| 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) |
| 2026-09-20 00:00 |
14:36:44.07 |
+19:37:28.5 |
HIP 71509 |
14.62 |
| 2026-09-20 12:00 |
14:36:47.84 |
+19:36:42.6 |
HIP 71413 |
14.53 |
| 2026-09-21 00:00 |
14:36:51.66 |
+19:35:56.9 |
HIP 71413 |
14.41 |
| 2026-09-21 12:00 |
14:36:55.51 |
+19:35:11.4 |
HIP 71413 |
14.39 |
| 2026-09-22 00:00 |
14:36:59.40 |
+19:34:26.2 |
HIP 71413 |
14.47 |
| 2026-09-22 12:00 |
14:37:03.33 |
+19:33:41.2 |
HIP 71413 |
14.66 |
| 2026-09-23 00:00 |
14:37:07.29 |
+19:32:56.5 |
HIP 71413 |
14.95 |
| 2026-09-23 12:00 |
14:37:11.29 |
+19:32:12.0 |
HIP 71413 |
15.34 |
| 2026-09-24 00:00 |
14:37:15.32 |
+19:31:27.8 |
HIP 71413 |
15.82 |
| 2026-09-24 12:00 |
14:37:19.39 |
+19:30:43.8 |
HIP 71413 |
16.39 |
| 2026-09-25 00:00 |
14:37:23.49 |
+19:30:00.1 |
HIP 71413 |
17.03 |
| 2026-09-25 12:00 |
14:37:27.63 |
+19:29:16.6 |
HIP 71413 |
17.74 |
| 2026-09-26 00:00 |
14:37:31.80 |
+19:28:33.4 |
HIP 71413 |
18.51 |
| 2026-09-26 12:00 |
14:37:36.01 |
+19:27:50.5 |
HIP 71413 |
19.34 |
| 2026-09-27 00:00 |
14:37:40.25 |
+19:27:07.8 |
HIP 71413 |
20.21 |
| 2026-09-27 12:00 |
14:37:44.52 |
+19:26:25.5 |
HIP 71413 |
21.13 |
| 2026-09-28 00:00 |
14:37:48.83 |
+19:25:43.4 |
HIP 71413 |
22.09 |
| 2026-09-28 12:00 |
14:37:53.16 |
+19:25:01.5 |
HIP 71413 |
23.08 |
| 2026-09-29 00:00 |
14:37:57.53 |
+19:24:20.0 |
HIP 71667 |
22.14 |
| 2026-09-29 12:00 |
14:38:01.94 |
+19:23:38.8 |
HIP 71667 |
21.16 |
| 2026-09-30 00:00 |
14:38:06.37 |
+19:22:57.8 |
HIP 71667 |
20.21 |
| 2026-09-30 12:00 |
14:38:10.83 |
+19:22:17.1 |
HIP 71667 |
19.27 |
| 2026-10-01 00:00 |
14:38:15.32 |
+19:21:36.8 |
HIP 71667 |
18.37 |
| 2026-10-01 12:00 |
14:38:19.85 |
+19:20:56.7 |
HIP 71667 |
17.50 |
| 2026-10-02 00:00 |
14:38:24.40 |
+19:20:16.9 |
HIP 71667 |
16.68 |
| 2026-10-02 12:00 |
14:38:28.99 |
+19:19:37.4 |
HIP 71667 |
15.90 |
| 2026-10-03 00:00 |
14:38:33.60 |
+19:18:58.3 |
HIP 71667 |
15.18 |
| 2026-10-03 12:00 |
14:38:38.24 |
+19:18:19.4 |
HIP 71667 |
14.53 |
| 2026-10-04 00:00 |
14:38:42.91 |
+19:17:40.9 |
HIP 71667 |
13.95 |
| 2026-10-04 12:00 |
14:38:47.61 |
+19:17:02.7 |
HIP 71667 |
13.46 |
| 2026-10-05 00:00 |
14:38:52.34 |
+19:16:24.8 |
HIP 71667 |
13.08 |
| 2026-10-05 12:00 |
14:38:57.09 |
+19:15:47.3 |
HIP 71667 |
12.79 |
| 2026-10-06 00:00 |
14:39:01.87 |
+19:15:10.0 |
HIP 71667 |
12.63 |
| 2026-10-06 12:00 |
14:39:06.68 |
+19:14:33.2 |
HIP 71667 |
12.59 |
| 2026-10-07 00:00 |
14:39:11.51 |
+19:13:56.6 |
HIP 71667 |
12.67 |
| 2026-10-07 12:00 |
14:39:16.37 |
+19:13:20.4 |
HIP 71667 |
12.87 |
| 2026-10-08 00:00 |
14:39:21.26 |
+19:12:44.5 |
HIP 71667 |
13.20 |
| 2026-10-08 12:00 |
14:39:26.16 |
+19:12:09.0 |
HIP 71667 |
13.63 |
| 2026-10-09 00:00 |
14:39:31.10 |
+19:11:33.8 |
HIP 71667 |
14.16 |
| 2026-10-09 12:00 |
14:39:36.06 |
+19:10:59.0 |
HIP 71667 |
14.78 |
| 2026-10-10 00:00 |
14:39:41.04 |
+19:10:24.5 |
HIP 71667 |
15.49 |
| 2026-10-10 12:00 |
14:39:46.04 |
+19:09:50.4 |
HIP 71667 |
16.26 |
| 2026-10-11 00:00 |
14:39:51.07 |
+19:09:16.7 |
HIP 71667 |
17.10 |