C/1989 A1 (Yanaka)
| Parameter |
Value |
| Designation |
C/1989 A1 (Yanaka) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1988-10-31T19:17:00.879360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:36Z |
| Obs used |
101 |
| NEO |
- |
| M1 |
5.700 |
| K1 |
16.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1989-02-04.0000000 |
| e |
0.99863759 |
| q (au) |
1.894621 |
| a (au) |
1390.639657 |
| i (deg) |
52.409723 |
| Ω (om, deg) |
157.088675 |
| ω (w, deg) |
351.561502 |
| M (ma, deg) |
0.001809 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.246 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.246 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.945 |
| 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 |
| 1989-01-02 |
1989-03-01 |
+9.5018 |
-3.170 |
| 1989-03-01 |
1989-04-30 |
-7.4846 |
+4.543 |
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 |
20:57:40.22 |
+05:38:57.9 |
HIP 103431 |
11.24 |
| 2026-02-03 12:00 |
20:57:42.15 |
+05:39:05.3 |
HIP 103431 |
11.37 |
| 2026-02-04 00:00 |
20:57:44.08 |
+05:39:12.7 |
HIP 103431 |
11.52 |
| 2026-02-04 12:00 |
20:57:46.01 |
+05:39:20.3 |
HIP 103431 |
11.68 |
| 2026-02-05 00:00 |
20:57:47.94 |
+05:39:27.9 |
HIP 103431 |
11.86 |
| 2026-02-05 12:00 |
20:57:49.87 |
+05:39:35.7 |
HIP 103431 |
12.06 |
| 2026-02-06 00:00 |
20:57:51.80 |
+05:39:43.5 |
HIP 103431 |
12.28 |
| 2026-02-06 12:00 |
20:57:53.72 |
+05:39:51.4 |
HIP 103431 |
12.51 |
| 2026-02-07 00:00 |
20:57:55.65 |
+05:39:59.4 |
HIP 103431 |
12.75 |
| 2026-02-07 12:00 |
20:57:57.57 |
+05:40:07.5 |
HIP 103431 |
13.01 |
| 2026-02-08 00:00 |
20:57:59.49 |
+05:40:15.7 |
HIP 103431 |
13.27 |
| 2026-02-08 12:00 |
20:58:01.41 |
+05:40:24.0 |
HIP 103431 |
13.55 |
| 2026-02-09 00:00 |
20:58:03.33 |
+05:40:32.4 |
HIP 103431 |
13.84 |
| 2026-02-09 12:00 |
20:58:05.24 |
+05:40:40.9 |
HIP 103431 |
14.15 |
| 2026-02-10 00:00 |
20:58:07.16 |
+05:40:49.4 |
HIP 103431 |
14.46 |
| 2026-02-10 12:00 |
20:58:09.07 |
+05:40:58.1 |
HIP 103431 |
14.78 |
| 2026-02-11 00:00 |
20:58:10.97 |
+05:41:06.8 |
HIP 103431 |
15.10 |
| 2026-02-11 12:00 |
20:58:12.88 |
+05:41:15.6 |
HIP 103431 |
15.44 |
| 2026-02-12 00:00 |
20:58:14.78 |
+05:41:24.5 |
HIP 103431 |
15.78 |
| 2026-02-12 12:00 |
20:58:16.68 |
+05:41:33.5 |
HIP 103431 |
16.13 |
| 2026-02-13 00:00 |
20:58:18.57 |
+05:41:42.6 |
HIP 103431 |
16.49 |
| 2026-02-13 12:00 |
20:58:20.47 |
+05:41:51.7 |
HIP 103431 |
16.85 |
| 2026-02-14 00:00 |
20:58:22.35 |
+05:42:00.9 |
HIP 103431 |
17.21 |
| 2026-02-14 12:00 |
20:58:24.24 |
+05:42:10.3 |
HIP 103431 |
17.58 |
| 2026-02-15 00:00 |
20:58:26.12 |
+05:42:19.7 |
HIP 103431 |
17.96 |
| 2026-02-15 12:00 |
20:58:28.00 |
+05:42:29.1 |
HIP 103431 |
18.34 |
| 2026-02-16 00:00 |
20:58:29.87 |
+05:42:38.7 |
HIP 103431 |
18.72 |
| 2026-02-16 12:00 |
20:58:31.74 |
+05:42:48.3 |
HIP 103431 |
19.11 |
| 2026-02-17 00:00 |
20:58:33.61 |
+05:42:58.0 |
HIP 103431 |
19.50 |
| 2026-02-17 12:00 |
20:58:35.47 |
+05:43:07.8 |
HIP 103431 |
19.90 |
| 2026-02-18 00:00 |
20:58:37.32 |
+05:43:17.7 |
HIP 103431 |
20.29 |
| 2026-02-18 12:00 |
20:58:39.17 |
+05:43:27.6 |
HIP 103431 |
20.69 |
| 2026-02-19 00:00 |
20:58:41.02 |
+05:43:37.7 |
HIP 103431 |
21.09 |
| 2026-02-19 12:00 |
20:58:42.86 |
+05:43:47.7 |
HIP 103649 |
21.40 |
| 2026-02-20 00:00 |
20:58:44.70 |
+05:43:57.9 |
HIP 103649 |
21.05 |
| 2026-02-20 12:00 |
20:58:46.53 |
+05:44:08.1 |
HIP 103649 |
20.70 |
| 2026-02-21 00:00 |
20:58:48.35 |
+05:44:18.5 |
HIP 103649 |
20.36 |
| 2026-02-21 12:00 |
20:58:50.17 |
+05:44:28.8 |
HIP 103649 |
20.03 |
| 2026-02-22 00:00 |
20:58:51.98 |
+05:44:39.3 |
HIP 103649 |
19.70 |
| 2026-02-22 12:00 |
20:58:53.79 |
+05:44:49.8 |
HIP 103649 |
19.39 |
| 2026-02-23 00:00 |
20:58:55.60 |
+05:45:00.4 |
HIP 103649 |
19.08 |
| 2026-02-23 12:00 |
20:58:57.39 |
+05:45:11.0 |
HIP 103649 |
18.78 |
| 2026-02-24 00:00 |
20:58:59.18 |
+05:45:21.7 |
HIP 103649 |
18.49 |