| Parameter |
Value |
| Designation |
151P/Helin |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2015-10-06T14:58:48.158400Z |
| Orbit solution date (soln_date, UTC) |
2022-05-19T21:13:49Z |
| Obs used |
420 |
| NEO |
- |
| M1 |
8.500 |
| K1 |
21.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-02-22.0000000 |
| e |
0.57089385 |
| q (au) |
2.491926 |
| a (au) |
5.807247 |
| i (deg) |
4.734715 |
| Ω (om, deg) |
143.554023 |
| ω (w, deg) |
215.530383 |
| M (ma, deg) |
215.436711 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.870 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.870 |
| n |
6.000 |
| gf |
0.929 |
| gb |
-0.828 |
| k |
0.997 |
| δ90 |
1.000 |
| 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) |
| 2026-09-20 00:00 |
14:20:16.55 |
-09:35:02.1 |
HIP 70187 |
21.30 |
| 2026-09-20 12:00 |
14:20:32.35 |
-09:36:32.7 |
HIP 70187 |
18.66 |
| 2026-09-21 00:00 |
14:20:48.22 |
-09:38:03.4 |
HIP 70187 |
16.65 |
| 2026-09-21 12:00 |
14:21:04.16 |
-09:39:34.2 |
HIP 70187 |
15.53 |
| 2026-09-22 00:00 |
14:21:20.18 |
-09:41:05.3 |
HIP 70187 |
15.52 |
| 2026-09-22 12:00 |
14:21:36.26 |
-09:42:36.5 |
HIP 70187 |
16.62 |
| 2026-09-23 00:00 |
14:21:52.41 |
-09:44:07.9 |
HIP 70187 |
18.65 |
| 2026-09-23 12:00 |
14:22:08.62 |
-09:45:39.4 |
HIP 70187 |
21.36 |
| 2026-09-24 00:00 |
14:22:24.91 |
-09:47:11.0 |
HIP 70187 |
24.53 |
| 2026-09-24 12:00 |
14:22:41.26 |
-09:48:42.9 |
HIP 70187 |
28.01 |
| 2026-09-25 00:00 |
14:22:57.68 |
-09:50:14.8 |
HIP 70187 |
31.71 |
| 2026-09-25 12:00 |
14:23:14.16 |
-09:51:46.9 |
HIP 70187 |
35.57 |
| 2026-09-26 00:00 |
14:23:30.71 |
-09:53:19.2 |
HIP 70187 |
39.54 |
| 2026-09-26 12:00 |
14:23:47.32 |
-09:54:51.5 |
HIP 70183 |
42.97 |
| 2026-09-27 00:00 |
14:24:04.00 |
-09:56:24.0 |
HIP 70183 |
45.31 |
| 2026-09-27 12:00 |
14:24:20.75 |
-09:57:56.6 |
HIP 70183 |
47.95 |
| 2026-09-28 00:00 |
14:24:37.55 |
-09:59:29.4 |
HIP 70688 |
44.41 |
| 2026-09-28 12:00 |
14:24:54.42 |
-10:01:02.2 |
HIP 70688 |
39.99 |
| 2026-09-29 00:00 |
14:25:11.35 |
-10:02:35.2 |
HIP 70688 |
35.55 |
| 2026-09-29 12:00 |
14:25:28.35 |
-10:04:08.3 |
HIP 70688 |
31.10 |
| 2026-09-30 00:00 |
14:25:45.40 |
-10:05:41.5 |
HIP 70688 |
26.65 |
| 2026-09-30 12:00 |
14:26:02.52 |
-10:07:14.8 |
HIP 70688 |
22.19 |
| 2026-10-01 00:00 |
14:26:19.69 |
-10:08:48.2 |
HIP 70688 |
17.73 |
| 2026-10-01 12:00 |
14:26:36.93 |
-10:10:21.6 |
HIP 70688 |
13.28 |
| 2026-10-02 00:00 |
14:26:54.23 |
-10:11:55.2 |
HIP 70688 |
8.89 |
| 2026-10-02 12:00 |
14:27:11.58 |
-10:13:28.9 |
HIP 70688 |
4.76 |
| 2026-10-03 00:00 |
14:27:29.00 |
-10:15:02.6 |
HIP 70688 |
2.77 |
| 2026-10-03 12:00 |
14:27:46.47 |
-10:16:36.5 |
HIP 70688 |
5.86 |
| 2026-10-04 00:00 |
14:28:04.00 |
-10:18:10.4 |
HIP 70688 |
10.16 |
| 2026-10-04 12:00 |
14:28:21.58 |
-10:19:44.3 |
HIP 70688 |
14.64 |
| 2026-10-05 00:00 |
14:28:39.23 |
-10:21:18.4 |
HIP 70867 |
18.03 |
| 2026-10-05 12:00 |
14:28:56.92 |
-10:22:52.5 |
HIP 70867 |
13.97 |
| 2026-10-06 00:00 |
14:29:14.68 |
-10:24:26.7 |
HIP 70867 |
10.39 |
| 2026-10-06 12:00 |
14:29:32.49 |
-10:26:00.9 |
HIP 70867 |
7.99 |
| 2026-10-07 00:00 |
14:29:50.35 |
-10:27:35.2 |
HIP 70867 |
7.94 |
| 2026-10-07 12:00 |
14:30:08.27 |
-10:29:09.5 |
HIP 70867 |
10.29 |
| 2026-10-08 00:00 |
14:30:26.24 |
-10:30:43.9 |
HIP 70867 |
13.89 |
| 2026-10-08 12:00 |
14:30:44.26 |
-10:32:18.3 |
HIP 70867 |
18.01 |
| 2026-10-09 00:00 |
14:31:02.34 |
-10:33:52.7 |
HIP 70867 |
22.37 |
| 2026-10-09 12:00 |
14:31:20.46 |
-10:35:27.2 |
HIP 71083 |
24.23 |
| 2026-10-10 00:00 |
14:31:38.64 |
-10:37:01.6 |
HIP 71083 |
20.77 |
| 2026-10-10 12:00 |
14:31:56.86 |
-10:38:36.2 |
HIP 71083 |
17.90 |
| 2026-10-11 00:00 |
14:32:15.14 |
-10:40:10.7 |
HIP 71083 |
15.96 |