C/1989 X1 (Austin)
| Parameter |
Value |
| Designation |
C/1989 X1 (Austin) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1990-04-09T23:13:18.471360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:38Z |
| Obs used |
266 |
| NEO |
- |
| M1 |
8.400 |
| K1 |
13.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1990-04-17.0000000 |
| e |
1.00022808 |
| q (au) |
0.349774 |
| a (au) |
-1533.545418 |
| i (deg) |
58.956368 |
| Ω (om, deg) |
75.925356 |
| ω (w, deg) |
61.576294 |
| M (ma, deg) |
0.000115 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.064 + 3.044\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.064 |
| n |
3.044 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
1.580 |
| 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 |
| 1989-12-06 |
1990-02-07 |
+5.2745 |
-3.494 |
| 1990-02-07 |
1990-04-09 |
-4.1984 |
-2.042 |
| 1990-04-10 |
1990-05-13 |
-0.8432 |
-0.130 |
| 1990-05-13 |
1990-07-24 |
+4.3331 |
+0.119 |
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 |
20:22:15.97 |
-63:22:31.5 |
HIP 100165 |
23.35 |
| 2026-02-03 12:00 |
20:22:20.18 |
-63:22:30.6 |
HIP 100165 |
23.78 |
| 2026-02-04 00:00 |
20:22:24.39 |
-63:22:29.8 |
HIP 100165 |
24.22 |
| 2026-02-04 12:00 |
20:22:28.58 |
-63:22:29.2 |
HIP 100165 |
24.66 |
| 2026-02-05 00:00 |
20:22:32.77 |
-63:22:28.8 |
HIP 100165 |
25.10 |
| 2026-02-05 12:00 |
20:22:36.95 |
-63:22:28.6 |
HIP 100165 |
25.54 |
| 2026-02-06 00:00 |
20:22:41.13 |
-63:22:28.5 |
HIP 100165 |
25.98 |
| 2026-02-06 12:00 |
20:22:45.29 |
-63:22:28.6 |
HIP 100165 |
26.42 |
| 2026-02-07 00:00 |
20:22:49.45 |
-63:22:28.9 |
HIP 100165 |
26.86 |
| 2026-02-07 12:00 |
20:22:53.60 |
-63:22:29.4 |
HIP 100165 |
27.31 |
| 2026-02-08 00:00 |
20:22:57.73 |
-63:22:30.0 |
HIP 100165 |
27.75 |
| 2026-02-08 12:00 |
20:23:01.86 |
-63:22:30.8 |
HIP 100165 |
28.20 |
| 2026-02-09 00:00 |
20:23:05.98 |
-63:22:31.8 |
HIP 100165 |
28.64 |
| 2026-02-09 12:00 |
20:23:10.09 |
-63:22:33.0 |
HIP 100165 |
29.09 |
| 2026-02-10 00:00 |
20:23:14.19 |
-63:22:34.3 |
HIP 100165 |
29.53 |
| 2026-02-10 12:00 |
20:23:18.28 |
-63:22:35.8 |
HIP 100165 |
29.98 |
| 2026-02-11 00:00 |
20:23:22.36 |
-63:22:37.5 |
HIP 100165 |
30.43 |
| 2026-02-11 12:00 |
20:23:26.43 |
-63:22:39.4 |
HIP 100165 |
30.87 |
| 2026-02-12 00:00 |
20:23:30.48 |
-63:22:41.4 |
HIP 100799 |
31.01 |
| 2026-02-12 12:00 |
20:23:34.53 |
-63:22:43.6 |
HIP 100799 |
30.76 |
| 2026-02-13 00:00 |
20:23:38.56 |
-63:22:46.0 |
HIP 100799 |
30.53 |
| 2026-02-13 12:00 |
20:23:42.58 |
-63:22:48.5 |
HIP 100799 |
30.30 |
| 2026-02-14 00:00 |
20:23:46.59 |
-63:22:51.2 |
HIP 100799 |
30.08 |
| 2026-02-14 12:00 |
20:23:50.58 |
-63:22:54.1 |
HIP 100799 |
29.87 |
| 2026-02-15 00:00 |
20:23:54.56 |
-63:22:57.2 |
HIP 100799 |
29.67 |
| 2026-02-15 12:00 |
20:23:58.53 |
-63:23:00.5 |
HIP 100799 |
29.47 |
| 2026-02-16 00:00 |
20:24:02.48 |
-63:23:03.9 |
HIP 100799 |
29.29 |
| 2026-02-16 12:00 |
20:24:06.42 |
-63:23:07.5 |
HIP 100799 |
29.11 |
| 2026-02-17 00:00 |
20:24:10.35 |
-63:23:11.3 |
HIP 100799 |
28.95 |
| 2026-02-17 12:00 |
20:24:14.26 |
-63:23:15.2 |
HIP 100799 |
28.79 |
| 2026-02-18 00:00 |
20:24:18.16 |
-63:23:19.3 |
HIP 100799 |
28.64 |
| 2026-02-18 12:00 |
20:24:22.04 |
-63:23:23.6 |
HIP 100799 |
28.50 |
| 2026-02-19 00:00 |
20:24:25.90 |
-63:23:28.1 |
HIP 100799 |
28.38 |
| 2026-02-19 12:00 |
20:24:29.75 |
-63:23:32.7 |
HIP 100799 |
28.26 |
| 2026-02-20 00:00 |
20:24:33.59 |
-63:23:37.5 |
HIP 100799 |
28.15 |
| 2026-02-20 12:00 |
20:24:37.41 |
-63:23:42.5 |
HIP 100799 |
28.05 |
| 2026-02-21 00:00 |
20:24:41.21 |
-63:23:47.6 |
HIP 100799 |
27.96 |
| 2026-02-21 12:00 |
20:24:44.99 |
-63:23:53.0 |
HIP 100799 |
27.88 |
| 2026-02-22 00:00 |
20:24:48.76 |
-63:23:58.4 |
HIP 100799 |
27.81 |
| 2026-02-22 12:00 |
20:24:52.51 |
-63:24:04.1 |
HIP 100799 |
27.75 |
| 2026-02-23 00:00 |
20:24:56.24 |
-63:24:09.9 |
HIP 100799 |
27.70 |
| 2026-02-23 12:00 |
20:24:59.96 |
-63:24:15.9 |
HIP 100799 |
27.66 |
| 2026-02-24 00:00 |
20:25:03.65 |
-63:24:22.1 |
HIP 100799 |
27.63 |