| Parameter |
Value |
| Designation |
P/2021 R8 (Sheppard) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-10-07T12:21:16.145280Z |
| Orbit solution date (soln_date, UTC) |
2021-12-07T11:12:02Z |
| Obs used |
26 |
| NEO |
- |
| M1 |
18.600 |
| K1 |
10.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-09-05T13:08:45.772800Z |
| Discovery magnitude (MPC) |
21.69 G |
| Discovery observatory (MPC) |
T09 · Subaru Telescope, Maunakea |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-09-16.0000000 |
| e |
0.29404210 |
| q (au) |
2.130978 |
| a (au) |
3.018562 |
| i (deg) |
2.203054 |
| Ω (om, deg) |
167.025325 |
| ω (w, deg) |
190.793883 |
| M (ma, deg) |
355.956657 |
Magnitude
Scatter + Global Linear
$$
M_a = (16.419 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
16.419 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.900 |
| k |
1.000 |
| δ90 |
10.000 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
20:17:52.54 |
-16:57:44.5 |
HIP 100047 |
19.36 |
| 2026-07-29 12:00 |
20:17:27.72 |
-16:59:32.4 |
HIP 100047 |
18.53 |
| 2026-07-30 00:00 |
20:17:02.91 |
-17:01:20.6 |
HIP 100047 |
19.70 |
| 2026-07-30 12:00 |
20:16:38.12 |
-17:03:09.0 |
HIP 100047 |
22.57 |
| 2026-07-31 00:00 |
20:16:13.35 |
-17:04:57.7 |
HIP 99823 |
19.94 |
| 2026-07-31 12:00 |
20:15:48.61 |
-17:06:46.4 |
HIP 99823 |
17.81 |
| 2026-08-01 00:00 |
20:15:23.92 |
-17:08:35.4 |
HIP 99823 |
17.71 |
| 2026-08-01 12:00 |
20:14:59.28 |
-17:10:24.4 |
HIP 99823 |
19.65 |
| 2026-08-02 00:00 |
20:14:34.71 |
-17:12:13.5 |
HIP 99823 |
23.12 |
| 2026-08-02 12:00 |
20:14:10.20 |
-17:14:02.6 |
HIP 99710 |
26.64 |
| 2026-08-03 00:00 |
20:13:45.78 |
-17:15:51.8 |
HIP 99710 |
24.92 |
| 2026-08-03 12:00 |
20:13:21.44 |
-17:17:40.9 |
HIP 99710 |
24.63 |
| 2026-08-04 00:00 |
20:12:57.20 |
-17:19:30.0 |
HIP 99710 |
25.80 |
| 2026-08-04 12:00 |
20:12:33.06 |
-17:21:19.0 |
HIP 99710 |
28.22 |
| 2026-08-05 00:00 |
20:12:09.04 |
-17:23:07.9 |
HIP 99455 |
28.85 |
| 2026-08-05 12:00 |
20:11:45.15 |
-17:24:56.7 |
HIP 99468 |
25.32 |
| 2026-08-06 00:00 |
20:11:21.39 |
-17:26:45.2 |
HIP 99468 |
22.61 |
| 2026-08-06 12:00 |
20:10:57.77 |
-17:28:33.6 |
HIP 99468 |
21.25 |
| 2026-08-07 00:00 |
20:10:34.30 |
-17:30:21.8 |
HIP 99468 |
21.48 |
| 2026-08-07 12:00 |
20:10:11.00 |
-17:32:09.6 |
HIP 99468 |
23.22 |
| 2026-08-08 00:00 |
20:09:47.86 |
-17:33:57.2 |
HIP 99468 |
26.14 |
| 2026-08-08 12:00 |
20:09:24.90 |
-17:35:44.5 |
HIP 99247 |
27.37 |
| 2026-08-09 00:00 |
20:09:02.14 |
-17:37:31.4 |
HIP 99247 |
24.38 |
| 2026-08-09 12:00 |
20:08:39.56 |
-17:39:17.9 |
HIP 99247 |
22.46 |
| 2026-08-10 00:00 |
20:08:17.20 |
-17:41:04.0 |
HIP 99247 |
21.86 |
| 2026-08-10 12:00 |
20:07:55.05 |
-17:42:49.7 |
HIP 99247 |
22.66 |
| 2026-08-11 00:00 |
20:07:33.12 |
-17:44:34.9 |
HIP 99247 |
24.68 |
| 2026-08-11 12:00 |
20:07:11.43 |
-17:46:19.5 |
HIP 98970 |
22.92 |
| 2026-08-12 00:00 |
20:06:49.98 |
-17:48:03.7 |
HIP 98970 |
18.42 |
| 2026-08-12 12:00 |
20:06:28.78 |
-17:49:47.3 |
HIP 98970 |
14.59 |
| 2026-08-13 00:00 |
20:06:07.84 |
-17:51:30.2 |
HIP 98970 |
12.01 |
| 2026-08-13 12:00 |
20:05:47.17 |
-17:53:12.6 |
HIP 98970 |
11.45 |
| 2026-08-14 00:00 |
20:05:26.77 |
-17:54:54.3 |
HIP 98970 |
13.11 |
| 2026-08-14 12:00 |
20:05:06.66 |
-17:56:35.4 |
HIP 98970 |
16.25 |
| 2026-08-15 00:00 |
20:04:46.84 |
-17:58:15.7 |
HIP 98970 |
20.14 |
| 2026-08-15 12:00 |
20:04:27.32 |
-17:59:55.3 |
HIP 98732 |
22.92 |
| 2026-08-16 00:00 |
20:04:08.11 |
-18:01:34.2 |
HIP 98732 |
18.43 |
| 2026-08-16 12:00 |
20:03:49.21 |
-18:03:12.3 |
HIP 98732 |
14.22 |
| 2026-08-17 00:00 |
20:03:30.64 |
-18:04:49.6 |
HIP 98732 |
10.57 |
| 2026-08-17 12:00 |
20:03:12.39 |
-18:06:26.0 |
HIP 98732 |
8.10 |
| 2026-08-18 00:00 |
20:02:54.48 |
-18:08:01.7 |
HIP 98732 |
7.85 |
| 2026-08-18 12:00 |
20:02:36.91 |
-18:09:36.4 |
HIP 98732 |
9.88 |
| 2026-08-19 00:00 |
20:02:19.68 |
-18:11:10.3 |
HIP 98732 |
13.10 |