| 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
$$
M_a = (10.536 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.536 |
| n |
6.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
16:37:57.99 |
-20:27:27.8 |
HIP 81325 |
26.82 |
| 2026-03-26 12:00 |
16:37:55.73 |
-20:27:21.0 |
HIP 81325 |
26.36 |
| 2026-03-27 00:00 |
16:37:53.39 |
-20:27:14.1 |
HIP 81325 |
25.89 |
| 2026-03-27 12:00 |
16:37:50.99 |
-20:27:07.1 |
HIP 81325 |
25.41 |
| 2026-03-28 00:00 |
16:37:48.53 |
-20:27:00.0 |
HIP 81325 |
24.92 |
| 2026-03-28 12:00 |
16:37:45.99 |
-20:26:52.6 |
HIP 81325 |
24.43 |
| 2026-03-29 00:00 |
16:37:43.40 |
-20:26:45.2 |
HIP 81325 |
23.92 |
| 2026-03-29 12:00 |
16:37:40.73 |
-20:26:37.7 |
HIP 81325 |
23.41 |
| 2026-03-30 00:00 |
16:37:38.00 |
-20:26:30.1 |
HIP 81325 |
22.90 |
| 2026-03-30 12:00 |
16:37:35.21 |
-20:26:22.3 |
HIP 81325 |
22.38 |
| 2026-03-31 00:00 |
16:37:32.35 |
-20:26:14.5 |
HIP 81325 |
21.86 |
| 2026-03-31 12:00 |
16:37:29.42 |
-20:26:06.5 |
HIP 81325 |
21.34 |
| 2026-04-01 00:00 |
16:37:26.43 |
-20:25:58.4 |
HIP 81325 |
20.82 |
| 2026-04-01 12:00 |
16:37:23.38 |
-20:25:50.1 |
HIP 81325 |
20.30 |
| 2026-04-02 00:00 |
16:37:20.26 |
-20:25:41.8 |
HIP 81325 |
19.78 |
| 2026-04-02 12:00 |
16:37:17.08 |
-20:25:33.3 |
HIP 81325 |
19.27 |
| 2026-04-03 00:00 |
16:37:13.84 |
-20:25:24.7 |
HIP 81325 |
18.77 |
| 2026-04-03 12:00 |
16:37:10.53 |
-20:25:16.0 |
HIP 81325 |
18.28 |
| 2026-04-04 00:00 |
16:37:07.16 |
-20:25:07.2 |
HIP 81325 |
17.80 |
| 2026-04-04 12:00 |
16:37:03.73 |
-20:24:58.3 |
HIP 81325 |
17.33 |
| 2026-04-05 00:00 |
16:37:00.24 |
-20:24:49.2 |
HIP 81325 |
16.89 |
| 2026-04-05 12:00 |
16:36:56.68 |
-20:24:40.1 |
HIP 81325 |
16.47 |
| 2026-04-06 00:00 |
16:36:53.06 |
-20:24:30.8 |
HIP 81325 |
16.08 |
| 2026-04-06 12:00 |
16:36:49.38 |
-20:24:21.4 |
HIP 81325 |
15.73 |
| 2026-04-07 00:00 |
16:36:45.64 |
-20:24:11.9 |
HIP 81325 |
15.40 |
| 2026-04-07 12:00 |
16:36:41.84 |
-20:24:02.3 |
HIP 81325 |
15.13 |
| 2026-04-08 00:00 |
16:36:37.98 |
-20:23:52.6 |
HIP 81325 |
14.90 |
| 2026-04-08 12:00 |
16:36:34.06 |
-20:23:42.7 |
HIP 81325 |
14.72 |
| 2026-04-09 00:00 |
16:36:30.08 |
-20:23:32.8 |
HIP 81325 |
14.60 |
| 2026-04-09 12:00 |
16:36:26.04 |
-20:23:22.7 |
HIP 81325 |
14.54 |
| 2026-04-10 00:00 |
16:36:21.94 |
-20:23:12.6 |
HIP 81325 |
14.54 |
| 2026-04-10 12:00 |
16:36:17.78 |
-20:23:02.3 |
HIP 81325 |
14.61 |
| 2026-04-11 00:00 |
16:36:13.56 |
-20:22:51.9 |
HIP 81325 |
14.76 |
| 2026-04-11 12:00 |
16:36:09.29 |
-20:22:41.4 |
HIP 81325 |
14.97 |
| 2026-04-12 00:00 |
16:36:04.96 |
-20:22:30.9 |
HIP 81325 |
15.25 |
| 2026-04-12 12:00 |
16:36:00.57 |
-20:22:20.2 |
HIP 81325 |
15.60 |
| 2026-04-13 00:00 |
16:35:56.12 |
-20:22:09.4 |
HIP 81325 |
16.02 |
| 2026-04-13 12:00 |
16:35:51.62 |
-20:21:58.5 |
HIP 81325 |
16.50 |
| 2026-04-14 00:00 |
16:35:47.06 |
-20:21:47.5 |
HIP 81325 |
17.04 |
| 2026-04-14 12:00 |
16:35:42.44 |
-20:21:36.3 |
HIP 81325 |
17.64 |
| 2026-04-15 00:00 |
16:35:37.77 |
-20:21:25.1 |
HIP 81325 |
18.30 |
| 2026-04-15 12:00 |
16:35:33.05 |
-20:21:13.8 |
HIP 81325 |
19.00 |
| 2026-04-16 00:00 |
16:35:28.27 |
-20:21:02.4 |
HIP 81325 |
19.76 |