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) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 13:31:08.03 | -10:45:38.1 | HIP 65821 | 22.81 |
| 2026-07-29 12:00 | 13:31:16.55 | -10:46:04.2 | HIP 65821 | 24.94 |
| 2026-07-30 00:00 | 13:31:25.20 | -10:46:31.0 | HIP 65821 | 27.11 |
| 2026-07-30 12:00 | 13:31:33.98 | -10:46:58.7 | HIP 65821 | 29.31 |
| 2026-07-31 00:00 | 13:31:42.89 | -10:47:27.1 | HIP 66018 | 28.43 |
| 2026-07-31 12:00 | 13:31:51.93 | -10:47:56.4 | HIP 66018 | 27.61 |
| 2026-08-01 00:00 | 13:32:01.09 | -10:48:26.4 | HIP 66018 | 26.95 |
| 2026-08-01 12:00 | 13:32:10.38 | -10:48:57.2 | HIP 66018 | 26.45 |
| 2026-08-02 00:00 | 13:32:19.79 | -10:49:28.9 | HIP 66018 | 26.15 |
| 2026-08-02 12:00 | 13:32:29.32 | -10:50:01.2 | HIP 66018 | 26.06 |
| 2026-08-03 00:00 | 13:32:38.98 | -10:50:34.4 | HIP 66018 | 26.18 |
| 2026-08-03 12:00 | 13:32:48.77 | -10:51:08.3 | HIP 66018 | 26.53 |
| 2026-08-04 00:00 | 13:32:58.67 | -10:51:43.0 | HIP 66018 | 27.11 |
| 2026-08-04 12:00 | 13:33:08.70 | -10:52:18.5 | HIP 66018 | 27.90 |
| 2026-08-05 00:00 | 13:33:18.85 | -10:52:54.7 | HIP 66265 | 27.98 |
| 2026-08-05 12:00 | 13:33:29.12 | -10:53:31.6 | HIP 66265 | 26.39 |
| 2026-08-06 00:00 | 13:33:39.51 | -10:54:09.3 | HIP 66265 | 24.95 |
| 2026-08-06 12:00 | 13:33:50.02 | -10:54:47.7 | HIP 66265 | 23.71 |
| 2026-08-07 00:00 | 13:34:00.65 | -10:55:26.9 | HIP 66265 | 22.71 |
| 2026-08-07 12:00 | 13:34:11.40 | -10:56:06.8 | HIP 66265 | 21.99 |
| 2026-08-08 00:00 | 13:34:22.26 | -10:56:47.4 | HIP 66265 | 21.60 |
| 2026-08-08 12:00 | 13:34:33.25 | -10:57:28.8 | HIP 66265 | 21.56 |
| 2026-08-09 00:00 | 13:34:44.35 | -10:58:10.8 | HIP 66265 | 21.89 |
| 2026-08-09 12:00 | 13:34:55.56 | -10:58:53.6 | HIP 66265 | 22.58 |
| 2026-08-10 00:00 | 13:35:06.89 | -10:59:37.1 | HIP 66265 | 23.61 |
| 2026-08-10 12:00 | 13:35:18.33 | -11:00:21.3 | HIP 66362 | 23.25 |
| 2026-08-11 00:00 | 13:35:29.89 | -11:01:06.2 | HIP 66362 | 22.47 |
| 2026-08-11 12:00 | 13:35:41.56 | -11:01:51.7 | HIP 66362 | 22.05 |
| 2026-08-12 00:00 | 13:35:53.34 | -11:02:38.0 | HIP 66362 | 22.03 |
| 2026-08-12 12:00 | 13:36:05.24 | -11:03:24.9 | HIP 66362 | 22.43 |
| 2026-08-13 00:00 | 13:36:17.24 | -11:04:12.5 | HIP 66362 | 23.23 |
| 2026-08-13 12:00 | 13:36:29.36 | -11:05:00.8 | HIP 66362 | 24.40 |
| 2026-08-14 00:00 | 13:36:41.58 | -11:05:49.7 | HIP 66362 | 25.91 |
| 2026-08-14 12:00 | 13:36:53.92 | -11:06:39.3 | HIP 66548 | 23.55 |
| 2026-08-15 00:00 | 13:37:06.36 | -11:07:29.6 | HIP 66548 | 20.53 |
| 2026-08-15 12:00 | 13:37:18.90 | -11:08:20.4 | HIP 66548 | 17.54 |
| 2026-08-16 00:00 | 13:37:31.56 | -11:09:12.0 | HIP 66548 | 14.62 |
| 2026-08-16 12:00 | 13:37:44.32 | -11:10:04.1 | HIP 66548 | 11.83 |
| 2026-08-17 00:00 | 13:37:57.18 | -11:10:56.9 | HIP 66548 | 9.33 |
| 2026-08-17 12:00 | 13:38:10.15 | -11:11:50.3 | HIP 66548 | 7.44 |
| 2026-08-18 00:00 | 13:38:23.22 | -11:12:44.3 | HIP 66548 | 6.76 |
| 2026-08-18 12:00 | 13:38:36.39 | -11:13:38.9 | HIP 66548 | 7.63 |
| 2026-08-19 00:00 | 13:38:49.66 | -11:14:34.1 | HIP 66548 | 9.69 |