C/1996 B2 (Hyakutake)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/1996 B2 (Hyakutake) |
| Type | C |
| Perihelion (tp_cal, UTC) | 1996-05-01T09:27:34.128000Z |
| Orbit solution date (soln_date, UTC) | 2021-04-15T23:29:47Z |
| Obs used | 977 |
| NEO | - |
| M1 | 7.400 |
| K1 | 10.750 |
| PC | 0.030 |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 1996-03-15.0000000 |
| e | 0.99989165 |
| q (au) | 0.230224 |
| a (au) | 2124.755444 |
| i (deg) | 124.922049 |
| Ω (om, deg) | 188.045132 |
| ω (w, deg) | 130.175121 |
| M (ma, deg) | 359.999523 |
Magnitude
Scatter + Global Linear
$$ M_a = (5.511 + 2.906\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 5.511 |
| n | 2.906 |
| gf | 0.800 |
| gb | -0.500 |
| k | 0.874 |
| δ90 | 1.000 |
| 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 |
|---|---|---|---|
| 1996-01-01 | 1996-02-19 | +29.8235 | -6.481 |
| 1996-02-19 | 1996-03-29 | +2.2342 | -0.120 |
| 1996-03-29 | 1996-05-01 | -0.2001 | +0.012 |
| 1996-05-01 | 1996-05-17 | +4.8585 | +1.527 |
| 1996-05-17 | 1996-06-11 | -2.2356 | -0.537 |
| 1996-06-11 | 1996-07-06 | +3.6146 | -0.826 |
| 1996-07-06 | 1996-08-01 | +3.0246 | -0.925 |
| 1996-08-01 | 1996-10-24 | +15.0784 | -4.852 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-07-29 00:00 | 13:38:23.34 | -58:04:24.6 | HIP 66505 | 8.74 |
| 2026-07-29 12:00 | 13:38:23.97 | -58:04:01.9 | HIP 66505 | 9.12 |
| 2026-07-30 00:00 | 13:38:24.63 | -58:03:39.4 | HIP 66505 | 9.50 |
| 2026-07-30 12:00 | 13:38:25.33 | -58:03:16.9 | HIP 66505 | 9.88 |
| 2026-07-31 00:00 | 13:38:26.05 | -58:02:54.6 | HIP 66505 | 10.26 |
| 2026-07-31 12:00 | 13:38:26.81 | -58:02:32.3 | HIP 66505 | 10.64 |
| 2026-08-01 00:00 | 13:38:27.60 | -58:02:10.2 | HIP 66505 | 11.03 |
| 2026-08-01 12:00 | 13:38:28.42 | -58:01:48.2 | HIP 66505 | 11.41 |
| 2026-08-02 00:00 | 13:38:29.26 | -58:01:26.3 | HIP 66505 | 11.79 |
| 2026-08-02 12:00 | 13:38:30.14 | -58:01:04.5 | HIP 66505 | 12.17 |
| 2026-08-03 00:00 | 13:38:31.05 | -58:00:42.8 | HIP 66505 | 12.55 |
| 2026-08-03 12:00 | 13:38:32.00 | -58:00:21.3 | HIP 66505 | 12.93 |
| 2026-08-04 00:00 | 13:38:32.97 | -57:59:59.8 | HIP 66505 | 13.31 |
| 2026-08-04 12:00 | 13:38:33.97 | -57:59:38.5 | HIP 66505 | 13.69 |
| 2026-08-05 00:00 | 13:38:35.00 | -57:59:17.3 | HIP 66505 | 14.07 |
| 2026-08-05 12:00 | 13:38:36.06 | -57:58:56.3 | HIP 66505 | 14.45 |
| 2026-08-06 00:00 | 13:38:37.16 | -57:58:35.3 | HIP 66505 | 14.82 |
| 2026-08-06 12:00 | 13:38:38.28 | -57:58:14.5 | HIP 66505 | 15.20 |
| 2026-08-07 00:00 | 13:38:39.43 | -57:57:53.8 | HIP 66505 | 15.58 |
| 2026-08-07 12:00 | 13:38:40.61 | -57:57:33.3 | HIP 66505 | 15.95 |
| 2026-08-08 00:00 | 13:38:41.83 | -57:57:12.8 | HIP 66505 | 16.33 |
| 2026-08-08 12:00 | 13:38:43.07 | -57:56:52.5 | HIP 66505 | 16.70 |
| 2026-08-09 00:00 | 13:38:44.34 | -57:56:32.4 | HIP 66505 | 17.08 |
| 2026-08-09 12:00 | 13:38:45.64 | -57:56:12.3 | HIP 66505 | 17.45 |
| 2026-08-10 00:00 | 13:38:46.97 | -57:55:52.4 | HIP 66402 | 17.81 |
| 2026-08-10 12:00 | 13:38:48.34 | -57:55:32.7 | HIP 66402 | 17.82 |
| 2026-08-11 00:00 | 13:38:49.73 | -57:55:13.1 | HIP 66402 | 17.84 |
| 2026-08-11 12:00 | 13:38:51.15 | -57:54:53.6 | HIP 66575 | 17.53 |
| 2026-08-12 00:00 | 13:38:52.59 | -57:54:34.3 | HIP 66575 | 17.22 |
| 2026-08-12 12:00 | 13:38:54.07 | -57:54:15.1 | HIP 66575 | 16.90 |
| 2026-08-13 00:00 | 13:38:55.58 | -57:53:56.0 | HIP 66575 | 16.60 |
| 2026-08-13 12:00 | 13:38:57.11 | -57:53:37.1 | HIP 66575 | 16.29 |
| 2026-08-14 00:00 | 13:38:58.68 | -57:53:18.4 | HIP 66575 | 16.00 |
| 2026-08-14 12:00 | 13:39:00.27 | -57:52:59.8 | HIP 66575 | 15.71 |
| 2026-08-15 00:00 | 13:39:01.89 | -57:52:41.3 | HIP 66575 | 15.42 |
| 2026-08-15 12:00 | 13:39:03.54 | -57:52:23.0 | HIP 66575 | 15.15 |
| 2026-08-16 00:00 | 13:39:05.22 | -57:52:04.9 | HIP 66575 | 14.88 |
| 2026-08-16 12:00 | 13:39:06.92 | -57:51:46.9 | HIP 66575 | 14.62 |
| 2026-08-17 00:00 | 13:39:08.65 | -57:51:29.1 | HIP 66575 | 14.36 |
| 2026-08-17 12:00 | 13:39:10.41 | -57:51:11.4 | HIP 66575 | 14.12 |
| 2026-08-18 00:00 | 13:39:12.20 | -57:50:53.9 | HIP 66575 | 13.89 |
| 2026-08-18 12:00 | 13:39:14.01 | -57:50:36.5 | HIP 66575 | 13.66 |
| 2026-08-19 00:00 | 13:39:15.86 | -57:50:19.3 | HIP 66575 | 13.45 |