| Parameter |
Value |
| Designation |
C/1991 L4 (Helin-Alu) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1992-02-19T22:39:07.948800Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:41Z |
| Obs used |
80 |
| NEO |
- |
| M1 |
10.100 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1992-06-10.0000000 |
| e |
1.00017877 |
| q (au) |
4.849875 |
| a (au) |
-27129.680481 |
| i (deg) |
49.292514 |
| Ω (om, deg) |
253.650707 |
| ω (w, deg) |
30.794475 |
| M (ma, deg) |
0.000024 |
Magnitude
Scatter + Global Linear
$$
M_a = (0.872 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
0.872 |
| n |
6.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
04:36:42.78 |
+24:54:27.6 |
HIP 21591 |
29.01 |
| 2026-06-01 12:00 |
04:36:45.16 |
+24:54:30.8 |
HIP 21591 |
28.68 |
| 2026-06-02 00:00 |
04:36:47.53 |
+24:54:34.1 |
HIP 21591 |
28.36 |
| 2026-06-02 12:00 |
04:36:49.90 |
+24:54:37.3 |
HIP 21591 |
28.05 |
| 2026-06-03 00:00 |
04:36:52.28 |
+24:54:40.5 |
HIP 21591 |
27.75 |
| 2026-06-03 12:00 |
04:36:54.65 |
+24:54:43.8 |
HIP 21591 |
27.45 |
| 2026-06-04 00:00 |
04:36:57.02 |
+24:54:47.1 |
HIP 21591 |
27.16 |
| 2026-06-04 12:00 |
04:36:59.40 |
+24:54:50.3 |
HIP 21591 |
26.88 |
| 2026-06-05 00:00 |
04:37:01.77 |
+24:54:53.6 |
HIP 21591 |
26.61 |
| 2026-06-05 12:00 |
04:37:04.14 |
+24:54:56.9 |
HIP 21591 |
26.35 |
| 2026-06-06 00:00 |
04:37:06.51 |
+24:55:00.2 |
HIP 21591 |
26.09 |
| 2026-06-06 12:00 |
04:37:08.87 |
+24:55:03.5 |
HIP 21591 |
25.85 |
| 2026-06-07 00:00 |
04:37:11.24 |
+24:55:06.8 |
HIP 21591 |
25.61 |
| 2026-06-07 12:00 |
04:37:13.60 |
+24:55:10.2 |
HIP 21591 |
25.39 |
| 2026-06-08 00:00 |
04:37:15.97 |
+24:55:13.5 |
HIP 21591 |
25.17 |
| 2026-06-08 12:00 |
04:37:18.33 |
+24:55:16.8 |
HIP 21591 |
24.96 |
| 2026-06-09 00:00 |
04:37:20.69 |
+24:55:20.2 |
HIP 21591 |
24.77 |
| 2026-06-09 12:00 |
04:37:23.04 |
+24:55:23.5 |
HIP 21591 |
24.58 |
| 2026-06-10 00:00 |
04:37:25.40 |
+24:55:26.9 |
HIP 21591 |
24.40 |
| 2026-06-10 12:00 |
04:37:27.75 |
+24:55:30.2 |
HIP 21591 |
24.24 |
| 2026-06-11 00:00 |
04:37:30.10 |
+24:55:33.6 |
HIP 21591 |
24.09 |
| 2026-06-11 12:00 |
04:37:32.44 |
+24:55:37.0 |
HIP 21591 |
23.95 |
| 2026-06-12 00:00 |
04:37:34.79 |
+24:55:40.4 |
HIP 21591 |
23.82 |
| 2026-06-12 12:00 |
04:37:37.13 |
+24:55:43.8 |
HIP 21591 |
23.70 |
| 2026-06-13 00:00 |
04:37:39.46 |
+24:55:47.1 |
HIP 21591 |
23.59 |
| 2026-06-13 12:00 |
04:37:41.80 |
+24:55:50.5 |
HIP 21591 |
23.50 |
| 2026-06-14 00:00 |
04:37:44.12 |
+24:55:53.9 |
HIP 21591 |
23.41 |
| 2026-06-14 12:00 |
04:37:46.45 |
+24:55:57.3 |
HIP 21591 |
23.34 |
| 2026-06-15 00:00 |
04:37:48.77 |
+24:56:00.7 |
HIP 21591 |
23.28 |
| 2026-06-15 12:00 |
04:37:51.09 |
+24:56:04.1 |
HIP 21591 |
23.24 |
| 2026-06-16 00:00 |
04:37:53.40 |
+24:56:07.5 |
HIP 21591 |
23.20 |
| 2026-06-16 12:00 |
04:37:55.71 |
+24:56:10.9 |
HIP 21591 |
23.18 |
| 2026-06-17 00:00 |
04:37:58.01 |
+24:56:14.3 |
HIP 21591 |
23.17 |
| 2026-06-17 12:00 |
04:38:00.31 |
+24:56:17.7 |
HIP 21591 |
23.17 |
| 2026-06-18 00:00 |
04:38:02.61 |
+24:56:21.2 |
HIP 21591 |
23.19 |
| 2026-06-18 12:00 |
04:38:04.90 |
+24:56:24.6 |
HIP 21591 |
23.21 |
| 2026-06-19 00:00 |
04:38:07.18 |
+24:56:28.0 |
HIP 21591 |
23.25 |
| 2026-06-19 12:00 |
04:38:09.46 |
+24:56:31.4 |
HIP 21591 |
23.30 |
| 2026-06-20 00:00 |
04:38:11.73 |
+24:56:34.8 |
HIP 21689 |
23.11 |
| 2026-06-20 12:00 |
04:38:14.00 |
+24:56:38.2 |
HIP 21689 |
22.72 |
| 2026-06-21 00:00 |
04:38:16.26 |
+24:56:41.6 |
HIP 21689 |
22.33 |
| 2026-06-21 12:00 |
04:38:18.51 |
+24:56:45.0 |
HIP 21689 |
21.94 |
| 2026-06-22 00:00 |
04:38:20.76 |
+24:56:48.4 |
HIP 21689 |
21.56 |