| Parameter |
Value |
| Designation |
C/1973 D1 (Kohoutek) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1973-06-07T04:20:15.918720Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:22Z |
| Obs used |
42 |
| NEO |
- |
| M1 |
9.700 |
| K1 |
18.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1973-04-20.0000000 |
| e |
0.99874973 |
| q (au) |
1.382021 |
| a (au) |
1105.378577 |
| i (deg) |
121.598063 |
| Ω (om, deg) |
164.817374 |
| ω (w, deg) |
74.859255 |
| M (ma, deg) |
359.998708 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.986 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.986 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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) |
| 2026-03-26 00:00 |
21:54:07.30 |
-63:32:45.2 |
HIP 108310 |
21.73 |
| 2026-03-26 12:00 |
21:54:09.83 |
-63:32:52.8 |
HIP 108310 |
21.60 |
| 2026-03-27 00:00 |
21:54:12.35 |
-63:33:00.6 |
HIP 108310 |
21.49 |
| 2026-03-27 12:00 |
21:54:14.86 |
-63:33:08.5 |
HIP 108310 |
21.37 |
| 2026-03-28 00:00 |
21:54:17.34 |
-63:33:16.6 |
HIP 108310 |
21.27 |
| 2026-03-28 12:00 |
21:54:19.81 |
-63:33:24.8 |
HIP 108310 |
21.17 |
| 2026-03-29 00:00 |
21:54:22.26 |
-63:33:33.2 |
HIP 108310 |
21.08 |
| 2026-03-29 12:00 |
21:54:24.69 |
-63:33:41.7 |
HIP 108310 |
21.00 |
| 2026-03-30 00:00 |
21:54:27.10 |
-63:33:50.3 |
HIP 108310 |
20.92 |
| 2026-03-30 12:00 |
21:54:29.50 |
-63:33:59.1 |
HIP 108310 |
20.85 |
| 2026-03-31 00:00 |
21:54:31.87 |
-63:34:08.1 |
HIP 108310 |
20.79 |
| 2026-03-31 12:00 |
21:54:34.23 |
-63:34:17.1 |
HIP 108310 |
20.74 |
| 2026-04-01 00:00 |
21:54:36.57 |
-63:34:26.3 |
HIP 108310 |
20.69 |
| 2026-04-01 12:00 |
21:54:38.89 |
-63:34:35.7 |
HIP 108310 |
20.65 |
| 2026-04-02 00:00 |
21:54:41.19 |
-63:34:45.1 |
HIP 108310 |
20.62 |
| 2026-04-02 12:00 |
21:54:43.47 |
-63:34:54.7 |
HIP 108310 |
20.60 |
| 2026-04-03 00:00 |
21:54:45.74 |
-63:35:04.5 |
HIP 108310 |
20.58 |
| 2026-04-03 12:00 |
21:54:47.98 |
-63:35:14.4 |
HIP 108310 |
20.57 |
| 2026-04-04 00:00 |
21:54:50.20 |
-63:35:24.4 |
HIP 108310 |
20.57 |
| 2026-04-04 12:00 |
21:54:52.40 |
-63:35:34.5 |
HIP 108310 |
20.58 |
| 2026-04-05 00:00 |
21:54:54.59 |
-63:35:44.8 |
HIP 108310 |
20.59 |
| 2026-04-05 12:00 |
21:54:56.75 |
-63:35:55.3 |
HIP 108310 |
20.61 |
| 2026-04-06 00:00 |
21:54:58.89 |
-63:36:05.8 |
HIP 108310 |
20.64 |
| 2026-04-06 12:00 |
21:55:01.02 |
-63:36:16.5 |
HIP 108310 |
20.67 |
| 2026-04-07 00:00 |
21:55:03.12 |
-63:36:27.3 |
HIP 108310 |
20.72 |
| 2026-04-07 12:00 |
21:55:05.20 |
-63:36:38.3 |
HIP 108310 |
20.77 |
| 2026-04-08 00:00 |
21:55:07.26 |
-63:36:49.3 |
HIP 108310 |
20.82 |
| 2026-04-08 12:00 |
21:55:09.30 |
-63:37:00.5 |
HIP 108310 |
20.89 |
| 2026-04-09 00:00 |
21:55:11.32 |
-63:37:11.9 |
HIP 108310 |
20.96 |
| 2026-04-09 12:00 |
21:55:13.31 |
-63:37:23.3 |
HIP 108310 |
21.04 |
| 2026-04-10 00:00 |
21:55:15.29 |
-63:37:34.9 |
HIP 108310 |
21.12 |
| 2026-04-10 12:00 |
21:55:17.24 |
-63:37:46.6 |
HIP 108310 |
21.21 |
| 2026-04-11 00:00 |
21:55:19.18 |
-63:37:58.5 |
HIP 108310 |
21.31 |
| 2026-04-11 12:00 |
21:55:21.09 |
-63:38:10.4 |
HIP 108310 |
21.41 |
| 2026-04-12 00:00 |
21:55:22.97 |
-63:38:22.5 |
HIP 108310 |
21.52 |
| 2026-04-12 12:00 |
21:55:24.84 |
-63:38:34.7 |
HIP 108310 |
21.64 |
| 2026-04-13 00:00 |
21:55:26.68 |
-63:38:47.1 |
HIP 108310 |
21.76 |
| 2026-04-13 12:00 |
21:55:28.50 |
-63:38:59.5 |
HIP 108310 |
21.89 |
| 2026-04-14 00:00 |
21:55:30.30 |
-63:39:12.1 |
HIP 108310 |
22.02 |
| 2026-04-14 12:00 |
21:55:32.08 |
-63:39:24.8 |
HIP 108310 |
22.16 |
| 2026-04-15 00:00 |
21:55:33.83 |
-63:39:37.6 |
HIP 108310 |
22.31 |
| 2026-04-15 12:00 |
21:55:35.56 |
-63:39:50.6 |
HIP 108310 |
22.46 |
| 2026-04-16 00:00 |
21:55:37.26 |
-63:40:03.6 |
HIP 108310 |
22.62 |