| Parameter |
Value |
| Designation |
C/1983 J2 (IRAS) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1983-01-18T15:30:12.680640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:31Z |
| Obs used |
7 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1983-05-30.0000000 |
| e |
0.99471612 |
| q (au) |
1.416663 |
| a (au) |
268.110599 |
| i (deg) |
152.173465 |
| Ω (om, deg) |
119.690042 |
| ω (w, deg) |
227.019078 |
| M (ma, deg) |
0.029490 |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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 |
06:09:51.01 |
+37:16:14.6 |
HIP 29238 |
18.03 |
| 2026-07-29 12:00 |
06:09:52.76 |
+37:16:18.0 |
HIP 29238 |
17.97 |
| 2026-07-30 00:00 |
06:09:54.51 |
+37:16:21.5 |
HIP 29238 |
17.92 |
| 2026-07-30 12:00 |
06:09:56.24 |
+37:16:25.0 |
HIP 29238 |
17.88 |
| 2026-07-31 00:00 |
06:09:57.97 |
+37:16:28.5 |
HIP 29238 |
17.84 |
| 2026-07-31 12:00 |
06:09:59.68 |
+37:16:32.1 |
HIP 29238 |
17.80 |
| 2026-08-01 00:00 |
06:10:01.38 |
+37:16:35.7 |
HIP 29238 |
17.77 |
| 2026-08-01 12:00 |
06:10:03.08 |
+37:16:39.4 |
HIP 29238 |
17.75 |
| 2026-08-02 00:00 |
06:10:04.76 |
+37:16:43.1 |
HIP 29238 |
17.73 |
| 2026-08-02 12:00 |
06:10:06.43 |
+37:16:46.9 |
HIP 29238 |
17.72 |
| 2026-08-03 00:00 |
06:10:08.09 |
+37:16:50.7 |
HIP 29238 |
17.71 |
| 2026-08-03 12:00 |
06:10:09.74 |
+37:16:54.6 |
HIP 29238 |
17.71 |
| 2026-08-04 00:00 |
06:10:11.38 |
+37:16:58.5 |
HIP 29238 |
17.72 |
| 2026-08-04 12:00 |
06:10:13.00 |
+37:17:02.4 |
HIP 29238 |
17.72 |
| 2026-08-05 00:00 |
06:10:14.62 |
+37:17:06.4 |
HIP 29238 |
17.74 |
| 2026-08-05 12:00 |
06:10:16.22 |
+37:17:10.4 |
HIP 29238 |
17.76 |
| 2026-08-06 00:00 |
06:10:17.81 |
+37:17:14.5 |
HIP 29238 |
17.78 |
| 2026-08-06 12:00 |
06:10:19.39 |
+37:17:18.6 |
HIP 29238 |
17.80 |
| 2026-08-07 00:00 |
06:10:20.96 |
+37:17:22.7 |
HIP 29238 |
17.84 |
| 2026-08-07 12:00 |
06:10:22.52 |
+37:17:26.9 |
HIP 29238 |
17.87 |
| 2026-08-08 00:00 |
06:10:24.06 |
+37:17:31.1 |
HIP 29238 |
17.91 |
| 2026-08-08 12:00 |
06:10:25.60 |
+37:17:35.4 |
HIP 29238 |
17.96 |
| 2026-08-09 00:00 |
06:10:27.11 |
+37:17:39.7 |
HIP 29238 |
18.00 |
| 2026-08-09 12:00 |
06:10:28.62 |
+37:17:44.1 |
HIP 29238 |
18.05 |
| 2026-08-10 00:00 |
06:10:30.12 |
+37:17:48.5 |
HIP 29238 |
18.11 |
| 2026-08-10 12:00 |
06:10:31.60 |
+37:17:52.9 |
HIP 29238 |
18.17 |
| 2026-08-11 00:00 |
06:10:33.07 |
+37:17:57.4 |
HIP 29238 |
18.23 |
| 2026-08-11 12:00 |
06:10:34.52 |
+37:18:01.9 |
HIP 29238 |
18.29 |
| 2026-08-12 00:00 |
06:10:35.96 |
+37:18:06.5 |
HIP 29238 |
18.36 |
| 2026-08-12 12:00 |
06:10:37.39 |
+37:18:11.0 |
HIP 29238 |
18.43 |
| 2026-08-13 00:00 |
06:10:38.81 |
+37:18:15.7 |
HIP 29238 |
18.50 |
| 2026-08-13 12:00 |
06:10:40.21 |
+37:18:20.4 |
HIP 29238 |
18.57 |
| 2026-08-14 00:00 |
06:10:41.60 |
+37:18:25.1 |
HIP 29238 |
18.65 |
| 2026-08-14 12:00 |
06:10:42.97 |
+37:18:29.8 |
HIP 29238 |
18.73 |
| 2026-08-15 00:00 |
06:10:44.34 |
+37:18:34.6 |
HIP 29238 |
18.81 |
| 2026-08-15 12:00 |
06:10:45.68 |
+37:18:39.4 |
HIP 29238 |
18.89 |
| 2026-08-16 00:00 |
06:10:47.02 |
+37:18:44.3 |
HIP 29238 |
18.97 |
| 2026-08-16 12:00 |
06:10:48.33 |
+37:18:49.2 |
HIP 29238 |
19.06 |
| 2026-08-17 00:00 |
06:10:49.64 |
+37:18:54.1 |
HIP 29238 |
19.14 |
| 2026-08-17 12:00 |
06:10:50.93 |
+37:18:59.1 |
HIP 29238 |
19.23 |
| 2026-08-18 00:00 |
06:10:52.20 |
+37:19:04.1 |
HIP 29238 |
19.32 |
| 2026-08-18 12:00 |
06:10:53.47 |
+37:19:09.1 |
HIP 29238 |
19.41 |
| 2026-08-19 00:00 |
06:10:54.71 |
+37:19:14.2 |
HIP 29238 |
19.50 |