| Parameter |
Value |
| Designation |
C/1965 S2 (Alcock) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1965-10-26T03:16:48.961920Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:17Z |
| Obs used |
29 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1965-10-11.0000000 |
| e |
1.00034477 |
| q (au) |
1.293959 |
| a (au) |
-3753.106898 |
| i (deg) |
65.010799 |
| Ω (om, deg) |
175.619427 |
| ω (w, deg) |
150.520426 |
| M (ma, deg) |
-0.000065 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.066 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.066 |
| n |
6.000 |
| gf |
1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
09:21:51.54 |
-26:01:18.1 |
HIP 45902 |
5.98 |
| 2026-03-26 12:00 |
09:21:50.54 |
-26:01:04.5 |
HIP 45902 |
5.66 |
| 2026-03-27 00:00 |
09:21:49.54 |
-26:00:50.7 |
HIP 45902 |
5.35 |
| 2026-03-27 12:00 |
09:21:48.56 |
-26:00:37.0 |
HIP 45902 |
5.04 |
| 2026-03-28 00:00 |
09:21:47.59 |
-26:00:23.1 |
HIP 45902 |
4.73 |
| 2026-03-28 12:00 |
09:21:46.62 |
-26:00:09.3 |
HIP 45902 |
4.43 |
| 2026-03-29 00:00 |
09:21:45.67 |
-25:59:55.4 |
HIP 45902 |
4.13 |
| 2026-03-29 12:00 |
09:21:44.73 |
-25:59:41.4 |
HIP 45902 |
3.83 |
| 2026-03-30 00:00 |
09:21:43.79 |
-25:59:27.4 |
HIP 45902 |
3.54 |
| 2026-03-30 12:00 |
09:21:42.87 |
-25:59:13.4 |
HIP 45902 |
3.25 |
| 2026-03-31 00:00 |
09:21:41.96 |
-25:58:59.3 |
HIP 45902 |
2.97 |
| 2026-03-31 12:00 |
09:21:41.05 |
-25:58:45.2 |
HIP 45902 |
2.70 |
| 2026-04-01 00:00 |
09:21:40.16 |
-25:58:31.0 |
HIP 45902 |
2.45 |
| 2026-04-01 12:00 |
09:21:39.28 |
-25:58:16.8 |
HIP 45902 |
2.20 |
| 2026-04-02 00:00 |
09:21:38.41 |
-25:58:02.6 |
HIP 45902 |
1.98 |
| 2026-04-02 12:00 |
09:21:37.54 |
-25:57:48.3 |
HIP 45902 |
1.79 |
| 2026-04-03 00:00 |
09:21:36.69 |
-25:57:34.0 |
HIP 45902 |
1.63 |
| 2026-04-03 12:00 |
09:21:35.85 |
-25:57:19.7 |
HIP 45902 |
1.53 |
| 2026-04-04 00:00 |
09:21:35.02 |
-25:57:05.3 |
HIP 45902 |
1.48 |
| 2026-04-04 12:00 |
09:21:34.20 |
-25:56:51.0 |
HIP 45902 |
1.49 |
| 2026-04-05 00:00 |
09:21:33.40 |
-25:56:36.5 |
HIP 45902 |
1.57 |
| 2026-04-05 12:00 |
09:21:32.60 |
-25:56:22.1 |
HIP 45902 |
1.70 |
| 2026-04-06 00:00 |
09:21:31.81 |
-25:56:07.6 |
HIP 45902 |
1.87 |
| 2026-04-06 12:00 |
09:21:31.04 |
-25:55:53.1 |
HIP 45902 |
2.07 |
| 2026-04-07 00:00 |
09:21:30.27 |
-25:55:38.6 |
HIP 45902 |
2.29 |
| 2026-04-07 12:00 |
09:21:29.52 |
-25:55:24.0 |
HIP 45902 |
2.53 |
| 2026-04-08 00:00 |
09:21:28.77 |
-25:55:09.4 |
HIP 45902 |
2.77 |
| 2026-04-08 12:00 |
09:21:28.04 |
-25:54:54.8 |
HIP 45902 |
3.03 |
| 2026-04-09 00:00 |
09:21:27.32 |
-25:54:40.2 |
HIP 45902 |
3.30 |
| 2026-04-09 12:00 |
09:21:26.61 |
-25:54:25.5 |
HIP 45902 |
3.56 |
| 2026-04-10 00:00 |
09:21:25.91 |
-25:54:10.9 |
HIP 45902 |
3.83 |
| 2026-04-10 12:00 |
09:21:25.23 |
-25:53:56.2 |
HIP 45902 |
4.11 |
| 2026-04-11 00:00 |
09:21:24.55 |
-25:53:41.5 |
HIP 45902 |
4.38 |
| 2026-04-11 12:00 |
09:21:23.89 |
-25:53:26.7 |
HIP 45902 |
4.66 |
| 2026-04-12 00:00 |
09:21:23.23 |
-25:53:12.0 |
HIP 45902 |
4.94 |
| 2026-04-12 12:00 |
09:21:22.59 |
-25:52:57.3 |
HIP 45902 |
5.21 |
| 2026-04-13 00:00 |
09:21:21.96 |
-25:52:42.5 |
HIP 45902 |
5.49 |
| 2026-04-13 12:00 |
09:21:21.35 |
-25:52:27.7 |
HIP 45902 |
5.77 |
| 2026-04-14 00:00 |
09:21:20.74 |
-25:52:12.9 |
HIP 45902 |
6.05 |
| 2026-04-14 12:00 |
09:21:20.15 |
-25:51:58.1 |
HIP 45902 |
6.32 |
| 2026-04-15 00:00 |
09:21:19.56 |
-25:51:43.3 |
HIP 45902 |
6.60 |
| 2026-04-15 12:00 |
09:21:18.99 |
-25:51:28.5 |
HIP 45902 |
6.88 |
| 2026-04-16 00:00 |
09:21:18.43 |
-25:51:13.7 |
HIP 45902 |
7.15 |