2P/Encke
Metadata
| Parameter | Value |
|---|---|
| Designation | 2P/Encke |
| Type | P |
| Perihelion (tp_cal, UTC) | 2023-10-22T03:35:18.398400Z |
| Orbit solution date (soln_date, UTC) | 2025-12-15T09:34:26Z |
| Obs used | 640 |
| NEO | Yes |
| M1 | 15.600 |
| K1 | 4.500 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2022-09-25.0000000 |
| e | 0.84774970 |
| q (au) | 0.337948 |
| a (au) | 2.219689 |
| i (deg) | 11.412278 |
| Ω (om, deg) | 334.193585 |
| ω (w, deg) | 187.134246 |
| M (ma, deg) | 243.126069 |
Magnitude
Scatter + Global Linear
$$ M_a = (17.349 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 17.349 |
| n | 2.000 |
| gf | 1.000 |
| gb | -0.707 |
| k | 0.800 |
| 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 |
|---|---|---|---|
| 2025-06-29 | 2026-07-13 | -11.0146 | +6.700 |
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 | 01:31:20.41 | +16:54:00.0 | HIP 7143 | 10.59 |
| 2026-07-29 12:00 | 01:31:31.19 | +16:57:06.2 | HIP 7143 | 7.62 |
| 2026-07-30 00:00 | 01:31:41.70 | +17:00:11.8 | HIP 7143 | 6.10 |
| 2026-07-30 12:00 | 01:31:51.93 | +17:03:16.9 | HIP 7143 | 6.95 |
| 2026-07-31 00:00 | 01:32:01.89 | +17:06:21.4 | HIP 7143 | 9.50 |
| 2026-07-31 12:00 | 01:32:11.57 | +17:09:25.3 | HIP 7143 | 12.72 |
| 2026-08-01 00:00 | 01:32:20.96 | +17:12:28.6 | HIP 7143 | 16.19 |
| 2026-08-01 12:00 | 01:32:30.06 | +17:15:31.3 | HIP 7081 | 19.26 |
| 2026-08-02 00:00 | 01:32:38.88 | +17:18:33.3 | HIP 7081 | 22.36 |
| 2026-08-02 12:00 | 01:32:47.39 | +17:21:34.8 | HIP 7282 | 24.18 |
| 2026-08-03 00:00 | 01:32:55.61 | +17:24:35.6 | HIP 7282 | 20.59 |
| 2026-08-03 12:00 | 01:33:03.52 | +17:27:35.8 | HIP 7282 | 17.06 |
| 2026-08-04 00:00 | 01:33:11.12 | +17:30:35.2 | HIP 7282 | 13.59 |
| 2026-08-04 12:00 | 01:33:18.41 | +17:33:34.1 | HIP 7282 | 10.19 |
| 2026-08-05 00:00 | 01:33:25.38 | +17:36:32.2 | HIP 7282 | 6.92 |
| 2026-08-05 12:00 | 01:33:32.04 | +17:39:29.6 | HIP 7282 | 3.95 |
| 2026-08-06 00:00 | 01:33:38.36 | +17:42:26.3 | HIP 7282 | 2.47 |
| 2026-08-06 12:00 | 01:33:44.36 | +17:45:22.3 | HIP 7282 | 4.31 |
| 2026-08-07 00:00 | 01:33:50.02 | +17:48:17.5 | HIP 7282 | 7.21 |
| 2026-08-07 12:00 | 01:33:55.34 | +17:51:12.0 | HIP 7282 | 10.27 |
| 2026-08-08 00:00 | 01:34:00.32 | +17:54:05.7 | HIP 7282 | 13.35 |
| 2026-08-08 12:00 | 01:34:04.95 | +17:56:58.6 | HIP 7282 | 16.41 |
| 2026-08-09 00:00 | 01:34:09.22 | +17:59:50.6 | HIP 7282 | 19.45 |
| 2026-08-09 12:00 | 01:34:13.14 | +18:02:41.9 | HIP 7282 | 22.45 |
| 2026-08-10 00:00 | 01:34:16.69 | +18:05:32.3 | HIP 7359 | 23.40 |
| 2026-08-10 12:00 | 01:34:19.88 | +18:08:21.9 | HIP 7359 | 20.48 |
| 2026-08-11 00:00 | 01:34:22.69 | +18:11:10.6 | HIP 7359 | 17.61 |
| 2026-08-11 12:00 | 01:34:25.13 | +18:13:58.4 | HIP 7359 | 14.80 |
| 2026-08-12 00:00 | 01:34:27.18 | +18:16:45.3 | HIP 7359 | 12.06 |
| 2026-08-12 12:00 | 01:34:28.85 | +18:19:31.2 | HIP 7359 | 9.43 |
| 2026-08-13 00:00 | 01:34:30.13 | +18:22:16.2 | HIP 7359 | 7.00 |
| 2026-08-13 12:00 | 01:34:31.01 | +18:25:00.3 | HIP 7359 | 5.03 |
| 2026-08-14 00:00 | 01:34:31.49 | +18:27:43.4 | HIP 7359 | 4.17 |
| 2026-08-14 12:00 | 01:34:31.56 | +18:30:25.5 | HIP 7359 | 4.99 |
| 2026-08-15 00:00 | 01:34:31.22 | +18:33:06.5 | HIP 7359 | 6.91 |
| 2026-08-15 12:00 | 01:34:30.47 | +18:35:46.6 | HIP 7359 | 9.25 |
| 2026-08-16 00:00 | 01:34:29.30 | +18:38:25.6 | HIP 7359 | 11.76 |
| 2026-08-16 12:00 | 01:34:27.70 | +18:41:03.5 | HIP 7288 | 9.93 |
| 2026-08-17 00:00 | 01:34:25.67 | +18:43:40.4 | HIP 7288 | 8.24 |
| 2026-08-17 12:00 | 01:34:23.21 | +18:46:16.1 | HIP 7288 | 7.05 |
| 2026-08-18 00:00 | 01:34:20.31 | +18:48:50.7 | HIP 7288 | 6.66 |
| 2026-08-18 12:00 | 01:34:16.96 | +18:51:24.2 | HIP 7288 | 7.20 |
| 2026-08-19 00:00 | 01:34:13.16 | +18:53:56.5 | HIP 7288 | 8.51 |