C/1973 E1 (Kohoutek)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/1973 E1 (Kohoutek) |
| Type | C |
| Perihelion (tp_cal, UTC) | 1973-12-28T10:20:11.054400Z |
| Orbit solution date (soln_date, UTC) | 2021-04-15T23:29:22Z |
| Obs used | 812 |
| NEO | - |
| M1 | 5.800 |
| K1 | 9.000 |
| PC | 0.030 |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 1973-12-06.0000000 |
| e | 1.00000781 |
| q (au) | 0.142425 |
| a (au) | -18236.507048 |
| i (deg) | 14.304145 |
| Ω (om, deg) | 258.489491 |
| ω (w, deg) | 37.797569 |
| M (ma, deg) | -0.000009 |
Magnitude
Scatter + Global Linear
$$ M_a = (6.623 + 3.235\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 6.623 |
| n | 3.235 |
| gf | 0.800 |
| gb | -0.633 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) | End (UTC) | a | b |
|---|---|---|---|
| 1973-01-28 | 1973-05-13 | +16.7992 | -9.089 |
| 1973-05-13 | 1973-10-27 | +2.0895 | -0.432 |
| 1973-10-27 | 1973-12-11 | +1.8010 | -0.605 |
| 1973-12-11 | 1973-12-22 | -4.2228 | -1.803 |
| 1974-01-03 | 1974-01-31 | -1.4588 | -0.127 |
| 1974-01-31 | 1974-02-24 | +4.7312 | +0.049 |
| 1974-02-24 | 1974-03-23 | +12.3726 | -1.280 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-03-26 00:00 | 07:21:36.34 | +14:18:26.0 | HIP 35772 | 16.67 |
| 2026-03-26 12:00 | 07:21:35.96 | +14:18:29.8 | HIP 35772 | 16.76 |
| 2026-03-27 00:00 | 07:21:35.60 | +14:18:33.5 | HIP 35772 | 16.85 |
| 2026-03-27 12:00 | 07:21:35.25 | +14:18:37.2 | HIP 35772 | 16.94 |
| 2026-03-28 00:00 | 07:21:34.91 | +14:18:40.8 | HIP 35772 | 17.03 |
| 2026-03-28 12:00 | 07:21:34.59 | +14:18:44.5 | HIP 35772 | 17.11 |
| 2026-03-29 00:00 | 07:21:34.28 | +14:18:48.1 | HIP 35772 | 17.19 |
| 2026-03-29 12:00 | 07:21:33.98 | +14:18:51.7 | HIP 35772 | 17.27 |
| 2026-03-30 00:00 | 07:21:33.69 | +14:18:55.3 | HIP 35772 | 17.35 |
| 2026-03-30 12:00 | 07:21:33.42 | +14:18:58.8 | HIP 35772 | 17.42 |
| 2026-03-31 00:00 | 07:21:33.16 | +14:19:02.3 | HIP 35772 | 17.49 |
| 2026-03-31 12:00 | 07:21:32.92 | +14:19:05.8 | HIP 35772 | 17.55 |
| 2026-04-01 00:00 | 07:21:32.69 | +14:19:09.3 | HIP 35772 | 17.61 |
| 2026-04-01 12:00 | 07:21:32.47 | +14:19:12.8 | HIP 35772 | 17.67 |
| 2026-04-02 00:00 | 07:21:32.26 | +14:19:16.2 | HIP 35772 | 17.73 |
| 2026-04-02 12:00 | 07:21:32.07 | +14:19:19.6 | HIP 35772 | 17.78 |
| 2026-04-03 00:00 | 07:21:31.89 | +14:19:23.0 | HIP 35772 | 17.83 |
| 2026-04-03 12:00 | 07:21:31.73 | +14:19:26.4 | HIP 35772 | 17.88 |
| 2026-04-04 00:00 | 07:21:31.57 | +14:19:29.7 | HIP 35772 | 17.92 |
| 2026-04-04 12:00 | 07:21:31.43 | +14:19:33.0 | HIP 35772 | 17.96 |
| 2026-04-05 00:00 | 07:21:31.31 | +14:19:36.3 | HIP 35772 | 18.00 |
| 2026-04-05 12:00 | 07:21:31.20 | +14:19:39.6 | HIP 35772 | 18.03 |
| 2026-04-06 00:00 | 07:21:31.10 | +14:19:42.8 | HIP 35772 | 18.06 |
| 2026-04-06 12:00 | 07:21:31.01 | +14:19:46.0 | HIP 35772 | 18.09 |
| 2026-04-07 00:00 | 07:21:30.94 | +14:19:49.2 | HIP 35772 | 18.11 |
| 2026-04-07 12:00 | 07:21:30.88 | +14:19:52.4 | HIP 35772 | 18.14 |
| 2026-04-08 00:00 | 07:21:30.83 | +14:19:55.5 | HIP 35772 | 18.16 |
| 2026-04-08 12:00 | 07:21:30.80 | +14:19:58.6 | HIP 35772 | 18.17 |
| 2026-04-09 00:00 | 07:21:30.78 | +14:20:01.7 | HIP 35772 | 18.18 |
| 2026-04-09 12:00 | 07:21:30.77 | +14:20:04.7 | HIP 35772 | 18.19 |
| 2026-04-10 00:00 | 07:21:30.78 | +14:20:07.8 | HIP 35772 | 18.20 |
| 2026-04-10 12:00 | 07:21:30.80 | +14:20:10.7 | HIP 35772 | 18.20 |
| 2026-04-11 00:00 | 07:21:30.83 | +14:20:13.7 | HIP 35772 | 18.20 |
| 2026-04-11 12:00 | 07:21:30.88 | +14:20:16.6 | HIP 35772 | 18.20 |
| 2026-04-12 00:00 | 07:21:30.94 | +14:20:19.6 | HIP 35772 | 18.19 |
| 2026-04-12 12:00 | 07:21:31.01 | +14:20:22.4 | HIP 35772 | 18.18 |
| 2026-04-13 00:00 | 07:21:31.10 | +14:20:25.3 | HIP 35772 | 18.17 |
| 2026-04-13 12:00 | 07:21:31.20 | +14:20:28.1 | HIP 35772 | 18.16 |
| 2026-04-14 00:00 | 07:21:31.31 | +14:20:30.9 | HIP 35772 | 18.14 |
| 2026-04-14 12:00 | 07:21:31.44 | +14:20:33.7 | HIP 35772 | 18.12 |
| 2026-04-15 00:00 | 07:21:31.57 | +14:20:36.4 | HIP 35772 | 18.09 |
| 2026-04-15 12:00 | 07:21:31.73 | +14:20:39.1 | HIP 35772 | 18.06 |
| 2026-04-16 00:00 | 07:21:31.89 | +14:20:41.8 | HIP 35772 | 18.03 |