| Parameter |
Value |
| Designation |
C/2017 Y1 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-08-31T11:16:29.493120Z |
| Orbit solution date (soln_date, UTC) |
2022-07-06T03:12:22Z |
| Obs used |
92 |
| NEO |
- |
| M1 |
9.300 |
| K1 |
13.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2018-03-09.0000000 |
| e |
0.99901916 |
| q (au) |
3.718608 |
| a (au) |
3791.251402 |
| i (deg) |
55.240118 |
| Ω (om, deg) |
307.509679 |
| ω (w, deg) |
134.447483 |
| M (ma, deg) |
0.000800 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.514 + 4.991\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.514 |
| n |
4.991 |
| gf |
0.935 |
| gb |
-0.899 |
| k |
0.999 |
| δ90 |
5.121 |
| 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 |
11:29:41.43 |
-57:10:29.0 |
HIP 56153 |
7.74 |
| 2026-09-20 12:00 |
11:29:51.35 |
-57:11:01.0 |
HIP 56153 |
6.70 |
| 2026-09-21 00:00 |
11:30:01.26 |
-57:11:33.5 |
HIP 56153 |
5.84 |
| 2026-09-21 12:00 |
11:30:11.17 |
-57:12:06.5 |
HIP 56153 |
5.25 |
| 2026-09-22 00:00 |
11:30:21.06 |
-57:12:40.1 |
HIP 56153 |
5.03 |
| 2026-09-22 12:00 |
11:30:30.95 |
-57:13:14.2 |
HIP 56153 |
5.24 |
| 2026-09-23 00:00 |
11:30:40.83 |
-57:13:48.8 |
HIP 56153 |
5.82 |
| 2026-09-23 12:00 |
11:30:50.70 |
-57:14:23.9 |
HIP 56153 |
6.68 |
| 2026-09-24 00:00 |
11:31:00.56 |
-57:14:59.5 |
HIP 56153 |
7.73 |
| 2026-09-24 12:00 |
11:31:10.40 |
-57:15:35.6 |
HIP 56153 |
8.91 |
| 2026-09-25 00:00 |
11:31:20.24 |
-57:16:12.3 |
HIP 56153 |
10.16 |
| 2026-09-25 12:00 |
11:31:30.07 |
-57:16:49.4 |
HIP 56153 |
11.47 |
| 2026-09-26 00:00 |
11:31:39.88 |
-57:17:27.1 |
HIP 56153 |
12.82 |
| 2026-09-26 12:00 |
11:31:49.68 |
-57:18:05.2 |
HIP 56153 |
14.20 |
| 2026-09-27 00:00 |
11:31:59.47 |
-57:18:43.9 |
HIP 56153 |
15.59 |
| 2026-09-27 12:00 |
11:32:09.25 |
-57:19:23.1 |
HIP 56365 |
15.17 |
| 2026-09-28 00:00 |
11:32:19.01 |
-57:20:02.7 |
HIP 56365 |
13.88 |
| 2026-09-28 12:00 |
11:32:28.75 |
-57:20:42.9 |
HIP 56365 |
12.62 |
| 2026-09-29 00:00 |
11:32:38.49 |
-57:21:23.5 |
HIP 56365 |
11.41 |
| 2026-09-29 12:00 |
11:32:48.20 |
-57:22:04.6 |
HIP 56365 |
10.26 |
| 2026-09-30 00:00 |
11:32:57.91 |
-57:22:46.3 |
HIP 56365 |
9.20 |
| 2026-09-30 12:00 |
11:33:07.59 |
-57:23:28.4 |
HIP 56365 |
8.26 |
| 2026-10-01 00:00 |
11:33:17.26 |
-57:24:11.0 |
HIP 56365 |
7.49 |
| 2026-10-01 12:00 |
11:33:26.91 |
-57:24:54.1 |
HIP 56365 |
6.94 |
| 2026-10-02 00:00 |
11:33:36.55 |
-57:25:37.7 |
HIP 56365 |
6.68 |
| 2026-10-02 12:00 |
11:33:46.17 |
-57:26:21.7 |
HIP 56365 |
6.73 |
| 2026-10-03 00:00 |
11:33:55.77 |
-57:27:06.3 |
HIP 56365 |
7.10 |
| 2026-10-03 12:00 |
11:34:05.35 |
-57:27:51.3 |
HIP 56365 |
7.73 |
| 2026-10-04 00:00 |
11:34:14.91 |
-57:28:36.8 |
HIP 56365 |
8.57 |
| 2026-10-04 12:00 |
11:34:24.45 |
-57:29:22.8 |
HIP 56442 |
8.27 |
| 2026-10-05 00:00 |
11:34:33.97 |
-57:30:09.3 |
HIP 56442 |
7.70 |
| 2026-10-05 12:00 |
11:34:43.46 |
-57:30:56.2 |
HIP 56442 |
7.38 |
| 2026-10-06 00:00 |
11:34:52.94 |
-57:31:43.6 |
HIP 56442 |
7.34 |
| 2026-10-06 12:00 |
11:35:02.40 |
-57:32:31.4 |
HIP 56442 |
7.60 |
| 2026-10-07 00:00 |
11:35:11.83 |
-57:33:19.8 |
HIP 56442 |
8.12 |
| 2026-10-07 12:00 |
11:35:21.24 |
-57:34:08.6 |
HIP 56442 |
8.86 |
| 2026-10-08 00:00 |
11:35:30.62 |
-57:34:57.8 |
HIP 56442 |
9.77 |
| 2026-10-08 12:00 |
11:35:39.99 |
-57:35:47.5 |
HIP 56442 |
10.81 |
| 2026-10-09 00:00 |
11:35:49.32 |
-57:36:37.7 |
HIP 56442 |
11.94 |
| 2026-10-09 12:00 |
11:35:58.63 |
-57:37:28.3 |
HIP 56442 |
13.15 |
| 2026-10-10 00:00 |
11:36:07.92 |
-57:38:19.4 |
HIP 56442 |
14.40 |
| 2026-10-10 12:00 |
11:36:17.17 |
-57:39:11.0 |
HIP 56442 |
15.70 |
| 2026-10-11 00:00 |
11:36:26.41 |
-57:40:02.9 |
HIP 56442 |
17.02 |