| Parameter |
Value |
| Designation |
P/2021 HS (PANSTARRS) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-08-06T09:22:36.661440Z |
| Orbit solution date (soln_date, UTC) |
2021-12-17T03:12:57Z |
| Obs used |
181 |
| NEO |
Yes |
| M1 |
20.600 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-07-03.0000000 |
| e |
0.81016790 |
| q (au) |
0.796446 |
| a (au) |
4.195528 |
| i (deg) |
12.171396 |
| Ω (om, deg) |
262.395858 |
| ω (w, deg) |
46.086196 |
| M (ma, deg) |
356.055743 |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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 |
08:49:03.61 |
+09:07:56.5 |
HIP 43317 |
17.25 |
| 2026-07-29 12:00 |
08:49:19.11 |
+09:06:50.8 |
HIP 43317 |
15.17 |
| 2026-07-30 00:00 |
08:49:34.62 |
+09:05:44.7 |
HIP 43317 |
13.93 |
| 2026-07-30 12:00 |
08:49:50.14 |
+09:04:38.3 |
HIP 43317 |
13.77 |
| 2026-07-31 00:00 |
08:50:05.66 |
+09:03:31.6 |
HIP 43317 |
14.73 |
| 2026-07-31 12:00 |
08:50:21.18 |
+09:02:24.6 |
HIP 43317 |
16.62 |
| 2026-08-01 00:00 |
08:50:36.70 |
+09:01:17.2 |
HIP 43317 |
19.16 |
| 2026-08-01 12:00 |
08:50:52.23 |
+09:00:09.6 |
HIP 43317 |
22.13 |
| 2026-08-02 00:00 |
08:51:07.76 |
+08:59:01.6 |
HIP 43582 |
21.89 |
| 2026-08-02 12:00 |
08:51:23.29 |
+08:57:53.3 |
HIP 43582 |
18.53 |
| 2026-08-03 00:00 |
08:51:38.82 |
+08:56:44.7 |
HIP 43582 |
15.47 |
| 2026-08-03 12:00 |
08:51:54.35 |
+08:55:35.7 |
HIP 43582 |
12.94 |
| 2026-08-04 00:00 |
08:52:09.88 |
+08:54:26.5 |
HIP 43582 |
11.31 |
| 2026-08-04 12:00 |
08:52:25.41 |
+08:53:17.0 |
HIP 43582 |
10.97 |
| 2026-08-05 00:00 |
08:52:40.94 |
+08:52:07.1 |
HIP 43582 |
12.04 |
| 2026-08-05 12:00 |
08:52:56.46 |
+08:50:57.0 |
HIP 43582 |
14.21 |
| 2026-08-06 00:00 |
08:53:11.99 |
+08:49:46.5 |
HIP 43582 |
17.07 |
| 2026-08-06 12:00 |
08:53:27.51 |
+08:48:35.8 |
HIP 43582 |
20.32 |
| 2026-08-07 00:00 |
08:53:43.02 |
+08:47:24.7 |
HIP 43692 |
22.42 |
| 2026-08-07 12:00 |
08:53:58.53 |
+08:46:13.4 |
HIP 43692 |
20.93 |
| 2026-08-08 00:00 |
08:54:14.04 |
+08:45:01.8 |
HIP 43692 |
20.14 |
| 2026-08-08 12:00 |
08:54:29.54 |
+08:43:49.9 |
HIP 43692 |
20.13 |
| 2026-08-09 00:00 |
08:54:45.03 |
+08:42:37.7 |
HIP 43692 |
20.90 |
| 2026-08-09 12:00 |
08:55:00.52 |
+08:41:25.2 |
HIP 43692 |
22.37 |
| 2026-08-10 00:00 |
08:55:15.99 |
+08:40:12.4 |
HIP 43692 |
24.41 |
| 2026-08-10 12:00 |
08:55:31.46 |
+08:38:59.3 |
HIP 43692 |
26.90 |
| 2026-08-11 00:00 |
08:55:46.92 |
+08:37:46.0 |
HIP 43692 |
29.72 |
| 2026-08-11 12:00 |
08:56:02.38 |
+08:36:32.4 |
HIP 43692 |
32.79 |
| 2026-08-12 00:00 |
08:56:17.82 |
+08:35:18.6 |
HIP 43692 |
36.03 |
| 2026-08-12 12:00 |
08:56:33.24 |
+08:34:04.4 |
HIP 44079 |
38.68 |
| 2026-08-13 00:00 |
08:56:48.66 |
+08:32:50.0 |
HIP 44079 |
34.81 |
| 2026-08-13 12:00 |
08:57:04.07 |
+08:31:35.4 |
HIP 44079 |
30.97 |
| 2026-08-14 00:00 |
08:57:19.46 |
+08:30:20.5 |
HIP 44079 |
27.18 |
| 2026-08-14 12:00 |
08:57:34.83 |
+08:29:05.3 |
HIP 44079 |
23.47 |
| 2026-08-15 00:00 |
08:57:50.20 |
+08:27:49.9 |
HIP 44079 |
19.86 |
| 2026-08-15 12:00 |
08:58:05.54 |
+08:26:34.2 |
HIP 44079 |
16.44 |
| 2026-08-16 00:00 |
08:58:20.87 |
+08:25:18.3 |
HIP 44079 |
13.35 |
| 2026-08-16 12:00 |
08:58:36.19 |
+08:24:02.1 |
HIP 44079 |
10.86 |
| 2026-08-17 00:00 |
08:58:51.49 |
+08:22:45.7 |
HIP 44079 |
9.45 |
| 2026-08-17 12:00 |
08:59:06.76 |
+08:21:29.1 |
HIP 44079 |
9.63 |
| 2026-08-18 00:00 |
08:59:22.03 |
+08:20:12.3 |
HIP 44079 |
11.30 |
| 2026-08-18 12:00 |
08:59:37.27 |
+08:18:55.2 |
HIP 44079 |
13.94 |
| 2026-08-19 00:00 |
08:59:52.49 |
+08:17:37.9 |
HIP 44079 |
17.10 |