| Parameter |
Value |
| Designation |
P/2021 R4 (Wierzchos) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-10-13T22:05:15.889920Z |
| Orbit solution date (soln_date, UTC) |
2021-11-20T19:13:09Z |
| Obs used |
76 |
| NEO |
- |
| M1 |
16.300 |
| K1 |
10.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-09-06T09:39:32.976000Z |
| Discovery magnitude (MPC) |
21.16 G |
| Discovery observatory (MPC) |
G96 · University of Arizona Mt. Lemmon Survey |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-09-24.0000000 |
| e |
0.58615107 |
| q (au) |
2.325993 |
| a (au) |
5.620391 |
| i (deg) |
21.040112 |
| Ω (om, deg) |
321.256290 |
| ω (w, deg) |
56.624470 |
| M (ma, deg) |
358.526498 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.933 + 3.415\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.933 |
| n |
3.415 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
11:17:26.68 |
-08:49:25.0 |
HIP 55139 |
6.61 |
| 2026-07-29 12:00 |
11:17:37.93 |
-08:50:19.8 |
HIP 55139 |
7.20 |
| 2026-07-30 00:00 |
11:17:49.23 |
-08:51:15.1 |
HIP 55139 |
8.79 |
| 2026-07-30 12:00 |
11:18:00.59 |
-08:52:11.0 |
HIP 55139 |
10.96 |
| 2026-07-31 00:00 |
11:18:11.99 |
-08:53:07.5 |
HIP 55139 |
13.45 |
| 2026-07-31 12:00 |
11:18:23.45 |
-08:54:04.5 |
HIP 55139 |
16.11 |
| 2026-08-01 00:00 |
11:18:34.96 |
-08:55:02.2 |
HIP 55139 |
18.88 |
| 2026-08-01 12:00 |
11:18:46.52 |
-08:56:00.5 |
HIP 55364 |
21.67 |
| 2026-08-02 00:00 |
11:18:58.13 |
-08:56:59.3 |
HIP 55364 |
19.10 |
| 2026-08-02 12:00 |
11:19:09.79 |
-08:57:58.7 |
HIP 55364 |
16.68 |
| 2026-08-03 00:00 |
11:19:21.49 |
-08:58:58.7 |
HIP 55364 |
14.50 |
| 2026-08-03 12:00 |
11:19:33.25 |
-08:59:59.2 |
HIP 55364 |
12.67 |
| 2026-08-04 00:00 |
11:19:45.05 |
-09:01:00.3 |
HIP 55364 |
11.40 |
| 2026-08-04 12:00 |
11:19:56.90 |
-09:02:02.0 |
HIP 55364 |
10.89 |
| 2026-08-05 00:00 |
11:20:08.79 |
-09:03:04.3 |
HIP 55364 |
11.25 |
| 2026-08-05 12:00 |
11:20:20.73 |
-09:04:07.1 |
HIP 55364 |
12.42 |
| 2026-08-06 00:00 |
11:20:32.72 |
-09:05:10.5 |
HIP 55364 |
14.20 |
| 2026-08-06 12:00 |
11:20:44.75 |
-09:06:14.4 |
HIP 55364 |
16.42 |
| 2026-08-07 00:00 |
11:20:56.83 |
-09:07:19.0 |
HIP 55364 |
18.92 |
| 2026-08-07 12:00 |
11:21:08.95 |
-09:08:24.0 |
HIP 55364 |
21.60 |
| 2026-08-08 00:00 |
11:21:21.11 |
-09:09:29.6 |
HIP 55364 |
24.43 |
| 2026-08-08 12:00 |
11:21:33.32 |
-09:10:35.8 |
HIP 55531 |
24.27 |
| 2026-08-09 00:00 |
11:21:45.57 |
-09:11:42.5 |
HIP 55531 |
23.68 |
| 2026-08-09 12:00 |
11:21:57.86 |
-09:12:49.8 |
HIP 55606 |
23.12 |
| 2026-08-10 00:00 |
11:22:10.20 |
-09:13:57.6 |
HIP 55606 |
19.99 |
| 2026-08-10 12:00 |
11:22:22.57 |
-09:15:05.9 |
HIP 55606 |
16.89 |
| 2026-08-11 00:00 |
11:22:34.98 |
-09:16:14.8 |
HIP 55606 |
13.85 |
| 2026-08-11 12:00 |
11:22:47.44 |
-09:17:24.2 |
HIP 55606 |
10.94 |
| 2026-08-12 00:00 |
11:22:59.93 |
-09:18:34.2 |
HIP 55606 |
8.31 |
| 2026-08-12 12:00 |
11:23:12.46 |
-09:19:44.7 |
HIP 55606 |
6.34 |
| 2026-08-13 00:00 |
11:23:25.03 |
-09:20:55.7 |
HIP 55606 |
5.77 |
| 2026-08-13 12:00 |
11:23:37.64 |
-09:22:07.2 |
HIP 55606 |
6.96 |
| 2026-08-14 00:00 |
11:23:50.29 |
-09:23:19.3 |
HIP 55606 |
9.28 |
| 2026-08-14 12:00 |
11:24:02.97 |
-09:24:31.8 |
HIP 55606 |
12.10 |
| 2026-08-15 00:00 |
11:24:15.68 |
-09:25:44.9 |
HIP 55606 |
15.15 |
| 2026-08-15 12:00 |
11:24:28.43 |
-09:26:58.5 |
HIP 55606 |
18.32 |
| 2026-08-16 00:00 |
11:24:41.22 |
-09:28:12.6 |
HIP 55606 |
21.57 |
| 2026-08-16 12:00 |
11:24:54.04 |
-09:29:27.2 |
HIP 55606 |
24.87 |
| 2026-08-17 00:00 |
11:25:06.89 |
-09:30:42.3 |
HIP 55815 |
28.10 |
| 2026-08-17 12:00 |
11:25:19.77 |
-09:31:57.9 |
HIP 55815 |
25.22 |
| 2026-08-18 00:00 |
11:25:32.69 |
-09:33:14.0 |
HIP 55815 |
22.47 |
| 2026-08-18 12:00 |
11:25:45.64 |
-09:34:30.5 |
HIP 55815 |
19.92 |
| 2026-08-19 00:00 |
11:25:58.62 |
-09:35:47.6 |
HIP 55815 |
17.67 |