| Parameter |
Value |
| Designation |
P/2015 W2 (Catalina) |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2015-09-30T21:23:50.429760Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:17Z |
| Obs used |
188 |
| NEO |
- |
| M1 |
8.800 |
| K1 |
21.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-12-05.0000000 |
| e |
0.63410542 |
| q (au) |
2.678336 |
| a (au) |
7.319966 |
| i (deg) |
11.611215 |
| Ω (om, deg) |
294.247294 |
| ω (w, deg) |
117.626508 |
| M (ma, deg) |
3.240245 |
Magnitude
Scatter + Global Linear
$$
M_a = (18.559 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
18.559 |
| n |
2.000 |
| gf |
0.972 |
| gb |
-0.724 |
| k |
0.800 |
| δ90 |
9.994 |
| 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 |
15:38:57.64 |
-30:15:19.5 |
HIP 76754 |
25.08 |
| 2026-03-26 12:00 |
15:38:52.60 |
-30:15:24.7 |
HIP 76754 |
25.93 |
| 2026-03-27 00:00 |
15:38:47.47 |
-30:15:29.5 |
HIP 76754 |
26.82 |
| 2026-03-27 12:00 |
15:38:42.25 |
-30:15:33.8 |
HIP 76754 |
27.73 |
| 2026-03-28 00:00 |
15:38:36.95 |
-30:15:37.8 |
HIP 76754 |
28.67 |
| 2026-03-28 12:00 |
15:38:31.57 |
-30:15:41.3 |
HIP 76600 |
29.08 |
| 2026-03-29 00:00 |
15:38:26.10 |
-30:15:44.5 |
HIP 76600 |
29.22 |
| 2026-03-29 12:00 |
15:38:20.55 |
-30:15:47.2 |
HIP 76600 |
29.41 |
| 2026-03-30 00:00 |
15:38:14.91 |
-30:15:49.5 |
HIP 76600 |
29.64 |
| 2026-03-30 12:00 |
15:38:09.20 |
-30:15:51.4 |
HIP 76600 |
29.92 |
| 2026-03-31 00:00 |
15:38:03.40 |
-30:15:52.9 |
HIP 76406 |
29.65 |
| 2026-03-31 12:00 |
15:37:57.52 |
-30:15:54.0 |
HIP 76406 |
28.68 |
| 2026-04-01 00:00 |
15:37:51.56 |
-30:15:54.7 |
HIP 76406 |
27.71 |
| 2026-04-01 12:00 |
15:37:45.52 |
-30:15:55.0 |
HIP 76406 |
26.77 |
| 2026-04-02 00:00 |
15:37:39.40 |
-30:15:54.8 |
HIP 76406 |
25.85 |
| 2026-04-02 12:00 |
15:37:33.21 |
-30:15:54.2 |
HIP 76406 |
24.97 |
| 2026-04-03 00:00 |
15:37:26.93 |
-30:15:53.2 |
HIP 76406 |
24.11 |
| 2026-04-03 12:00 |
15:37:20.58 |
-30:15:51.8 |
HIP 76406 |
23.31 |
| 2026-04-04 00:00 |
15:37:14.15 |
-30:15:50.0 |
HIP 76406 |
22.55 |
| 2026-04-04 12:00 |
15:37:07.64 |
-30:15:47.7 |
HIP 76406 |
21.85 |
| 2026-04-05 00:00 |
15:37:01.06 |
-30:15:45.1 |
HIP 76406 |
21.22 |
| 2026-04-05 12:00 |
15:36:54.40 |
-30:15:42.0 |
HIP 76406 |
20.67 |
| 2026-04-06 00:00 |
15:36:47.67 |
-30:15:38.5 |
HIP 76406 |
20.21 |
| 2026-04-06 12:00 |
15:36:40.86 |
-30:15:34.5 |
HIP 76406 |
19.85 |
| 2026-04-07 00:00 |
15:36:33.99 |
-30:15:30.2 |
HIP 76406 |
19.60 |
| 2026-04-07 12:00 |
15:36:27.03 |
-30:15:25.4 |
HIP 76406 |
19.46 |
| 2026-04-08 00:00 |
15:36:20.01 |
-30:15:20.1 |
HIP 76406 |
19.44 |
| 2026-04-08 12:00 |
15:36:12.92 |
-30:15:14.5 |
HIP 76406 |
19.55 |
| 2026-04-09 00:00 |
15:36:05.75 |
-30:15:08.4 |
HIP 76406 |
19.79 |
| 2026-04-09 12:00 |
15:35:58.52 |
-30:15:01.9 |
HIP 76406 |
20.15 |
| 2026-04-10 00:00 |
15:35:51.21 |
-30:14:55.0 |
HIP 76406 |
20.63 |
| 2026-04-10 12:00 |
15:35:43.84 |
-30:14:47.6 |
HIP 76406 |
21.24 |
| 2026-04-11 00:00 |
15:35:36.40 |
-30:14:39.8 |
HIP 76406 |
21.96 |
| 2026-04-11 12:00 |
15:35:28.89 |
-30:14:31.6 |
HIP 76406 |
22.78 |
| 2026-04-12 00:00 |
15:35:21.32 |
-30:14:23.0 |
HIP 76406 |
23.69 |
| 2026-04-12 12:00 |
15:35:13.68 |
-30:14:13.9 |
HIP 76406 |
24.70 |
| 2026-04-13 00:00 |
15:35:05.97 |
-30:14:04.4 |
HIP 76406 |
25.79 |
| 2026-04-13 12:00 |
15:34:58.20 |
-30:13:54.4 |
HIP 76406 |
26.95 |
| 2026-04-14 00:00 |
15:34:50.37 |
-30:13:44.1 |
HIP 76406 |
28.18 |
| 2026-04-14 12:00 |
15:34:42.48 |
-30:13:33.3 |
HIP 76406 |
29.47 |
| 2026-04-15 00:00 |
15:34:34.53 |
-30:13:22.0 |
HIP 76406 |
30.81 |
| 2026-04-15 12:00 |
15:34:26.51 |
-30:13:10.4 |
HIP 76406 |
32.21 |
| 2026-04-16 00:00 |
15:34:18.44 |
-30:12:58.3 |
HIP 76406 |
33.65 |