| Parameter |
Value |
| Designation |
C/1989 Y1 (Skorichenko-George) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1990-04-11T22:18:59.575680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:38Z |
| Obs used |
106 |
| NEO |
- |
| M1 |
5.300 |
| K1 |
12.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1990-02-24.0000000 |
| e |
1.00030135 |
| q (au) |
1.569168 |
| a (au) |
-5207.172639 |
| i (deg) |
59.365874 |
| Ω (om, deg) |
280.009427 |
| ω (w, deg) |
137.833282 |
| M (ma, deg) |
-0.000123 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.464 + 4.016\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.464 |
| n |
4.016 |
| gf |
1.000 |
| gb |
-1.000 |
| 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 |
| 1988-06-13 |
1989-12-28 |
+1.3205 |
-0.610 |
| 1989-12-28 |
1990-04-11 |
-4.1211 |
+0.921 |
| 1990-04-12 |
1991-03-18 |
+3.8685 |
+0.256 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
13:59:33.11 |
-64:53:37.5 |
HIP 68295 |
5.62 |
| 2026-09-20 12:00 |
13:59:36.82 |
-64:53:29.4 |
HIP 68295 |
5.87 |
| 2026-09-21 00:00 |
13:59:40.55 |
-64:53:21.6 |
HIP 68295 |
6.13 |
| 2026-09-21 12:00 |
13:59:44.30 |
-64:53:13.9 |
HIP 68295 |
6.42 |
| 2026-09-22 00:00 |
13:59:48.07 |
-64:53:06.4 |
HIP 68295 |
6.72 |
| 2026-09-22 12:00 |
13:59:51.85 |
-64:52:59.0 |
HIP 68295 |
7.04 |
| 2026-09-23 00:00 |
13:59:55.66 |
-64:52:51.9 |
HIP 68436 |
6.85 |
| 2026-09-23 12:00 |
13:59:59.48 |
-64:52:45.0 |
HIP 68436 |
6.50 |
| 2026-09-24 00:00 |
14:00:03.32 |
-64:52:38.2 |
HIP 68436 |
6.16 |
| 2026-09-24 12:00 |
14:00:07.18 |
-64:52:31.7 |
HIP 68436 |
5.84 |
| 2026-09-25 00:00 |
14:00:11.06 |
-64:52:25.3 |
HIP 68436 |
5.53 |
| 2026-09-25 12:00 |
14:00:14.96 |
-64:52:19.2 |
HIP 68436 |
5.24 |
| 2026-09-26 00:00 |
14:00:18.87 |
-64:52:13.2 |
HIP 68436 |
4.97 |
| 2026-09-26 12:00 |
14:00:22.80 |
-64:52:07.4 |
HIP 68436 |
4.72 |
| 2026-09-27 00:00 |
14:00:26.74 |
-64:52:01.8 |
HIP 68436 |
4.51 |
| 2026-09-27 12:00 |
14:00:30.70 |
-64:51:56.4 |
HIP 68436 |
4.33 |
| 2026-09-28 00:00 |
14:00:34.68 |
-64:51:51.2 |
HIP 68436 |
4.20 |
| 2026-09-28 12:00 |
14:00:38.68 |
-64:51:46.2 |
HIP 68436 |
4.10 |
| 2026-09-29 00:00 |
14:00:42.69 |
-64:51:41.4 |
HIP 68436 |
4.06 |
| 2026-09-29 12:00 |
14:00:46.71 |
-64:51:36.8 |
HIP 68436 |
4.06 |
| 2026-09-30 00:00 |
14:00:50.75 |
-64:51:32.4 |
HIP 68436 |
4.12 |
| 2026-09-30 12:00 |
14:00:54.81 |
-64:51:28.2 |
HIP 68436 |
4.22 |
| 2026-10-01 00:00 |
14:00:58.88 |
-64:51:24.1 |
HIP 68436 |
4.37 |
| 2026-10-01 12:00 |
14:01:02.97 |
-64:51:20.3 |
HIP 68436 |
4.55 |
| 2026-10-02 00:00 |
14:01:07.07 |
-64:51:16.7 |
HIP 68436 |
4.78 |
| 2026-10-02 12:00 |
14:01:11.18 |
-64:51:13.2 |
HIP 68436 |
5.04 |
| 2026-10-03 00:00 |
14:01:15.31 |
-64:51:10.0 |
HIP 68436 |
5.32 |
| 2026-10-03 12:00 |
14:01:19.45 |
-64:51:06.9 |
HIP 68436 |
5.63 |
| 2026-10-04 00:00 |
14:01:23.61 |
-64:51:04.1 |
HIP 68436 |
5.96 |
| 2026-10-04 12:00 |
14:01:27.77 |
-64:51:01.4 |
HIP 68436 |
6.30 |
| 2026-10-05 00:00 |
14:01:31.95 |
-64:50:59.0 |
HIP 68436 |
6.66 |
| 2026-10-05 12:00 |
14:01:36.15 |
-64:50:56.7 |
HIP 68574 |
6.54 |
| 2026-10-06 00:00 |
14:01:40.35 |
-64:50:54.7 |
HIP 68574 |
6.26 |
| 2026-10-06 12:00 |
14:01:44.57 |
-64:50:52.8 |
HIP 68574 |
5.99 |
| 2026-10-07 00:00 |
14:01:48.80 |
-64:50:51.2 |
HIP 68574 |
5.74 |
| 2026-10-07 12:00 |
14:01:53.05 |
-64:50:49.7 |
HIP 68574 |
5.51 |
| 2026-10-08 00:00 |
14:01:57.30 |
-64:50:48.5 |
HIP 68574 |
5.30 |
| 2026-10-08 12:00 |
14:02:01.56 |
-64:50:47.4 |
HIP 68574 |
5.13 |
| 2026-10-09 00:00 |
14:02:05.84 |
-64:50:46.5 |
HIP 68574 |
4.98 |
| 2026-10-09 12:00 |
14:02:10.12 |
-64:50:45.9 |
HIP 68574 |
4.87 |
| 2026-10-10 00:00 |
14:02:14.42 |
-64:50:45.4 |
HIP 68574 |
4.80 |
| 2026-10-10 12:00 |
14:02:18.72 |
-64:50:45.2 |
HIP 68574 |
4.77 |
| 2026-10-11 00:00 |
14:02:23.04 |
-64:50:45.1 |
HIP 68574 |
4.77 |