| 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) |
| 2026-09-25 00:00 |
11:42:47.57 |
-11:29:46.4 |
HIP 57105 |
5.67 |
| 2026-09-25 12:00 |
11:43:01.34 |
-11:31:31.2 |
HIP 57105 |
8.91 |
| 2026-09-26 00:00 |
11:43:15.11 |
-11:33:16.2 |
HIP 57105 |
12.46 |
| 2026-09-26 12:00 |
11:43:28.87 |
-11:35:01.5 |
HIP 57105 |
16.13 |
| 2026-09-27 00:00 |
11:43:42.62 |
-11:36:47.0 |
HIP 57281 |
17.47 |
| 2026-09-27 12:00 |
11:43:56.35 |
-11:38:32.7 |
HIP 57281 |
15.71 |
| 2026-09-28 00:00 |
11:44:10.08 |
-11:40:18.6 |
HIP 57281 |
14.75 |
| 2026-09-28 12:00 |
11:44:23.79 |
-11:42:04.8 |
HIP 57281 |
14.74 |
| 2026-09-29 00:00 |
11:44:37.48 |
-11:43:51.3 |
HIP 57281 |
15.69 |
| 2026-09-29 12:00 |
11:44:51.17 |
-11:45:37.9 |
HIP 57281 |
17.43 |
| 2026-09-30 00:00 |
11:45:04.84 |
-11:47:24.8 |
HIP 57281 |
19.75 |
| 2026-09-30 12:00 |
11:45:18.50 |
-11:49:11.8 |
HIP 57414 |
18.48 |
| 2026-10-01 00:00 |
11:45:32.14 |
-11:50:59.1 |
HIP 57414 |
14.83 |
| 2026-10-01 12:00 |
11:45:45.76 |
-11:52:46.6 |
HIP 57414 |
11.27 |
| 2026-10-02 00:00 |
11:45:59.37 |
-11:54:34.4 |
HIP 57414 |
7.91 |
| 2026-10-02 12:00 |
11:46:12.97 |
-11:56:22.3 |
HIP 57414 |
5.17 |
| 2026-10-03 00:00 |
11:46:26.54 |
-11:58:10.4 |
HIP 57414 |
4.41 |
| 2026-10-03 12:00 |
11:46:40.10 |
-11:59:58.7 |
HIP 57414 |
6.37 |
| 2026-10-04 00:00 |
11:46:53.64 |
-12:01:47.2 |
HIP 57414 |
9.50 |
| 2026-10-04 12:00 |
11:47:07.16 |
-12:03:36.0 |
HIP 57414 |
12.97 |
| 2026-10-05 00:00 |
11:47:20.67 |
-12:05:24.9 |
HIP 57494 |
16.49 |
| 2026-10-05 12:00 |
11:47:34.15 |
-12:07:13.9 |
HIP 57494 |
19.27 |
| 2026-10-06 00:00 |
11:47:47.61 |
-12:09:03.2 |
HIP 57494 |
22.34 |
| 2026-10-06 12:00 |
11:48:01.05 |
-12:10:52.7 |
HIP 57494 |
25.59 |
| 2026-10-07 00:00 |
11:48:14.47 |
-12:12:42.3 |
HIP 57634 |
27.13 |
| 2026-10-07 12:00 |
11:48:27.86 |
-12:14:32.1 |
HIP 57634 |
24.11 |
| 2026-10-08 00:00 |
11:48:41.24 |
-12:16:22.0 |
HIP 57634 |
21.32 |
| 2026-10-08 12:00 |
11:48:54.59 |
-12:18:12.2 |
HIP 57634 |
18.86 |
| 2026-10-09 00:00 |
11:49:07.91 |
-12:20:02.4 |
HIP 57634 |
16.88 |
| 2026-10-09 12:00 |
11:49:21.21 |
-12:21:52.9 |
HIP 57634 |
15.55 |
| 2026-10-10 00:00 |
11:49:34.49 |
-12:23:43.4 |
HIP 57634 |
15.05 |
| 2026-10-10 12:00 |
11:49:47.73 |
-12:25:34.2 |
HIP 57634 |
15.45 |
| 2026-10-11 00:00 |
11:50:00.96 |
-12:27:25.0 |
HIP 57634 |
16.68 |
| 2026-10-11 12:00 |
11:50:14.15 |
-12:29:16.0 |
HIP 57634 |
18.58 |
| 2026-10-12 00:00 |
11:50:27.31 |
-12:31:07.2 |
HIP 57634 |
20.97 |
| 2026-10-12 12:00 |
11:50:40.45 |
-12:32:58.5 |
HIP 57753 |
19.05 |
| 2026-10-13 00:00 |
11:50:53.56 |
-12:34:49.8 |
HIP 57753 |
17.51 |
| 2026-10-13 12:00 |
11:51:06.64 |
-12:36:41.4 |
HIP 57753 |
16.66 |
| 2026-10-14 00:00 |
11:51:19.68 |
-12:38:33.0 |
HIP 57753 |
16.59 |
| 2026-10-14 12:00 |
11:51:32.70 |
-12:40:24.7 |
HIP 57753 |
17.32 |
| 2026-10-15 00:00 |
11:51:45.68 |
-12:42:16.6 |
HIP 57753 |
18.75 |
| 2026-10-15 12:00 |
11:51:58.63 |
-12:44:08.5 |
HIP 57753 |
20.73 |
| 2026-10-16 00:00 |
11:52:11.55 |
-12:46:00.6 |
HIP 57753 |
23.12 |