| Parameter |
Value |
| Designation |
C/2018 A4 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2018-05-18T19:21:20.165760Z |
| Orbit solution date (soln_date, UTC) |
2023-05-03T22:42:49Z |
| Obs used |
79 |
| NEO |
- |
| M1 |
8.400 |
| K1 |
22.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-01-15.0000000 |
| e |
0.80435873 |
| q (au) |
2.402567 |
| a (au) |
12.280471 |
| i (deg) |
3.148025 |
| Ω (om, deg) |
97.634759 |
| ω (w, deg) |
356.135345 |
| M (ma, deg) |
357.164531 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.546 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.546 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
16:25:33.22 |
-19:58:57.7 |
HIP 80464 |
8.86 |
| 2026-06-01 12:00 |
16:25:26.00 |
-19:58:42.2 |
HIP 80464 |
8.47 |
| 2026-06-02 00:00 |
16:25:18.79 |
-19:58:26.8 |
HIP 80464 |
8.42 |
| 2026-06-02 12:00 |
16:25:11.58 |
-19:58:11.3 |
HIP 80464 |
8.72 |
| 2026-06-03 00:00 |
16:25:04.37 |
-19:57:55.8 |
HIP 80464 |
9.32 |
| 2026-06-03 12:00 |
16:24:57.18 |
-19:57:40.4 |
HIP 80464 |
10.18 |
| 2026-06-04 00:00 |
16:24:49.99 |
-19:57:25.0 |
HIP 80464 |
11.24 |
| 2026-06-04 12:00 |
16:24:42.81 |
-19:57:09.7 |
HIP 80343 |
9.98 |
| 2026-06-05 00:00 |
16:24:35.64 |
-19:56:54.4 |
HIP 80343 |
8.73 |
| 2026-06-05 12:00 |
16:24:28.48 |
-19:56:39.1 |
HIP 80343 |
7.65 |
| 2026-06-06 00:00 |
16:24:21.33 |
-19:56:23.8 |
HIP 80343 |
6.83 |
| 2026-06-06 12:00 |
16:24:14.19 |
-19:56:08.6 |
HIP 80343 |
6.37 |
| 2026-06-07 00:00 |
16:24:07.06 |
-19:55:53.4 |
HIP 80343 |
6.35 |
| 2026-06-07 12:00 |
16:23:59.95 |
-19:55:38.2 |
HIP 80343 |
6.76 |
| 2026-06-08 00:00 |
16:23:52.84 |
-19:55:23.1 |
HIP 80343 |
7.53 |
| 2026-06-08 12:00 |
16:23:45.75 |
-19:55:08.1 |
HIP 80343 |
8.57 |
| 2026-06-09 00:00 |
16:23:38.68 |
-19:54:53.0 |
HIP 80343 |
9.79 |
| 2026-06-09 12:00 |
16:23:31.62 |
-19:54:38.1 |
HIP 80343 |
11.12 |
| 2026-06-10 00:00 |
16:23:24.58 |
-19:54:23.1 |
HIP 80343 |
12.54 |
| 2026-06-10 12:00 |
16:23:17.55 |
-19:54:08.3 |
HIP 80343 |
14.01 |
| 2026-06-11 00:00 |
16:23:10.54 |
-19:53:53.4 |
HIP 80343 |
15.51 |
| 2026-06-11 12:00 |
16:23:03.55 |
-19:53:38.6 |
HIP 80343 |
17.04 |
| 2026-06-12 00:00 |
16:22:56.58 |
-19:53:23.9 |
HIP 80343 |
18.59 |
| 2026-06-12 12:00 |
16:22:49.63 |
-19:53:09.3 |
HIP 80343 |
20.15 |
| 2026-06-13 00:00 |
16:22:42.69 |
-19:52:54.6 |
HIP 80343 |
21.72 |
| 2026-06-13 12:00 |
16:22:35.78 |
-19:52:40.1 |
HIP 80109 |
20.94 |
| 2026-06-14 00:00 |
16:22:28.89 |
-19:52:25.6 |
HIP 80109 |
19.41 |
| 2026-06-14 12:00 |
16:22:22.02 |
-19:52:11.2 |
HIP 80109 |
17.90 |
| 2026-06-15 00:00 |
16:22:15.17 |
-19:51:56.8 |
HIP 80109 |
16.41 |
| 2026-06-15 12:00 |
16:22:08.35 |
-19:51:42.5 |
HIP 80109 |
14.96 |
| 2026-06-16 00:00 |
16:22:01.55 |
-19:51:28.3 |
HIP 80109 |
13.55 |
| 2026-06-16 12:00 |
16:21:54.78 |
-19:51:14.1 |
HIP 80109 |
12.20 |
| 2026-06-17 00:00 |
16:21:48.03 |
-19:51:00.0 |
HIP 80109 |
10.92 |
| 2026-06-17 12:00 |
16:21:41.31 |
-19:50:46.0 |
HIP 80109 |
9.75 |
| 2026-06-18 00:00 |
16:21:34.61 |
-19:50:32.1 |
HIP 80109 |
8.71 |
| 2026-06-18 12:00 |
16:21:27.94 |
-19:50:18.2 |
HIP 80109 |
7.86 |
| 2026-06-19 00:00 |
16:21:21.30 |
-19:50:04.4 |
HIP 80109 |
7.27 |
| 2026-06-19 12:00 |
16:21:14.69 |
-19:49:50.7 |
HIP 80109 |
6.99 |
| 2026-06-20 00:00 |
16:21:08.11 |
-19:49:37.1 |
HIP 80109 |
7.05 |
| 2026-06-20 12:00 |
16:21:01.56 |
-19:49:23.5 |
HIP 80109 |
7.45 |
| 2026-06-21 00:00 |
16:20:55.04 |
-19:49:10.0 |
HIP 80109 |
8.12 |
| 2026-06-21 12:00 |
16:20:48.55 |
-19:48:56.7 |
HIP 80109 |
9.01 |
| 2026-06-22 00:00 |
16:20:42.09 |
-19:48:43.4 |
HIP 80109 |
10.06 |