| Parameter |
Value |
| Designation |
C/1932 Y1 (Dodwell-Forbes) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1932-12-30T12:36:55.002240Z |
| Orbit solution date (soln_date, UTC) |
2023-12-04T20:32:29Z |
| Obs used |
23 |
| NEO |
- |
| M1 |
9.100 |
| K1 |
15.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1933-01-20.0000000 |
| e |
0.97216017 |
| q (au) |
1.130765 |
| a (au) |
40.616795 |
| i (deg) |
24.502460 |
| Ω (om, deg) |
78.589152 |
| ω (w, deg) |
327.357273 |
| M (ma, deg) |
0.077957 |
Magnitude
Scatter + Global Linear
$$
M_a = (7.943 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
7.943 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
15:05:42.29 |
-03:06:43.7 |
HIP 73708 |
29.84 |
| 2026-09-20 12:00 |
15:05:43.25 |
-03:06:52.3 |
HIP 73708 |
30.12 |
| 2026-09-21 00:00 |
15:05:44.22 |
-03:07:00.9 |
HIP 73708 |
30.40 |
| 2026-09-21 12:00 |
15:05:45.19 |
-03:07:09.5 |
HIP 73708 |
30.68 |
| 2026-09-22 00:00 |
15:05:46.18 |
-03:07:18.1 |
HIP 73708 |
30.97 |
| 2026-09-22 12:00 |
15:05:47.18 |
-03:07:26.7 |
HIP 73708 |
31.25 |
| 2026-09-23 00:00 |
15:05:48.18 |
-03:07:35.3 |
HIP 73708 |
31.54 |
| 2026-09-23 12:00 |
15:05:49.20 |
-03:07:44.0 |
HIP 73708 |
31.83 |
| 2026-09-24 00:00 |
15:05:50.23 |
-03:07:52.6 |
HIP 73708 |
32.13 |
| 2026-09-24 12:00 |
15:05:51.26 |
-03:08:01.2 |
HIP 73708 |
32.42 |
| 2026-09-25 00:00 |
15:05:52.30 |
-03:08:09.9 |
HIP 73708 |
32.72 |
| 2026-09-25 12:00 |
15:05:53.36 |
-03:08:18.5 |
HIP 73708 |
33.02 |
| 2026-09-26 00:00 |
15:05:54.42 |
-03:08:27.2 |
HIP 73708 |
33.32 |
| 2026-09-26 12:00 |
15:05:55.49 |
-03:08:35.8 |
HIP 73708 |
33.62 |
| 2026-09-27 00:00 |
15:05:56.57 |
-03:08:44.5 |
HIP 73708 |
33.93 |
| 2026-09-27 12:00 |
15:05:57.66 |
-03:08:53.1 |
HIP 73708 |
34.24 |
| 2026-09-28 00:00 |
15:05:58.76 |
-03:09:01.8 |
HIP 73708 |
34.55 |
| 2026-09-28 12:00 |
15:05:59.86 |
-03:09:10.4 |
HIP 73708 |
34.86 |
| 2026-09-29 00:00 |
15:06:00.98 |
-03:09:19.1 |
HIP 73708 |
35.17 |
| 2026-09-29 12:00 |
15:06:02.10 |
-03:09:27.7 |
HIP 73708 |
35.48 |
| 2026-09-30 00:00 |
15:06:03.23 |
-03:09:36.4 |
HIP 73708 |
35.80 |
| 2026-09-30 12:00 |
15:06:04.37 |
-03:09:45.0 |
HIP 73708 |
36.12 |
| 2026-10-01 00:00 |
15:06:05.52 |
-03:09:53.7 |
HIP 73912 |
36.30 |
| 2026-10-01 12:00 |
15:06:06.68 |
-03:10:02.3 |
HIP 73912 |
36.13 |
| 2026-10-02 00:00 |
15:06:07.85 |
-03:10:11.0 |
HIP 73912 |
35.96 |
| 2026-10-02 12:00 |
15:06:09.02 |
-03:10:19.6 |
HIP 73912 |
35.80 |
| 2026-10-03 00:00 |
15:06:10.20 |
-03:10:28.3 |
HIP 73912 |
35.64 |
| 2026-10-03 12:00 |
15:06:11.39 |
-03:10:36.9 |
HIP 73912 |
35.48 |
| 2026-10-04 00:00 |
15:06:12.59 |
-03:10:45.5 |
HIP 73912 |
35.33 |
| 2026-10-04 12:00 |
15:06:13.79 |
-03:10:54.1 |
HIP 73912 |
35.17 |
| 2026-10-05 00:00 |
15:06:15.01 |
-03:11:02.8 |
HIP 73912 |
35.02 |
| 2026-10-05 12:00 |
15:06:16.23 |
-03:11:11.4 |
HIP 73912 |
34.87 |
| 2026-10-06 00:00 |
15:06:17.46 |
-03:11:20.0 |
HIP 73912 |
34.73 |
| 2026-10-06 12:00 |
15:06:18.70 |
-03:11:28.6 |
HIP 73912 |
34.59 |
| 2026-10-07 00:00 |
15:06:19.94 |
-03:11:37.1 |
HIP 73912 |
34.45 |
| 2026-10-07 12:00 |
15:06:21.19 |
-03:11:45.7 |
HIP 73912 |
34.31 |
| 2026-10-08 00:00 |
15:06:22.45 |
-03:11:54.3 |
HIP 73912 |
34.18 |
| 2026-10-08 12:00 |
15:06:23.72 |
-03:12:02.8 |
HIP 73912 |
34.05 |
| 2026-10-09 00:00 |
15:06:24.99 |
-03:12:11.3 |
HIP 73912 |
33.92 |
| 2026-10-09 12:00 |
15:06:26.27 |
-03:12:19.9 |
HIP 73912 |
33.80 |
| 2026-10-10 00:00 |
15:06:27.56 |
-03:12:28.4 |
HIP 73912 |
33.68 |
| 2026-10-10 12:00 |
15:06:28.85 |
-03:12:36.9 |
HIP 73912 |
33.56 |
| 2026-10-11 00:00 |
15:06:30.15 |
-03:12:45.4 |
HIP 73912 |
33.45 |