIP 108861 |
5.13 |
| 2026-09-23 00:00 |
22:02:35.22 |
+41:24:23.6 |
HIP 108861 |
6.73 |
| 2026-09-23 12:00 |
22:02:26.26 |
+41:23:27.0 |
HIP 108861 |
8.46 |
| 2026-09-24 00:00 |
22:02:17.36 |
+41:22:29.8 |
HIP 108861 |
10.26 |
| 2026-09-24 12:00 |
22:02:08.50 |
+41:21:32.0 |
HIP 108745 |
11.83 |
| 2026-09-25 00:00 |
22:01:59.70 |
+41:20:33.5 |
HIP 108745 |
12.20 |
| 2026-09-25 12:00 |
22:01:50.96 |
+41:19:34.4 |
HIP 108745 |
12.86 |
| 2026-09-26 00:00 |
22:01:42.28 |
+41:18:34.8 |
HIP 108745 |
13.77 |
| 2026-09-26 12:00 |
22:01:33.65 |
+41:17:34.6 |
HIP 108697 |
13.68 |
| 2026-09-27 00:00 |
22:01:25.07 |
+41:16:33.7 |
HIP 108697 |
12.23 |
| 2026-09-27 12:00 |
22:01:16.56 |
+41:15:32.3 |
HIP 108697 |
10.92 |
| 2026-09-28 00:00 |
22:01:08.11 |
+41:14:30.4 |
HIP 108697 |
9.79 |
| 2026-09-28 12:00 |
22:00:59.71 |
+41:13:27.8 |
HIP 108697 |
8.91 |
| 2026-09-29 00:00 |
22:00:51.38 |
+41:12:24.8 |
HIP 108697 |
8.37 |
| 2026-09-29 12:00 |
22:00:43.10 |
+41:11:21.1 |
HIP 108697 |
8.21 |
| 2026-09-30 00:00 |
22:00:34.89 |
+41:10:17.0 |
HIP 108697 |
8.47 |
| 2026-09-30 12:00 |
22:00:26.74 |
+41:09:12.3 |
HIP 108697 |
9.11 |
| 2026-10-01 00:00 |
22:00:18.65 |
+41:08:07.0 |
HIP 108697 |
10.04 |
| 2026-10-01 12:00 |
22:00:10.63 |
+41:07:01.3 |
HIP 108697 |
11.20 |
| 2026-10-02 00:00 |
22:00:02.67 |
+41:05:55.0 |
HIP 108697 |
12.52 |
| 2026-10-02 12:00 |
21:59:54.77 |
+41:04:48.2 |
HIP 108697 |
13.95 |
| 2026-10-03 00:00 |
21:59:46.94 |
+41:03:41.0 |
HIP 108697 |
15.47 |
| 2026-10-03 12:00 |
21:59:39.18 |
+41:02:33.2 |
HIP 108697 |
17.03 |
| 2026-10-04 00:00 |
21:59:31.48 |
+41:01:25.0 |
HIP 108697 |
18.64 |
| 2026-10-04 12:00 |
21:59:23.85 |
+41:00:16.3 |
HIP 108697 |
20.28 |
| 2026-10-05 00:00 |
21:59:16.28 |
+40:59:07.1 |
HIP 108697 |
21.95 |
| 2026-10-05 12:00 |
21:59:08.79 |
+40:57:57.4 |
HIP 108697 |
23.63 |
| 2026-10-06 00:00 |
21:59:01.36 |
+40:56:47.4 |
HIP 108697 |
25.32 |
| 2026-10-06 12:00 |
21:58:54.01 |
+40:55:36.8 |
HIP 108697 |
27.01 |
| 2026-10-07 00:00 |
21:58:46.72 |
+40:54:25.8 |
HIP 108697 |
28.72 |
| 2026-10-07 12:00 |
21:58:39.51 |
+40:53:14.4 |
HIP 108697 |
30.42 |
| 2026-10-08 00:00 |
21:58:32.37 |
+40:52:02.6 |
HIP 108697 |
32.13 |
| 2026-10-08 12:00 |
21:58:25.30 |
+40:50:50.4 |
HIP 108238 |
31.41 |
| 2026-10-09 00:00 |
21:58:18.30 |
+40:49:37.8 |
HIP 108238 |
30.06 |
| 2026-10-09 12:00 |
21:58:11.37 |
+40:48:24.8 |
HIP 108238 |
28.77 |
| 2026-10-10 00:00 |
21:58:04.52 |
+40:47:11.4 |
HIP 108238 |
27.55 |
| 2026-10-10 12:00 |
21:57:57.74 |
+40:45:57.6 |
HIP 108238 |
26.41 |
| 2026-10-11 00:00 |
21:57:51.04 |
+40:44:43.4 |
HIP 108238 |
25.35 |