| Parameter |
Value |
| Designation |
C/2017 U7 (PANSTARRS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-09-11T17:19:45.906240Z |
| Orbit solution date (soln_date, UTC) |
2024-05-30T01:12:17Z |
| Obs used |
915 |
| NEO |
- |
| M1 |
6.300 |
| K1 |
8.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2017-10-29T07:49:16.032000Z |
| Discovery magnitude (MPC) |
20.10 i |
| Discovery observatory (MPC) |
F51 · Pan-STARRS 1, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2020-01-08.0000000 |
| e |
1.00164840 |
| q (au) |
6.417510 |
| a (au) |
-3893.179319 |
| i (deg) |
142.635219 |
| Ω (om, deg) |
276.232353 |
| ω (w, deg) |
326.068994 |
| M (ma, deg) |
0.000480 |
Magnitude
Scatter + Global Linear
$$
M_a = (-0.376 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-0.376 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.958 |
| k |
1.000 |
| δ90 |
10.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2017-08-18 |
2019-09-07 |
+24.0875 |
-19.664 |
| 2019-09-15 |
2022-08-03 |
+3.9040 |
-3.583 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
14:34:42.36 |
+21:07:00.7 |
HIP 71339 |
9.30 |
| 2026-07-29 12:00 |
14:34:40.48 |
+21:06:13.3 |
HIP 71339 |
9.93 |
| 2026-07-30 00:00 |
14:34:38.66 |
+21:05:25.7 |
HIP 71339 |
10.59 |
| 2026-07-30 12:00 |
14:34:36.90 |
+21:04:37.9 |
HIP 71339 |
11.27 |
| 2026-07-31 00:00 |
14:34:35.21 |
+21:03:49.9 |
HIP 71339 |
11.97 |
| 2026-07-31 12:00 |
14:34:33.58 |
+21:03:01.7 |
HIP 71339 |
12.68 |
| 2026-08-01 00:00 |
14:34:32.01 |
+21:02:13.3 |
HIP 71339 |
13.40 |
| 2026-08-01 12:00 |
14:34:30.51 |
+21:01:24.7 |
HIP 71339 |
14.13 |
| 2026-08-02 00:00 |
14:34:29.06 |
+21:00:35.9 |
HIP 71339 |
14.86 |
| 2026-08-02 12:00 |
14:34:27.68 |
+20:59:46.9 |
HIP 71339 |
15.60 |
| 2026-08-03 00:00 |
14:34:26.37 |
+20:58:57.7 |
HIP 71339 |
16.35 |
| 2026-08-03 12:00 |
14:34:25.11 |
+20:58:08.4 |
HIP 71339 |
17.10 |
| 2026-08-04 00:00 |
14:34:23.92 |
+20:57:18.8 |
HIP 71339 |
17.85 |
| 2026-08-04 12:00 |
14:34:22.79 |
+20:56:29.1 |
HIP 71339 |
18.60 |
| 2026-08-05 00:00 |
14:34:21.73 |
+20:55:39.3 |
HIP 71339 |
19.35 |
| 2026-08-05 12:00 |
14:34:20.72 |
+20:54:49.2 |
HIP 71339 |
20.11 |
| 2026-08-06 00:00 |
14:34:19.78 |
+20:53:59.1 |
HIP 71339 |
20.86 |
| 2026-08-06 12:00 |
14:34:18.90 |
+20:53:08.7 |
HIP 71339 |
21.62 |
| 2026-08-07 00:00 |
14:34:18.08 |
+20:52:18.2 |
HIP 71339 |
22.37 |
| 2026-08-07 12:00 |
14:34:17.32 |
+20:51:27.6 |
HIP 71339 |
23.13 |
| 2026-08-08 00:00 |
14:34:16.63 |
+20:50:36.8 |
HIP 71339 |
23.88 |
| 2026-08-08 12:00 |
14:34:15.99 |
+20:49:45.9 |
HIP 71339 |
24.64 |
| 2026-08-09 00:00 |
14:34:15.42 |
+20:48:54.9 |
HIP 71339 |
25.39 |
| 2026-08-09 12:00 |
14:34:14.91 |
+20:48:03.8 |
HIP 71339 |
26.15 |
| 2026-08-10 00:00 |
14:34:14.46 |
+20:47:12.5 |
HIP 71339 |
26.90 |
| 2026-08-10 12:00 |
14:34:14.07 |
+20:46:21.1 |
HIP 71339 |
27.66 |
| 2026-08-11 00:00 |
14:34:13.74 |
+20:45:29.6 |
HIP 71339 |
28.41 |
| 2026-08-11 12:00 |
14:34:13.47 |
+20:44:38.0 |
HIP 71366 |
28.12 |
| 2026-08-12 00:00 |
14:34:13.27 |
+20:43:46.3 |
HIP 71366 |
27.59 |
| 2026-08-12 12:00 |
14:34:13.12 |
+20:42:54.4 |
HIP 71366 |
27.07 |
| 2026-08-13 00:00 |
14:34:13.04 |
+20:42:02.5 |
HIP 71366 |
26.56 |
| 2026-08-13 12:00 |
14:34:13.01 |
+20:41:10.6 |
HIP 71366 |
26.05 |
| 2026-08-14 00:00 |
14:34:13.04 |
+20:40:18.5 |
HIP 71366 |
25.55 |
| 2026-08-14 12:00 |
14:34:13.14 |
+20:39:26.4 |
HIP 71366 |
25.06 |
| 2026-08-15 00:00 |
14:34:13.29 |
+20:38:34.1 |
HIP 71366 |
24.57 |
| 2026-08-15 12:00 |
14:34:13.50 |
+20:37:41.9 |
HIP 71366 |
24.10 |
| 2026-08-16 00:00 |
14:34:13.78 |
+20:36:49.5 |
HIP 71366 |
23.63 |
| 2026-08-16 12:00 |
14:34:14.11 |
+20:35:57.1 |
HIP 71366 |
23.17 |
| 2026-08-17 00:00 |
14:34:14.50 |
+20:35:04.7 |
HIP 71366 |
22.73 |
| 2026-08-17 12:00 |
14:34:14.94 |
+20:34:12.2 |
HIP 71366 |
22.30 |
| 2026-08-18 00:00 |
14:34:15.45 |
+20:33:19.7 |
HIP 71366 |
21.88 |
| 2026-08-18 12:00 |
14:34:16.01 |
+20:32:27.1 |
HIP 71366 |
21.48 |
| 2026-08-19 00:00 |
14:34:16.63 |
+20:31:34.5 |
HIP 71366 |
21.09 |