C/2017 U7 (PANSTARRS)
| 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) |
| 2026-02-03 00:00 |
15:12:10.27 |
+17:30:47.9 |
HIP 74300 |
15.60 |
| 2026-02-03 12:00 |
15:12:09.62 |
+17:32:09.1 |
HIP 74300 |
16.15 |
| 2026-02-04 00:00 |
15:12:08.91 |
+17:33:30.7 |
HIP 74300 |
16.78 |
| 2026-02-04 12:00 |
15:12:08.12 |
+17:34:52.6 |
HIP 74300 |
17.49 |
| 2026-02-05 00:00 |
15:12:07.27 |
+17:36:14.8 |
HIP 74300 |
18.27 |
| 2026-02-05 12:00 |
15:12:06.35 |
+17:37:37.4 |
HIP 74300 |
19.11 |
| 2026-02-06 00:00 |
15:12:05.36 |
+17:39:00.3 |
HIP 74300 |
20.00 |
| 2026-02-06 12:00 |
15:12:04.29 |
+17:40:23.5 |
HIP 74300 |
20.94 |
| 2026-02-07 00:00 |
15:12:03.16 |
+17:41:47.0 |
HIP 74300 |
21.93 |
| 2026-02-07 12:00 |
15:12:01.96 |
+17:43:10.8 |
HIP 74300 |
22.97 |
| 2026-02-08 00:00 |
15:12:00.69 |
+17:44:34.9 |
HIP 74300 |
24.03 |
| 2026-02-08 12:00 |
15:11:59.35 |
+17:45:59.3 |
HIP 74300 |
25.13 |
| 2026-02-09 00:00 |
15:11:57.94 |
+17:47:23.9 |
HIP 74300 |
26.26 |
| 2026-02-09 12:00 |
15:11:56.46 |
+17:48:48.9 |
HIP 74478 |
25.59 |
| 2026-02-10 00:00 |
15:11:54.91 |
+17:50:14.2 |
HIP 74478 |
24.79 |
| 2026-02-10 12:00 |
15:11:53.29 |
+17:51:39.7 |
HIP 74478 |
24.06 |
| 2026-02-11 00:00 |
15:11:51.60 |
+17:53:05.5 |
HIP 74478 |
23.40 |
| 2026-02-11 12:00 |
15:11:49.84 |
+17:54:31.5 |
HIP 74478 |
22.84 |
| 2026-02-12 00:00 |
15:11:48.00 |
+17:55:57.8 |
HIP 74478 |
22.38 |
| 2026-02-12 12:00 |
15:11:46.10 |
+17:57:24.4 |
HIP 74478 |
22.02 |
| 2026-02-13 00:00 |
15:11:44.12 |
+17:58:51.2 |
HIP 74478 |
21.77 |
| 2026-02-13 12:00 |
15:11:42.08 |
+18:00:18.2 |
HIP 74478 |
21.64 |
| 2026-02-14 00:00 |
15:11:39.96 |
+18:01:45.5 |
HIP 74478 |
21.63 |
| 2026-02-14 12:00 |
15:11:37.77 |
+18:03:13.0 |
HIP 74478 |
21.75 |
| 2026-02-15 00:00 |
15:11:35.51 |
+18:04:40.7 |
HIP 74478 |
21.99 |
| 2026-02-15 12:00 |
15:11:33.18 |
+18:06:08.6 |
HIP 74478 |
22.36 |
| 2026-02-16 00:00 |
15:11:30.78 |
+18:07:36.8 |
HIP 74478 |
22.84 |
| 2026-02-16 12:00 |
15:11:28.31 |
+18:09:05.1 |
HIP 74478 |
23.44 |
| 2026-02-17 00:00 |
15:11:25.76 |
+18:10:33.7 |
HIP 74478 |
24.15 |
| 2026-02-17 12:00 |
15:11:23.15 |
+18:12:02.4 |
HIP 74307 |
24.47 |
| 2026-02-18 00:00 |
15:11:20.46 |
+18:13:31.3 |
HIP 74307 |
22.96 |
| 2026-02-18 12:00 |
15:11:17.70 |
+18:15:00.4 |
HIP 74307 |
21.46 |
| 2026-02-19 00:00 |
15:11:14.87 |
+18:16:29.7 |
HIP 74307 |
19.97 |
| 2026-02-19 12:00 |
15:11:11.97 |
+18:17:59.1 |
HIP 74307 |
18.50 |
| 2026-02-20 00:00 |
15:11:09.00 |
+18:19:28.7 |
HIP 74307 |
17.07 |
| 2026-02-20 12:00 |
15:11:05.96 |
+18:20:58.5 |
HIP 74307 |
15.68 |
| 2026-02-21 00:00 |
15:11:02.84 |
+18:22:28.4 |
HIP 74307 |
14.35 |
| 2026-02-21 12:00 |
15:10:59.66 |
+18:23:58.4 |
HIP 74307 |
13.10 |
| 2026-02-22 00:00 |
15:10:56.40 |
+18:25:28.6 |
HIP 74307 |
11.96 |
| 2026-02-22 12:00 |
15:10:53.08 |
+18:26:58.8 |
HIP 74307 |
10.96 |
| 2026-02-23 00:00 |
15:10:49.68 |
+18:28:29.3 |
HIP 74307 |
10.17 |
| 2026-02-23 12:00 |
15:10:46.21 |
+18:29:59.8 |
HIP 74307 |
9.63 |
| 2026-02-24 00:00 |
15:10:42.68 |
+18:31:30.4 |
HIP 74307 |
9.38 |