| 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) |
| 2026-09-20 00:00 |
11:59:47.44 |
-49:48:03.9 |
HIP 58431 |
16.12 |
| 2026-09-20 12:00 |
11:59:56.16 |
-49:48:33.6 |
HIP 58431 |
16.56 |
| 2026-09-21 00:00 |
12:00:04.89 |
-49:49:03.9 |
HIP 58578 |
16.51 |
| 2026-09-21 12:00 |
12:00:13.62 |
-49:49:34.6 |
HIP 58647 |
15.49 |
| 2026-09-22 00:00 |
12:00:22.36 |
-49:50:05.9 |
HIP 58647 |
14.04 |
| 2026-09-22 12:00 |
12:00:31.09 |
-49:50:37.7 |
HIP 58647 |
12.60 |
| 2026-09-23 00:00 |
12:00:39.82 |
-49:51:10.0 |
HIP 58647 |
11.17 |
| 2026-09-23 12:00 |
12:00:48.55 |
-49:51:42.8 |
HIP 58647 |
9.76 |
| 2026-09-24 00:00 |
12:00:57.29 |
-49:52:16.1 |
HIP 58647 |
8.37 |
| 2026-09-24 12:00 |
12:01:06.02 |
-49:52:50.0 |
HIP 58647 |
7.03 |
| 2026-09-25 00:00 |
12:01:14.75 |
-49:53:24.3 |
HIP 58647 |
5.77 |
| 2026-09-25 12:00 |
12:01:23.47 |
-49:53:59.2 |
HIP 58647 |
4.65 |
| 2026-09-26 00:00 |
12:01:32.20 |
-49:54:34.6 |
HIP 58647 |
3.82 |
| 2026-09-26 12:00 |
12:01:40.92 |
-49:55:10.5 |
HIP 58647 |
3.48 |
| 2026-09-27 00:00 |
12:01:49.64 |
-49:55:46.9 |
HIP 58647 |
3.78 |
| 2026-09-27 12:00 |
12:01:58.36 |
-49:56:23.8 |
HIP 58647 |
4.58 |
| 2026-09-28 00:00 |
12:02:07.07 |
-49:57:01.2 |
HIP 58647 |
5.69 |
| 2026-09-28 12:00 |
12:02:15.77 |
-49:57:39.1 |
HIP 58647 |
6.97 |
| 2026-09-29 00:00 |
12:02:24.48 |
-49:58:17.5 |
HIP 58647 |
8.32 |
| 2026-09-29 12:00 |
12:02:33.17 |
-49:58:56.4 |
HIP 58647 |
9.74 |
| 2026-09-30 00:00 |
12:02:41.86 |
-49:59:35.8 |
HIP 58647 |
11.18 |
| 2026-09-30 12:00 |
12:02:50.55 |
-50:00:15.7 |
HIP 58647 |
12.65 |
| 2026-10-01 00:00 |
12:02:59.23 |
-50:00:56.1 |
HIP 58647 |
14.13 |
| 2026-10-01 12:00 |
12:03:07.90 |
-50:01:37.0 |
HIP 58879 |
13.95 |
| 2026-10-02 00:00 |
12:03:16.56 |
-50:02:18.4 |
HIP 58879 |
12.53 |
| 2026-10-02 12:00 |
12:03:25.22 |
-50:03:00.2 |
HIP 58879 |
11.16 |
| 2026-10-03 00:00 |
12:03:33.86 |
-50:03:42.6 |
HIP 58879 |
9.84 |
| 2026-10-03 12:00 |
12:03:42.50 |
-50:04:25.4 |
HIP 58879 |
8.61 |
| 2026-10-04 00:00 |
12:03:51.13 |
-50:05:08.7 |
HIP 58879 |
7.51 |
| 2026-10-04 12:00 |
12:03:59.75 |
-50:05:52.5 |
HIP 58879 |
6.60 |
| 2026-10-05 00:00 |
12:04:08.36 |
-50:06:36.8 |
HIP 58879 |
5.97 |
| 2026-10-05 12:00 |
12:04:16.96 |
-50:07:21.5 |
HIP 58879 |
5.73 |
| 2026-10-06 00:00 |
12:04:25.54 |
-50:08:06.8 |
HIP 58879 |
5.92 |
| 2026-10-06 12:00 |
12:04:34.12 |
-50:08:52.5 |
HIP 58879 |
6.50 |
| 2026-10-07 00:00 |
12:04:42.68 |
-50:09:38.7 |
HIP 58879 |
7.38 |
| 2026-10-07 12:00 |
12:04:51.23 |
-50:10:25.3 |
HIP 58955 |
7.43 |
| 2026-10-08 00:00 |
12:04:59.76 |
-50:11:12.4 |
HIP 58955 |
5.99 |
| 2026-10-08 12:00 |
12:05:08.29 |
-50:12:00.0 |
HIP 58955 |
4.64 |
| 2026-10-09 00:00 |
12:05:16.79 |
-50:12:48.1 |
HIP 58955 |
3.47 |
| 2026-10-09 12:00 |
12:05:25.29 |
-50:13:36.6 |
HIP 58955 |
2.75 |
| 2026-10-10 00:00 |
12:05:33.76 |
-50:14:25.6 |
HIP 58955 |
2.83 |
| 2026-10-10 12:00 |
12:05:42.22 |
-50:15:15.0 |
HIP 58955 |
3.67 |
| 2026-10-11 00:00 |
12:05:50.67 |
-50:16:04.9 |
HIP 59027 |
3.11 |