| Parameter |
Value |
| Designation |
C/1974 C1 (Bradfield) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1974-03-18T08:33:10.964160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:22Z |
| Obs used |
173 |
| NEO |
- |
| M1 |
8.600 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1974-04-20.0000000 |
| e |
0.99973403 |
| q (au) |
0.503190 |
| a (au) |
1891.926449 |
| i (deg) |
61.284581 |
| Ω (om, deg) |
143.733056 |
| ω (w, deg) |
333.133285 |
| M (ma, deg) |
0.000391 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.576 + 2.404\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.576 |
| n |
2.404 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
0.989 |
| 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 |
| 1974-02-14 |
1974-03-18 |
-1.9064 |
-0.077 |
| 1974-03-18 |
1974-04-08 |
-3.6784 |
-0.875 |
| 1974-04-08 |
1974-05-07 |
+1.3780 |
+0.127 |
| 1974-05-07 |
1974-06-13 |
-1.2851 |
+0.024 |
| 1974-06-13 |
1974-09-15 |
+11.1440 |
-3.135 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
19:56:05.11 |
+11:06:10.6 |
HIP 98103 |
19.38 |
| 2026-09-20 12:00 |
19:56:04.39 |
+11:05:58.0 |
HIP 98103 |
19.60 |
| 2026-09-21 00:00 |
19:56:03.68 |
+11:05:45.5 |
HIP 98103 |
19.83 |
| 2026-09-21 12:00 |
19:56:02.98 |
+11:05:32.9 |
HIP 98103 |
20.07 |
| 2026-09-22 00:00 |
19:56:02.29 |
+11:05:20.3 |
HIP 98103 |
20.30 |
| 2026-09-22 12:00 |
19:56:01.61 |
+11:05:07.6 |
HIP 98103 |
20.53 |
| 2026-09-23 00:00 |
19:56:00.95 |
+11:04:55.0 |
HIP 98103 |
20.76 |
| 2026-09-23 12:00 |
19:56:00.29 |
+11:04:42.3 |
HIP 98103 |
21.00 |
| 2026-09-24 00:00 |
19:55:59.65 |
+11:04:29.6 |
HIP 98103 |
21.23 |
| 2026-09-24 12:00 |
19:55:59.02 |
+11:04:17.0 |
HIP 98103 |
21.47 |
| 2026-09-25 00:00 |
19:55:58.40 |
+11:04:04.2 |
HIP 98103 |
21.70 |
| 2026-09-25 12:00 |
19:55:57.80 |
+11:03:51.5 |
HIP 98103 |
21.94 |
| 2026-09-26 00:00 |
19:55:57.20 |
+11:03:38.8 |
HIP 98103 |
22.17 |
| 2026-09-26 12:00 |
19:55:56.62 |
+11:03:26.1 |
HIP 98020 |
22.24 |
| 2026-09-27 00:00 |
19:55:56.05 |
+11:03:13.3 |
HIP 98020 |
21.98 |
| 2026-09-27 12:00 |
19:55:55.49 |
+11:03:00.6 |
HIP 98020 |
21.73 |
| 2026-09-28 00:00 |
19:55:54.95 |
+11:02:47.8 |
HIP 98020 |
21.48 |
| 2026-09-28 12:00 |
19:55:54.41 |
+11:02:35.0 |
HIP 98020 |
21.23 |
| 2026-09-29 00:00 |
19:55:53.89 |
+11:02:22.2 |
HIP 98020 |
20.98 |
| 2026-09-29 12:00 |
19:55:53.38 |
+11:02:09.5 |
HIP 98020 |
20.73 |
| 2026-09-30 00:00 |
19:55:52.88 |
+11:01:56.7 |
HIP 98020 |
20.49 |
| 2026-09-30 12:00 |
19:55:52.40 |
+11:01:43.9 |
HIP 98020 |
20.24 |
| 2026-10-01 00:00 |
19:55:51.93 |
+11:01:31.1 |
HIP 98020 |
20.00 |
| 2026-10-01 12:00 |
19:55:51.47 |
+11:01:18.3 |
HIP 98020 |
19.76 |
| 2026-10-02 00:00 |
19:55:51.02 |
+11:01:05.5 |
HIP 98020 |
19.52 |
| 2026-10-02 12:00 |
19:55:50.58 |
+11:00:52.7 |
HIP 98020 |
19.28 |
| 2026-10-03 00:00 |
19:55:50.16 |
+11:00:39.9 |
HIP 98020 |
19.05 |
| 2026-10-03 12:00 |
19:55:49.75 |
+11:00:27.1 |
HIP 98020 |
18.81 |
| 2026-10-04 00:00 |
19:55:49.35 |
+11:00:14.3 |
HIP 98020 |
18.58 |
| 2026-10-04 12:00 |
19:55:48.97 |
+11:00:01.5 |
HIP 98020 |
18.35 |
| 2026-10-05 00:00 |
19:55:48.59 |
+10:59:48.7 |
HIP 98020 |
18.12 |
| 2026-10-05 12:00 |
19:55:48.23 |
+10:59:35.9 |
HIP 98020 |
17.89 |
| 2026-10-06 00:00 |
19:55:47.89 |
+10:59:23.1 |
HIP 98020 |
17.66 |
| 2026-10-06 12:00 |
19:55:47.55 |
+10:59:10.4 |
HIP 98020 |
17.44 |
| 2026-10-07 00:00 |
19:55:47.23 |
+10:58:57.6 |
HIP 98020 |
17.22 |
| 2026-10-07 12:00 |
19:55:46.92 |
+10:58:44.8 |
HIP 98020 |
17.00 |
| 2026-10-08 00:00 |
19:55:46.63 |
+10:58:32.1 |
HIP 98020 |
16.78 |
| 2026-10-08 12:00 |
19:55:46.34 |
+10:58:19.4 |
HIP 98020 |
16.56 |
| 2026-10-09 00:00 |
19:55:46.08 |
+10:58:06.7 |
HIP 98020 |
16.35 |
| 2026-10-09 12:00 |
19:55:45.82 |
+10:57:54.0 |
HIP 98020 |
16.14 |
| 2026-10-10 00:00 |
19:55:45.57 |
+10:57:41.3 |
HIP 98020 |
15.93 |
| 2026-10-10 12:00 |
19:55:45.34 |
+10:57:28.6 |
HIP 98020 |
15.72 |
| 2026-10-11 00:00 |
19:55:45.13 |
+10:57:15.9 |
HIP 98020 |
15.52 |