| 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) |
| 2026-07-29 00:00 |
04:40:40.97 |
+25:00:37.0 |
HIP 21759 |
5.17 |
| 2026-07-29 12:00 |
04:40:42.39 |
+25:00:39.5 |
HIP 21759 |
5.44 |
| 2026-07-30 00:00 |
04:40:43.79 |
+25:00:42.0 |
HIP 21759 |
5.70 |
| 2026-07-30 12:00 |
04:40:45.19 |
+25:00:44.4 |
HIP 21759 |
5.97 |
| 2026-07-31 00:00 |
04:40:46.56 |
+25:00:46.9 |
HIP 21759 |
6.25 |
| 2026-07-31 12:00 |
04:40:47.92 |
+25:00:49.3 |
HIP 21759 |
6.52 |
| 2026-08-01 00:00 |
04:40:49.26 |
+25:00:51.7 |
HIP 21759 |
6.79 |
| 2026-08-01 12:00 |
04:40:50.59 |
+25:00:54.1 |
HIP 21759 |
7.06 |
| 2026-08-02 00:00 |
04:40:51.90 |
+25:00:56.5 |
HIP 21759 |
7.33 |
| 2026-08-02 12:00 |
04:40:53.20 |
+25:00:58.8 |
HIP 21759 |
7.60 |
| 2026-08-03 00:00 |
04:40:54.48 |
+25:01:01.1 |
HIP 21759 |
7.87 |
| 2026-08-03 12:00 |
04:40:55.74 |
+25:01:03.4 |
HIP 21759 |
8.14 |
| 2026-08-04 00:00 |
04:40:56.99 |
+25:01:05.6 |
HIP 21759 |
8.40 |
| 2026-08-04 12:00 |
04:40:58.22 |
+25:01:07.9 |
HIP 21759 |
8.66 |
| 2026-08-05 00:00 |
04:40:59.43 |
+25:01:10.1 |
HIP 21759 |
8.92 |
| 2026-08-05 12:00 |
04:41:00.63 |
+25:01:12.3 |
HIP 21759 |
9.18 |
| 2026-08-06 00:00 |
04:41:01.81 |
+25:01:14.4 |
HIP 21759 |
9.43 |
| 2026-08-06 12:00 |
04:41:02.98 |
+25:01:16.6 |
HIP 21759 |
9.68 |
| 2026-08-07 00:00 |
04:41:04.13 |
+25:01:18.7 |
HIP 21759 |
9.93 |
| 2026-08-07 12:00 |
04:41:05.26 |
+25:01:20.8 |
HIP 21759 |
10.18 |
| 2026-08-08 00:00 |
04:41:06.37 |
+25:01:22.8 |
HIP 21759 |
10.42 |
| 2026-08-08 12:00 |
04:41:07.47 |
+25:01:24.9 |
HIP 21759 |
10.66 |
| 2026-08-09 00:00 |
04:41:08.55 |
+25:01:26.9 |
HIP 21759 |
10.90 |
| 2026-08-09 12:00 |
04:41:09.61 |
+25:01:28.9 |
HIP 21759 |
11.13 |
| 2026-08-10 00:00 |
04:41:10.65 |
+25:01:30.8 |
HIP 21759 |
11.36 |
| 2026-08-10 12:00 |
04:41:11.68 |
+25:01:32.8 |
HIP 21759 |
11.58 |
| 2026-08-11 00:00 |
04:41:12.69 |
+25:01:34.7 |
HIP 21759 |
11.81 |
| 2026-08-11 12:00 |
04:41:13.68 |
+25:01:36.5 |
HIP 21759 |
12.03 |
| 2026-08-12 00:00 |
04:41:14.65 |
+25:01:38.4 |
HIP 21759 |
12.24 |
| 2026-08-12 12:00 |
04:41:15.61 |
+25:01:40.2 |
HIP 21759 |
12.45 |
| 2026-08-13 00:00 |
04:41:16.55 |
+25:01:42.0 |
HIP 21759 |
12.66 |
| 2026-08-13 12:00 |
04:41:17.47 |
+25:01:43.7 |
HIP 21759 |
12.86 |
| 2026-08-14 00:00 |
04:41:18.37 |
+25:01:45.5 |
HIP 21759 |
13.06 |
| 2026-08-14 12:00 |
04:41:19.25 |
+25:01:47.2 |
HIP 21759 |
13.26 |
| 2026-08-15 00:00 |
04:41:20.12 |
+25:01:48.8 |
HIP 21759 |
13.45 |
| 2026-08-15 12:00 |
04:41:20.97 |
+25:01:50.5 |
HIP 21759 |
13.64 |
| 2026-08-16 00:00 |
04:41:21.80 |
+25:01:52.1 |
HIP 21759 |
13.82 |
| 2026-08-16 12:00 |
04:41:22.61 |
+25:01:53.7 |
HIP 21759 |
14.01 |
| 2026-08-17 00:00 |
04:41:23.40 |
+25:01:55.2 |
HIP 21759 |
14.18 |
| 2026-08-17 12:00 |
04:41:24.17 |
+25:01:56.8 |
HIP 21759 |
14.35 |
| 2026-08-18 00:00 |
04:41:24.93 |
+25:01:58.3 |
HIP 21759 |
14.52 |
| 2026-08-18 12:00 |
04:41:25.67 |
+25:01:59.7 |
HIP 21759 |
14.69 |
| 2026-08-19 00:00 |
04:41:26.38 |
+25:02:01.2 |
HIP 21759 |
14.85 |