| Parameter |
Value |
| Designation |
C/1984 S1 (Meier) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1984-10-13T23:45:57.159360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:31Z |
| Obs used |
12 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1984-09-23.0000000 |
| e |
0.99898032 |
| q (au) |
0.856608 |
| a (au) |
840.076952 |
| i (deg) |
145.614483 |
| Ω (om, deg) |
11.711482 |
| ω (w, deg) |
128.076601 |
| M (ma, deg) |
359.999150 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.608 + 3.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.608 |
| n |
3.000 |
| gf |
1.000 |
| gb |
-1.000 |
| k |
0.800 |
| 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 |
05:00:55.30 |
-08:15:33.2 |
HIP 23262 |
24.70 |
| 2026-09-20 12:00 |
05:00:54.90 |
-08:15:47.1 |
HIP 23262 |
24.44 |
| 2026-09-21 00:00 |
05:00:54.49 |
-08:16:01.0 |
HIP 23262 |
24.19 |
| 2026-09-21 12:00 |
05:00:54.07 |
-08:16:14.9 |
HIP 23262 |
23.94 |
| 2026-09-22 00:00 |
05:00:53.63 |
-08:16:28.7 |
HIP 23262 |
23.68 |
| 2026-09-22 12:00 |
05:00:53.17 |
-08:16:42.6 |
HIP 23262 |
23.43 |
| 2026-09-23 00:00 |
05:00:52.70 |
-08:16:56.5 |
HIP 23262 |
23.17 |
| 2026-09-23 12:00 |
05:00:52.21 |
-08:17:10.3 |
HIP 23262 |
22.91 |
| 2026-09-24 00:00 |
05:00:51.71 |
-08:17:24.2 |
HIP 23262 |
22.65 |
| 2026-09-24 12:00 |
05:00:51.19 |
-08:17:38.0 |
HIP 23262 |
22.39 |
| 2026-09-25 00:00 |
05:00:50.66 |
-08:17:51.9 |
HIP 23262 |
22.13 |
| 2026-09-25 12:00 |
05:00:50.12 |
-08:18:05.7 |
HIP 23262 |
21.87 |
| 2026-09-26 00:00 |
05:00:49.56 |
-08:18:19.5 |
HIP 23262 |
21.60 |
| 2026-09-26 12:00 |
05:00:48.98 |
-08:18:33.3 |
HIP 23262 |
21.34 |
| 2026-09-27 00:00 |
05:00:48.39 |
-08:18:47.1 |
HIP 23262 |
21.07 |
| 2026-09-27 12:00 |
05:00:47.79 |
-08:19:00.9 |
HIP 23262 |
20.80 |
| 2026-09-28 00:00 |
05:00:47.17 |
-08:19:14.6 |
HIP 23262 |
20.54 |
| 2026-09-28 12:00 |
05:00:46.53 |
-08:19:28.4 |
HIP 23262 |
20.27 |
| 2026-09-29 00:00 |
05:00:45.88 |
-08:19:42.1 |
HIP 23262 |
20.00 |
| 2026-09-29 12:00 |
05:00:45.22 |
-08:19:55.8 |
HIP 23262 |
19.73 |
| 2026-09-30 00:00 |
05:00:44.54 |
-08:20:09.5 |
HIP 23262 |
19.46 |
| 2026-09-30 12:00 |
05:00:43.85 |
-08:20:23.2 |
HIP 23262 |
19.19 |
| 2026-10-01 00:00 |
05:00:43.14 |
-08:20:36.8 |
HIP 23262 |
18.92 |
| 2026-10-01 12:00 |
05:00:42.42 |
-08:20:50.5 |
HIP 23262 |
18.65 |
| 2026-10-02 00:00 |
05:00:41.68 |
-08:21:04.1 |
HIP 23262 |
18.37 |
| 2026-10-02 12:00 |
05:00:40.93 |
-08:21:17.7 |
HIP 23262 |
18.10 |
| 2026-10-03 00:00 |
05:00:40.17 |
-08:21:31.2 |
HIP 23262 |
17.83 |
| 2026-10-03 12:00 |
05:00:39.39 |
-08:21:44.8 |
HIP 23262 |
17.56 |
| 2026-10-04 00:00 |
05:00:38.59 |
-08:21:58.3 |
HIP 23262 |
17.29 |
| 2026-10-04 12:00 |
05:00:37.78 |
-08:22:11.7 |
HIP 23262 |
17.02 |
| 2026-10-05 00:00 |
05:00:36.96 |
-08:22:25.2 |
HIP 23262 |
16.75 |
| 2026-10-05 12:00 |
05:00:36.12 |
-08:22:38.6 |
HIP 23262 |
16.48 |
| 2026-10-06 00:00 |
05:00:35.27 |
-08:22:52.0 |
HIP 23262 |
16.21 |
| 2026-10-06 12:00 |
05:00:34.41 |
-08:23:05.4 |
HIP 23262 |
15.94 |
| 2026-10-07 00:00 |
05:00:33.53 |
-08:23:18.7 |
HIP 23262 |
15.68 |
| 2026-10-07 12:00 |
05:00:32.63 |
-08:23:32.0 |
HIP 23262 |
15.41 |
| 2026-10-08 00:00 |
05:00:31.73 |
-08:23:45.3 |
HIP 23262 |
15.15 |
| 2026-10-08 12:00 |
05:00:30.80 |
-08:23:58.5 |
HIP 23262 |
14.89 |
| 2026-10-09 00:00 |
05:00:29.87 |
-08:24:11.7 |
HIP 23262 |
14.63 |
| 2026-10-09 12:00 |
05:00:28.92 |
-08:24:24.8 |
HIP 23262 |
14.37 |
| 2026-10-10 00:00 |
05:00:27.96 |
-08:24:37.9 |
HIP 23262 |
14.12 |
| 2026-10-10 12:00 |
05:00:26.98 |
-08:24:51.0 |
HIP 23262 |
13.87 |
| 2026-10-11 00:00 |
05:00:25.99 |
-08:25:04.0 |
HIP 23262 |
13.62 |