218P/LINEAR
Metadata
| Parameter | Value |
|---|---|
| Designation | 218P/LINEAR |
| Type | P |
| Perihelion (tp_cal, UTC) | 2015-04-23T12:22:13.497600Z |
| Orbit solution date (soln_date, UTC) | 2026-05-11T09:35:38Z |
| Obs used | 517 |
| NEO | Yes |
| M1 | 15.500 |
| K1 | 13.500 |
| PC | 0.030 |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2017-10-09.0000000 |
| e | 0.62196566 |
| q (au) | 1.170562 |
| a (au) | 3.096443 |
| i (deg) | 2.725398 |
| Ω (om, deg) | 176.027605 |
| ω (w, deg) | 59.673629 |
| M (ma, deg) | 162.705828 |
Magnitude
Scatter + Global Linear
$$ M_a = (14.634 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 14.634 |
| n | 6.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 2023-12-21 | 2026-05-15 | -9.4317 | +1.112 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Finding Chart
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 23:48:43.94 | +00:28:48.8 | HIP 117457 | 4.31 |
| 2026-07-29 12:00 | 23:48:28.84 | +00:26:39.4 | HIP 117457 | 7.27 |
| 2026-07-30 00:00 | 23:48:13.24 | +00:24:26.5 | HIP 117457 | 11.31 |
| 2026-07-30 12:00 | 23:47:57.12 | +00:22:10.0 | HIP 117457 | 15.74 |
| 2026-07-31 00:00 | 23:47:40.50 | +00:19:50.1 | HIP 117260 | 20.36 |
| 2026-07-31 12:00 | 23:47:23.37 | +00:17:26.6 | HIP 117260 | 18.83 |
| 2026-08-01 00:00 | 23:47:05.75 | +00:14:59.7 | HIP 117215 | 16.43 |
| 2026-08-01 12:00 | 23:46:47.63 | +00:12:29.3 | HIP 117215 | 12.31 |
| 2026-08-02 00:00 | 23:46:29.02 | +00:09:55.5 | HIP 117215 | 9.27 |
| 2026-08-02 12:00 | 23:46:09.92 | +00:07:18.3 | HIP 117215 | 8.77 |
| 2026-08-03 00:00 | 23:45:50.34 | +00:04:37.8 | HIP 117215 | 11.36 |
| 2026-08-03 12:00 | 23:45:30.27 | +00:01:53.8 | HIP 117215 | 15.71 |
| 2026-08-04 00:00 | 23:45:09.74 | -00:00:53.4 | HIP 117215 | 20.85 |
| 2026-08-04 12:00 | 23:44:48.73 | -00:03:43.9 | HIP 117016 | 23.40 |
| 2026-08-05 00:00 | 23:44:27.25 | -00:06:37.7 | HIP 117016 | 17.57 |
| 2026-08-05 12:00 | 23:44:05.31 | -00:09:34.6 | HIP 117016 | 11.87 |
| 2026-08-06 00:00 | 23:43:42.92 | -00:12:34.8 | HIP 117016 | 7.06 |
| 2026-08-06 12:00 | 23:43:20.08 | -00:15:38.1 | HIP 117016 | 6.33 |
| 2026-08-07 00:00 | 23:42:56.79 | -00:18:44.6 | HIP 117016 | 10.78 |
| 2026-08-07 12:00 | 23:42:33.06 | -00:21:54.1 | HIP 117016 | 16.83 |
| 2026-08-08 00:00 | 23:42:08.90 | -00:25:06.6 | HIP 116826 | 21.69 |
| 2026-08-08 12:00 | 23:41:44.30 | -00:28:22.1 | HIP 116826 | 16.35 |
| 2026-08-09 00:00 | 23:41:19.29 | -00:31:40.6 | HIP 116826 | 12.65 |
| 2026-08-09 12:00 | 23:40:53.86 | -00:35:02.0 | HIP 116826 | 12.38 |
| 2026-08-10 00:00 | 23:40:28.03 | -00:38:26.2 | HIP 116756 | 12.35 |
| 2026-08-10 12:00 | 23:40:01.79 | -00:41:53.2 | HIP 116756 | 4.94 |
| 2026-08-11 00:00 | 23:39:35.17 | -00:45:22.9 | HIP 116756 | 2.60 |
| 2026-08-11 12:00 | 23:39:08.15 | -00:48:55.4 | HIP 116756 | 10.21 |
| 2026-08-12 00:00 | 23:38:40.76 | -00:52:30.4 | HIP 116643 | 6.24 |
| 2026-08-12 12:00 | 23:38:13.00 | -00:56:08.1 | HIP 116643 | 4.08 |
| 2026-08-13 00:00 | 23:37:44.88 | -00:59:48.2 | HIP 116643 | 10.91 |
| 2026-08-13 12:00 | 23:37:16.40 | -01:03:30.8 | HIP 116643 | 18.73 |
| 2026-08-14 00:00 | 23:36:47.59 | -01:07:15.8 | HIP 116629 | 23.54 |
| 2026-08-14 12:00 | 23:36:18.43 | -01:11:03.1 | HIP 116559 | 24.95 |
| 2026-08-15 00:00 | 23:35:48.95 | -01:14:52.7 | HIP 116359 | 23.18 |
| 2026-08-15 12:00 | 23:35:19.16 | -01:18:44.4 | HIP 116359 | 15.20 |
| 2026-08-16 00:00 | 23:34:49.06 | -01:22:38.3 | HIP 116359 | 8.05 |
| 2026-08-16 12:00 | 23:34:18.65 | -01:26:34.2 | HIP 116359 | 6.51 |
| 2026-08-17 00:00 | 23:33:47.97 | -01:30:32.1 | HIP 116359 | 12.97 |
| 2026-08-17 12:00 | 23:33:17.00 | -01:34:32.0 | HIP 116359 | 21.13 |
| 2026-08-18 00:00 | 23:32:45.76 | -01:38:33.6 | HIP 116359 | 29.68 |
| 2026-08-18 12:00 | 23:32:14.27 | -01:42:37.1 | HIP 116146 | 37.69 |
| 2026-08-19 00:00 | 23:31:42.52 | -01:46:42.2 | HIP 115945 | 33.87 |