| Parameter |
Value |
| Designation |
C/1983 H1 (IRAS-Araki-Alcock) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1983-05-21T06:06:31.124160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:29Z |
| Obs used |
347 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1983-05-13.0000000 |
| e |
0.98988782 |
| q (au) |
0.991341 |
| a (au) |
98.034357 |
| i (deg) |
73.251379 |
| Ω (om, deg) |
49.102458 |
| ω (w, deg) |
192.850689 |
| M (ma, deg) |
359.991618 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.784 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.784 |
| n |
6.000 |
| gf |
0.800 |
| gb |
-0.513 |
| k |
0.800 |
| δ90 |
1.000 |
| 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) |
| 2026-09-20 00:00 |
03:09:50.18 |
+18:47:56.9 |
HIP 14675 |
14.36 |
| 2026-09-20 12:00 |
03:09:49.00 |
+18:47:53.3 |
HIP 14675 |
14.35 |
| 2026-09-21 00:00 |
03:09:47.80 |
+18:47:49.6 |
HIP 14675 |
14.36 |
| 2026-09-21 12:00 |
03:09:46.59 |
+18:47:45.8 |
HIP 14675 |
14.36 |
| 2026-09-22 00:00 |
03:09:45.37 |
+18:47:42.0 |
HIP 14675 |
14.38 |
| 2026-09-22 12:00 |
03:09:44.13 |
+18:47:38.1 |
HIP 14675 |
14.40 |
| 2026-09-23 00:00 |
03:09:42.88 |
+18:47:34.2 |
HIP 14675 |
14.43 |
| 2026-09-23 12:00 |
03:09:41.62 |
+18:47:30.3 |
HIP 14675 |
14.46 |
| 2026-09-24 00:00 |
03:09:40.34 |
+18:47:26.2 |
HIP 14675 |
14.50 |
| 2026-09-24 12:00 |
03:09:39.06 |
+18:47:22.2 |
HIP 14675 |
14.55 |
| 2026-09-25 00:00 |
03:09:37.76 |
+18:47:18.0 |
HIP 14675 |
14.61 |
| 2026-09-25 12:00 |
03:09:36.45 |
+18:47:13.9 |
HIP 14675 |
14.67 |
| 2026-09-26 00:00 |
03:09:35.12 |
+18:47:09.6 |
HIP 14675 |
14.74 |
| 2026-09-26 12:00 |
03:09:33.79 |
+18:47:05.3 |
HIP 14675 |
14.82 |
| 2026-09-27 00:00 |
03:09:32.44 |
+18:47:01.0 |
HIP 14675 |
14.91 |
| 2026-09-27 12:00 |
03:09:31.08 |
+18:46:56.6 |
HIP 14675 |
15.00 |
| 2026-09-28 00:00 |
03:09:29.70 |
+18:46:52.2 |
HIP 14675 |
15.10 |
| 2026-09-28 12:00 |
03:09:28.32 |
+18:46:47.7 |
HIP 14675 |
15.21 |
| 2026-09-29 00:00 |
03:09:26.92 |
+18:46:43.1 |
HIP 14675 |
15.33 |
| 2026-09-29 12:00 |
03:09:25.51 |
+18:46:38.6 |
HIP 14586 |
15.29 |
| 2026-09-30 00:00 |
03:09:24.09 |
+18:46:33.9 |
HIP 14586 |
14.96 |
| 2026-09-30 12:00 |
03:09:22.66 |
+18:46:29.2 |
HIP 14586 |
14.63 |
| 2026-10-01 00:00 |
03:09:21.22 |
+18:46:24.5 |
HIP 14586 |
14.29 |
| 2026-10-01 12:00 |
03:09:19.77 |
+18:46:19.7 |
HIP 14586 |
13.96 |
| 2026-10-02 00:00 |
03:09:18.30 |
+18:46:14.8 |
HIP 14586 |
13.62 |
| 2026-10-02 12:00 |
03:09:16.82 |
+18:46:10.0 |
HIP 14586 |
13.28 |
| 2026-10-03 00:00 |
03:09:15.34 |
+18:46:05.0 |
HIP 14586 |
12.94 |
| 2026-10-03 12:00 |
03:09:13.84 |
+18:46:00.0 |
HIP 14586 |
12.60 |
| 2026-10-04 00:00 |
03:09:12.33 |
+18:45:55.0 |
HIP 14586 |
12.26 |
| 2026-10-04 12:00 |
03:09:10.81 |
+18:45:49.9 |
HIP 14586 |
11.92 |
| 2026-10-05 00:00 |
03:09:09.28 |
+18:45:44.8 |
HIP 14586 |
11.57 |
| 2026-10-05 12:00 |
03:09:07.74 |
+18:45:39.6 |
HIP 14586 |
11.23 |
| 2026-10-06 00:00 |
03:09:06.18 |
+18:45:34.4 |
HIP 14586 |
10.89 |
| 2026-10-06 12:00 |
03:09:04.62 |
+18:45:29.1 |
HIP 14586 |
10.54 |
| 2026-10-07 00:00 |
03:09:03.05 |
+18:45:23.8 |
HIP 14586 |
10.20 |
| 2026-10-07 12:00 |
03:09:01.47 |
+18:45:18.5 |
HIP 14586 |
9.85 |
| 2026-10-08 00:00 |
03:08:59.87 |
+18:45:13.0 |
HIP 14586 |
9.51 |
| 2026-10-08 12:00 |
03:08:58.27 |
+18:45:07.6 |
HIP 14586 |
9.17 |
| 2026-10-09 00:00 |
03:08:56.66 |
+18:45:02.1 |
HIP 14586 |
8.83 |
| 2026-10-09 12:00 |
03:08:55.04 |
+18:44:56.6 |
HIP 14586 |
8.50 |
| 2026-10-10 00:00 |
03:08:53.41 |
+18:44:51.0 |
HIP 14586 |
8.17 |
| 2026-10-10 12:00 |
03:08:51.76 |
+18:44:45.4 |
HIP 14586 |
7.84 |
| 2026-10-11 00:00 |
03:08:50.11 |
+18:44:39.7 |
HIP 14586 |
7.51 |