| 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) |
| 2026-05-12 00:00 |
15:07:49.86 |
-02:56:15.2 |
HIP 73972 |
40.33 |
| 2026-05-12 12:00 |
15:07:48.38 |
-02:56:09.4 |
HIP 73972 |
40.13 |
| 2026-05-13 00:00 |
15:07:46.89 |
-02:56:03.7 |
HIP 73972 |
39.93 |
| 2026-05-13 12:00 |
15:07:45.41 |
-02:55:58.0 |
HIP 73972 |
39.73 |
| 2026-05-14 00:00 |
15:07:43.92 |
-02:55:52.4 |
HIP 73972 |
39.54 |
| 2026-05-14 12:00 |
15:07:42.44 |
-02:55:46.8 |
HIP 73972 |
39.35 |
| 2026-05-15 00:00 |
15:07:40.96 |
-02:55:41.3 |
HIP 73972 |
39.16 |
| 2026-05-15 12:00 |
15:07:39.48 |
-02:55:35.8 |
HIP 73972 |
38.98 |
| 2026-05-16 00:00 |
15:07:38.00 |
-02:55:30.4 |
HIP 73972 |
38.80 |
| 2026-05-16 12:00 |
15:07:36.52 |
-02:55:25.0 |
HIP 73972 |
38.63 |
| 2026-05-17 00:00 |
15:07:35.04 |
-02:55:19.7 |
HIP 73972 |
38.46 |
| 2026-05-17 12:00 |
15:07:33.57 |
-02:55:14.5 |
HIP 73972 |
38.29 |
| 2026-05-18 00:00 |
15:07:32.09 |
-02:55:09.3 |
HIP 73972 |
38.13 |
| 2026-05-18 12:00 |
15:07:30.62 |
-02:55:04.2 |
HIP 73972 |
37.97 |
| 2026-05-19 00:00 |
15:07:29.15 |
-02:54:59.1 |
HIP 73972 |
37.82 |
| 2026-05-19 12:00 |
15:07:27.68 |
-02:54:54.1 |
HIP 73972 |
37.67 |
| 2026-05-20 00:00 |
15:07:26.22 |
-02:54:49.1 |
HIP 73972 |
37.52 |
| 2026-05-20 12:00 |
15:07:24.75 |
-02:54:44.2 |
HIP 73972 |
37.38 |
| 2026-05-21 00:00 |
15:07:23.29 |
-02:54:39.4 |
HIP 73972 |
37.24 |
| 2026-05-21 12:00 |
15:07:21.83 |
-02:54:34.6 |
HIP 73972 |
37.11 |
| 2026-05-22 00:00 |
15:07:20.38 |
-02:54:29.9 |
HIP 73972 |
36.98 |
| 2026-05-22 12:00 |
15:07:18.92 |
-02:54:25.3 |
HIP 73972 |
36.86 |
| 2026-05-23 00:00 |
15:07:17.47 |
-02:54:20.7 |
HIP 73972 |
36.74 |
| 2026-05-23 12:00 |
15:07:16.02 |
-02:54:16.1 |
HIP 73972 |
36.62 |
| 2026-05-24 00:00 |
15:07:14.58 |
-02:54:11.7 |
HIP 73972 |
36.51 |
| 2026-05-24 12:00 |
15:07:13.14 |
-02:54:07.2 |
HIP 73972 |
36.41 |
| 2026-05-25 00:00 |
15:07:11.70 |
-02:54:02.9 |
HIP 73972 |
36.30 |
| 2026-05-25 12:00 |
15:07:10.26 |
-02:53:58.6 |
HIP 73972 |
36.21 |
| 2026-05-26 00:00 |
15:07:08.83 |
-02:53:54.4 |
HIP 73972 |
36.11 |
| 2026-05-26 12:00 |
15:07:07.40 |
-02:53:50.2 |
HIP 73972 |
36.03 |
| 2026-05-27 00:00 |
15:07:05.98 |
-02:53:46.1 |
HIP 73972 |
35.94 |
| 2026-05-27 12:00 |
15:07:04.56 |
-02:53:42.1 |
HIP 73972 |
35.86 |
| 2026-05-28 00:00 |
15:07:03.14 |
-02:53:38.1 |
HIP 73972 |
35.79 |
| 2026-05-28 12:00 |
15:07:01.72 |
-02:53:34.2 |
HIP 73972 |
35.72 |
| 2026-05-29 00:00 |
15:07:00.31 |
-02:53:30.3 |
HIP 73972 |
35.65 |
| 2026-05-29 12:00 |
15:06:58.91 |
-02:53:26.6 |
HIP 73972 |
35.59 |
| 2026-05-30 00:00 |
15:06:57.51 |
-02:53:22.8 |
HIP 73972 |
35.54 |
| 2026-05-30 12:00 |
15:06:56.11 |
-02:53:19.2 |
HIP 73972 |
35.48 |
| 2026-05-31 00:00 |
15:06:54.72 |
-02:53:15.6 |
HIP 73972 |
35.44 |
| 2026-05-31 12:00 |
15:06:53.33 |
-02:53:12.1 |
HIP 73972 |
35.39 |
| 2026-06-01 00:00 |
15:06:51.95 |
-02:53:08.6 |
HIP 73972 |
35.35 |
| 2026-06-01 12:00 |
15:06:50.57 |
-02:53:05.2 |
HIP 73972 |
35.32 |
| 2026-06-02 00:00 |
15:06:49.19 |
-02:53:01.9 |
HIP 73972 |
35.29 |