| 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) |
| 2026-07-29 00:00 |
22:07:32.36 |
-12:45:38.0 |
HIP 109170 |
18.30 |
| 2026-07-29 12:00 |
22:07:23.19 |
-12:46:40.9 |
HIP 109170 |
18.02 |
| 2026-07-30 00:00 |
22:07:13.96 |
-12:47:44.0 |
HIP 109170 |
18.07 |
| 2026-07-30 12:00 |
22:07:04.69 |
-12:48:47.3 |
HIP 109170 |
18.47 |
| 2026-07-31 00:00 |
22:06:55.37 |
-12:49:50.8 |
HIP 109170 |
19.18 |
| 2026-07-31 12:00 |
22:06:46.00 |
-12:50:54.6 |
HIP 109170 |
20.19 |
| 2026-08-01 00:00 |
22:06:36.59 |
-12:51:58.5 |
HIP 109170 |
21.46 |
| 2026-08-01 12:00 |
22:06:27.14 |
-12:53:02.6 |
HIP 109170 |
22.94 |
| 2026-08-02 00:00 |
22:06:17.64 |
-12:54:06.8 |
HIP 109001 |
20.57 |
| 2026-08-02 12:00 |
22:06:08.09 |
-12:55:11.3 |
HIP 109001 |
18.05 |
| 2026-08-03 00:00 |
22:05:58.51 |
-12:56:15.9 |
HIP 109001 |
15.53 |
| 2026-08-03 12:00 |
22:05:48.89 |
-12:57:20.7 |
HIP 109001 |
13.01 |
| 2026-08-04 00:00 |
22:05:39.22 |
-12:58:25.7 |
HIP 109001 |
10.53 |
| 2026-08-04 12:00 |
22:05:29.52 |
-12:59:30.8 |
HIP 109001 |
8.09 |
| 2026-08-05 00:00 |
22:05:19.78 |
-13:00:36.0 |
HIP 109001 |
5.79 |
| 2026-08-05 12:00 |
22:05:10.00 |
-13:01:41.4 |
HIP 109001 |
3.91 |
| 2026-08-06 00:00 |
22:05:00.19 |
-13:02:46.9 |
HIP 109001 |
3.27 |
| 2026-08-06 12:00 |
22:04:50.34 |
-13:03:52.5 |
HIP 109001 |
4.46 |
| 2026-08-07 00:00 |
22:04:40.46 |
-13:04:58.3 |
HIP 109001 |
6.57 |
| 2026-08-07 12:00 |
22:04:30.54 |
-13:06:04.2 |
HIP 108931 |
7.73 |
| 2026-08-08 00:00 |
22:04:20.60 |
-13:07:10.2 |
HIP 108931 |
6.97 |
| 2026-08-08 12:00 |
22:04:10.62 |
-13:08:16.2 |
HIP 108931 |
7.18 |
| 2026-08-09 00:00 |
22:04:00.61 |
-13:09:22.4 |
HIP 108931 |
8.30 |
| 2026-08-09 12:00 |
22:03:50.58 |
-13:10:28.7 |
HIP 108931 |
10.03 |
| 2026-08-10 00:00 |
22:03:40.52 |
-13:11:35.0 |
HIP 108931 |
12.11 |
| 2026-08-10 12:00 |
22:03:30.43 |
-13:12:41.5 |
HIP 108931 |
14.41 |
| 2026-08-11 00:00 |
22:03:20.32 |
-13:13:47.9 |
HIP 108931 |
16.82 |
| 2026-08-11 12:00 |
22:03:10.19 |
-13:14:54.5 |
HIP 108931 |
19.32 |
| 2026-08-12 00:00 |
22:03:00.03 |
-13:16:01.1 |
HIP 108931 |
21.87 |
| 2026-08-12 12:00 |
22:02:49.85 |
-13:17:07.7 |
HIP 108931 |
24.45 |
| 2026-08-13 00:00 |
22:02:39.65 |
-13:18:14.4 |
HIP 108931 |
27.07 |
| 2026-08-13 12:00 |
22:02:29.44 |
-13:19:21.1 |
HIP 108692 |
27.12 |
| 2026-08-14 00:00 |
22:02:19.20 |
-13:20:27.8 |
HIP 108692 |
26.08 |
| 2026-08-14 12:00 |
22:02:08.95 |
-13:21:34.6 |
HIP 108692 |
25.29 |
| 2026-08-15 00:00 |
22:01:58.69 |
-13:22:41.3 |
HIP 108692 |
24.77 |
| 2026-08-15 12:00 |
22:01:48.41 |
-13:23:48.1 |
HIP 108692 |
24.55 |
| 2026-08-16 00:00 |
22:01:38.12 |
-13:24:54.8 |
HIP 108647 |
24.61 |
| 2026-08-16 12:00 |
22:01:27.81 |
-13:26:01.6 |
HIP 108647 |
22.27 |
| 2026-08-17 00:00 |
22:01:17.50 |
-13:27:08.3 |
HIP 108647 |
20.04 |
| 2026-08-17 12:00 |
22:01:07.18 |
-13:28:15.0 |
HIP 108647 |
17.94 |
| 2026-08-18 00:00 |
22:00:56.85 |
-13:29:21.6 |
HIP 108647 |
16.05 |
| 2026-08-18 12:00 |
22:00:46.51 |
-13:30:28.2 |
HIP 108647 |
14.42 |
| 2026-08-19 00:00 |
22:00:36.17 |
-13:31:34.8 |
HIP 108647 |
13.18 |