C/1995 Y1 (Hyakutake)
| Parameter |
Value |
| Designation |
C/1995 Y1 (Hyakutake) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1996-02-24T06:53:53.528640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:47Z |
| Obs used |
259 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
15.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1996-02-24.0000000 |
| e |
1.00026947 |
| q (au) |
1.054617 |
| a (au) |
-3913.664483 |
| i (deg) |
54.466072 |
| Ω (om, deg) |
195.761478 |
| ω (w, deg) |
46.348701 |
| M (ma, deg) |
-0.000001 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.861 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.861 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.998 |
| k |
1.000 |
| 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 |
| 1995-12-27 |
1996-01-15 |
-32.9619 |
+4.433 |
| 1996-01-15 |
1996-02-24 |
+5.8871 |
-0.300 |
| 1996-02-24 |
1996-07-18 |
+2.0313 |
-0.181 |
| 1996-07-18 |
1996-10-05 |
+7.6754 |
-1.742 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
02:36:50.05 |
-10:01:06.0 |
HIP 12126 |
16.93 |
| 2026-02-03 12:00 |
02:36:50.18 |
-10:00:51.6 |
HIP 12126 |
17.15 |
| 2026-02-04 00:00 |
02:36:50.34 |
-10:00:37.2 |
HIP 12126 |
17.38 |
| 2026-02-04 12:00 |
02:36:50.51 |
-10:00:22.7 |
HIP 12126 |
17.60 |
| 2026-02-05 00:00 |
02:36:50.70 |
-10:00:08.2 |
HIP 12126 |
17.84 |
| 2026-02-05 12:00 |
02:36:50.91 |
-09:59:53.6 |
HIP 12126 |
18.07 |
| 2026-02-06 00:00 |
02:36:51.13 |
-09:59:38.9 |
HIP 12126 |
18.31 |
| 2026-02-06 12:00 |
02:36:51.38 |
-09:59:24.2 |
HIP 12126 |
18.55 |
| 2026-02-07 00:00 |
02:36:51.65 |
-09:59:09.3 |
HIP 12126 |
18.80 |
| 2026-02-07 12:00 |
02:36:51.93 |
-09:58:54.5 |
HIP 12126 |
19.05 |
| 2026-02-08 00:00 |
02:36:52.23 |
-09:58:39.5 |
HIP 12126 |
19.30 |
| 2026-02-08 12:00 |
02:36:52.55 |
-09:58:24.5 |
HIP 12126 |
19.56 |
| 2026-02-09 00:00 |
02:36:52.89 |
-09:58:09.5 |
HIP 12126 |
19.82 |
| 2026-02-09 12:00 |
02:36:53.25 |
-09:57:54.4 |
HIP 12126 |
20.08 |
| 2026-02-10 00:00 |
02:36:53.63 |
-09:57:39.2 |
HIP 12126 |
20.35 |
| 2026-02-10 12:00 |
02:36:54.02 |
-09:57:24.0 |
HIP 12126 |
20.61 |
| 2026-02-11 00:00 |
02:36:54.44 |
-09:57:08.7 |
HIP 12126 |
20.89 |
| 2026-02-11 12:00 |
02:36:54.87 |
-09:56:53.3 |
HIP 12126 |
21.16 |
| 2026-02-12 00:00 |
02:36:55.32 |
-09:56:38.0 |
HIP 12126 |
21.44 |
| 2026-02-12 12:00 |
02:36:55.79 |
-09:56:22.5 |
HIP 12126 |
21.72 |
| 2026-02-13 00:00 |
02:36:56.28 |
-09:56:07.0 |
HIP 12126 |
22.00 |
| 2026-02-13 12:00 |
02:36:56.79 |
-09:55:51.5 |
HIP 12126 |
22.29 |
| 2026-02-14 00:00 |
02:36:57.31 |
-09:55:35.9 |
HIP 12126 |
22.58 |
| 2026-02-14 12:00 |
02:36:57.85 |
-09:55:20.3 |
HIP 12126 |
22.87 |
| 2026-02-15 00:00 |
02:36:58.41 |
-09:55:04.6 |
HIP 12126 |
23.17 |
| 2026-02-15 12:00 |
02:36:58.99 |
-09:54:48.9 |
HIP 12126 |
23.47 |
| 2026-02-16 00:00 |
02:36:59.59 |
-09:54:33.1 |
HIP 12126 |
23.77 |
| 2026-02-16 12:00 |
02:37:00.21 |
-09:54:17.3 |
HIP 12126 |
24.07 |
| 2026-02-17 00:00 |
02:37:00.84 |
-09:54:01.4 |
HIP 12126 |
24.38 |
| 2026-02-17 12:00 |
02:37:01.49 |
-09:53:45.6 |
HIP 12126 |
24.69 |
| 2026-02-18 00:00 |
02:37:02.16 |
-09:53:29.6 |
HIP 12126 |
25.00 |
| 2026-02-18 12:00 |
02:37:02.85 |
-09:53:13.7 |
HIP 12126 |
25.32 |
| 2026-02-19 00:00 |
02:37:03.55 |
-09:52:57.7 |
HIP 12126 |
25.63 |
| 2026-02-19 12:00 |
02:37:04.27 |
-09:52:41.7 |
HIP 12126 |
25.95 |
| 2026-02-20 00:00 |
02:37:05.01 |
-09:52:25.6 |
HIP 12126 |
26.28 |
| 2026-02-20 12:00 |
02:37:05.77 |
-09:52:09.5 |
HIP 12126 |
26.60 |
| 2026-02-21 00:00 |
02:37:06.55 |
-09:51:53.4 |
HIP 12126 |
26.93 |
| 2026-02-21 12:00 |
02:37:07.34 |
-09:51:37.3 |
HIP 12126 |
27.26 |
| 2026-02-22 00:00 |
02:37:08.15 |
-09:51:21.1 |
HIP 12126 |
27.59 |
| 2026-02-22 12:00 |
02:37:08.98 |
-09:51:04.9 |
HIP 12126 |
27.93 |
| 2026-02-23 00:00 |
02:37:09.82 |
-09:50:48.7 |
HIP 12126 |
28.26 |
| 2026-02-23 12:00 |
02:37:10.68 |
-09:50:32.4 |
HIP 12126 |
28.60 |
| 2026-02-24 00:00 |
02:37:11.56 |
-09:50:16.2 |
HIP 12363 |
28.92 |