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) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 13:55:58.59 | -12:30:18.1 | HIP 67972 | 12.03 |
| 2026-09-20 12:00 | 13:56:17.00 | -12:31:41.2 | HIP 67972 | 16.73 |
| 2026-09-21 00:00 | 13:56:35.47 | -12:33:04.6 | HIP 67972 | 21.45 |
| 2026-09-21 12:00 | 13:56:53.99 | -12:34:28.2 | HIP 67972 | 26.18 |
| 2026-09-22 00:00 | 13:57:12.57 | -12:35:52.1 | HIP 67972 | 30.92 |
| 2026-09-22 12:00 | 13:57:31.21 | -12:37:16.2 | HIP 67972 | 35.68 |
| 2026-09-23 00:00 | 13:57:49.90 | -12:38:40.5 | HIP 68396 | 32.99 |
| 2026-09-23 12:00 | 13:58:08.64 | -12:40:05.1 | HIP 68396 | 28.30 |
| 2026-09-24 00:00 | 13:58:27.44 | -12:41:29.9 | HIP 68396 | 23.64 |
| 2026-09-24 12:00 | 13:58:46.29 | -12:42:54.9 | HIP 68396 | 19.03 |
| 2026-09-25 00:00 | 13:59:05.19 | -12:44:20.1 | HIP 68396 | 14.55 |
| 2026-09-25 12:00 | 13:59:24.14 | -12:45:45.6 | HIP 68396 | 10.36 |
| 2026-09-26 00:00 | 13:59:43.14 | -12:47:11.3 | HIP 68396 | 7.05 |
| 2026-09-26 12:00 | 14:00:02.20 | -12:48:37.1 | HIP 68396 | 6.25 |
| 2026-09-27 00:00 | 14:00:21.30 | -12:50:03.2 | HIP 68396 | 8.72 |
| 2026-09-27 12:00 | 14:00:40.45 | -12:51:29.5 | HIP 68396 | 12.67 |
| 2026-09-28 00:00 | 14:00:59.65 | -12:52:56.0 | HIP 68396 | 17.13 |
| 2026-09-28 12:00 | 14:01:18.90 | -12:54:22.6 | HIP 68396 | 21.78 |
| 2026-09-29 00:00 | 14:01:38.19 | -12:55:49.4 | HIP 68396 | 26.54 |
| 2026-09-29 12:00 | 14:01:57.54 | -12:57:16.5 | HIP 68396 | 31.36 |
| 2026-09-30 00:00 | 14:02:16.92 | -12:58:43.7 | HIP 68696 | 27.95 |
| 2026-09-30 12:00 | 14:02:36.36 | -13:00:11.0 | HIP 68696 | 23.54 |
| 2026-10-01 00:00 | 14:02:55.84 | -13:01:38.6 | HIP 68696 | 19.38 |
| 2026-10-01 12:00 | 14:03:15.36 | -13:03:06.3 | HIP 68696 | 15.69 |
| 2026-10-02 00:00 | 14:03:34.93 | -13:04:34.1 | HIP 68696 | 12.89 |
| 2026-10-02 12:00 | 14:03:54.54 | -13:06:02.1 | HIP 68696 | 11.65 |
| 2026-10-03 00:00 | 14:04:14.19 | -13:07:30.3 | HIP 68696 | 12.46 |
| 2026-10-03 12:00 | 14:04:33.89 | -13:08:58.6 | HIP 68696 | 15.01 |
| 2026-10-04 00:00 | 14:04:53.63 | -13:10:27.1 | HIP 68855 | 16.65 |
| 2026-10-04 12:00 | 14:05:13.41 | -13:11:55.7 | HIP 68855 | 13.08 |
| 2026-10-05 00:00 | 14:05:33.23 | -13:13:24.4 | HIP 68855 | 10.74 |
| 2026-10-05 12:00 | 14:05:53.09 | -13:14:53.2 | HIP 68855 | 10.52 |
| 2026-10-06 00:00 | 14:06:12.99 | -13:16:22.2 | HIP 68855 | 12.54 |
| 2026-10-06 12:00 | 14:06:32.93 | -13:17:51.3 | HIP 68855 | 15.98 |
| 2026-10-07 00:00 | 14:06:52.91 | -13:19:20.5 | HIP 69060 | 18.62 |
| 2026-10-07 12:00 | 14:07:12.93 | -13:20:49.9 | HIP 69060 | 13.59 |
| 2026-10-08 00:00 | 14:07:32.98 | -13:22:19.3 | HIP 69060 | 8.63 |
| 2026-10-08 12:00 | 14:07:53.07 | -13:23:48.8 | HIP 69060 | 4.04 |
| 2026-10-09 00:00 | 14:08:13.19 | -13:25:18.4 | HIP 69060 | 3.21 |
| 2026-10-09 12:00 | 14:08:33.35 | -13:26:48.2 | HIP 69060 | 7.54 |
| 2026-10-10 00:00 | 14:08:53.54 | -13:28:18.0 | HIP 69060 | 12.49 |
| 2026-10-10 12:00 | 14:09:13.77 | -13:29:47.8 | HIP 69060 | 17.56 |
| 2026-10-11 00:00 | 14:09:34.03 | -13:31:17.8 | HIP 69060 | 22.66 |