| 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) |
| 2026-03-26 00:00 |
18:38:35.84 |
+01:55:12.5 |
HIP 91323 |
18.54 |
| 2026-03-26 12:00 |
18:38:36.62 |
+01:55:42.6 |
HIP 91323 |
19.01 |
| 2026-03-27 00:00 |
18:38:37.36 |
+01:56:12.7 |
HIP 91323 |
19.46 |
| 2026-03-27 12:00 |
18:38:38.05 |
+01:56:42.8 |
HIP 91323 |
19.92 |
| 2026-03-28 00:00 |
18:38:38.70 |
+01:57:12.9 |
HIP 91323 |
20.37 |
| 2026-03-28 12:00 |
18:38:39.29 |
+01:57:42.9 |
HIP 91323 |
20.81 |
| 2026-03-29 00:00 |
18:38:39.84 |
+01:58:13.0 |
HIP 91323 |
21.25 |
| 2026-03-29 12:00 |
18:38:40.34 |
+01:58:43.0 |
HIP 91323 |
21.68 |
| 2026-03-30 00:00 |
18:38:40.80 |
+01:59:12.9 |
HIP 91323 |
22.10 |
| 2026-03-30 12:00 |
18:38:41.20 |
+01:59:42.9 |
HIP 91323 |
22.53 |
| 2026-03-31 00:00 |
18:38:41.56 |
+02:00:12.8 |
HIP 91323 |
22.94 |
| 2026-03-31 12:00 |
18:38:41.87 |
+02:00:42.7 |
HIP 91323 |
23.35 |
| 2026-04-01 00:00 |
18:38:42.14 |
+02:01:12.5 |
HIP 91323 |
23.76 |
| 2026-04-01 12:00 |
18:38:42.35 |
+02:01:42.4 |
HIP 91323 |
24.16 |
| 2026-04-02 00:00 |
18:38:42.52 |
+02:02:12.1 |
HIP 91296 |
24.47 |
| 2026-04-02 12:00 |
18:38:42.64 |
+02:02:41.8 |
HIP 91296 |
24.23 |
| 2026-04-03 00:00 |
18:38:42.72 |
+02:03:11.5 |
HIP 91296 |
24.00 |
| 2026-04-03 12:00 |
18:38:42.74 |
+02:03:41.2 |
HIP 91296 |
23.76 |
| 2026-04-04 00:00 |
18:38:42.72 |
+02:04:10.7 |
HIP 91296 |
23.52 |
| 2026-04-04 12:00 |
18:38:42.65 |
+02:04:40.3 |
HIP 91296 |
23.27 |
| 2026-04-05 00:00 |
18:38:42.54 |
+02:05:09.7 |
HIP 91296 |
23.03 |
| 2026-04-05 12:00 |
18:38:42.37 |
+02:05:39.1 |
HIP 91296 |
22.78 |
| 2026-04-06 00:00 |
18:38:42.16 |
+02:06:08.5 |
HIP 91296 |
22.53 |
| 2026-04-06 12:00 |
18:38:41.90 |
+02:06:37.8 |
HIP 91296 |
22.27 |
| 2026-04-07 00:00 |
18:38:41.59 |
+02:07:07.0 |
HIP 91296 |
22.02 |
| 2026-04-07 12:00 |
18:38:41.24 |
+02:07:36.1 |
HIP 91296 |
21.76 |
| 2026-04-08 00:00 |
18:38:40.83 |
+02:08:05.2 |
HIP 91296 |
21.50 |
| 2026-04-08 12:00 |
18:38:40.39 |
+02:08:34.2 |
HIP 91296 |
21.23 |
| 2026-04-09 00:00 |
18:38:39.89 |
+02:09:03.1 |
HIP 91296 |
20.97 |
| 2026-04-09 12:00 |
18:38:39.34 |
+02:09:32.0 |
HIP 91296 |
20.70 |
| 2026-04-10 00:00 |
18:38:38.75 |
+02:10:00.8 |
HIP 91296 |
20.43 |
| 2026-04-10 12:00 |
18:38:38.11 |
+02:10:29.4 |
HIP 91296 |
20.15 |
| 2026-04-11 00:00 |
18:38:37.42 |
+02:10:58.0 |
HIP 91296 |
19.88 |
| 2026-04-11 12:00 |
18:38:36.69 |
+02:11:26.5 |
HIP 91296 |
19.60 |
| 2026-04-12 00:00 |
18:38:35.91 |
+02:11:55.0 |
HIP 91296 |
19.32 |
| 2026-04-12 12:00 |
18:38:35.08 |
+02:12:23.3 |
HIP 91296 |
19.04 |
| 2026-04-13 00:00 |
18:38:34.20 |
+02:12:51.5 |
HIP 91296 |
18.75 |
| 2026-04-13 12:00 |
18:38:33.28 |
+02:13:19.6 |
HIP 91296 |
18.47 |
| 2026-04-14 00:00 |
18:38:32.31 |
+02:13:47.6 |
HIP 91296 |
18.18 |
| 2026-04-14 12:00 |
18:38:31.29 |
+02:14:15.5 |
HIP 91296 |
17.90 |
| 2026-04-15 00:00 |
18:38:30.22 |
+02:14:43.3 |
HIP 91296 |
17.61 |
| 2026-04-15 12:00 |
18:38:29.11 |
+02:15:11.0 |
HIP 91296 |
17.33 |
| 2026-04-16 00:00 |
18:38:27.95 |
+02:15:38.6 |
HIP 91296 |
17.04 |