C/2021 X2 (Bok)
| Parameter |
Value |
| Designation |
C/2021 X2 (Bok) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2022-07-08T03:45:12.778560Z |
| Orbit solution date (soln_date, UTC) |
2024-04-15T15:43:28Z |
| Obs used |
95 |
| NEO |
- |
| M1 |
10.600 |
| K1 |
16.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-12-01T09:04:17.558400Z |
| Discovery magnitude (MPC) |
21.60 G |
| Discovery observatory (MPC) |
V00 · Kitt Peak-Bok |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-06-25.0000000 |
| e |
1.00130749 |
| q (au) |
2.994542 |
| a (au) |
-2290.292591 |
| i (deg) |
137.143974 |
| Ω (om, deg) |
228.798155 |
| ω (w, deg) |
193.283930 |
| M (ma, deg) |
-0.000118 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.258 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.258 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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) |
| 2026-02-03 00:00 |
18:21:25.63 |
-52:47:36.4 |
HIP 89864 |
18.61 |
| 2026-02-03 12:00 |
18:21:35.29 |
-52:48:06.9 |
HIP 89864 |
19.03 |
| 2026-02-04 00:00 |
18:21:44.85 |
-52:48:37.9 |
HIP 89864 |
19.55 |
| 2026-02-04 12:00 |
18:21:54.33 |
-52:49:09.4 |
HIP 89864 |
20.16 |
| 2026-02-05 00:00 |
18:22:03.71 |
-52:49:41.4 |
HIP 89864 |
20.84 |
| 2026-02-05 12:00 |
18:22:13.01 |
-52:50:13.9 |
HIP 89864 |
21.59 |
| 2026-02-06 00:00 |
18:22:22.22 |
-52:50:46.9 |
HIP 89864 |
22.40 |
| 2026-02-06 12:00 |
18:22:31.33 |
-52:51:20.4 |
HIP 89864 |
23.26 |
| 2026-02-07 00:00 |
18:22:40.36 |
-52:51:54.3 |
HIP 89864 |
24.16 |
| 2026-02-07 12:00 |
18:22:49.28 |
-52:52:28.8 |
HIP 89864 |
25.10 |
| 2026-02-08 00:00 |
18:22:58.12 |
-52:53:03.8 |
HIP 89864 |
26.08 |
| 2026-02-08 12:00 |
18:23:06.86 |
-52:53:39.3 |
HIP 89864 |
27.08 |
| 2026-02-09 00:00 |
18:23:15.50 |
-52:54:15.2 |
HIP 90341 |
26.20 |
| 2026-02-09 12:00 |
18:23:24.05 |
-52:54:51.6 |
HIP 90341 |
24.78 |
| 2026-02-10 00:00 |
18:23:32.50 |
-52:55:28.6 |
HIP 90341 |
23.37 |
| 2026-02-10 12:00 |
18:23:40.85 |
-52:56:06.0 |
HIP 90341 |
21.97 |
| 2026-02-11 00:00 |
18:23:49.10 |
-52:56:43.9 |
HIP 90341 |
20.59 |
| 2026-02-11 12:00 |
18:23:57.24 |
-52:57:22.2 |
HIP 90341 |
19.21 |
| 2026-02-12 00:00 |
18:24:05.29 |
-52:58:01.1 |
HIP 90341 |
17.86 |
| 2026-02-12 12:00 |
18:24:13.24 |
-52:58:40.4 |
HIP 90341 |
16.51 |
| 2026-02-13 00:00 |
18:24:21.08 |
-52:59:20.2 |
HIP 90341 |
15.18 |
| 2026-02-13 12:00 |
18:24:28.81 |
-53:00:00.5 |
HIP 90341 |
13.87 |
| 2026-02-14 00:00 |
18:24:36.44 |
-53:00:41.3 |
HIP 90341 |
12.58 |
| 2026-02-14 12:00 |
18:24:43.97 |
-53:01:22.5 |
HIP 90341 |
11.32 |
| 2026-02-15 00:00 |
18:24:51.39 |
-53:02:04.2 |
HIP 90341 |
10.09 |
| 2026-02-15 12:00 |
18:24:58.69 |
-53:02:46.3 |
HIP 90341 |
8.89 |
| 2026-02-16 00:00 |
18:25:05.89 |
-53:03:28.9 |
HIP 90341 |
7.75 |
| 2026-02-16 12:00 |
18:25:12.98 |
-53:04:12.0 |
HIP 90341 |
6.68 |
| 2026-02-17 00:00 |
18:25:19.96 |
-53:04:55.6 |
HIP 90341 |
5.72 |
| 2026-02-17 12:00 |
18:25:26.83 |
-53:05:39.5 |
HIP 90341 |
4.92 |
| 2026-02-18 00:00 |
18:25:33.58 |
-53:06:24.0 |
HIP 90341 |
4.36 |
| 2026-02-18 12:00 |
18:25:40.22 |
-53:07:08.9 |
HIP 90341 |
4.15 |
| 2026-02-19 00:00 |
18:25:46.75 |
-53:07:54.2 |
HIP 90341 |
4.31 |
| 2026-02-19 12:00 |
18:25:53.16 |
-53:08:40.0 |
HIP 90341 |
4.81 |
| 2026-02-20 00:00 |
18:25:59.45 |
-53:09:26.2 |
HIP 90341 |
5.55 |
| 2026-02-20 12:00 |
18:26:05.63 |
-53:10:12.9 |
HIP 90341 |
6.44 |
| 2026-02-21 00:00 |
18:26:11.68 |
-53:11:00.0 |
HIP 90341 |
7.42 |
| 2026-02-21 12:00 |
18:26:17.62 |
-53:11:47.5 |
HIP 90341 |
8.46 |
| 2026-02-22 00:00 |
18:26:23.44 |
-53:12:35.4 |
HIP 90341 |
9.53 |
| 2026-02-22 12:00 |
18:26:29.14 |
-53:13:23.8 |
HIP 90341 |
10.63 |
| 2026-02-23 00:00 |
18:26:34.72 |
-53:14:12.6 |
HIP 90341 |
11.73 |
| 2026-02-23 12:00 |
18:26:40.17 |
-53:15:01.8 |
HIP 90341 |
12.85 |
| 2026-02-24 00:00 |
18:26:45.51 |
-53:15:51.5 |
HIP 90341 |
13.97 |