| Parameter |
Value |
| Designation |
C/1988 A1 (Liller) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1988-03-31T02:45:25.882560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:36Z |
| Obs used |
427 |
| NEO |
- |
| M1 |
6.600 |
| K1 |
9.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1988-04-26.0000000 |
| e |
0.99656338 |
| q (au) |
0.841336 |
| a (au) |
244.814711 |
| i (deg) |
73.322355 |
| Ω (om, deg) |
31.515349 |
| ω (w, deg) |
57.387934 |
| M (ma, deg) |
0.006660 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.936 + 3.835\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.936 |
| n |
3.835 |
| gf |
1.000 |
| gb |
-0.500 |
| 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 |
| 1988-01-12 |
1988-03-31 |
+0.6520 |
+0.817 |
| 1988-04-03 |
1988-08-12 |
-0.1051 |
-0.062 |
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 |
13:36:04.14 |
-56:00:56.2 |
HIP 66410 |
11.04 |
| 2026-09-20 12:00 |
13:36:06.93 |
-56:00:53.6 |
HIP 66410 |
10.83 |
| 2026-09-21 00:00 |
13:36:09.74 |
-56:00:51.1 |
HIP 66410 |
10.62 |
| 2026-09-21 12:00 |
13:36:12.55 |
-56:00:48.9 |
HIP 66410 |
10.43 |
| 2026-09-22 00:00 |
13:36:15.38 |
-56:00:46.8 |
HIP 66410 |
10.24 |
| 2026-09-22 12:00 |
13:36:18.22 |
-56:00:44.8 |
HIP 66410 |
10.06 |
| 2026-09-23 00:00 |
13:36:21.07 |
-56:00:43.1 |
HIP 66410 |
9.89 |
| 2026-09-23 12:00 |
13:36:23.93 |
-56:00:41.5 |
HIP 66410 |
9.73 |
| 2026-09-24 00:00 |
13:36:26.81 |
-56:00:40.2 |
HIP 66410 |
9.58 |
| 2026-09-24 12:00 |
13:36:29.69 |
-56:00:39.0 |
HIP 66410 |
9.44 |
| 2026-09-25 00:00 |
13:36:32.59 |
-56:00:38.0 |
HIP 66410 |
9.31 |
| 2026-09-25 12:00 |
13:36:35.49 |
-56:00:37.1 |
HIP 66410 |
9.19 |
| 2026-09-26 00:00 |
13:36:38.41 |
-56:00:36.5 |
HIP 66410 |
9.09 |
| 2026-09-26 12:00 |
13:36:41.34 |
-56:00:36.0 |
HIP 66410 |
9.01 |
| 2026-09-27 00:00 |
13:36:44.27 |
-56:00:35.7 |
HIP 66410 |
8.93 |
| 2026-09-27 12:00 |
13:36:47.22 |
-56:00:35.6 |
HIP 66483 |
8.56 |
| 2026-09-28 00:00 |
13:36:50.17 |
-56:00:35.7 |
HIP 66483 |
8.15 |
| 2026-09-28 12:00 |
13:36:53.14 |
-56:00:35.9 |
HIP 66483 |
7.74 |
| 2026-09-29 00:00 |
13:36:56.11 |
-56:00:36.3 |
HIP 66483 |
7.34 |
| 2026-09-29 12:00 |
13:36:59.10 |
-56:00:36.9 |
HIP 66483 |
6.93 |
| 2026-09-30 00:00 |
13:37:02.09 |
-56:00:37.7 |
HIP 66483 |
6.53 |
| 2026-09-30 12:00 |
13:37:05.09 |
-56:00:38.7 |
HIP 66483 |
6.12 |
| 2026-10-01 00:00 |
13:37:08.10 |
-56:00:39.9 |
HIP 66483 |
5.72 |
| 2026-10-01 12:00 |
13:37:11.12 |
-56:00:41.2 |
HIP 66483 |
5.32 |
| 2026-10-02 00:00 |
13:37:14.15 |
-56:00:42.7 |
HIP 66483 |
4.93 |
| 2026-10-02 12:00 |
13:37:17.18 |
-56:00:44.4 |
HIP 66483 |
4.54 |
| 2026-10-03 00:00 |
13:37:20.22 |
-56:00:46.3 |
HIP 66483 |
4.15 |
| 2026-10-03 12:00 |
13:37:23.27 |
-56:00:48.3 |
HIP 66483 |
3.78 |
| 2026-10-04 00:00 |
13:37:26.33 |
-56:00:50.6 |
HIP 66483 |
3.42 |
| 2026-10-04 12:00 |
13:37:29.40 |
-56:00:53.0 |
HIP 66483 |
3.08 |
| 2026-10-05 00:00 |
13:37:32.47 |
-56:00:55.6 |
HIP 66483 |
2.77 |
| 2026-10-05 12:00 |
13:37:35.55 |
-56:00:58.4 |
HIP 66483 |
2.49 |
| 2026-10-06 00:00 |
13:37:38.63 |
-56:01:01.4 |
HIP 66483 |
2.27 |
| 2026-10-06 12:00 |
13:37:41.72 |
-56:01:04.5 |
HIP 66483 |
2.11 |
| 2026-10-07 00:00 |
13:37:44.82 |
-56:01:07.9 |
HIP 66483 |
2.04 |
| 2026-10-07 12:00 |
13:37:47.92 |
-56:01:11.4 |
HIP 66483 |
2.06 |
| 2026-10-08 00:00 |
13:37:51.03 |
-56:01:15.1 |
HIP 66483 |
2.18 |
| 2026-10-08 12:00 |
13:37:54.15 |
-56:01:18.9 |
HIP 66483 |
2.38 |
| 2026-10-09 00:00 |
13:37:57.27 |
-56:01:23.0 |
HIP 66483 |
2.64 |
| 2026-10-09 12:00 |
13:38:00.39 |
-56:01:27.2 |
HIP 66483 |
2.94 |
| 2026-10-10 00:00 |
13:38:03.52 |
-56:01:31.6 |
HIP 66483 |
3.28 |
| 2026-10-10 12:00 |
13:38:06.65 |
-56:01:36.2 |
HIP 66483 |
3.65 |
| 2026-10-11 00:00 |
13:38:09.79 |
-56:01:41.0 |
HIP 66483 |
4.03 |