| 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 |
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 |
08:13:52.61 |
+11:25:59.3 |
HIP 40214 |
21.73 |
| 2026-07-29 12:00 |
08:14:22.29 |
+11:24:16.7 |
HIP 40452 |
17.48 |
| 2026-07-30 00:00 |
08:14:51.96 |
+11:22:33.5 |
HIP 40452 |
10.67 |
| 2026-07-30 12:00 |
08:15:21.64 |
+11:20:49.6 |
HIP 40452 |
5.82 |
| 2026-07-31 00:00 |
08:15:51.31 |
+11:19:05.2 |
HIP 40452 |
8.11 |
| 2026-07-31 12:00 |
08:16:20.99 |
+11:17:20.1 |
HIP 40580 |
11.97 |
| 2026-08-01 00:00 |
08:16:50.67 |
+11:15:34.4 |
HIP 40580 |
6.86 |
| 2026-08-01 12:00 |
08:17:20.35 |
+11:13:48.1 |
HIP 40580 |
7.94 |
| 2026-08-02 00:00 |
08:17:50.02 |
+11:12:01.3 |
HIP 40580 |
13.84 |
| 2026-08-02 12:00 |
08:18:19.70 |
+11:10:13.8 |
HIP 40580 |
20.79 |
| 2026-08-03 00:00 |
08:18:49.37 |
+11:08:25.7 |
HIP 40580 |
28.03 |
| 2026-08-03 12:00 |
08:19:19.04 |
+11:06:37.0 |
HIP 40580 |
35.38 |
| 2026-08-04 00:00 |
08:19:48.71 |
+11:04:47.7 |
HIP 40983 |
29.81 |
| 2026-08-04 12:00 |
08:20:18.37 |
+11:02:57.8 |
HIP 40983 |
22.45 |
| 2026-08-05 00:00 |
08:20:48.03 |
+11:01:07.3 |
HIP 40983 |
15.24 |
| 2026-08-05 12:00 |
08:21:17.68 |
+10:59:16.2 |
HIP 40983 |
8.54 |
| 2026-08-06 00:00 |
08:21:47.33 |
+10:57:24.5 |
HIP 40983 |
5.16 |
| 2026-08-06 12:00 |
08:22:16.97 |
+10:55:32.2 |
HIP 40983 |
9.66 |
| 2026-08-07 00:00 |
08:22:46.61 |
+10:53:39.4 |
HIP 41027 |
15.06 |
| 2026-08-07 12:00 |
08:23:16.24 |
+10:51:45.9 |
HIP 41163 |
16.83 |
| 2026-08-08 00:00 |
08:23:45.86 |
+10:49:51.9 |
HIP 41163 |
12.16 |
| 2026-08-08 12:00 |
08:24:15.47 |
+10:47:57.2 |
HIP 41163 |
11.19 |
| 2026-08-09 00:00 |
08:24:45.07 |
+10:46:02.0 |
HIP 41163 |
14.69 |
| 2026-08-09 12:00 |
08:25:14.67 |
+10:44:06.2 |
HIP 41344 |
17.88 |
| 2026-08-10 00:00 |
08:25:44.25 |
+10:42:09.9 |
HIP 41344 |
15.43 |
| 2026-08-10 12:00 |
08:26:13.82 |
+10:40:12.9 |
HIP 41344 |
16.43 |
| 2026-08-11 00:00 |
08:26:43.38 |
+10:38:15.4 |
HIP 41344 |
20.38 |
| 2026-08-11 12:00 |
08:27:12.93 |
+10:36:17.3 |
HIP 41344 |
25.96 |
| 2026-08-12 00:00 |
08:27:42.46 |
+10:34:18.7 |
HIP 41585 |
21.69 |
| 2026-08-12 12:00 |
08:28:11.98 |
+10:32:19.5 |
HIP 41585 |
19.35 |
| 2026-08-13 00:00 |
08:28:41.49 |
+10:30:19.7 |
HIP 41613 |
14.21 |
| 2026-08-13 12:00 |
08:29:10.97 |
+10:28:19.3 |
HIP 41613 |
11.56 |
| 2026-08-14 00:00 |
08:29:40.45 |
+10:26:18.5 |
HIP 41613 |
13.36 |
| 2026-08-14 12:00 |
08:30:09.90 |
+10:24:17.0 |
HIP 41613 |
18.34 |
| 2026-08-15 00:00 |
08:30:39.34 |
+10:22:15.0 |
HIP 41613 |
24.64 |
| 2026-08-15 12:00 |
08:31:08.76 |
+10:20:12.5 |
HIP 41904 |
27.69 |
| 2026-08-16 00:00 |
08:31:38.16 |
+10:18:09.4 |
HIP 41904 |
20.79 |
| 2026-08-16 12:00 |
08:32:07.54 |
+10:16:05.8 |
HIP 41904 |
14.51 |
| 2026-08-17 00:00 |
08:32:36.90 |
+10:14:01.7 |
HIP 41904 |
10.09 |
| 2026-08-17 12:00 |
08:33:06.23 |
+10:11:57.0 |
HIP 41904 |
10.29 |
| 2026-08-18 00:00 |
08:33:35.55 |
+10:09:51.8 |
HIP 41904 |
14.92 |
| 2026-08-18 12:00 |
08:34:04.84 |
+10:07:46.1 |
HIP 41904 |
21.26 |
| 2026-08-19 00:00 |
08:34:34.11 |
+10:05:39.9 |
HIP 41904 |
28.17 |