C/2021 K2 (MASTER)
| Parameter |
Value |
| Designation |
C/2021 K2 (MASTER) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2021-09-09T03:37:31.964160Z |
| Orbit solution date (soln_date, UTC) |
2022-07-16T01:42:47Z |
| Obs used |
80 |
| NEO |
- |
| M1 |
8.000 |
| K1 |
10.000 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2021-05-22T23:28:21.792000Z |
| Discovery magnitude (MPC) |
18.70 R |
| Discovery observatory (MPC) |
K95 · MASTER-SAAO Observatory, Sutherland |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-10-19.0000000 |
| e |
1.00120074 |
| q (au) |
5.467026 |
| a (au) |
-4553.055334 |
| i (deg) |
100.845478 |
| Ω (om, deg) |
282.245058 |
| ω (w, deg) |
343.321986 |
| M (ma, deg) |
0.000128 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.807 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.807 |
| n |
2.000 |
| gf |
0.997 |
| gb |
-1.000 |
| k |
1.000 |
| δ90 |
9.959 |
| 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 |
17:31:32.82 |
+49:20:56.0 |
HIP 85880 |
14.58 |
| 2026-02-03 12:00 |
17:31:40.86 |
+49:23:23.1 |
HIP 85880 |
13.53 |
| 2026-02-04 00:00 |
17:31:48.82 |
+49:25:51.0 |
HIP 85880 |
13.02 |
| 2026-02-04 12:00 |
17:31:56.68 |
+49:28:19.7 |
HIP 85880 |
13.12 |
| 2026-02-05 00:00 |
17:32:04.46 |
+49:30:49.1 |
HIP 85769 |
13.56 |
| 2026-02-05 12:00 |
17:32:12.15 |
+49:33:19.3 |
HIP 85769 |
11.89 |
| 2026-02-06 00:00 |
17:32:19.74 |
+49:35:50.2 |
HIP 85769 |
10.68 |
| 2026-02-06 12:00 |
17:32:27.24 |
+49:38:21.8 |
HIP 85769 |
10.10 |
| 2026-02-07 00:00 |
17:32:34.64 |
+49:40:54.1 |
HIP 85769 |
10.26 |
| 2026-02-07 12:00 |
17:32:41.96 |
+49:43:27.1 |
HIP 85769 |
11.13 |
| 2026-02-08 00:00 |
17:32:49.17 |
+49:46:00.8 |
HIP 85769 |
12.57 |
| 2026-02-08 12:00 |
17:32:56.29 |
+49:48:35.2 |
HIP 85769 |
14.41 |
| 2026-02-09 00:00 |
17:33:03.32 |
+49:51:10.4 |
HIP 85769 |
16.51 |
| 2026-02-09 12:00 |
17:33:10.24 |
+49:53:46.1 |
HIP 85769 |
18.80 |
| 2026-02-10 00:00 |
17:33:17.07 |
+49:56:22.6 |
HIP 85769 |
21.21 |
| 2026-02-10 12:00 |
17:33:23.79 |
+49:58:59.7 |
HIP 85769 |
23.71 |
| 2026-02-11 00:00 |
17:33:30.42 |
+50:01:37.5 |
HIP 85717 |
24.75 |
| 2026-02-11 12:00 |
17:33:36.94 |
+50:04:16.0 |
HIP 85717 |
25.65 |
| 2026-02-12 00:00 |
17:33:43.36 |
+50:06:55.0 |
HIP 85717 |
26.80 |
| 2026-02-12 12:00 |
17:33:49.68 |
+50:09:34.7 |
HIP 85717 |
28.18 |
| 2026-02-13 00:00 |
17:33:55.90 |
+50:12:15.1 |
HIP 86202 |
29.44 |
| 2026-02-13 12:00 |
17:34:02.01 |
+50:14:56.0 |
HIP 86202 |
29.06 |
| 2026-02-14 00:00 |
17:34:08.01 |
+50:17:37.6 |
HIP 86202 |
28.97 |
| 2026-02-14 12:00 |
17:34:13.91 |
+50:20:19.8 |
HIP 86202 |
29.19 |
| 2026-02-15 00:00 |
17:34:19.70 |
+50:23:02.5 |
HIP 86202 |
29.70 |
| 2026-02-15 12:00 |
17:34:25.38 |
+50:25:45.9 |
HIP 86202 |
30.50 |
| 2026-02-16 00:00 |
17:34:30.96 |
+50:28:29.8 |
HIP 86241 |
29.99 |
| 2026-02-16 12:00 |
17:34:36.42 |
+50:31:14.2 |
HIP 86241 |
28.20 |
| 2026-02-17 00:00 |
17:34:41.77 |
+50:33:59.3 |
HIP 86241 |
26.62 |
| 2026-02-17 12:00 |
17:34:47.01 |
+50:36:44.9 |
HIP 86241 |
25.29 |
| 2026-02-18 00:00 |
17:34:52.14 |
+50:39:31.0 |
HIP 86241 |
24.24 |
| 2026-02-18 12:00 |
17:34:57.16 |
+50:42:17.6 |
HIP 86241 |
23.53 |
| 2026-02-19 00:00 |
17:35:02.06 |
+50:45:04.8 |
HIP 86191 |
21.59 |
| 2026-02-19 12:00 |
17:35:06.85 |
+50:47:52.4 |
HIP 86191 |
19.26 |
| 2026-02-20 00:00 |
17:35:11.52 |
+50:50:40.6 |
HIP 86191 |
17.13 |
| 2026-02-20 12:00 |
17:35:16.07 |
+50:53:29.3 |
HIP 86191 |
15.26 |
| 2026-02-21 00:00 |
17:35:20.51 |
+50:56:18.4 |
HIP 86191 |
13.78 |
| 2026-02-21 12:00 |
17:35:24.83 |
+50:59:08.0 |
HIP 86191 |
12.81 |
| 2026-02-22 00:00 |
17:35:29.04 |
+51:01:58.0 |
HIP 86185 |
11.66 |
| 2026-02-22 12:00 |
17:35:33.12 |
+51:04:48.5 |
HIP 86185 |
10.57 |
| 2026-02-23 00:00 |
17:35:37.08 |
+51:07:39.5 |
HIP 86185 |
10.23 |
| 2026-02-23 12:00 |
17:35:40.93 |
+51:10:30.8 |
HIP 86185 |
10.73 |
| 2026-02-24 00:00 |
17:35:44.65 |
+51:13:22.6 |
HIP 86185 |
11.96 |