| 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) |
| 2026-09-20 00:00 |
09:14:58.63 |
+06:49:34.4 |
HIP 45471 |
22.33 |
| 2026-09-20 12:00 |
09:15:11.28 |
+06:48:09.0 |
HIP 45471 |
19.28 |
| 2026-09-21 00:00 |
09:15:23.86 |
+06:46:43.6 |
HIP 45471 |
16.40 |
| 2026-09-21 12:00 |
09:15:36.38 |
+06:45:18.2 |
HIP 45471 |
13.77 |
| 2026-09-22 00:00 |
09:15:48.83 |
+06:43:52.8 |
HIP 45471 |
11.58 |
| 2026-09-22 12:00 |
09:16:01.23 |
+06:42:27.4 |
HIP 45471 |
10.08 |
| 2026-09-23 00:00 |
09:16:13.56 |
+06:41:02.0 |
HIP 45471 |
9.59 |
| 2026-09-23 12:00 |
09:16:25.82 |
+06:39:36.6 |
HIP 45471 |
10.24 |
| 2026-09-24 00:00 |
09:16:38.03 |
+06:38:11.3 |
HIP 45471 |
11.84 |
| 2026-09-24 12:00 |
09:16:50.16 |
+06:36:46.0 |
HIP 45471 |
14.05 |
| 2026-09-25 00:00 |
09:17:02.23 |
+06:35:20.7 |
HIP 45471 |
16.62 |
| 2026-09-25 12:00 |
09:17:14.24 |
+06:33:55.4 |
HIP 45471 |
19.40 |
| 2026-09-26 00:00 |
09:17:26.17 |
+06:32:30.1 |
HIP 45471 |
22.31 |
| 2026-09-26 12:00 |
09:17:38.04 |
+06:31:04.9 |
HIP 45471 |
25.30 |
| 2026-09-27 00:00 |
09:17:49.85 |
+06:29:39.8 |
HIP 45471 |
28.33 |
| 2026-09-27 12:00 |
09:18:01.58 |
+06:28:14.6 |
HIP 45471 |
31.39 |
| 2026-09-28 00:00 |
09:18:13.24 |
+06:26:49.6 |
HIP 45471 |
34.47 |
| 2026-09-28 12:00 |
09:18:24.84 |
+06:25:24.5 |
HIP 45471 |
37.55 |
| 2026-09-29 00:00 |
09:18:36.36 |
+06:23:59.6 |
HIP 45653 |
40.57 |
| 2026-09-29 12:00 |
09:18:47.81 |
+06:22:34.6 |
HIP 45653 |
42.33 |
| 2026-09-30 00:00 |
09:18:59.19 |
+06:21:09.8 |
HIP 45653 |
44.25 |
| 2026-09-30 12:00 |
09:19:10.50 |
+06:19:45.0 |
HIP 45901 |
45.99 |
| 2026-10-01 00:00 |
09:19:21.73 |
+06:18:20.3 |
HIP 45950 |
43.75 |
| 2026-10-01 12:00 |
09:19:32.89 |
+06:16:55.6 |
HIP 45950 |
40.99 |
| 2026-10-02 00:00 |
09:19:43.97 |
+06:15:31.1 |
HIP 45950 |
38.30 |
| 2026-10-02 12:00 |
09:19:54.98 |
+06:14:06.6 |
HIP 45950 |
35.69 |
| 2026-10-03 00:00 |
09:20:05.91 |
+06:12:42.2 |
HIP 45950 |
33.18 |
| 2026-10-03 12:00 |
09:20:16.77 |
+06:11:17.9 |
HIP 45950 |
30.78 |
| 2026-10-04 00:00 |
09:20:27.55 |
+06:09:53.7 |
HIP 45950 |
28.53 |
| 2026-10-04 12:00 |
09:20:38.25 |
+06:08:29.6 |
HIP 45950 |
26.45 |
| 2026-10-05 00:00 |
09:20:48.87 |
+06:07:05.6 |
HIP 45950 |
24.58 |
| 2026-10-05 12:00 |
09:20:59.41 |
+06:05:41.7 |
HIP 45950 |
22.96 |
| 2026-10-06 00:00 |
09:21:09.87 |
+06:04:18.0 |
HIP 45950 |
21.65 |
| 2026-10-06 12:00 |
09:21:20.25 |
+06:02:54.3 |
HIP 45950 |
20.69 |
| 2026-10-07 00:00 |
09:21:30.55 |
+06:01:30.8 |
HIP 45950 |
20.12 |
| 2026-10-07 12:00 |
09:21:40.76 |
+06:00:07.4 |
HIP 45950 |
19.98 |
| 2026-10-08 00:00 |
09:21:50.89 |
+05:58:44.2 |
HIP 45950 |
20.25 |
| 2026-10-08 12:00 |
09:22:00.94 |
+05:57:21.1 |
HIP 45950 |
20.93 |
| 2026-10-09 00:00 |
09:22:10.90 |
+05:55:58.1 |
HIP 45942 |
21.25 |
| 2026-10-09 12:00 |
09:22:20.77 |
+05:54:35.3 |
HIP 45942 |
20.10 |
| 2026-10-10 00:00 |
09:22:30.56 |
+05:53:12.6 |
HIP 45942 |
19.30 |
| 2026-10-10 12:00 |
09:22:40.26 |
+05:51:50.1 |
HIP 45942 |
18.87 |
| 2026-10-11 00:00 |
09:22:49.87 |
+05:50:27.8 |
HIP 45942 |
18.84 |