103P/Hartley 2
Metadata
| Parameter | Value |
|---|---|
| Designation | 103P/Hartley 2 |
| Type | P |
| Perihelion (tp_cal, UTC) | 2017-04-20T10:59:29.739840Z |
| Orbit solution date (soln_date, UTC) | 2025-05-01T10:45:38Z |
| Obs used | 8768 |
| NEO | Yes |
| M1 | 16.000 |
| K1 | 4.500 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2015-05-10.0000000 |
| e | 0.69359786 |
| q (au) | 1.064947 |
| a (au) | 3.475652 |
| i (deg) | 13.599468 |
| Ω (om, deg) | 219.742174 |
| ω (w, deg) | 181.321844 |
| M (ma, deg) | 251.782173 |
Magnitude
Scatter + Global Linear
$$ M_a = (15.100 + 3.424\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 15.100 |
| n | 3.424 |
| gf | 1.000 |
| gb | -0.827 |
| k | 0.954 |
| 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 |
|---|---|---|---|
| 2023-04-17 | 2024-02-18 | +8.1437 | -2.155 |
| 2024-02-18 | 2025-04-28 | -2.9095 | +0.580 |
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) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 13:40:34.21 | -12:51:52.5 | HIP 66758 | 7.91 |
| 2026-05-12 12:00 | 13:40:18.70 | -12:49:57.1 | HIP 66758 | 10.43 |
| 2026-05-13 00:00 | 13:40:03.30 | -12:48:02.2 | HIP 66758 | 13.79 |
| 2026-05-13 12:00 | 13:39:48.02 | -12:46:07.8 | HIP 66758 | 17.50 |
| 2026-05-14 00:00 | 13:39:32.85 | -12:44:13.8 | HIP 66758 | 21.35 |
| 2026-05-14 12:00 | 13:39:17.80 | -12:42:20.4 | HIP 66758 | 25.28 |
| 2026-05-15 00:00 | 13:39:02.86 | -12:40:27.5 | HIP 66758 | 29.23 |
| 2026-05-15 12:00 | 13:38:48.05 | -12:38:35.2 | HIP 66453 | 28.12 |
| 2026-05-16 00:00 | 13:38:33.35 | -12:36:43.4 | HIP 66453 | 24.23 |
| 2026-05-16 12:00 | 13:38:18.78 | -12:34:52.1 | HIP 66453 | 20.43 |
| 2026-05-17 00:00 | 13:38:04.34 | -12:33:01.5 | HIP 66453 | 16.75 |
| 2026-05-17 12:00 | 13:37:50.02 | -12:31:11.5 | HIP 66453 | 13.28 |
| 2026-05-18 00:00 | 13:37:35.83 | -12:29:22.0 | HIP 66453 | 10.18 |
| 2026-05-18 12:00 | 13:37:21.77 | -12:27:33.2 | HIP 66453 | 7.85 |
| 2026-05-19 00:00 | 13:37:07.84 | -12:25:45.1 | HIP 66453 | 7.04 |
| 2026-05-19 12:00 | 13:36:54.05 | -12:23:57.6 | HIP 66453 | 8.18 |
| 2026-05-20 00:00 | 13:36:40.39 | -12:22:10.7 | HIP 66453 | 10.62 |
| 2026-05-20 12:00 | 13:36:26.87 | -12:20:24.5 | HIP 66453 | 13.65 |
| 2026-05-21 00:00 | 13:36:13.49 | -12:18:39.1 | HIP 66453 | 16.93 |
| 2026-05-21 12:00 | 13:36:00.25 | -12:16:54.3 | HIP 66453 | 20.33 |
| 2026-05-22 00:00 | 13:35:47.15 | -12:15:10.2 | HIP 66453 | 23.77 |
| 2026-05-22 12:00 | 13:35:34.19 | -12:13:26.8 | HIP 66453 | 27.23 |
| 2026-05-23 00:00 | 13:35:21.37 | -12:11:44.2 | HIP 66453 | 30.69 |
| 2026-05-23 12:00 | 13:35:08.70 | -12:10:02.3 | HIP 66233 | 32.24 |
| 2026-05-24 00:00 | 13:34:56.17 | -12:08:21.2 | HIP 66233 | 33.05 |
| 2026-05-24 12:00 | 13:34:43.79 | -12:06:40.8 | HIP 66233 | 34.19 |
| 2026-05-25 00:00 | 13:34:31.55 | -12:05:01.2 | HIP 66216 | 32.96 |
| 2026-05-25 12:00 | 13:34:19.47 | -12:03:22.4 | HIP 66216 | 31.14 |
| 2026-05-26 00:00 | 13:34:07.54 | -12:01:44.4 | HIP 66216 | 29.61 |
| 2026-05-26 12:00 | 13:33:55.75 | -12:00:07.1 | HIP 66216 | 28.41 |
| 2026-05-27 00:00 | 13:33:44.12 | -11:58:30.7 | HIP 66216 | 27.55 |
| 2026-05-27 12:00 | 13:33:32.64 | -11:56:55.1 | HIP 66216 | 27.05 |
| 2026-05-28 00:00 | 13:33:21.31 | -11:55:20.3 | HIP 66216 | 26.94 |
| 2026-05-28 12:00 | 13:33:10.14 | -11:53:46.3 | HIP 66216 | 27.18 |
| 2026-05-29 00:00 | 13:32:59.12 | -11:52:13.2 | HIP 66216 | 27.77 |
| 2026-05-29 12:00 | 13:32:48.26 | -11:50:40.9 | HIP 66216 | 28.67 |
| 2026-05-30 00:00 | 13:32:37.56 | -11:49:09.5 | HIP 66216 | 29.83 |
| 2026-05-30 12:00 | 13:32:27.01 | -11:47:38.9 | HIP 66216 | 31.22 |
| 2026-05-31 00:00 | 13:32:16.62 | -11:46:09.2 | HIP 66018 | 30.92 |
| 2026-05-31 12:00 | 13:32:06.39 | -11:44:40.4 | HIP 66018 | 29.30 |
| 2026-06-01 00:00 | 13:31:56.32 | -11:43:12.5 | HIP 66018 | 27.91 |
| 2026-06-01 12:00 | 13:31:46.40 | -11:41:45.4 | HIP 66018 | 26.77 |
| 2026-06-02 00:00 | 13:31:36.65 | -11:40:19.3 | HIP 66018 | 25.88 |