| Parameter |
Value |
| Designation |
409P/LONEOS-Hill |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-01-25T16:59:38.414400Z |
| Orbit solution date (soln_date, UTC) |
2022-03-08T19:44:12Z |
| Obs used |
1705 |
| NEO |
- |
| M1 |
14.200 |
| K1 |
8.750 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-11-03T11:40:07.680000Z |
| Discovery magnitude (MPC) |
19.56 g |
| Discovery observatory (MPC) |
I41 · Palomar Mountain–ZTF |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-06-28.0000000 |
| e |
0.71072113 |
| q (au) |
1.751020 |
| a (au) |
6.053052 |
| i (deg) |
17.144587 |
| Ω (om, deg) |
143.781749 |
| ω (w, deg) |
15.044814 |
| M (ma, deg) |
200.916834 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.371 + 4.559\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.371 |
| n |
4.559 |
| gf |
0.977 |
| gb |
-0.608 |
| k |
0.800 |
| δ90 |
1.735 |
| 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 |
| 2019-10-24 |
2020-11-05 |
-7.0398 |
+2.913 |
| 2020-11-05 |
2021-01-24 |
+19.2514 |
-4.902 |
| 2021-01-26 |
2021-07-05 |
+4.7721 |
-1.442 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
21:50:15.09 |
-14:36:16.2 |
HIP 107861 |
17.36 |
| 2026-09-20 12:00 |
21:50:06.81 |
-14:37:06.9 |
HIP 107861 |
18.38 |
| 2026-09-21 00:00 |
21:49:58.60 |
-14:37:57.2 |
HIP 107861 |
19.58 |
| 2026-09-21 12:00 |
21:49:50.46 |
-14:38:47.0 |
HIP 107861 |
20.92 |
| 2026-09-22 00:00 |
21:49:42.38 |
-14:39:36.5 |
HIP 107861 |
22.37 |
| 2026-09-22 12:00 |
21:49:34.37 |
-14:40:25.5 |
HIP 107861 |
23.91 |
| 2026-09-23 00:00 |
21:49:26.44 |
-14:41:14.1 |
HIP 107861 |
25.51 |
| 2026-09-23 12:00 |
21:49:18.57 |
-14:42:02.3 |
HIP 107714 |
25.24 |
| 2026-09-24 00:00 |
21:49:10.77 |
-14:42:50.0 |
HIP 107714 |
24.41 |
| 2026-09-24 12:00 |
21:49:03.05 |
-14:43:37.3 |
HIP 107714 |
23.73 |
| 2026-09-25 00:00 |
21:48:55.40 |
-14:44:24.2 |
HIP 107714 |
23.21 |
| 2026-09-25 12:00 |
21:48:47.82 |
-14:45:10.6 |
HIP 107714 |
22.86 |
| 2026-09-26 00:00 |
21:48:40.31 |
-14:45:56.6 |
HIP 107569 |
22.19 |
| 2026-09-26 12:00 |
21:48:32.88 |
-14:46:42.1 |
HIP 107569 |
20.64 |
| 2026-09-27 00:00 |
21:48:25.53 |
-14:47:27.2 |
HIP 107569 |
19.18 |
| 2026-09-27 12:00 |
21:48:18.25 |
-14:48:11.8 |
HIP 107569 |
17.82 |
| 2026-09-28 00:00 |
21:48:11.05 |
-14:48:55.9 |
HIP 107569 |
16.58 |
| 2026-09-28 12:00 |
21:48:03.92 |
-14:49:39.6 |
HIP 107569 |
15.49 |
| 2026-09-29 00:00 |
21:47:56.88 |
-14:50:22.9 |
HIP 107569 |
14.56 |
| 2026-09-29 12:00 |
21:47:49.91 |
-14:51:05.6 |
HIP 107569 |
13.83 |
| 2026-09-30 00:00 |
21:47:43.03 |
-14:51:48.0 |
HIP 107569 |
13.32 |
| 2026-09-30 12:00 |
21:47:36.22 |
-14:52:29.8 |
HIP 107569 |
13.04 |
| 2026-10-01 00:00 |
21:47:29.49 |
-14:53:11.2 |
HIP 107569 |
13.00 |
| 2026-10-01 12:00 |
21:47:22.85 |
-14:53:52.0 |
HIP 107569 |
13.20 |
| 2026-10-02 00:00 |
21:47:16.29 |
-14:54:32.4 |
HIP 107569 |
13.62 |
| 2026-10-02 12:00 |
21:47:09.81 |
-14:55:12.4 |
HIP 107569 |
14.22 |
| 2026-10-03 00:00 |
21:47:03.41 |
-14:55:51.8 |
HIP 107569 |
14.98 |
| 2026-10-03 12:00 |
21:46:57.10 |
-14:56:30.8 |
HIP 107569 |
15.88 |
| 2026-10-04 00:00 |
21:46:50.88 |
-14:57:09.2 |
HIP 107569 |
16.87 |
| 2026-10-04 12:00 |
21:46:44.74 |
-14:57:47.2 |
HIP 107450 |
17.02 |
| 2026-10-05 00:00 |
21:46:38.68 |
-14:58:24.7 |
HIP 107450 |
15.48 |
| 2026-10-05 12:00 |
21:46:32.72 |
-14:59:01.7 |
HIP 107450 |
13.97 |
| 2026-10-06 00:00 |
21:46:26.84 |
-14:59:38.2 |
HIP 107450 |
12.50 |
| 2026-10-06 12:00 |
21:46:21.05 |
-15:00:14.2 |
HIP 107450 |
11.07 |
| 2026-10-07 00:00 |
21:46:15.35 |
-15:00:49.6 |
HIP 107450 |
9.69 |
| 2026-10-07 12:00 |
21:46:09.73 |
-15:01:24.6 |
HIP 107450 |
8.37 |
| 2026-10-08 00:00 |
21:46:04.21 |
-15:01:59.1 |
HIP 107450 |
7.13 |
| 2026-10-08 12:00 |
21:45:58.78 |
-15:02:33.0 |
HIP 107450 |
6.00 |
| 2026-10-09 00:00 |
21:45:53.44 |
-15:03:06.4 |
HIP 107450 |
5.05 |
| 2026-10-09 12:00 |
21:45:48.19 |
-15:03:39.4 |
HIP 107450 |
4.35 |
| 2026-10-10 00:00 |
21:45:43.03 |
-15:04:11.8 |
HIP 107450 |
4.02 |
| 2026-10-10 12:00 |
21:45:37.97 |
-15:04:43.6 |
HIP 107450 |
4.12 |
| 2026-10-11 00:00 |
21:45:33.00 |
-15:05:15.0 |
HIP 107450 |
4.62 |