| Parameter |
Value |
| Designation |
C/1979 Y1 (Bradfield) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1979-12-21T14:38:01.069440Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:29Z |
| Obs used |
127 |
| NEO |
- |
| M1 |
8.500 |
| K1 |
14.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1980-01-25.0000000 |
| e |
0.98803814 |
| q (au) |
0.545301 |
| a (au) |
45.586646 |
| i (deg) |
148.602533 |
| Ω (om, deg) |
103.215535 |
| ω (w, deg) |
257.609730 |
| M (ma, deg) |
0.110124 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.331 + 4.383\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.331 |
| n |
4.383 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 1979-12-26 |
1980-01-04 |
+1.4679 |
-0.064 |
| 1980-01-04 |
1980-01-25 |
+5.5414 |
+0.963 |
| 1980-01-25 |
1980-03-02 |
-4.9082 |
+0.307 |
| 1980-03-02 |
1980-03-17 |
-4.0819 |
-0.038 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
01:25:32.76 |
+41:01:43.4 |
HIP 6663 |
19.43 |
| 2026-07-29 12:00 |
01:25:32.17 |
+41:01:56.3 |
HIP 6663 |
19.21 |
| 2026-07-30 00:00 |
01:25:31.56 |
+41:02:09.1 |
HIP 6663 |
19.00 |
| 2026-07-30 12:00 |
01:25:30.93 |
+41:02:21.8 |
HIP 6663 |
18.78 |
| 2026-07-31 00:00 |
01:25:30.28 |
+41:02:34.4 |
HIP 6663 |
18.57 |
| 2026-07-31 12:00 |
01:25:29.61 |
+41:02:46.9 |
HIP 6663 |
18.37 |
| 2026-08-01 00:00 |
01:25:28.92 |
+41:02:59.3 |
HIP 6663 |
18.16 |
| 2026-08-01 12:00 |
01:25:28.21 |
+41:03:11.5 |
HIP 6663 |
17.96 |
| 2026-08-02 00:00 |
01:25:27.48 |
+41:03:23.7 |
HIP 6663 |
17.76 |
| 2026-08-02 12:00 |
01:25:26.73 |
+41:03:35.8 |
HIP 6663 |
17.57 |
| 2026-08-03 00:00 |
01:25:25.96 |
+41:03:47.7 |
HIP 6663 |
17.37 |
| 2026-08-03 12:00 |
01:25:25.17 |
+41:03:59.6 |
HIP 6663 |
17.18 |
| 2026-08-04 00:00 |
01:25:24.36 |
+41:04:11.3 |
HIP 6663 |
17.00 |
| 2026-08-04 12:00 |
01:25:23.53 |
+41:04:22.9 |
HIP 6663 |
16.82 |
| 2026-08-05 00:00 |
01:25:22.68 |
+41:04:34.5 |
HIP 6663 |
16.64 |
| 2026-08-05 12:00 |
01:25:21.82 |
+41:04:45.8 |
HIP 6663 |
16.47 |
| 2026-08-06 00:00 |
01:25:20.93 |
+41:04:57.1 |
HIP 6663 |
16.30 |
| 2026-08-06 12:00 |
01:25:20.02 |
+41:05:08.3 |
HIP 6663 |
16.13 |
| 2026-08-07 00:00 |
01:25:19.10 |
+41:05:19.3 |
HIP 6663 |
15.97 |
| 2026-08-07 12:00 |
01:25:18.15 |
+41:05:30.3 |
HIP 6663 |
15.82 |
| 2026-08-08 00:00 |
01:25:17.19 |
+41:05:41.1 |
HIP 6663 |
15.67 |
| 2026-08-08 12:00 |
01:25:16.20 |
+41:05:51.8 |
HIP 6663 |
15.52 |
| 2026-08-09 00:00 |
01:25:15.20 |
+41:06:02.3 |
HIP 6663 |
15.38 |
| 2026-08-09 12:00 |
01:25:14.18 |
+41:06:12.8 |
HIP 6663 |
15.25 |
| 2026-08-10 00:00 |
01:25:13.13 |
+41:06:23.1 |
HIP 6663 |
15.12 |
| 2026-08-10 12:00 |
01:25:12.07 |
+41:06:33.3 |
HIP 6663 |
15.00 |
| 2026-08-11 00:00 |
01:25:10.99 |
+41:06:43.3 |
HIP 6663 |
14.89 |
| 2026-08-11 12:00 |
01:25:09.89 |
+41:06:53.3 |
HIP 6663 |
14.78 |
| 2026-08-12 00:00 |
01:25:08.78 |
+41:07:03.1 |
HIP 6663 |
14.68 |
| 2026-08-12 12:00 |
01:25:07.64 |
+41:07:12.8 |
HIP 6663 |
14.59 |
| 2026-08-13 00:00 |
01:25:06.48 |
+41:07:22.4 |
HIP 6663 |
14.50 |
| 2026-08-13 12:00 |
01:25:05.31 |
+41:07:31.8 |
HIP 6663 |
14.42 |
| 2026-08-14 00:00 |
01:25:04.11 |
+41:07:41.1 |
HIP 6663 |
14.35 |
| 2026-08-14 12:00 |
01:25:02.90 |
+41:07:50.3 |
HIP 6663 |
14.29 |
| 2026-08-15 00:00 |
01:25:01.67 |
+41:07:59.3 |
HIP 6663 |
14.24 |
| 2026-08-15 12:00 |
01:25:00.42 |
+41:08:08.2 |
HIP 6663 |
14.19 |
| 2026-08-16 00:00 |
01:24:59.16 |
+41:08:17.0 |
HIP 6663 |
14.16 |
| 2026-08-16 12:00 |
01:24:57.87 |
+41:08:25.6 |
HIP 6663 |
14.13 |
| 2026-08-17 00:00 |
01:24:56.57 |
+41:08:34.1 |
HIP 6663 |
14.11 |
| 2026-08-17 12:00 |
01:24:55.25 |
+41:08:42.5 |
HIP 6663 |
14.10 |
| 2026-08-18 00:00 |
01:24:53.91 |
+41:08:50.7 |
HIP 6663 |
14.10 |
| 2026-08-18 12:00 |
01:24:52.55 |
+41:08:58.8 |
HIP 6663 |
14.11 |
| 2026-08-19 00:00 |
01:24:51.17 |
+41:09:06.8 |
HIP 6663 |
14.13 |