| Parameter |
Value |
| Designation |
C/2017 A1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-05-17T03:02:11.906880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:28Z |
| Obs used |
196 |
| NEO |
- |
| M1 |
7.900 |
| K1 |
21.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-02-09.0000000 |
| e |
0.97149920 |
| q (au) |
2.290367 |
| a (au) |
80.361507 |
| i (deg) |
49.793627 |
| Ω (om, deg) |
121.067433 |
| ω (w, deg) |
2.044588 |
| M (ma, deg) |
359.867117 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.659 + 5.781\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.659 |
| n |
5.781 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
1.000 |
| δ90 |
1.000 |
| 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 |
18:24:12.31 |
+02:24:40.9 |
HIP 90148 |
6.58 |
| 2026-07-29 12:00 |
18:24:07.98 |
+02:24:14.0 |
HIP 90148 |
5.92 |
| 2026-07-30 00:00 |
18:24:03.67 |
+02:23:46.8 |
HIP 90148 |
5.45 |
| 2026-07-30 12:00 |
18:23:59.39 |
+02:23:19.4 |
HIP 90148 |
5.22 |
| 2026-07-31 00:00 |
18:23:55.14 |
+02:22:51.7 |
HIP 90148 |
5.24 |
| 2026-07-31 12:00 |
18:23:50.91 |
+02:22:23.8 |
HIP 90148 |
5.51 |
| 2026-08-01 00:00 |
18:23:46.71 |
+02:21:55.7 |
HIP 90148 |
6.00 |
| 2026-08-01 12:00 |
18:23:42.54 |
+02:21:27.4 |
HIP 90148 |
6.66 |
| 2026-08-02 00:00 |
18:23:38.40 |
+02:20:58.8 |
HIP 90148 |
7.43 |
| 2026-08-02 12:00 |
18:23:34.29 |
+02:20:30.0 |
HIP 90148 |
8.29 |
| 2026-08-03 00:00 |
18:23:30.20 |
+02:20:01.0 |
HIP 90148 |
9.21 |
| 2026-08-03 12:00 |
18:23:26.15 |
+02:19:31.8 |
HIP 90148 |
10.17 |
| 2026-08-04 00:00 |
18:23:22.12 |
+02:19:02.4 |
HIP 90148 |
11.16 |
| 2026-08-04 12:00 |
18:23:18.12 |
+02:18:32.7 |
HIP 90148 |
12.17 |
| 2026-08-05 00:00 |
18:23:14.16 |
+02:18:02.9 |
HIP 90148 |
13.20 |
| 2026-08-05 12:00 |
18:23:10.22 |
+02:17:32.8 |
HIP 90148 |
14.23 |
| 2026-08-06 00:00 |
18:23:06.32 |
+02:17:02.5 |
HIP 90148 |
15.27 |
| 2026-08-06 12:00 |
18:23:02.44 |
+02:16:32.0 |
HIP 90148 |
16.32 |
| 2026-08-07 00:00 |
18:22:58.60 |
+02:16:01.3 |
HIP 90148 |
17.36 |
| 2026-08-07 12:00 |
18:22:54.79 |
+02:15:30.4 |
HIP 90148 |
18.41 |
| 2026-08-08 00:00 |
18:22:51.01 |
+02:14:59.3 |
HIP 90148 |
19.46 |
| 2026-08-08 12:00 |
18:22:47.27 |
+02:14:28.0 |
HIP 90148 |
20.51 |
| 2026-08-09 00:00 |
18:22:43.55 |
+02:13:56.5 |
HIP 90148 |
21.56 |
| 2026-08-09 12:00 |
18:22:39.87 |
+02:13:24.9 |
HIP 90148 |
22.60 |
| 2026-08-10 00:00 |
18:22:36.23 |
+02:12:53.0 |
HIP 90148 |
23.64 |
| 2026-08-10 12:00 |
18:22:32.61 |
+02:12:20.9 |
HIP 90148 |
24.68 |
| 2026-08-11 00:00 |
18:22:29.04 |
+02:11:48.6 |
HIP 90148 |
25.71 |
| 2026-08-11 12:00 |
18:22:25.49 |
+02:11:16.2 |
HIP 90148 |
26.74 |
| 2026-08-12 00:00 |
18:22:21.98 |
+02:10:43.6 |
HIP 90148 |
27.76 |
| 2026-08-12 12:00 |
18:22:18.51 |
+02:10:10.8 |
HIP 90035 |
27.75 |
| 2026-08-13 00:00 |
18:22:15.07 |
+02:09:37.8 |
HIP 90035 |
27.21 |
| 2026-08-13 12:00 |
18:22:11.67 |
+02:09:04.6 |
HIP 90035 |
26.69 |
| 2026-08-14 00:00 |
18:22:08.30 |
+02:08:31.3 |
HIP 90035 |
26.19 |
| 2026-08-14 12:00 |
18:22:04.97 |
+02:07:57.8 |
HIP 90035 |
25.72 |
| 2026-08-15 00:00 |
18:22:01.68 |
+02:07:24.1 |
HIP 90035 |
25.27 |
| 2026-08-15 12:00 |
18:21:58.42 |
+02:06:50.3 |
HIP 90035 |
24.86 |
| 2026-08-16 00:00 |
18:21:55.20 |
+02:06:16.3 |
HIP 90035 |
24.47 |
| 2026-08-16 12:00 |
18:21:52.02 |
+02:05:42.2 |
HIP 90035 |
24.11 |
| 2026-08-17 00:00 |
18:21:48.87 |
+02:05:07.8 |
HIP 90035 |
23.78 |
| 2026-08-17 12:00 |
18:21:45.76 |
+02:04:33.4 |
HIP 90035 |
23.48 |
| 2026-08-18 00:00 |
18:21:42.69 |
+02:03:58.8 |
HIP 90035 |
23.21 |
| 2026-08-18 12:00 |
18:21:39.66 |
+02:03:24.0 |
HIP 90035 |
22.97 |
| 2026-08-19 00:00 |
18:21:36.67 |
+02:02:49.1 |
HIP 90035 |
22.76 |