| Parameter |
Value |
| Designation |
C/1981 G1 (Elias) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1981-08-18T09:31:39.573120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:29Z |
| Obs used |
20 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1982-01-23.0000000 |
| e |
1.00140214 |
| q (au) |
4.742646 |
| a (au) |
-3382.426552 |
| i (deg) |
115.300346 |
| Ω (om, deg) |
176.713357 |
| ω (w, deg) |
310.265581 |
| M (ma, deg) |
0.000790 |
Magnitude
Scatter + Global Linear
$$
M_a = (1.266 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
1.266 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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) |
| 2026-09-20 00:00 |
00:31:39.11 |
+80:05:27.4 |
HIP 2142 |
11.94 |
| 2026-09-20 12:00 |
00:31:29.75 |
+80:05:28.5 |
HIP 2142 |
11.55 |
| 2026-09-21 00:00 |
00:31:20.37 |
+80:05:29.5 |
HIP 2142 |
11.16 |
| 2026-09-21 12:00 |
00:31:10.97 |
+80:05:30.2 |
HIP 2142 |
10.77 |
| 2026-09-22 00:00 |
00:31:01.56 |
+80:05:30.6 |
HIP 2142 |
10.37 |
| 2026-09-22 12:00 |
00:30:52.14 |
+80:05:30.8 |
HIP 2142 |
9.98 |
| 2026-09-23 00:00 |
00:30:42.70 |
+80:05:30.8 |
HIP 2142 |
9.59 |
| 2026-09-23 12:00 |
00:30:33.25 |
+80:05:30.6 |
HIP 2142 |
9.19 |
| 2026-09-24 00:00 |
00:30:23.79 |
+80:05:30.1 |
HIP 2142 |
8.79 |
| 2026-09-24 12:00 |
00:30:14.31 |
+80:05:29.4 |
HIP 2142 |
8.40 |
| 2026-09-25 00:00 |
00:30:04.83 |
+80:05:28.4 |
HIP 2142 |
8.00 |
| 2026-09-25 12:00 |
00:29:55.34 |
+80:05:27.2 |
HIP 2142 |
7.61 |
| 2026-09-26 00:00 |
00:29:45.84 |
+80:05:25.8 |
HIP 2142 |
7.21 |
| 2026-09-26 12:00 |
00:29:36.33 |
+80:05:24.1 |
HIP 2142 |
6.81 |
| 2026-09-27 00:00 |
00:29:26.82 |
+80:05:22.2 |
HIP 2142 |
6.42 |
| 2026-09-27 12:00 |
00:29:17.30 |
+80:05:20.0 |
HIP 2142 |
6.02 |
| 2026-09-28 00:00 |
00:29:07.77 |
+80:05:17.6 |
HIP 2142 |
5.63 |
| 2026-09-28 12:00 |
00:28:58.25 |
+80:05:15.0 |
HIP 2142 |
5.23 |
| 2026-09-29 00:00 |
00:28:48.71 |
+80:05:12.1 |
HIP 2142 |
4.84 |
| 2026-09-29 12:00 |
00:28:39.18 |
+80:05:09.0 |
HIP 2142 |
4.45 |
| 2026-09-30 00:00 |
00:28:29.64 |
+80:05:05.7 |
HIP 2142 |
4.06 |
| 2026-09-30 12:00 |
00:28:20.11 |
+80:05:02.1 |
HIP 2142 |
3.67 |
| 2026-10-01 00:00 |
00:28:10.57 |
+80:04:58.3 |
HIP 2142 |
3.29 |
| 2026-10-01 12:00 |
00:28:01.03 |
+80:04:54.2 |
HIP 2142 |
2.92 |
| 2026-10-02 00:00 |
00:27:51.50 |
+80:04:49.9 |
HIP 2142 |
2.56 |
| 2026-10-02 12:00 |
00:27:41.97 |
+80:04:45.4 |
HIP 2142 |
2.21 |
| 2026-10-03 00:00 |
00:27:32.44 |
+80:04:40.6 |
HIP 2142 |
1.89 |
| 2026-10-03 12:00 |
00:27:22.91 |
+80:04:35.6 |
HIP 2142 |
1.61 |
| 2026-10-04 00:00 |
00:27:13.39 |
+80:04:30.3 |
HIP 2142 |
1.40 |
| 2026-10-04 12:00 |
00:27:03.88 |
+80:04:24.8 |
HIP 2142 |
1.29 |
| 2026-10-05 00:00 |
00:26:54.38 |
+80:04:19.1 |
HIP 2142 |
1.31 |
| 2026-10-05 12:00 |
00:26:44.88 |
+80:04:13.1 |
HIP 2142 |
1.46 |
| 2026-10-06 00:00 |
00:26:35.39 |
+80:04:06.9 |
HIP 2142 |
1.69 |
| 2026-10-06 12:00 |
00:26:25.91 |
+80:04:00.4 |
HIP 2142 |
1.99 |
| 2026-10-07 00:00 |
00:26:16.44 |
+80:03:53.7 |
HIP 2142 |
2.33 |
| 2026-10-07 12:00 |
00:26:06.98 |
+80:03:46.8 |
HIP 2142 |
2.68 |
| 2026-10-08 00:00 |
00:25:57.54 |
+80:03:39.7 |
HIP 2142 |
3.06 |
| 2026-10-08 12:00 |
00:25:48.11 |
+80:03:32.2 |
HIP 2142 |
3.44 |
| 2026-10-09 00:00 |
00:25:38.69 |
+80:03:24.6 |
HIP 2142 |
3.84 |
| 2026-10-09 12:00 |
00:25:29.29 |
+80:03:16.7 |
HIP 2142 |
4.24 |
| 2026-10-10 00:00 |
00:25:19.91 |
+80:03:08.6 |
HIP 2142 |
4.64 |
| 2026-10-10 12:00 |
00:25:10.54 |
+80:03:00.3 |
HIP 2142 |
5.05 |
| 2026-10-11 00:00 |
00:25:01.19 |
+80:02:51.7 |
HIP 2142 |
5.45 |