| Parameter |
Value |
| Designation |
C/2016 C2 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2016-04-19T14:19:31.131840Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:23Z |
| Obs used |
148 |
| NEO |
- |
| M1 |
13.800 |
| K1 |
20.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-03-12.0000000 |
| e |
0.97563583 |
| q (au) |
1.559754 |
| a (au) |
64.018322 |
| i (deg) |
38.156610 |
| Ω (om, deg) |
24.404634 |
| ω (w, deg) |
214.403353 |
| M (ma, deg) |
359.925732 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.251 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.251 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
01:56:11.81 |
+16:57:23.6 |
HIP 8968 |
17.01 |
| 2026-07-29 12:00 |
01:56:11.54 |
+16:57:32.2 |
HIP 8968 |
16.86 |
| 2026-07-30 00:00 |
01:56:11.23 |
+16:57:40.6 |
HIP 8968 |
16.70 |
| 2026-07-30 12:00 |
01:56:10.89 |
+16:57:48.8 |
HIP 8968 |
16.54 |
| 2026-07-31 00:00 |
01:56:10.50 |
+16:57:56.7 |
HIP 8968 |
16.38 |
| 2026-07-31 12:00 |
01:56:10.08 |
+16:58:04.4 |
HIP 8968 |
16.22 |
| 2026-08-01 00:00 |
01:56:09.61 |
+16:58:12.0 |
HIP 8968 |
16.05 |
| 2026-08-01 12:00 |
01:56:09.10 |
+16:58:19.3 |
HIP 8968 |
15.88 |
| 2026-08-02 00:00 |
01:56:08.55 |
+16:58:26.3 |
HIP 8968 |
15.71 |
| 2026-08-02 12:00 |
01:56:07.97 |
+16:58:33.2 |
HIP 8968 |
15.54 |
| 2026-08-03 00:00 |
01:56:07.34 |
+16:58:39.9 |
HIP 8968 |
15.36 |
| 2026-08-03 12:00 |
01:56:06.67 |
+16:58:46.3 |
HIP 8968 |
15.18 |
| 2026-08-04 00:00 |
01:56:05.96 |
+16:58:52.5 |
HIP 8968 |
15.00 |
| 2026-08-04 12:00 |
01:56:05.21 |
+16:58:58.5 |
HIP 8968 |
14.82 |
| 2026-08-05 00:00 |
01:56:04.42 |
+16:59:04.3 |
HIP 8968 |
14.64 |
| 2026-08-05 12:00 |
01:56:03.59 |
+16:59:09.9 |
HIP 8968 |
14.45 |
| 2026-08-06 00:00 |
01:56:02.72 |
+16:59:15.2 |
HIP 8968 |
14.26 |
| 2026-08-06 12:00 |
01:56:01.81 |
+16:59:20.3 |
HIP 8968 |
14.08 |
| 2026-08-07 00:00 |
01:56:00.86 |
+16:59:25.2 |
HIP 8968 |
13.89 |
| 2026-08-07 12:00 |
01:55:59.87 |
+16:59:29.9 |
HIP 8968 |
13.70 |
| 2026-08-08 00:00 |
01:55:58.84 |
+16:59:34.4 |
HIP 8968 |
13.52 |
| 2026-08-08 12:00 |
01:55:57.77 |
+16:59:38.6 |
HIP 8968 |
13.33 |
| 2026-08-09 00:00 |
01:55:56.66 |
+16:59:42.6 |
HIP 8968 |
13.15 |
| 2026-08-09 12:00 |
01:55:55.50 |
+16:59:46.4 |
HIP 8968 |
12.97 |
| 2026-08-10 00:00 |
01:55:54.31 |
+16:59:50.0 |
HIP 8968 |
12.79 |
| 2026-08-10 12:00 |
01:55:53.08 |
+16:59:53.3 |
HIP 8968 |
12.61 |
| 2026-08-11 00:00 |
01:55:51.81 |
+16:59:56.4 |
HIP 8968 |
12.44 |
| 2026-08-11 12:00 |
01:55:50.49 |
+16:59:59.3 |
HIP 8968 |
12.28 |
| 2026-08-12 00:00 |
01:55:49.14 |
+17:00:02.0 |
HIP 8968 |
12.12 |
| 2026-08-12 12:00 |
01:55:47.75 |
+17:00:04.4 |
HIP 8968 |
11.96 |
| 2026-08-13 00:00 |
01:55:46.32 |
+17:00:06.7 |
HIP 8968 |
11.82 |
| 2026-08-13 12:00 |
01:55:44.84 |
+17:00:08.7 |
HIP 8968 |
11.68 |
| 2026-08-14 00:00 |
01:55:43.33 |
+17:00:10.4 |
HIP 8968 |
11.56 |
| 2026-08-14 12:00 |
01:55:41.78 |
+17:00:12.0 |
HIP 8968 |
11.45 |
| 2026-08-15 00:00 |
01:55:40.19 |
+17:00:13.3 |
HIP 8968 |
11.35 |
| 2026-08-15 12:00 |
01:55:38.56 |
+17:00:14.4 |
HIP 8968 |
11.26 |
| 2026-08-16 00:00 |
01:55:36.89 |
+17:00:15.3 |
HIP 8968 |
11.19 |
| 2026-08-16 12:00 |
01:55:35.18 |
+17:00:15.9 |
HIP 8968 |
11.14 |
| 2026-08-17 00:00 |
01:55:33.44 |
+17:00:16.3 |
HIP 8968 |
11.10 |
| 2026-08-17 12:00 |
01:55:31.65 |
+17:00:16.5 |
HIP 8968 |
11.09 |
| 2026-08-18 00:00 |
01:55:29.83 |
+17:00:16.5 |
HIP 8968 |
11.09 |
| 2026-08-18 12:00 |
01:55:27.96 |
+17:00:16.3 |
HIP 8968 |
11.12 |
| 2026-08-19 00:00 |
01:55:26.06 |
+17:00:15.8 |
HIP 8968 |
11.17 |