C/1995 O1 (Hale-Bopp)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/1995 O1 (Hale-Bopp) |
| Type | C |
| Perihelion (tp_cal, UTC) | 1997-03-29T15:14:15.973440Z |
| Orbit solution date (soln_date, UTC) | 2022-08-01T01:56:46Z |
| Obs used | 66 |
| NEO | - |
| M1 | 4.800 |
| K1 | 4.000 |
| PC | - |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 2022-09-15.0000000 |
| e | 0.99498100 |
| q (au) | 0.890538 |
| a (au) | 177.433384 |
| i (deg) | 89.287594 |
| Ω (om, deg) | 282.733421 |
| ω (w, deg) | 130.414667 |
| M (ma, deg) | 3.878386 |
Magnitude
Scatter + Global Linear
$$ M_a = (-1.380 + 3.909\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | -1.380 |
| n | 3.909 |
| gf | 1.000 |
| gb | -0.775 |
| k | 0.992 |
| 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 |
|---|---|---|---|
| 1993-04-27 | 1995-08-14 | +22.3833 | -18.478 |
| 1995-08-14 | 1996-10-19 | +1.1208 | -0.683 |
| 1996-10-19 | 1996-11-12 | -13.5265 | +5.695 |
| 1996-11-12 | 1997-03-29 | +1.5785 | +0.131 |
| 1997-03-29 | 1997-10-13 | +1.1436 | -0.117 |
| 1997-10-13 | 2000-02-10 | -1.1481 | +1.410 |
| 2000-02-10 | 2013-08-13 | +6.3115 | -6.332 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-09-20 00:00 | 21:50:49.76 | -85:25:37.3 | HIP 108129 | 24.02 |
| 2026-09-20 12:00 | 21:50:26.26 | -85:25:21.8 | HIP 108129 | 23.86 |
| 2026-09-21 00:00 | 21:50:02.94 | -85:25:06.0 | HIP 108129 | 23.71 |
| 2026-09-21 12:00 | 21:49:39.79 | -85:24:49.9 | HIP 108129 | 23.56 |
| 2026-09-22 00:00 | 21:49:16.82 | -85:24:33.6 | HIP 108129 | 23.42 |
| 2026-09-22 12:00 | 21:48:54.02 | -85:24:16.9 | HIP 108129 | 23.29 |
| 2026-09-23 00:00 | 21:48:31.42 | -85:24:00.0 | HIP 108129 | 23.17 |
| 2026-09-23 12:00 | 21:48:08.99 | -85:23:42.7 | HIP 108129 | 23.05 |
| 2026-09-24 00:00 | 21:47:46.75 | -85:23:25.1 | HIP 108129 | 22.94 |
| 2026-09-24 12:00 | 21:47:24.70 | -85:23:07.3 | HIP 108129 | 22.84 |
| 2026-09-25 00:00 | 21:47:02.84 | -85:22:49.2 | HIP 108129 | 22.74 |
| 2026-09-25 12:00 | 21:46:41.17 | -85:22:30.8 | HIP 108129 | 22.65 |
| 2026-09-26 00:00 | 21:46:19.69 | -85:22:12.2 | HIP 108129 | 22.57 |
| 2026-09-26 12:00 | 21:45:58.41 | -85:21:53.2 | HIP 108129 | 22.49 |
| 2026-09-27 00:00 | 21:45:37.32 | -85:21:34.0 | HIP 108129 | 22.43 |
| 2026-09-27 12:00 | 21:45:16.44 | -85:21:14.5 | HIP 108129 | 22.37 |
| 2026-09-28 00:00 | 21:44:55.75 | -85:20:54.8 | HIP 108129 | 22.32 |
| 2026-09-28 12:00 | 21:44:35.27 | -85:20:34.8 | HIP 108129 | 22.27 |
| 2026-09-29 00:00 | 21:44:14.99 | -85:20:14.5 | HIP 108129 | 22.24 |
| 2026-09-29 12:00 | 21:43:54.92 | -85:19:54.0 | HIP 108129 | 22.21 |
| 2026-09-30 00:00 | 21:43:35.05 | -85:19:33.2 | HIP 108129 | 22.19 |
| 2026-09-30 12:00 | 21:43:15.39 | -85:19:12.1 | HIP 108129 | 22.18 |
| 2026-10-01 00:00 | 21:42:55.95 | -85:18:50.8 | HIP 108129 | 22.17 |
| 2026-10-01 12:00 | 21:42:36.71 | -85:18:29.2 | HIP 108129 | 22.18 |
| 2026-10-02 00:00 | 21:42:17.68 | -85:18:07.4 | HIP 108129 | 22.19 |
| 2026-10-02 12:00 | 21:41:58.87 | -85:17:45.3 | HIP 108129 | 22.21 |
| 2026-10-03 00:00 | 21:41:40.28 | -85:17:23.0 | HIP 105628 | 22.18 |
| 2026-10-03 12:00 | 21:41:21.90 | -85:17:00.4 | HIP 105628 | 21.82 |
| 2026-10-04 00:00 | 21:41:03.74 | -85:16:37.6 | HIP 105628 | 21.47 |
| 2026-10-04 12:00 | 21:40:45.80 | -85:16:14.6 | HIP 105628 | 21.13 |
| 2026-10-05 00:00 | 21:40:28.08 | -85:15:51.3 | HIP 105628 | 20.80 |
| 2026-10-05 12:00 | 21:40:10.59 | -85:15:27.8 | HIP 105628 | 20.49 |
| 2026-10-06 00:00 | 21:39:53.31 | -85:15:04.1 | HIP 105628 | 20.19 |
| 2026-10-06 12:00 | 21:39:36.26 | -85:14:40.1 | HIP 105628 | 19.90 |
| 2026-10-07 00:00 | 21:39:19.44 | -85:14:15.9 | HIP 105628 | 19.63 |
| 2026-10-07 12:00 | 21:39:02.84 | -85:13:51.5 | HIP 105628 | 19.37 |
| 2026-10-08 00:00 | 21:38:46.47 | -85:13:26.8 | HIP 105628 | 19.13 |
| 2026-10-08 12:00 | 21:38:30.33 | -85:13:02.0 | HIP 105628 | 18.91 |
| 2026-10-09 00:00 | 21:38:14.42 | -85:12:36.9 | HIP 105628 | 18.70 |
| 2026-10-09 12:00 | 21:37:58.74 | -85:12:11.6 | HIP 105628 | 18.51 |
| 2026-10-10 00:00 | 21:37:43.29 | -85:11:46.1 | HIP 105628 | 18.34 |
| 2026-10-10 12:00 | 21:37:28.08 | -85:11:20.4 | HIP 105628 | 18.19 |
| 2026-10-11 00:00 | 21:37:13.09 | -85:10:54.5 | HIP 105628 | 18.05 |