| 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) |
| 2026-09-20 00:00 |
18:19:52.59 |
+01:22:23.3 |
HIP 89768 |
12.26 |
| 2026-09-20 12:00 |
18:19:52.41 |
+01:21:44.2 |
HIP 89768 |
12.46 |
| 2026-09-21 00:00 |
18:19:52.29 |
+01:21:05.1 |
HIP 89768 |
12.70 |
| 2026-09-21 12:00 |
18:19:52.20 |
+01:20:26.1 |
HIP 89768 |
12.98 |
| 2026-09-22 00:00 |
18:19:52.17 |
+01:19:47.1 |
HIP 89768 |
13.29 |
| 2026-09-22 12:00 |
18:19:52.17 |
+01:19:08.1 |
HIP 89768 |
13.63 |
| 2026-09-23 00:00 |
18:19:52.23 |
+01:18:29.2 |
HIP 89768 |
14.01 |
| 2026-09-23 12:00 |
18:19:52.33 |
+01:17:50.3 |
HIP 89768 |
14.42 |
| 2026-09-24 00:00 |
18:19:52.48 |
+01:17:11.4 |
HIP 89768 |
14.85 |
| 2026-09-24 12:00 |
18:19:52.67 |
+01:16:32.6 |
HIP 89768 |
15.30 |
| 2026-09-25 00:00 |
18:19:52.90 |
+01:15:53.8 |
HIP 89768 |
15.78 |
| 2026-09-25 12:00 |
18:19:53.19 |
+01:15:15.0 |
HIP 89768 |
16.27 |
| 2026-09-26 00:00 |
18:19:53.51 |
+01:14:36.3 |
HIP 89768 |
16.78 |
| 2026-09-26 12:00 |
18:19:53.89 |
+01:13:57.6 |
HIP 89768 |
17.31 |
| 2026-09-27 00:00 |
18:19:54.31 |
+01:13:19.0 |
HIP 89768 |
17.86 |
| 2026-09-27 12:00 |
18:19:54.77 |
+01:12:40.5 |
HIP 89768 |
18.42 |
| 2026-09-28 00:00 |
18:19:55.28 |
+01:12:01.9 |
HIP 89768 |
18.99 |
| 2026-09-28 12:00 |
18:19:55.83 |
+01:11:23.5 |
HIP 89768 |
19.57 |
| 2026-09-29 00:00 |
18:19:56.43 |
+01:10:45.1 |
HIP 89768 |
20.16 |
| 2026-09-29 12:00 |
18:19:57.08 |
+01:10:06.8 |
HIP 89768 |
20.77 |
| 2026-09-30 00:00 |
18:19:57.77 |
+01:09:28.5 |
HIP 89789 |
20.58 |
| 2026-09-30 12:00 |
18:19:58.50 |
+01:08:50.3 |
HIP 89789 |
20.07 |
| 2026-10-01 00:00 |
18:19:59.29 |
+01:08:12.1 |
HIP 89789 |
19.58 |
| 2026-10-01 12:00 |
18:20:00.11 |
+01:07:34.1 |
HIP 89789 |
19.10 |
| 2026-10-02 00:00 |
18:20:00.98 |
+01:06:56.1 |
HIP 89789 |
18.64 |
| 2026-10-02 12:00 |
18:20:01.90 |
+01:06:18.1 |
HIP 89789 |
18.20 |
| 2026-10-03 00:00 |
18:20:02.86 |
+01:05:40.3 |
HIP 89789 |
17.78 |
| 2026-10-03 12:00 |
18:20:03.86 |
+01:05:02.5 |
HIP 89789 |
17.38 |
| 2026-10-04 00:00 |
18:20:04.91 |
+01:04:24.8 |
HIP 89789 |
17.01 |
| 2026-10-04 12:00 |
18:20:06.00 |
+01:03:47.2 |
HIP 89789 |
16.66 |
| 2026-10-05 00:00 |
18:20:07.14 |
+01:03:09.7 |
HIP 89789 |
16.35 |
| 2026-10-05 12:00 |
18:20:08.33 |
+01:02:32.2 |
HIP 89789 |
16.07 |
| 2026-10-06 00:00 |
18:20:09.56 |
+01:01:54.9 |
HIP 89789 |
15.82 |
| 2026-10-06 12:00 |
18:20:10.83 |
+01:01:17.6 |
HIP 89789 |
15.60 |
| 2026-10-07 00:00 |
18:20:12.15 |
+01:00:40.5 |
HIP 89789 |
15.43 |
| 2026-10-07 12:00 |
18:20:13.51 |
+01:00:03.4 |
HIP 89789 |
15.29 |
| 2026-10-08 00:00 |
18:20:14.91 |
+00:59:26.4 |
HIP 89789 |
15.20 |
| 2026-10-08 12:00 |
18:20:16.36 |
+00:58:49.6 |
HIP 89789 |
15.15 |
| 2026-10-09 00:00 |
18:20:17.86 |
+00:58:12.8 |
HIP 89789 |
15.14 |
| 2026-10-09 12:00 |
18:20:19.39 |
+00:57:36.2 |
HIP 89789 |
15.18 |
| 2026-10-10 00:00 |
18:20:20.97 |
+00:56:59.6 |
HIP 89789 |
15.26 |
| 2026-10-10 12:00 |
18:20:22.60 |
+00:56:23.2 |
HIP 89789 |
15.39 |
| 2026-10-11 00:00 |
18:20:24.27 |
+00:55:46.9 |
HIP 89789 |
15.56 |