| Parameter |
Value |
| Designation |
C/2003 H3 (NEAT) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2003-04-24T05:32:24.740160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:29Z |
| Obs used |
765 |
| NEO |
- |
| M1 |
11.800 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2003-08-01.0000000 |
| e |
0.99978175 |
| q (au) |
2.901439 |
| a (au) |
13294.090063 |
| i (deg) |
42.811675 |
| Ω (om, deg) |
269.417235 |
| ω (w, deg) |
6.477416 |
| M (ma, deg) |
0.000064 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.461 + 2.567\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.461 |
| n |
2.567 |
| gf |
1.000 |
| gb |
-0.709 |
| 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) |
| 2026-09-25 00:00 |
04:36:22.91 |
+38:02:44.7 |
HIP 21565 |
16.38 |
| 2026-09-25 12:00 |
04:36:21.77 |
+38:02:51.8 |
HIP 21565 |
16.58 |
| 2026-09-26 00:00 |
04:36:20.60 |
+38:02:58.9 |
HIP 21565 |
16.79 |
| 2026-09-26 12:00 |
04:36:19.40 |
+38:03:05.8 |
HIP 21565 |
17.00 |
| 2026-09-27 00:00 |
04:36:18.17 |
+38:03:12.7 |
HIP 21565 |
17.22 |
| 2026-09-27 12:00 |
04:36:16.91 |
+38:03:19.5 |
HIP 21565 |
17.45 |
| 2026-09-28 00:00 |
04:36:15.63 |
+38:03:26.2 |
HIP 21565 |
17.68 |
| 2026-09-28 12:00 |
04:36:14.32 |
+38:03:32.9 |
HIP 21565 |
17.92 |
| 2026-09-29 00:00 |
04:36:12.98 |
+38:03:39.4 |
HIP 21565 |
18.17 |
| 2026-09-29 12:00 |
04:36:11.62 |
+38:03:45.9 |
HIP 21565 |
18.42 |
| 2026-09-30 00:00 |
04:36:10.23 |
+38:03:52.3 |
HIP 21565 |
18.69 |
| 2026-09-30 12:00 |
04:36:08.81 |
+38:03:58.6 |
HIP 21565 |
18.95 |
| 2026-10-01 00:00 |
04:36:07.36 |
+38:04:04.8 |
HIP 21565 |
19.23 |
| 2026-10-01 12:00 |
04:36:05.89 |
+38:04:11.0 |
HIP 21565 |
19.51 |
| 2026-10-02 00:00 |
04:36:04.39 |
+38:04:17.0 |
HIP 21565 |
19.79 |
| 2026-10-02 12:00 |
04:36:02.86 |
+38:04:23.0 |
HIP 21565 |
20.08 |
| 2026-10-03 00:00 |
04:36:01.31 |
+38:04:28.9 |
HIP 21565 |
20.38 |
| 2026-10-03 12:00 |
04:35:59.73 |
+38:04:34.6 |
HIP 21565 |
20.68 |
| 2026-10-04 00:00 |
04:35:58.12 |
+38:04:40.3 |
HIP 21565 |
20.99 |
| 2026-10-04 12:00 |
04:35:56.49 |
+38:04:45.9 |
HIP 21565 |
21.31 |
| 2026-10-05 00:00 |
04:35:54.83 |
+38:04:51.4 |
HIP 21565 |
21.63 |
| 2026-10-05 12:00 |
04:35:53.15 |
+38:04:56.9 |
HIP 21565 |
21.96 |
| 2026-10-06 00:00 |
04:35:51.44 |
+38:05:02.2 |
HIP 21565 |
22.29 |
| 2026-10-06 12:00 |
04:35:49.70 |
+38:05:07.4 |
HIP 21565 |
22.63 |
| 2026-10-07 00:00 |
04:35:47.94 |
+38:05:12.6 |
HIP 21565 |
22.97 |
| 2026-10-07 12:00 |
04:35:46.15 |
+38:05:17.6 |
HIP 21565 |
23.32 |
| 2026-10-08 00:00 |
04:35:44.33 |
+38:05:22.5 |
HIP 21565 |
23.68 |
| 2026-10-08 12:00 |
04:35:42.50 |
+38:05:27.4 |
HIP 21565 |
24.04 |
| 2026-10-09 00:00 |
04:35:40.63 |
+38:05:32.1 |
HIP 21565 |
24.41 |
| 2026-10-09 12:00 |
04:35:38.74 |
+38:05:36.8 |
HIP 21565 |
24.78 |
| 2026-10-10 00:00 |
04:35:36.82 |
+38:05:41.3 |
HIP 21565 |
25.15 |
| 2026-10-10 12:00 |
04:35:34.88 |
+38:05:45.8 |
HIP 21565 |
25.53 |
| 2026-10-11 00:00 |
04:35:32.92 |
+38:05:50.2 |
HIP 21565 |
25.92 |
| 2026-10-11 12:00 |
04:35:30.93 |
+38:05:54.4 |
HIP 21565 |
26.31 |
| 2026-10-12 00:00 |
04:35:28.92 |
+38:05:58.6 |
HIP 21565 |
26.71 |
| 2026-10-12 12:00 |
04:35:26.88 |
+38:06:02.6 |
HIP 21565 |
27.11 |
| 2026-10-13 00:00 |
04:35:24.81 |
+38:06:06.6 |
HIP 21565 |
27.52 |
| 2026-10-13 12:00 |
04:35:22.73 |
+38:06:10.4 |
HIP 21565 |
27.93 |
| 2026-10-14 00:00 |
04:35:20.62 |
+38:06:14.2 |
HIP 21565 |
28.34 |
| 2026-10-14 12:00 |
04:35:18.48 |
+38:06:17.8 |
HIP 21565 |
28.76 |
| 2026-10-15 00:00 |
04:35:16.33 |
+38:06:21.4 |
HIP 21565 |
29.19 |
| 2026-10-15 12:00 |
04:35:14.15 |
+38:06:24.8 |
HIP 21565 |
29.62 |
| 2026-10-16 00:00 |
04:35:11.94 |
+38:06:28.1 |
HIP 21565 |
30.05 |