| 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) |
| 2026-06-01 00:00 |
02:58:47.11 |
-04:43:25.9 |
HIP 13910 |
6.39 |
| 2026-06-01 12:00 |
02:58:51.22 |
-04:43:17.5 |
HIP 13910 |
5.67 |
| 2026-06-02 00:00 |
02:58:55.31 |
-04:43:09.4 |
HIP 13910 |
5.04 |
| 2026-06-02 12:00 |
02:58:59.39 |
-04:43:01.5 |
HIP 13910 |
4.57 |
| 2026-06-03 00:00 |
02:59:03.45 |
-04:42:53.8 |
HIP 13910 |
4.29 |
| 2026-06-03 12:00 |
02:59:07.49 |
-04:42:46.5 |
HIP 13910 |
4.23 |
| 2026-06-04 00:00 |
02:59:11.52 |
-04:42:39.3 |
HIP 13910 |
4.41 |
| 2026-06-04 12:00 |
02:59:15.54 |
-04:42:32.5 |
HIP 13910 |
4.80 |
| 2026-06-05 00:00 |
02:59:19.54 |
-04:42:25.8 |
HIP 13910 |
5.34 |
| 2026-06-05 12:00 |
02:59:23.52 |
-04:42:19.5 |
HIP 13910 |
6.00 |
| 2026-06-06 00:00 |
02:59:27.49 |
-04:42:13.4 |
HIP 13910 |
6.74 |
| 2026-06-06 12:00 |
02:59:31.44 |
-04:42:07.5 |
HIP 13910 |
7.53 |
| 2026-06-07 00:00 |
02:59:35.37 |
-04:42:01.9 |
HIP 13910 |
8.36 |
| 2026-06-07 12:00 |
02:59:39.29 |
-04:41:56.6 |
HIP 13910 |
9.21 |
| 2026-06-08 00:00 |
02:59:43.19 |
-04:41:51.5 |
HIP 13910 |
10.08 |
| 2026-06-08 12:00 |
02:59:47.07 |
-04:41:46.7 |
HIP 13910 |
10.96 |
| 2026-06-09 00:00 |
02:59:50.94 |
-04:41:42.2 |
HIP 13910 |
11.85 |
| 2026-06-09 12:00 |
02:59:54.79 |
-04:41:37.9 |
HIP 13910 |
12.74 |
| 2026-06-10 00:00 |
02:59:58.61 |
-04:41:33.9 |
HIP 13910 |
13.64 |
| 2026-06-10 12:00 |
03:00:02.42 |
-04:41:30.1 |
HIP 13910 |
14.54 |
| 2026-06-11 00:00 |
03:00:06.21 |
-04:41:26.6 |
HIP 13910 |
15.44 |
| 2026-06-11 12:00 |
03:00:09.99 |
-04:41:23.3 |
HIP 13910 |
16.34 |
| 2026-06-12 00:00 |
03:00:13.74 |
-04:41:20.3 |
HIP 13910 |
17.23 |
| 2026-06-12 12:00 |
03:00:17.47 |
-04:41:17.6 |
HIP 13910 |
18.13 |
| 2026-06-13 00:00 |
03:00:21.19 |
-04:41:15.2 |
HIP 13910 |
19.02 |
| 2026-06-13 12:00 |
03:00:24.88 |
-04:41:13.0 |
HIP 13910 |
19.91 |
| 2026-06-14 00:00 |
03:00:28.55 |
-04:41:11.0 |
HIP 13910 |
20.80 |
| 2026-06-14 12:00 |
03:00:32.20 |
-04:41:09.4 |
HIP 13910 |
21.68 |
| 2026-06-15 00:00 |
03:00:35.83 |
-04:41:07.9 |
HIP 13910 |
22.56 |
| 2026-06-15 12:00 |
03:00:39.44 |
-04:41:06.8 |
HIP 13910 |
23.43 |
| 2026-06-16 00:00 |
03:00:43.03 |
-04:41:05.9 |
HIP 13910 |
24.30 |
| 2026-06-16 12:00 |
03:00:46.60 |
-04:41:05.3 |
HIP 13910 |
25.17 |
| 2026-06-17 00:00 |
03:00:50.14 |
-04:41:04.9 |
HIP 13910 |
26.03 |
| 2026-06-17 12:00 |
03:00:53.67 |
-04:41:04.9 |
HIP 13910 |
26.88 |
| 2026-06-18 00:00 |
03:00:57.17 |
-04:41:05.0 |
HIP 13910 |
27.73 |
| 2026-06-18 12:00 |
03:01:00.64 |
-04:41:05.5 |
HIP 13910 |
28.58 |
| 2026-06-19 00:00 |
03:01:04.10 |
-04:41:06.2 |
HIP 13910 |
29.42 |
| 2026-06-19 12:00 |
03:01:07.53 |
-04:41:07.1 |
HIP 13910 |
30.26 |
| 2026-06-20 00:00 |
03:01:10.94 |
-04:41:08.3 |
HIP 13910 |
31.08 |
| 2026-06-20 12:00 |
03:01:14.32 |
-04:41:09.8 |
HIP 13910 |
31.91 |
| 2026-06-21 00:00 |
03:01:17.68 |
-04:41:11.6 |
HIP 13910 |
32.73 |
| 2026-06-21 12:00 |
03:01:21.02 |
-04:41:13.6 |
HIP 13910 |
33.54 |
| 2026-06-22 00:00 |
03:01:24.33 |
-04:41:15.8 |
HIP 14197 |
33.15 |