C/1980 Y1 (Bradfield)
Metadata
| Parameter | Value |
|---|---|
| Designation | C/1980 Y1 (Bradfield) |
| Type | C |
| Perihelion (tp_cal, UTC) | 1980-12-29T12:59:59.372160Z |
| Orbit solution date (soln_date, UTC) | 2021-04-15T23:29:29Z |
| Obs used | 32 |
| NEO | - |
| M1 | - |
| K1 | - |
| PC | 0.030 |
Osculating Elements
| Parameter | Value |
|---|---|
| Epoch (epoch_cal, TDB) | 1981-01-26.0000000 |
| e | 0.99972538 |
| q (au) | 0.259823 |
| a (au) | 946.110211 |
| i (deg) | 138.585179 |
| Ω (om, deg) | 115.351543 |
| ω (w, deg) | 358.294122 |
| M (ma, deg) | 0.000930 |
Magnitude
Scatter + Global Linear
$$ M_a = (7.110 + 2.589\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta $$ $$ \theta = 180^\circ - \alpha $$ $$ \Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b) $$ $$ \Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1 $$
Model Parameters
| Parameter | Value |
|---|---|
| H0 | 7.110 |
| n | 2.589 |
| gf | 0.800 |
| gb | -0.500 |
| k | 0.800 |
| δ90 | 1.000 |
| 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 |
|---|---|---|---|
| 1981-01-04 | 1981-01-13 | -4.7670 | -1.473 |
| 1981-01-13 | 1981-01-31 | +3.4551 | +0.349 |
| 1981-01-31 | 1981-08-27 | +10.1983 | +0.293 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) | RA (J2000) | Dec (J2000) | Nearest HIP | Dist from HIP (arcmin) |
|---|---|---|---|---|
| 2026-05-12 00:00 | 20:13:55.70 | -14:06:00.8 | HIP 99690 | 6.33 |
| 2026-05-12 12:00 | 20:13:55.13 | -14:06:00.4 | HIP 99690 | 6.28 |
| 2026-05-13 00:00 | 20:13:54.55 | -14:06:00.1 | HIP 99690 | 6.24 |
| 2026-05-13 12:00 | 20:13:53.96 | -14:05:59.8 | HIP 99690 | 6.19 |
| 2026-05-14 00:00 | 20:13:53.35 | -14:05:59.6 | HIP 99690 | 6.14 |
| 2026-05-14 12:00 | 20:13:52.73 | -14:05:59.5 | HIP 99690 | 6.09 |
| 2026-05-15 00:00 | 20:13:52.09 | -14:05:59.4 | HIP 99690 | 6.05 |
| 2026-05-15 12:00 | 20:13:51.45 | -14:05:59.3 | HIP 99690 | 6.01 |
| 2026-05-16 00:00 | 20:13:50.78 | -14:05:59.3 | HIP 99690 | 5.97 |
| 2026-05-16 12:00 | 20:13:50.11 | -14:05:59.4 | HIP 99690 | 5.93 |
| 2026-05-17 00:00 | 20:13:49.42 | -14:05:59.5 | HIP 99690 | 5.89 |
| 2026-05-17 12:00 | 20:13:48.72 | -14:05:59.6 | HIP 99690 | 5.86 |
| 2026-05-18 00:00 | 20:13:48.00 | -14:05:59.8 | HIP 99690 | 5.83 |
| 2026-05-18 12:00 | 20:13:47.28 | -14:06:00.1 | HIP 99690 | 5.81 |
| 2026-05-19 00:00 | 20:13:46.53 | -14:06:00.4 | HIP 99690 | 5.79 |
| 2026-05-19 12:00 | 20:13:45.78 | -14:06:00.7 | HIP 99690 | 5.77 |
| 2026-05-20 00:00 | 20:13:45.01 | -14:06:01.1 | HIP 99690 | 5.76 |
| 2026-05-20 12:00 | 20:13:44.23 | -14:06:01.6 | HIP 99690 | 5.76 |
| 2026-05-21 00:00 | 20:13:43.44 | -14:06:02.1 | HIP 99690 | 5.76 |
| 2026-05-21 12:00 | 20:13:42.64 | -14:06:02.7 | HIP 99690 | 5.76 |
| 2026-05-22 00:00 | 20:13:41.82 | -14:06:03.3 | HIP 99690 | 5.78 |
| 2026-05-22 12:00 | 20:13:40.99 | -14:06:03.9 | HIP 99690 | 5.80 |
| 2026-05-23 00:00 | 20:13:40.15 | -14:06:04.6 | HIP 99690 | 5.82 |
| 2026-05-23 12:00 | 20:13:39.29 | -14:06:05.4 | HIP 99690 | 5.85 |
| 2026-05-24 00:00 | 20:13:38.42 | -14:06:06.2 | HIP 99690 | 5.89 |
| 2026-05-24 12:00 | 20:13:37.54 | -14:06:07.1 | HIP 99690 | 5.94 |
| 2026-05-25 00:00 | 20:13:36.65 | -14:06:08.0 | HIP 99690 | 5.99 |
| 2026-05-25 12:00 | 20:13:35.74 | -14:06:09.0 | HIP 99690 | 6.05 |
| 2026-05-26 00:00 | 20:13:34.83 | -14:06:10.0 | HIP 99690 | 6.12 |
| 2026-05-26 12:00 | 20:13:33.90 | -14:06:11.1 | HIP 99690 | 6.20 |
| 2026-05-27 00:00 | 20:13:32.96 | -14:06:12.2 | HIP 99690 | 6.29 |
| 2026-05-27 12:00 | 20:13:32.01 | -14:06:13.4 | HIP 99690 | 6.38 |
| 2026-05-28 00:00 | 20:13:31.04 | -14:06:14.6 | HIP 99690 | 6.48 |
| 2026-05-28 12:00 | 20:13:30.07 | -14:06:15.8 | HIP 99690 | 6.59 |
| 2026-05-29 00:00 | 20:13:29.08 | -14:06:17.2 | HIP 99690 | 6.70 |
| 2026-05-29 12:00 | 20:13:28.08 | -14:06:18.5 | HIP 99690 | 6.83 |
| 2026-05-30 00:00 | 20:13:27.07 | -14:06:20.0 | HIP 99690 | 6.96 |
| 2026-05-30 12:00 | 20:13:26.04 | -14:06:21.4 | HIP 99690 | 7.10 |
| 2026-05-31 00:00 | 20:13:25.01 | -14:06:22.9 | HIP 99690 | 7.24 |
| 2026-05-31 12:00 | 20:13:23.97 | -14:06:24.5 | HIP 99690 | 7.39 |
| 2026-06-01 00:00 | 20:13:22.91 | -14:06:26.1 | HIP 99690 | 7.55 |
| 2026-06-01 12:00 | 20:13:21.84 | -14:06:27.8 | HIP 99690 | 7.72 |
| 2026-06-02 00:00 | 20:13:20.76 | -14:06:29.5 | HIP 99690 | 7.89 |