| Parameter |
Value |
| Designation |
C/2019 H1 (NEOWISE) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-04-27T17:40:42.101760Z |
| Orbit solution date (soln_date, UTC) |
2022-06-20T23:12:33Z |
| Obs used |
165 |
| NEO |
- |
| M1 |
16.900 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2019-04-18T21:12:57.600000Z |
| Discovery magnitude (MPC) |
18.00 R |
| Discovery observatory (MPC) |
C51 · WISE |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-05-16.0000000 |
| e |
0.99219409 |
| q (au) |
1.844784 |
| a (au) |
236.331687 |
| i (deg) |
104.580185 |
| Ω (om, deg) |
269.186008 |
| ω (w, deg) |
19.282675 |
| M (ma, deg) |
0.004955 |
Magnitude
Scatter + Global Linear
$$
M_a = (17.164 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
17.164 |
| n |
2.000 |
| gf |
0.999 |
| gb |
-0.518 |
| k |
0.800 |
| 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 |
06:24:39.42 |
+38:15:17.5 |
HIP 30512 |
9.46 |
| 2026-07-29 12:00 |
06:24:45.51 |
+38:15:17.8 |
HIP 30512 |
9.31 |
| 2026-07-30 00:00 |
06:24:51.56 |
+38:15:18.2 |
HIP 30512 |
9.31 |
| 2026-07-30 12:00 |
06:24:57.58 |
+38:15:18.8 |
HIP 30512 |
9.46 |
| 2026-07-31 00:00 |
06:25:03.57 |
+38:15:19.5 |
HIP 30512 |
9.76 |
| 2026-07-31 12:00 |
06:25:09.52 |
+38:15:20.4 |
HIP 30512 |
10.19 |
| 2026-08-01 00:00 |
06:25:15.45 |
+38:15:21.4 |
HIP 30512 |
10.72 |
| 2026-08-01 12:00 |
06:25:21.34 |
+38:15:22.6 |
HIP 30512 |
11.35 |
| 2026-08-02 00:00 |
06:25:27.20 |
+38:15:24.0 |
HIP 30512 |
12.06 |
| 2026-08-02 12:00 |
06:25:33.03 |
+38:15:25.5 |
HIP 30589 |
12.56 |
| 2026-08-03 00:00 |
06:25:38.82 |
+38:15:27.2 |
HIP 30589 |
12.46 |
| 2026-08-03 12:00 |
06:25:44.58 |
+38:15:29.0 |
HIP 30589 |
12.47 |
| 2026-08-04 00:00 |
06:25:50.31 |
+38:15:31.0 |
HIP 30589 |
12.58 |
| 2026-08-04 12:00 |
06:25:56.00 |
+38:15:33.1 |
HIP 30589 |
12.79 |
| 2026-08-05 00:00 |
06:26:01.66 |
+38:15:35.4 |
HIP 30589 |
13.09 |
| 2026-08-05 12:00 |
06:26:07.28 |
+38:15:37.9 |
HIP 30589 |
13.48 |
| 2026-08-06 00:00 |
06:26:12.86 |
+38:15:40.5 |
HIP 30589 |
13.95 |
| 2026-08-06 12:00 |
06:26:18.41 |
+38:15:43.3 |
HIP 30589 |
14.48 |
| 2026-08-07 00:00 |
06:26:23.92 |
+38:15:46.2 |
HIP 30589 |
15.07 |
| 2026-08-07 12:00 |
06:26:29.40 |
+38:15:49.3 |
HIP 30589 |
15.71 |
| 2026-08-08 00:00 |
06:26:34.84 |
+38:15:52.6 |
HIP 30589 |
16.40 |
| 2026-08-08 12:00 |
06:26:40.24 |
+38:15:56.0 |
HIP 30589 |
17.12 |
| 2026-08-09 00:00 |
06:26:45.60 |
+38:15:59.5 |
HIP 30589 |
17.87 |
| 2026-08-09 12:00 |
06:26:50.92 |
+38:16:03.2 |
HIP 30589 |
18.65 |
| 2026-08-10 00:00 |
06:26:56.21 |
+38:16:07.1 |
HIP 30589 |
19.45 |
| 2026-08-10 12:00 |
06:27:01.45 |
+38:16:11.1 |
HIP 30589 |
20.27 |
| 2026-08-11 00:00 |
06:27:06.65 |
+38:16:15.3 |
HIP 30589 |
21.10 |
| 2026-08-11 12:00 |
06:27:11.82 |
+38:16:19.6 |
HIP 30589 |
21.94 |
| 2026-08-12 00:00 |
06:27:16.94 |
+38:16:24.1 |
HIP 30589 |
22.79 |
| 2026-08-12 12:00 |
06:27:22.02 |
+38:16:28.7 |
HIP 30589 |
23.65 |
| 2026-08-13 00:00 |
06:27:27.06 |
+38:16:33.5 |
HIP 30589 |
24.52 |
| 2026-08-13 12:00 |
06:27:32.06 |
+38:16:38.4 |
HIP 30589 |
25.39 |
| 2026-08-14 00:00 |
06:27:37.02 |
+38:16:43.5 |
HIP 30589 |
26.26 |
| 2026-08-14 12:00 |
06:27:41.93 |
+38:16:48.8 |
HIP 30589 |
27.13 |
| 2026-08-15 00:00 |
06:27:46.80 |
+38:16:54.2 |
HIP 30589 |
28.00 |
| 2026-08-15 12:00 |
06:27:51.63 |
+38:16:59.7 |
HIP 30589 |
28.87 |
| 2026-08-16 00:00 |
06:27:56.41 |
+38:17:05.4 |
HIP 30589 |
29.74 |
| 2026-08-16 12:00 |
06:28:01.15 |
+38:17:11.2 |
HIP 30589 |
30.61 |
| 2026-08-17 00:00 |
06:28:05.84 |
+38:17:17.2 |
HIP 30589 |
31.48 |
| 2026-08-17 12:00 |
06:28:10.49 |
+38:17:23.4 |
HIP 30589 |
32.34 |
| 2026-08-18 00:00 |
06:28:15.09 |
+38:17:29.6 |
HIP 30589 |
33.20 |
| 2026-08-18 12:00 |
06:28:19.65 |
+38:17:36.1 |
HIP 30589 |
34.05 |
| 2026-08-19 00:00 |
06:28:24.16 |
+38:17:42.7 |
HIP 30589 |
34.90 |