221P/LINEAR
| Parameter |
Value |
| Designation |
221P/LINEAR |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2009-01-24T08:32:46.219200Z |
| Orbit solution date (soln_date, UTC) |
2022-10-28T22:13:13Z |
| Obs used |
627 |
| NEO |
- |
| M1 |
14.000 |
| K1 |
13.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-08-08.0000000 |
| e |
0.48757555 |
| q (au) |
1.779766 |
| a (au) |
3.473226 |
| i (deg) |
11.431021 |
| Ω (om, deg) |
229.989314 |
| ω (w, deg) |
39.511181 |
| M (ma, deg) |
140.944591 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.562 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.562 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.891 |
| k |
0.999 |
| δ90 |
9.995 |
| 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 |
06:52:58.95 |
+11:10:02.4 |
HIP 33082 |
11.73 |
| 2026-02-03 12:00 |
06:52:41.94 |
+11:10:57.1 |
HIP 33082 |
14.92 |
| 2026-02-04 00:00 |
06:52:25.09 |
+11:11:52.1 |
HIP 33082 |
18.52 |
| 2026-02-04 12:00 |
06:52:08.41 |
+11:12:47.4 |
HIP 33082 |
22.31 |
| 2026-02-05 00:00 |
06:51:51.90 |
+11:13:43.1 |
HIP 32962 |
25.71 |
| 2026-02-05 12:00 |
06:51:35.56 |
+11:14:39.0 |
HIP 32962 |
27.08 |
| 2026-02-06 00:00 |
06:51:19.40 |
+11:15:35.3 |
HIP 32858 |
25.01 |
| 2026-02-06 12:00 |
06:51:03.42 |
+11:16:32.0 |
HIP 32858 |
23.41 |
| 2026-02-07 00:00 |
06:50:47.61 |
+11:17:28.9 |
HIP 32858 |
22.41 |
| 2026-02-07 12:00 |
06:50:31.99 |
+11:18:26.1 |
HIP 32858 |
22.09 |
| 2026-02-08 00:00 |
06:50:16.55 |
+11:19:23.6 |
HIP 32858 |
22.44 |
| 2026-02-08 12:00 |
06:50:01.29 |
+11:20:21.4 |
HIP 32858 |
23.42 |
| 2026-02-09 00:00 |
06:49:46.23 |
+11:21:19.4 |
HIP 32858 |
24.92 |
| 2026-02-09 12:00 |
06:49:31.35 |
+11:22:17.8 |
HIP 32595 |
23.36 |
| 2026-02-10 00:00 |
06:49:16.67 |
+11:23:16.3 |
HIP 32595 |
19.63 |
| 2026-02-10 12:00 |
06:49:02.18 |
+11:24:15.1 |
HIP 32595 |
15.95 |
| 2026-02-11 00:00 |
06:48:47.88 |
+11:25:14.2 |
HIP 32595 |
12.31 |
| 2026-02-11 12:00 |
06:48:33.79 |
+11:26:13.5 |
HIP 32595 |
8.72 |
| 2026-02-12 00:00 |
06:48:19.89 |
+11:27:13.0 |
HIP 32595 |
5.18 |
| 2026-02-12 12:00 |
06:48:06.20 |
+11:28:12.7 |
HIP 32595 |
1.69 |
| 2026-02-13 00:00 |
06:47:52.70 |
+11:29:12.7 |
HIP 32595 |
1.81 |
| 2026-02-13 12:00 |
06:47:39.42 |
+11:30:12.8 |
HIP 32595 |
5.20 |
| 2026-02-14 00:00 |
06:47:26.34 |
+11:31:13.1 |
HIP 32595 |
8.55 |
| 2026-02-14 12:00 |
06:47:13.47 |
+11:32:13.6 |
HIP 32595 |
11.86 |
| 2026-02-15 00:00 |
06:47:00.81 |
+11:33:14.3 |
HIP 32595 |
15.12 |
| 2026-02-15 12:00 |
06:46:48.36 |
+11:34:15.1 |
HIP 32595 |
18.33 |
| 2026-02-16 00:00 |
06:46:36.12 |
+11:35:16.1 |
HIP 32595 |
21.49 |
| 2026-02-16 12:00 |
06:46:24.10 |
+11:36:17.2 |
HIP 32595 |
24.61 |
| 2026-02-17 00:00 |
06:46:12.30 |
+11:37:18.5 |
HIP 32595 |
27.67 |
| 2026-02-17 12:00 |
06:46:00.71 |
+11:38:19.9 |
HIP 32595 |
30.68 |
| 2026-02-18 00:00 |
06:45:49.34 |
+11:39:21.4 |
HIP 32247 |
28.06 |
| 2026-02-18 12:00 |
06:45:38.19 |
+11:40:23.0 |
HIP 32247 |
25.16 |
| 2026-02-19 00:00 |
06:45:27.27 |
+11:41:24.7 |
HIP 32247 |
22.33 |
| 2026-02-19 12:00 |
06:45:16.56 |
+11:42:26.5 |
HIP 32247 |
19.55 |
| 2026-02-20 00:00 |
06:45:06.08 |
+11:43:28.4 |
HIP 32247 |
16.84 |
| 2026-02-20 12:00 |
06:44:55.83 |
+11:44:30.4 |
HIP 32247 |
14.20 |
| 2026-02-21 00:00 |
06:44:45.80 |
+11:45:32.5 |
HIP 32247 |
11.65 |
| 2026-02-21 12:00 |
06:44:35.99 |
+11:46:34.6 |
HIP 32247 |
9.23 |
| 2026-02-22 00:00 |
06:44:26.42 |
+11:47:36.7 |
HIP 32247 |
7.01 |
| 2026-02-22 12:00 |
06:44:17.07 |
+11:48:38.9 |
HIP 32247 |
5.16 |
| 2026-02-23 00:00 |
06:44:07.95 |
+11:49:41.2 |
HIP 32247 |
4.12 |
| 2026-02-23 12:00 |
06:43:59.06 |
+11:50:43.5 |
HIP 32247 |
4.42 |
| 2026-02-24 00:00 |
06:43:50.40 |
+11:51:45.7 |
HIP 32247 |
5.78 |