C/2017 A1 (PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
18:33:29.02 |
+01:10:41.2 |
HIP 91016 |
10.19 |
| 2026-02-03 12:00 |
18:33:33.87 |
+01:10:59.6 |
HIP 91016 |
9.09 |
| 2026-02-04 00:00 |
18:33:38.68 |
+01:11:18.2 |
HIP 91016 |
8.05 |
| 2026-02-04 12:00 |
18:33:43.47 |
+01:11:37.1 |
HIP 91016 |
7.07 |
| 2026-02-05 00:00 |
18:33:48.23 |
+01:11:56.1 |
HIP 91016 |
6.19 |
| 2026-02-05 12:00 |
18:33:52.96 |
+01:12:15.4 |
HIP 91016 |
5.44 |
| 2026-02-06 00:00 |
18:33:57.66 |
+01:12:34.9 |
HIP 91016 |
4.88 |
| 2026-02-06 12:00 |
18:34:02.33 |
+01:12:54.6 |
HIP 91016 |
4.58 |
| 2026-02-07 00:00 |
18:34:06.97 |
+01:13:14.5 |
HIP 91016 |
4.59 |
| 2026-02-07 12:00 |
18:34:11.59 |
+01:13:34.7 |
HIP 91016 |
4.90 |
| 2026-02-08 00:00 |
18:34:16.17 |
+01:13:55.0 |
HIP 91016 |
5.45 |
| 2026-02-08 12:00 |
18:34:20.72 |
+01:14:15.5 |
HIP 91016 |
6.18 |
| 2026-02-09 00:00 |
18:34:25.25 |
+01:14:36.3 |
HIP 91016 |
7.02 |
| 2026-02-09 12:00 |
18:34:29.74 |
+01:14:57.2 |
HIP 91016 |
7.95 |
| 2026-02-10 00:00 |
18:34:34.20 |
+01:15:18.4 |
HIP 91016 |
8.92 |
| 2026-02-10 12:00 |
18:34:38.63 |
+01:15:39.7 |
HIP 91016 |
9.93 |
| 2026-02-11 00:00 |
18:34:43.03 |
+01:16:01.3 |
HIP 91016 |
10.96 |
| 2026-02-11 12:00 |
18:34:47.39 |
+01:16:23.0 |
HIP 91016 |
12.01 |
| 2026-02-12 00:00 |
18:34:51.73 |
+01:16:44.9 |
HIP 91016 |
13.06 |
| 2026-02-12 12:00 |
18:34:56.03 |
+01:17:07.0 |
HIP 91016 |
14.12 |
| 2026-02-13 00:00 |
18:35:00.30 |
+01:17:29.4 |
HIP 91016 |
15.19 |
| 2026-02-13 12:00 |
18:35:04.53 |
+01:17:51.9 |
HIP 91016 |
16.25 |
| 2026-02-14 00:00 |
18:35:08.73 |
+01:18:14.5 |
HIP 91016 |
17.31 |
| 2026-02-14 12:00 |
18:35:12.90 |
+01:18:37.4 |
HIP 91016 |
18.37 |
| 2026-02-15 00:00 |
18:35:17.03 |
+01:19:00.5 |
HIP 91016 |
19.43 |
| 2026-02-15 12:00 |
18:35:21.13 |
+01:19:23.7 |
HIP 91016 |
20.49 |
| 2026-02-16 00:00 |
18:35:25.19 |
+01:19:47.1 |
HIP 91016 |
21.54 |
| 2026-02-16 12:00 |
18:35:29.22 |
+01:20:10.7 |
HIP 91016 |
22.58 |
| 2026-02-17 00:00 |
18:35:33.21 |
+01:20:34.5 |
HIP 91016 |
23.62 |
| 2026-02-17 12:00 |
18:35:37.17 |
+01:20:58.4 |
HIP 91016 |
24.66 |
| 2026-02-18 00:00 |
18:35:41.09 |
+01:21:22.5 |
HIP 91016 |
25.69 |
| 2026-02-18 12:00 |
18:35:44.98 |
+01:21:46.8 |
HIP 91016 |
26.71 |
| 2026-02-19 00:00 |
18:35:48.83 |
+01:22:11.2 |
HIP 91016 |
27.73 |
| 2026-02-19 12:00 |
18:35:52.64 |
+01:22:35.8 |
HIP 91016 |
28.74 |
| 2026-02-20 00:00 |
18:35:56.42 |
+01:23:00.5 |
HIP 91016 |
29.74 |
| 2026-02-20 12:00 |
18:36:00.16 |
+01:23:25.4 |
HIP 91016 |
30.74 |
| 2026-02-21 00:00 |
18:36:03.86 |
+01:23:50.5 |
HIP 91323 |
30.73 |
| 2026-02-21 12:00 |
18:36:07.52 |
+01:24:15.7 |
HIP 91323 |
29.76 |
| 2026-02-22 00:00 |
18:36:11.14 |
+01:24:41.1 |
HIP 91323 |
28.81 |
| 2026-02-22 12:00 |
18:36:14.73 |
+01:25:06.6 |
HIP 91323 |
27.86 |
| 2026-02-23 00:00 |
18:36:18.28 |
+01:25:32.3 |
HIP 91323 |
26.91 |
| 2026-02-23 12:00 |
18:36:21.79 |
+01:25:58.1 |
HIP 91323 |
25.98 |
| 2026-02-24 00:00 |
18:36:25.26 |
+01:26:24.0 |
HIP 91323 |
25.05 |