| 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) |
| 2026-05-12 00:00 |
08:16:29.20 |
+10:32:45.7 |
HIP 40558 |
5.91 |
| 2026-05-12 12:00 |
08:16:36.14 |
+10:32:50.8 |
HIP 40558 |
4.21 |
| 2026-05-13 00:00 |
08:16:43.19 |
+10:32:55.4 |
HIP 40558 |
2.51 |
| 2026-05-13 12:00 |
08:16:50.35 |
+10:32:59.5 |
HIP 40558 |
0.90 |
| 2026-05-14 00:00 |
08:16:57.61 |
+10:33:03.0 |
HIP 40558 |
1.25 |
| 2026-05-14 12:00 |
08:17:04.98 |
+10:33:06.1 |
HIP 40558 |
2.97 |
| 2026-05-15 00:00 |
08:17:12.46 |
+10:33:08.6 |
HIP 40558 |
4.79 |
| 2026-05-15 12:00 |
08:17:20.03 |
+10:33:10.5 |
HIP 40558 |
6.64 |
| 2026-05-16 00:00 |
08:17:27.71 |
+10:33:12.0 |
HIP 40558 |
8.52 |
| 2026-05-16 12:00 |
08:17:35.50 |
+10:33:12.9 |
HIP 40558 |
10.42 |
| 2026-05-17 00:00 |
08:17:43.38 |
+10:33:13.3 |
HIP 40558 |
12.36 |
| 2026-05-17 12:00 |
08:17:51.37 |
+10:33:13.2 |
HIP 40558 |
14.32 |
| 2026-05-18 00:00 |
08:17:59.45 |
+10:33:12.6 |
HIP 40558 |
16.30 |
| 2026-05-18 12:00 |
08:18:07.64 |
+10:33:11.4 |
HIP 40558 |
18.31 |
| 2026-05-19 00:00 |
08:18:15.92 |
+10:33:09.7 |
HIP 40558 |
20.34 |
| 2026-05-19 12:00 |
08:18:24.30 |
+10:33:07.5 |
HIP 40558 |
22.40 |
| 2026-05-20 00:00 |
08:18:32.78 |
+10:33:04.8 |
HIP 40558 |
24.48 |
| 2026-05-20 12:00 |
08:18:41.36 |
+10:33:01.5 |
HIP 40558 |
26.59 |
| 2026-05-21 00:00 |
08:18:50.03 |
+10:32:57.8 |
HIP 40558 |
28.72 |
| 2026-05-21 12:00 |
08:18:58.80 |
+10:32:53.5 |
HIP 40558 |
30.87 |
| 2026-05-22 00:00 |
08:19:07.66 |
+10:32:48.7 |
HIP 40558 |
33.05 |
| 2026-05-22 12:00 |
08:19:16.61 |
+10:32:43.3 |
HIP 40558 |
35.25 |
| 2026-05-23 00:00 |
08:19:25.66 |
+10:32:37.5 |
HIP 40558 |
37.47 |
| 2026-05-23 12:00 |
08:19:34.80 |
+10:32:31.1 |
HIP 40558 |
39.72 |
| 2026-05-24 00:00 |
08:19:44.03 |
+10:32:24.2 |
HIP 41027 |
39.86 |
| 2026-05-24 12:00 |
08:19:53.35 |
+10:32:16.8 |
HIP 41027 |
37.64 |
| 2026-05-25 00:00 |
08:20:02.76 |
+10:32:08.9 |
HIP 41027 |
35.40 |
| 2026-05-25 12:00 |
08:20:12.26 |
+10:32:00.4 |
HIP 41027 |
33.16 |
| 2026-05-26 00:00 |
08:20:21.85 |
+10:31:51.5 |
HIP 41027 |
30.91 |
| 2026-05-26 12:00 |
08:20:31.53 |
+10:31:42.0 |
HIP 41027 |
28.66 |
| 2026-05-27 00:00 |
08:20:41.29 |
+10:31:32.1 |
HIP 41027 |
26.41 |
| 2026-05-27 12:00 |
08:20:51.14 |
+10:31:21.6 |
HIP 41027 |
24.18 |
| 2026-05-28 00:00 |
08:21:01.08 |
+10:31:10.6 |
HIP 41027 |
21.98 |
| 2026-05-28 12:00 |
08:21:11.10 |
+10:30:59.1 |
HIP 41027 |
19.82 |
| 2026-05-29 00:00 |
08:21:21.20 |
+10:30:47.1 |
HIP 41027 |
17.72 |
| 2026-05-29 12:00 |
08:21:31.39 |
+10:30:34.6 |
HIP 41027 |
15.73 |
| 2026-05-30 00:00 |
08:21:41.66 |
+10:30:21.5 |
HIP 41027 |
13.90 |
| 2026-05-30 12:00 |
08:21:52.01 |
+10:30:08.0 |
HIP 41027 |
12.31 |
| 2026-05-31 00:00 |
08:22:02.45 |
+10:29:54.0 |
HIP 41027 |
11.09 |
| 2026-05-31 12:00 |
08:22:12.96 |
+10:29:39.4 |
HIP 41027 |
10.38 |
| 2026-06-01 00:00 |
08:22:23.56 |
+10:29:24.4 |
HIP 41027 |
10.30 |
| 2026-06-01 12:00 |
08:22:34.24 |
+10:29:08.8 |
HIP 41027 |
10.88 |
| 2026-06-02 00:00 |
08:22:44.99 |
+10:28:52.8 |
HIP 41027 |
12.05 |