| Parameter |
Value |
| Designation |
C/1961 T1 (Seki) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1961-10-10T15:34:49.782720Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:14Z |
| Obs used |
15 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1961-11-12.0000000 |
| e |
0.99215002 |
| q (au) |
0.681202 |
| a (au) |
86.777590 |
| i (deg) |
155.712858 |
| Ω (om, deg) |
247.357198 |
| ω (w, deg) |
126.592481 |
| M (ma, deg) |
0.039444 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.055 + 4.579\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.055 |
| n |
4.579 |
| gf |
0.800 |
| 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) |
| 2026-05-12 00:00 |
21:03:38.71 |
-38:43:43.0 |
HIP 103882 |
9.87 |
| 2026-05-12 12:00 |
21:03:38.46 |
-38:43:52.0 |
HIP 103882 |
9.92 |
| 2026-05-13 00:00 |
21:03:38.19 |
-38:44:01.1 |
HIP 103882 |
9.97 |
| 2026-05-13 12:00 |
21:03:37.91 |
-38:44:10.1 |
HIP 103882 |
10.02 |
| 2026-05-14 00:00 |
21:03:37.61 |
-38:44:19.3 |
HIP 103882 |
10.07 |
| 2026-05-14 12:00 |
21:03:37.30 |
-38:44:28.4 |
HIP 103882 |
10.12 |
| 2026-05-15 00:00 |
21:03:36.97 |
-38:44:37.6 |
HIP 103882 |
10.18 |
| 2026-05-15 12:00 |
21:03:36.63 |
-38:44:46.8 |
HIP 103882 |
10.23 |
| 2026-05-16 00:00 |
21:03:36.27 |
-38:44:56.1 |
HIP 103882 |
10.28 |
| 2026-05-16 12:00 |
21:03:35.89 |
-38:45:05.4 |
HIP 103882 |
10.34 |
| 2026-05-17 00:00 |
21:03:35.50 |
-38:45:14.8 |
HIP 103882 |
10.39 |
| 2026-05-17 12:00 |
21:03:35.10 |
-38:45:24.1 |
HIP 103882 |
10.45 |
| 2026-05-18 00:00 |
21:03:34.68 |
-38:45:33.5 |
HIP 103882 |
10.51 |
| 2026-05-18 12:00 |
21:03:34.24 |
-38:45:43.0 |
HIP 103882 |
10.57 |
| 2026-05-19 00:00 |
21:03:33.79 |
-38:45:52.5 |
HIP 103882 |
10.63 |
| 2026-05-19 12:00 |
21:03:33.33 |
-38:46:02.0 |
HIP 103882 |
10.69 |
| 2026-05-20 00:00 |
21:03:32.84 |
-38:46:11.5 |
HIP 103882 |
10.75 |
| 2026-05-20 12:00 |
21:03:32.35 |
-38:46:21.1 |
HIP 103882 |
10.81 |
| 2026-05-21 00:00 |
21:03:31.84 |
-38:46:30.7 |
HIP 103882 |
10.88 |
| 2026-05-21 12:00 |
21:03:31.31 |
-38:46:40.3 |
HIP 103882 |
10.94 |
| 2026-05-22 00:00 |
21:03:30.77 |
-38:46:50.0 |
HIP 103882 |
11.01 |
| 2026-05-22 12:00 |
21:03:30.21 |
-38:46:59.7 |
HIP 103882 |
11.08 |
| 2026-05-23 00:00 |
21:03:29.64 |
-38:47:09.4 |
HIP 103882 |
11.15 |
| 2026-05-23 12:00 |
21:03:29.06 |
-38:47:19.2 |
HIP 103882 |
11.23 |
| 2026-05-24 00:00 |
21:03:28.46 |
-38:47:28.9 |
HIP 103882 |
11.30 |
| 2026-05-24 12:00 |
21:03:27.84 |
-38:47:38.7 |
HIP 103882 |
11.38 |
| 2026-05-25 00:00 |
21:03:27.21 |
-38:47:48.5 |
HIP 103882 |
11.46 |
| 2026-05-25 12:00 |
21:03:26.57 |
-38:47:58.4 |
HIP 103882 |
11.54 |
| 2026-05-26 00:00 |
21:03:25.91 |
-38:48:08.2 |
HIP 103882 |
11.62 |
| 2026-05-26 12:00 |
21:03:25.23 |
-38:48:18.1 |
HIP 103882 |
11.71 |
| 2026-05-27 00:00 |
21:03:24.54 |
-38:48:28.0 |
HIP 103882 |
11.80 |
| 2026-05-27 12:00 |
21:03:23.84 |
-38:48:38.0 |
HIP 103882 |
11.89 |
| 2026-05-28 00:00 |
21:03:23.12 |
-38:48:47.9 |
HIP 103882 |
11.98 |
| 2026-05-28 12:00 |
21:03:22.39 |
-38:48:57.9 |
HIP 103882 |
12.07 |
| 2026-05-29 00:00 |
21:03:21.65 |
-38:49:07.9 |
HIP 103882 |
12.17 |
| 2026-05-29 12:00 |
21:03:20.89 |
-38:49:17.9 |
HIP 103882 |
12.27 |
| 2026-05-30 00:00 |
21:03:20.11 |
-38:49:27.9 |
HIP 103882 |
12.37 |
| 2026-05-30 12:00 |
21:03:19.33 |
-38:49:37.9 |
HIP 103882 |
12.48 |
| 2026-05-31 00:00 |
21:03:18.52 |
-38:49:48.0 |
HIP 103832 |
12.54 |
| 2026-05-31 12:00 |
21:03:17.71 |
-38:49:58.1 |
HIP 103832 |
12.31 |
| 2026-06-01 00:00 |
21:03:16.88 |
-38:50:08.1 |
HIP 103832 |
12.08 |
| 2026-06-01 12:00 |
21:03:16.03 |
-38:50:18.2 |
HIP 103832 |
11.85 |
| 2026-06-02 00:00 |
21:03:15.18 |
-38:50:28.3 |
HIP 103832 |
11.62 |