| 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 |
1.585 |
| 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 |
+5.2737 |
-3.494 |
| 1990-02-07 |
1990-04-09 |
-4.1988 |
-2.041 |
| 1990-04-10 |
1990-05-13 |
-0.8424 |
-0.129 |
| 1990-05-13 |
1990-07-24 |
+4.3633 |
+0.116 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
20:28:59.78 |
-64:05:24.6 |
HIP 101182 |
11.87 |
| 2026-05-12 12:00 |
20:28:58.67 |
-64:05:45.8 |
HIP 101182 |
11.80 |
| 2026-05-13 00:00 |
20:28:57.54 |
-64:06:06.9 |
HIP 101182 |
11.75 |
| 2026-05-13 12:00 |
20:28:56.36 |
-64:06:28.1 |
HIP 101182 |
11.71 |
| 2026-05-14 00:00 |
20:28:55.16 |
-64:06:49.2 |
HIP 101182 |
11.68 |
| 2026-05-14 12:00 |
20:28:53.91 |
-64:07:10.4 |
HIP 101182 |
11.67 |
| 2026-05-15 00:00 |
20:28:52.63 |
-64:07:31.5 |
HIP 101182 |
11.68 |
| 2026-05-15 12:00 |
20:28:51.32 |
-64:07:52.6 |
HIP 101182 |
11.71 |
| 2026-05-16 00:00 |
20:28:49.97 |
-64:08:13.7 |
HIP 101182 |
11.74 |
| 2026-05-16 12:00 |
20:28:48.58 |
-64:08:34.8 |
HIP 101182 |
11.80 |
| 2026-05-17 00:00 |
20:28:47.16 |
-64:08:55.9 |
HIP 101182 |
11.87 |
| 2026-05-17 12:00 |
20:28:45.71 |
-64:09:16.9 |
HIP 101182 |
11.96 |
| 2026-05-18 00:00 |
20:28:44.22 |
-64:09:37.9 |
HIP 101182 |
12.06 |
| 2026-05-18 12:00 |
20:28:42.69 |
-64:09:58.9 |
HIP 101182 |
12.18 |
| 2026-05-19 00:00 |
20:28:41.13 |
-64:10:19.9 |
HIP 101182 |
12.31 |
| 2026-05-19 12:00 |
20:28:39.54 |
-64:10:40.8 |
HIP 101182 |
12.45 |
| 2026-05-20 00:00 |
20:28:37.91 |
-64:11:01.7 |
HIP 101182 |
12.61 |
| 2026-05-20 12:00 |
20:28:36.24 |
-64:11:22.6 |
HIP 101182 |
12.79 |
| 2026-05-21 00:00 |
20:28:34.55 |
-64:11:43.4 |
HIP 101064 |
12.83 |
| 2026-05-21 12:00 |
20:28:32.82 |
-64:12:04.2 |
HIP 101064 |
12.57 |
| 2026-05-22 00:00 |
20:28:31.05 |
-64:12:25.0 |
HIP 101064 |
12.33 |
| 2026-05-22 12:00 |
20:28:29.25 |
-64:12:45.7 |
HIP 101064 |
12.10 |
| 2026-05-23 00:00 |
20:28:27.42 |
-64:13:06.4 |
HIP 101064 |
11.88 |
| 2026-05-23 12:00 |
20:28:25.55 |
-64:13:27.1 |
HIP 101064 |
11.68 |
| 2026-05-24 00:00 |
20:28:23.65 |
-64:13:47.7 |
HIP 101064 |
11.48 |
| 2026-05-24 12:00 |
20:28:21.72 |
-64:14:08.2 |
HIP 101064 |
11.30 |
| 2026-05-25 00:00 |
20:28:19.76 |
-64:14:28.7 |
HIP 101064 |
11.13 |
| 2026-05-25 12:00 |
20:28:17.76 |
-64:14:49.2 |
HIP 101064 |
10.98 |
| 2026-05-26 00:00 |
20:28:15.73 |
-64:15:09.6 |
HIP 101064 |
10.84 |
| 2026-05-26 12:00 |
20:28:13.66 |
-64:15:30.0 |
HIP 101064 |
10.72 |
| 2026-05-27 00:00 |
20:28:11.57 |
-64:15:50.3 |
HIP 101064 |
10.62 |
| 2026-05-27 12:00 |
20:28:09.44 |
-64:16:10.5 |
HIP 101064 |
10.53 |
| 2026-05-28 00:00 |
20:28:07.28 |
-64:16:30.7 |
HIP 101064 |
10.47 |
| 2026-05-28 12:00 |
20:28:05.09 |
-64:16:50.9 |
HIP 101064 |
10.42 |
| 2026-05-29 00:00 |
20:28:02.86 |
-64:17:11.0 |
HIP 101064 |
10.39 |
| 2026-05-29 12:00 |
20:28:00.61 |
-64:17:31.0 |
HIP 101064 |
10.38 |
| 2026-05-30 00:00 |
20:27:58.32 |
-64:17:51.0 |
HIP 101064 |
10.39 |
| 2026-05-30 12:00 |
20:27:56.00 |
-64:18:10.9 |
HIP 101064 |
10.42 |
| 2026-05-31 00:00 |
20:27:53.65 |
-64:18:30.7 |
HIP 101064 |
10.47 |
| 2026-05-31 12:00 |
20:27:51.27 |
-64:18:50.5 |
HIP 101064 |
10.54 |
| 2026-06-01 00:00 |
20:27:48.86 |
-64:19:10.2 |
HIP 101064 |
10.63 |
| 2026-06-01 12:00 |
20:27:46.42 |
-64:19:29.9 |
HIP 101064 |
10.74 |
| 2026-06-02 00:00 |
20:27:43.94 |
-64:19:49.5 |
HIP 101064 |
10.87 |