| 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 |
+11.1441 |
-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) |
| 2026-03-26 00:00 |
20:01:15.55 |
+10:59:40.9 |
HIP 98508 |
7.93 |
| 2026-03-26 12:00 |
20:01:16.17 |
+10:59:53.2 |
HIP 98508 |
8.02 |
| 2026-03-27 00:00 |
20:01:16.79 |
+11:00:05.5 |
HIP 98508 |
8.12 |
| 2026-03-27 12:00 |
20:01:17.39 |
+11:00:17.9 |
HIP 98508 |
8.22 |
| 2026-03-28 00:00 |
20:01:17.98 |
+11:00:30.2 |
HIP 98508 |
8.33 |
| 2026-03-28 12:00 |
20:01:18.56 |
+11:00:42.5 |
HIP 98508 |
8.43 |
| 2026-03-29 00:00 |
20:01:19.13 |
+11:00:54.9 |
HIP 98508 |
8.55 |
| 2026-03-29 12:00 |
20:01:19.68 |
+11:01:07.2 |
HIP 98508 |
8.66 |
| 2026-03-30 00:00 |
20:01:20.23 |
+11:01:19.5 |
HIP 98508 |
8.78 |
| 2026-03-30 12:00 |
20:01:20.76 |
+11:01:31.9 |
HIP 98508 |
8.89 |
| 2026-03-31 00:00 |
20:01:21.27 |
+11:01:44.3 |
HIP 98508 |
9.01 |
| 2026-03-31 12:00 |
20:01:21.78 |
+11:01:56.6 |
HIP 98508 |
9.14 |
| 2026-04-01 00:00 |
20:01:22.27 |
+11:02:09.0 |
HIP 98508 |
9.26 |
| 2026-04-01 12:00 |
20:01:22.75 |
+11:02:21.3 |
HIP 98508 |
9.39 |
| 2026-04-02 00:00 |
20:01:23.22 |
+11:02:33.7 |
HIP 98508 |
9.51 |
| 2026-04-02 12:00 |
20:01:23.68 |
+11:02:46.0 |
HIP 98508 |
9.64 |
| 2026-04-03 00:00 |
20:01:24.12 |
+11:02:58.4 |
HIP 98508 |
9.77 |
| 2026-04-03 12:00 |
20:01:24.55 |
+11:03:10.7 |
HIP 98508 |
9.90 |
| 2026-04-04 00:00 |
20:01:24.97 |
+11:03:23.1 |
HIP 98508 |
10.03 |
| 2026-04-04 12:00 |
20:01:25.38 |
+11:03:35.4 |
HIP 98508 |
10.16 |
| 2026-04-05 00:00 |
20:01:25.77 |
+11:03:47.8 |
HIP 98508 |
10.29 |
| 2026-04-05 12:00 |
20:01:26.15 |
+11:04:00.1 |
HIP 98508 |
10.42 |
| 2026-04-06 00:00 |
20:01:26.52 |
+11:04:12.4 |
HIP 98508 |
10.55 |
| 2026-04-06 12:00 |
20:01:26.88 |
+11:04:24.7 |
HIP 98508 |
10.68 |
| 2026-04-07 00:00 |
20:01:27.22 |
+11:04:37.0 |
HIP 98508 |
10.82 |
| 2026-04-07 12:00 |
20:01:27.55 |
+11:04:49.3 |
HIP 98508 |
10.95 |
| 2026-04-08 00:00 |
20:01:27.87 |
+11:05:01.6 |
HIP 98508 |
11.08 |
| 2026-04-08 12:00 |
20:01:28.18 |
+11:05:13.9 |
HIP 98508 |
11.21 |
| 2026-04-09 00:00 |
20:01:28.47 |
+11:05:26.1 |
HIP 98508 |
11.34 |
| 2026-04-09 12:00 |
20:01:28.75 |
+11:05:38.4 |
HIP 98508 |
11.47 |
| 2026-04-10 00:00 |
20:01:29.02 |
+11:05:50.6 |
HIP 98508 |
11.60 |
| 2026-04-10 12:00 |
20:01:29.27 |
+11:06:02.8 |
HIP 98508 |
11.73 |
| 2026-04-11 00:00 |
20:01:29.51 |
+11:06:15.0 |
HIP 98508 |
11.85 |
| 2026-04-11 12:00 |
20:01:29.74 |
+11:06:27.2 |
HIP 98508 |
11.98 |
| 2026-04-12 00:00 |
20:01:29.95 |
+11:06:39.3 |
HIP 98508 |
12.11 |
| 2026-04-12 12:00 |
20:01:30.16 |
+11:06:51.5 |
HIP 98508 |
12.24 |
| 2026-04-13 00:00 |
20:01:30.35 |
+11:07:03.6 |
HIP 98508 |
12.36 |
| 2026-04-13 12:00 |
20:01:30.52 |
+11:07:15.7 |
HIP 98508 |
12.48 |
| 2026-04-14 00:00 |
20:01:30.69 |
+11:07:27.8 |
HIP 98508 |
12.61 |
| 2026-04-14 12:00 |
20:01:30.84 |
+11:07:39.8 |
HIP 98508 |
12.73 |
| 2026-04-15 00:00 |
20:01:30.98 |
+11:07:51.8 |
HIP 98508 |
12.85 |
| 2026-04-15 12:00 |
20:01:31.10 |
+11:08:03.9 |
HIP 98508 |
12.97 |
| 2026-04-16 00:00 |
20:01:31.21 |
+11:08:15.8 |
HIP 98508 |
13.09 |