C/2016 U1 (NEOWISE)
| Parameter |
Value |
| Designation |
C/2016 U1 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-01-14T00:24:03.925440Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:28Z |
| Obs used |
366 |
| NEO |
- |
| M1 |
13.100 |
| K1 |
12.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-12-12.0000000 |
| e |
1.00025297 |
| q (au) |
0.319170 |
| a (au) |
-1261.677714 |
| i (deg) |
46.434833 |
| Ω (om, deg) |
61.428521 |
| ω (w, deg) |
162.748270 |
| M (ma, deg) |
-0.000726 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.005 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.005 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.984 |
| k |
0.993 |
| δ90 |
9.928 |
| 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 |
| 2016-10-21 |
2017-01-12 |
-0.0100 |
-1.052 |
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 |
02:45:57.34 |
-06:32:52.1 |
HIP 12953 |
12.97 |
| 2026-02-03 12:00 |
02:45:57.45 |
-06:32:21.4 |
HIP 12953 |
13.32 |
| 2026-02-04 00:00 |
02:45:57.59 |
-06:31:50.6 |
HIP 12953 |
13.68 |
| 2026-02-04 12:00 |
02:45:57.78 |
-06:31:19.7 |
HIP 12953 |
14.04 |
| 2026-02-05 00:00 |
02:45:58.01 |
-06:30:48.6 |
HIP 12953 |
14.40 |
| 2026-02-05 12:00 |
02:45:58.28 |
-06:30:17.4 |
HIP 12953 |
14.78 |
| 2026-02-06 00:00 |
02:45:58.59 |
-06:29:46.0 |
HIP 12953 |
15.15 |
| 2026-02-06 12:00 |
02:45:58.94 |
-06:29:14.5 |
HIP 12953 |
15.53 |
| 2026-02-07 00:00 |
02:45:59.33 |
-06:28:42.9 |
HIP 12953 |
15.92 |
| 2026-02-07 12:00 |
02:45:59.76 |
-06:28:11.1 |
HIP 12953 |
16.31 |
| 2026-02-08 00:00 |
02:46:00.24 |
-06:27:39.2 |
HIP 12953 |
16.71 |
| 2026-02-08 12:00 |
02:46:00.75 |
-06:27:07.2 |
HIP 12953 |
17.11 |
| 2026-02-09 00:00 |
02:46:01.30 |
-06:26:35.0 |
HIP 12953 |
17.52 |
| 2026-02-09 12:00 |
02:46:01.90 |
-06:26:02.7 |
HIP 12953 |
17.93 |
| 2026-02-10 00:00 |
02:46:02.53 |
-06:25:30.3 |
HIP 12953 |
18.35 |
| 2026-02-10 12:00 |
02:46:03.21 |
-06:24:57.8 |
HIP 12953 |
18.77 |
| 2026-02-11 00:00 |
02:46:03.93 |
-06:24:25.1 |
HIP 12953 |
19.20 |
| 2026-02-11 12:00 |
02:46:04.68 |
-06:23:52.4 |
HIP 12953 |
19.64 |
| 2026-02-12 00:00 |
02:46:05.48 |
-06:23:19.5 |
HIP 12953 |
20.08 |
| 2026-02-12 12:00 |
02:46:06.31 |
-06:22:46.5 |
HIP 12953 |
20.52 |
| 2026-02-13 00:00 |
02:46:07.19 |
-06:22:13.4 |
HIP 12953 |
20.97 |
| 2026-02-13 12:00 |
02:46:08.10 |
-06:21:40.2 |
HIP 12953 |
21.43 |
| 2026-02-14 00:00 |
02:46:09.06 |
-06:21:06.9 |
HIP 12953 |
21.89 |
| 2026-02-14 12:00 |
02:46:10.05 |
-06:20:33.5 |
HIP 12953 |
22.36 |
| 2026-02-15 00:00 |
02:46:11.09 |
-06:20:00.0 |
HIP 12953 |
22.83 |
| 2026-02-15 12:00 |
02:46:12.16 |
-06:19:26.4 |
HIP 12953 |
23.31 |
| 2026-02-16 00:00 |
02:46:13.27 |
-06:18:52.7 |
HIP 12953 |
23.80 |
| 2026-02-16 12:00 |
02:46:14.42 |
-06:18:18.9 |
HIP 12953 |
24.29 |
| 2026-02-17 00:00 |
02:46:15.61 |
-06:17:45.1 |
HIP 12953 |
24.78 |
| 2026-02-17 12:00 |
02:46:16.84 |
-06:17:11.1 |
HIP 12977 |
24.67 |
| 2026-02-18 00:00 |
02:46:18.11 |
-06:16:37.1 |
HIP 12977 |
24.03 |
| 2026-02-18 12:00 |
02:46:19.42 |
-06:16:03.0 |
HIP 12977 |
23.38 |
| 2026-02-19 00:00 |
02:46:20.76 |
-06:15:28.8 |
HIP 12977 |
22.72 |
| 2026-02-19 12:00 |
02:46:22.14 |
-06:14:54.5 |
HIP 12977 |
22.06 |
| 2026-02-20 00:00 |
02:46:23.56 |
-06:14:20.2 |
HIP 12977 |
21.40 |
| 2026-02-20 12:00 |
02:46:25.02 |
-06:13:45.8 |
HIP 12977 |
20.74 |
| 2026-02-21 00:00 |
02:46:26.52 |
-06:13:11.3 |
HIP 12977 |
20.07 |
| 2026-02-21 12:00 |
02:46:28.05 |
-06:12:36.7 |
HIP 12977 |
19.39 |
| 2026-02-22 00:00 |
02:46:29.62 |
-06:12:02.1 |
HIP 12977 |
18.72 |
| 2026-02-22 12:00 |
02:46:31.23 |
-06:11:27.5 |
HIP 12977 |
18.04 |
| 2026-02-23 00:00 |
02:46:32.87 |
-06:10:52.8 |
HIP 12977 |
17.36 |
| 2026-02-23 12:00 |
02:46:34.55 |
-06:10:18.0 |
HIP 12977 |
16.68 |
| 2026-02-24 00:00 |
02:46:36.27 |
-06:09:43.2 |
HIP 12977 |
16.00 |