| 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) |
| 2026-05-12 00:00 |
18:36:27.08 |
+02:35:52.9 |
HIP 91300 |
14.64 |
| 2026-05-12 12:00 |
18:36:23.69 |
+02:36:11.0 |
HIP 91300 |
15.45 |
| 2026-05-13 00:00 |
18:36:20.25 |
+02:36:28.8 |
HIP 91300 |
16.28 |
| 2026-05-13 12:00 |
18:36:16.78 |
+02:36:46.4 |
HIP 91300 |
17.12 |
| 2026-05-14 00:00 |
18:36:13.28 |
+02:37:03.8 |
HIP 91300 |
17.98 |
| 2026-05-14 12:00 |
18:36:09.74 |
+02:37:20.9 |
HIP 91300 |
18.86 |
| 2026-05-15 00:00 |
18:36:06.16 |
+02:37:37.8 |
HIP 91300 |
19.75 |
| 2026-05-15 12:00 |
18:36:02.55 |
+02:37:54.4 |
HIP 91300 |
20.65 |
| 2026-05-16 00:00 |
18:35:58.90 |
+02:38:10.8 |
HIP 91300 |
21.56 |
| 2026-05-16 12:00 |
18:35:55.22 |
+02:38:26.9 |
HIP 91300 |
22.49 |
| 2026-05-17 00:00 |
18:35:51.51 |
+02:38:42.8 |
HIP 91300 |
23.43 |
| 2026-05-17 12:00 |
18:35:47.76 |
+02:38:58.4 |
HIP 91048 |
22.70 |
| 2026-05-18 00:00 |
18:35:43.98 |
+02:39:13.7 |
HIP 91048 |
21.91 |
| 2026-05-18 12:00 |
18:35:40.17 |
+02:39:28.8 |
HIP 91048 |
21.11 |
| 2026-05-19 00:00 |
18:35:36.32 |
+02:39:43.7 |
HIP 91048 |
20.33 |
| 2026-05-19 12:00 |
18:35:32.44 |
+02:39:58.2 |
HIP 91048 |
19.56 |
| 2026-05-20 00:00 |
18:35:28.53 |
+02:40:12.5 |
HIP 91048 |
18.80 |
| 2026-05-20 12:00 |
18:35:24.59 |
+02:40:26.6 |
HIP 91048 |
18.06 |
| 2026-05-21 00:00 |
18:35:20.61 |
+02:40:40.3 |
HIP 91048 |
17.33 |
| 2026-05-21 12:00 |
18:35:16.61 |
+02:40:53.8 |
HIP 91048 |
16.62 |
| 2026-05-22 00:00 |
18:35:12.57 |
+02:41:07.1 |
HIP 91048 |
15.94 |
| 2026-05-22 12:00 |
18:35:08.51 |
+02:41:20.0 |
HIP 91048 |
15.30 |
| 2026-05-23 00:00 |
18:35:04.42 |
+02:41:32.7 |
HIP 91048 |
14.68 |
| 2026-05-23 12:00 |
18:35:00.29 |
+02:41:45.1 |
HIP 91048 |
14.11 |
| 2026-05-24 00:00 |
18:34:56.14 |
+02:41:57.3 |
HIP 91048 |
13.59 |
| 2026-05-24 12:00 |
18:34:51.96 |
+02:42:09.2 |
HIP 91048 |
13.13 |
| 2026-05-25 00:00 |
18:34:47.75 |
+02:42:20.7 |
HIP 91048 |
12.73 |
| 2026-05-25 12:00 |
18:34:43.51 |
+02:42:32.0 |
HIP 91048 |
12.40 |
| 2026-05-26 00:00 |
18:34:39.25 |
+02:42:43.1 |
HIP 91048 |
12.16 |
| 2026-05-26 12:00 |
18:34:34.96 |
+02:42:53.8 |
HIP 91048 |
12.00 |
| 2026-05-27 00:00 |
18:34:30.64 |
+02:43:04.3 |
HIP 91048 |
11.93 |
| 2026-05-27 12:00 |
18:34:26.29 |
+02:43:14.5 |
HIP 91048 |
11.95 |
| 2026-05-28 00:00 |
18:34:21.92 |
+02:43:24.4 |
HIP 91048 |
12.07 |
| 2026-05-28 12:00 |
18:34:17.53 |
+02:43:34.0 |
HIP 91048 |
12.29 |
| 2026-05-29 00:00 |
18:34:13.11 |
+02:43:43.3 |
HIP 91048 |
12.59 |
| 2026-05-29 12:00 |
18:34:08.66 |
+02:43:52.3 |
HIP 91048 |
12.98 |
| 2026-05-30 00:00 |
18:34:04.19 |
+02:44:01.1 |
HIP 91048 |
13.45 |
| 2026-05-30 12:00 |
18:33:59.70 |
+02:44:09.5 |
HIP 91048 |
14.00 |
| 2026-05-31 00:00 |
18:33:55.18 |
+02:44:17.7 |
HIP 91048 |
14.61 |
| 2026-05-31 12:00 |
18:33:50.64 |
+02:44:25.6 |
HIP 91048 |
15.28 |
| 2026-06-01 00:00 |
18:33:46.07 |
+02:44:33.2 |
HIP 91048 |
16.00 |
| 2026-06-01 12:00 |
18:33:41.48 |
+02:44:40.5 |
HIP 91048 |
16.77 |
| 2026-06-02 00:00 |
18:33:36.87 |
+02:44:47.5 |
HIP 91048 |
17.58 |