| Parameter |
Value |
| Designation |
C/2018 A1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-10-20T10:16:17.644800Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:39Z |
| Obs used |
118 |
| NEO |
- |
| M1 |
15.100 |
| K1 |
5.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-02-06.0000000 |
| e |
0.90438598 |
| q (au) |
2.419351 |
| a (au) |
25.303307 |
| i (deg) |
53.559981 |
| Ω (om, deg) |
336.621053 |
| ω (w, deg) |
96.385267 |
| M (ma, deg) |
0.840729 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.981 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.981 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.738 |
| k |
0.800 |
| 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) |
| 2026-07-29 00:00 |
11:46:08.43 |
-49:48:11.4 |
HIP 57382 |
9.09 |
| 2026-07-29 12:00 |
11:46:14.36 |
-49:47:42.2 |
HIP 57382 |
9.85 |
| 2026-07-30 00:00 |
11:46:20.34 |
-49:47:13.4 |
HIP 57382 |
10.66 |
| 2026-07-30 12:00 |
11:46:26.37 |
-49:46:45.2 |
HIP 57524 |
11.30 |
| 2026-07-31 00:00 |
11:46:32.44 |
-49:46:17.5 |
HIP 57524 |
10.79 |
| 2026-07-31 12:00 |
11:46:38.56 |
-49:45:50.3 |
HIP 57524 |
10.35 |
| 2026-08-01 00:00 |
11:46:44.73 |
-49:45:23.7 |
HIP 57524 |
9.99 |
| 2026-08-01 12:00 |
11:46:50.94 |
-49:44:57.6 |
HIP 57524 |
9.74 |
| 2026-08-02 00:00 |
11:46:57.20 |
-49:44:32.1 |
HIP 57524 |
9.59 |
| 2026-08-02 12:00 |
11:47:03.51 |
-49:44:07.0 |
HIP 57524 |
9.56 |
| 2026-08-03 00:00 |
11:47:09.86 |
-49:43:42.5 |
HIP 57524 |
9.64 |
| 2026-08-03 12:00 |
11:47:16.26 |
-49:43:18.6 |
HIP 57524 |
9.83 |
| 2026-08-04 00:00 |
11:47:22.70 |
-49:42:55.2 |
HIP 57524 |
10.13 |
| 2026-08-04 12:00 |
11:47:29.19 |
-49:42:32.3 |
HIP 57524 |
10.54 |
| 2026-08-05 00:00 |
11:47:35.72 |
-49:42:10.0 |
HIP 57524 |
11.03 |
| 2026-08-05 12:00 |
11:47:42.30 |
-49:41:48.2 |
HIP 57524 |
11.60 |
| 2026-08-06 00:00 |
11:47:48.91 |
-49:41:27.0 |
HIP 57524 |
12.25 |
| 2026-08-06 12:00 |
11:47:55.58 |
-49:41:06.3 |
HIP 57524 |
12.95 |
| 2026-08-07 00:00 |
11:48:02.28 |
-49:40:46.2 |
HIP 57524 |
13.70 |
| 2026-08-07 12:00 |
11:48:09.02 |
-49:40:26.6 |
HIP 57524 |
14.50 |
| 2026-08-08 00:00 |
11:48:15.81 |
-49:40:07.6 |
HIP 57499 |
15.25 |
| 2026-08-08 12:00 |
11:48:22.64 |
-49:39:49.2 |
HIP 57499 |
15.84 |
| 2026-08-09 00:00 |
11:48:29.51 |
-49:39:31.2 |
HIP 57499 |
16.50 |
| 2026-08-09 12:00 |
11:48:36.42 |
-49:39:13.9 |
HIP 57710 |
16.14 |
| 2026-08-10 00:00 |
11:48:43.37 |
-49:38:57.1 |
HIP 57710 |
15.00 |
| 2026-08-10 12:00 |
11:48:50.36 |
-49:38:40.9 |
HIP 57710 |
13.86 |
| 2026-08-11 00:00 |
11:48:57.39 |
-49:38:25.2 |
HIP 57710 |
12.73 |
| 2026-08-11 12:00 |
11:49:04.46 |
-49:38:10.1 |
HIP 57710 |
11.60 |
| 2026-08-12 00:00 |
11:49:11.57 |
-49:37:55.6 |
HIP 57710 |
10.48 |
| 2026-08-12 12:00 |
11:49:18.72 |
-49:37:41.6 |
HIP 57710 |
9.37 |
| 2026-08-13 00:00 |
11:49:25.90 |
-49:37:28.2 |
HIP 57710 |
8.28 |
| 2026-08-13 12:00 |
11:49:33.12 |
-49:37:15.3 |
HIP 57710 |
7.23 |
| 2026-08-14 00:00 |
11:49:40.38 |
-49:37:03.0 |
HIP 57710 |
6.23 |
| 2026-08-14 12:00 |
11:49:47.67 |
-49:36:51.3 |
HIP 57710 |
5.31 |
| 2026-08-15 00:00 |
11:49:55.00 |
-49:36:40.2 |
HIP 57710 |
4.53 |
| 2026-08-15 12:00 |
11:50:02.36 |
-49:36:29.6 |
HIP 57710 |
3.98 |
| 2026-08-16 00:00 |
11:50:09.76 |
-49:36:19.6 |
HIP 57710 |
3.76 |
| 2026-08-16 12:00 |
11:50:17.19 |
-49:36:10.2 |
HIP 57710 |
3.93 |
| 2026-08-17 00:00 |
11:50:24.66 |
-49:36:01.3 |
HIP 57710 |
4.45 |
| 2026-08-17 12:00 |
11:50:32.16 |
-49:35:53.0 |
HIP 57710 |
5.21 |
| 2026-08-18 00:00 |
11:50:39.69 |
-49:35:45.3 |
HIP 57710 |
6.14 |
| 2026-08-18 12:00 |
11:50:47.25 |
-49:35:38.1 |
HIP 57710 |
7.17 |
| 2026-08-19 00:00 |
11:50:54.85 |
-49:35:31.6 |
HIP 57710 |
8.26 |