| 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) |
| 2026-07-29 00:00 |
20:20:40.48 |
-64:43:56.2 |
HIP 100614 |
23.68 |
| 2026-07-29 12:00 |
20:20:36.17 |
-64:43:59.8 |
HIP 100614 |
24.13 |
| 2026-07-30 00:00 |
20:20:31.87 |
-64:44:03.2 |
HIP 100614 |
24.58 |
| 2026-07-30 12:00 |
20:20:27.56 |
-64:44:06.4 |
HIP 100614 |
25.03 |
| 2026-07-31 00:00 |
20:20:23.26 |
-64:44:09.4 |
HIP 100614 |
25.48 |
| 2026-07-31 12:00 |
20:20:18.96 |
-64:44:12.3 |
HIP 100614 |
25.93 |
| 2026-08-01 00:00 |
20:20:14.66 |
-64:44:14.9 |
HIP 100614 |
26.38 |
| 2026-08-01 12:00 |
20:20:10.37 |
-64:44:17.4 |
HIP 100614 |
26.82 |
| 2026-08-02 00:00 |
20:20:06.08 |
-64:44:19.7 |
HIP 100614 |
27.27 |
| 2026-08-02 12:00 |
20:20:01.80 |
-64:44:21.8 |
HIP 100614 |
27.71 |
| 2026-08-03 00:00 |
20:19:57.52 |
-64:44:23.8 |
HIP 100614 |
28.16 |
| 2026-08-03 12:00 |
20:19:53.25 |
-64:44:25.5 |
HIP 100614 |
28.60 |
| 2026-08-04 00:00 |
20:19:48.98 |
-64:44:27.1 |
HIP 99831 |
28.93 |
| 2026-08-04 12:00 |
20:19:44.72 |
-64:44:28.5 |
HIP 99831 |
28.48 |
| 2026-08-05 00:00 |
20:19:40.46 |
-64:44:29.6 |
HIP 99831 |
28.03 |
| 2026-08-05 12:00 |
20:19:36.21 |
-64:44:30.7 |
HIP 99831 |
27.58 |
| 2026-08-06 00:00 |
20:19:31.97 |
-64:44:31.5 |
HIP 99831 |
27.13 |
| 2026-08-06 12:00 |
20:19:27.73 |
-64:44:32.1 |
HIP 99831 |
26.69 |
| 2026-08-07 00:00 |
20:19:23.50 |
-64:44:32.6 |
HIP 99831 |
26.24 |
| 2026-08-07 12:00 |
20:19:19.28 |
-64:44:32.8 |
HIP 99831 |
25.80 |
| 2026-08-08 00:00 |
20:19:15.07 |
-64:44:32.9 |
HIP 99831 |
25.36 |
| 2026-08-08 12:00 |
20:19:10.86 |
-64:44:32.8 |
HIP 99831 |
24.92 |
| 2026-08-09 00:00 |
20:19:06.67 |
-64:44:32.5 |
HIP 99831 |
24.48 |
| 2026-08-09 12:00 |
20:19:02.48 |
-64:44:32.1 |
HIP 99831 |
24.04 |
| 2026-08-10 00:00 |
20:18:58.31 |
-64:44:31.4 |
HIP 99831 |
23.61 |
| 2026-08-10 12:00 |
20:18:54.14 |
-64:44:30.6 |
HIP 99831 |
23.18 |
| 2026-08-11 00:00 |
20:18:49.98 |
-64:44:29.6 |
HIP 99831 |
22.75 |
| 2026-08-11 12:00 |
20:18:45.84 |
-64:44:28.3 |
HIP 99831 |
22.32 |
| 2026-08-12 00:00 |
20:18:41.70 |
-64:44:26.9 |
HIP 99831 |
21.89 |
| 2026-08-12 12:00 |
20:18:37.58 |
-64:44:25.4 |
HIP 99831 |
21.47 |
| 2026-08-13 00:00 |
20:18:33.47 |
-64:44:23.6 |
HIP 99831 |
21.05 |
| 2026-08-13 12:00 |
20:18:29.37 |
-64:44:21.6 |
HIP 99831 |
20.63 |
| 2026-08-14 00:00 |
20:18:25.28 |
-64:44:19.5 |
HIP 99831 |
20.22 |
| 2026-08-14 12:00 |
20:18:21.21 |
-64:44:17.2 |
HIP 99831 |
19.81 |
| 2026-08-15 00:00 |
20:18:17.15 |
-64:44:14.7 |
HIP 99831 |
19.40 |
| 2026-08-15 12:00 |
20:18:13.10 |
-64:44:12.0 |
HIP 99831 |
18.99 |
| 2026-08-16 00:00 |
20:18:09.06 |
-64:44:09.1 |
HIP 99831 |
18.59 |
| 2026-08-16 12:00 |
20:18:05.04 |
-64:44:06.1 |
HIP 99831 |
18.19 |
| 2026-08-17 00:00 |
20:18:01.04 |
-64:44:02.8 |
HIP 99831 |
17.80 |
| 2026-08-17 12:00 |
20:17:57.05 |
-64:43:59.4 |
HIP 99831 |
17.41 |
| 2026-08-18 00:00 |
20:17:53.07 |
-64:43:55.8 |
HIP 99831 |
17.03 |
| 2026-08-18 12:00 |
20:17:49.11 |
-64:43:52.0 |
HIP 99831 |
16.65 |
| 2026-08-19 00:00 |
20:17:45.17 |
-64:43:48.1 |
HIP 99831 |
16.27 |