| 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 |
0.996 |
| gb |
-0.724 |
| 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) |
| 2026-09-20 00:00 |
15:16:17.53 |
-27:43:35.7 |
HIP 74675 |
11.51 |
| 2026-09-20 12:00 |
15:16:25.57 |
-27:43:42.3 |
HIP 74675 |
12.94 |
| 2026-09-21 00:00 |
15:16:33.67 |
-27:43:49.3 |
HIP 74675 |
14.46 |
| 2026-09-21 12:00 |
15:16:41.84 |
-27:43:56.6 |
HIP 74675 |
16.06 |
| 2026-09-22 00:00 |
15:16:50.07 |
-27:44:04.2 |
HIP 74815 |
17.20 |
| 2026-09-22 12:00 |
15:16:58.36 |
-27:44:12.2 |
HIP 74815 |
16.42 |
| 2026-09-23 00:00 |
15:17:06.71 |
-27:44:20.5 |
HIP 74815 |
15.82 |
| 2026-09-23 12:00 |
15:17:15.12 |
-27:44:29.2 |
HIP 74815 |
15.40 |
| 2026-09-24 00:00 |
15:17:23.60 |
-27:44:38.2 |
HIP 74815 |
15.20 |
| 2026-09-24 12:00 |
15:17:32.13 |
-27:44:47.5 |
HIP 74815 |
15.23 |
| 2026-09-25 00:00 |
15:17:40.73 |
-27:44:57.1 |
HIP 74815 |
15.49 |
| 2026-09-25 12:00 |
15:17:49.38 |
-27:45:07.0 |
HIP 74815 |
15.97 |
| 2026-09-26 00:00 |
15:17:58.10 |
-27:45:17.3 |
HIP 74934 |
16.49 |
| 2026-09-26 12:00 |
15:18:06.87 |
-27:45:27.9 |
HIP 74934 |
15.20 |
| 2026-09-27 00:00 |
15:18:15.70 |
-27:45:38.8 |
HIP 74934 |
14.06 |
| 2026-09-27 12:00 |
15:18:24.59 |
-27:45:50.1 |
HIP 74934 |
13.11 |
| 2026-09-28 00:00 |
15:18:33.54 |
-27:46:01.6 |
HIP 74934 |
12.38 |
| 2026-09-28 12:00 |
15:18:42.54 |
-27:46:13.5 |
HIP 74934 |
11.95 |
| 2026-09-29 00:00 |
15:18:51.60 |
-27:46:25.7 |
HIP 74934 |
11.83 |
| 2026-09-29 12:00 |
15:19:00.72 |
-27:46:38.2 |
HIP 74934 |
12.06 |
| 2026-09-30 00:00 |
15:19:09.89 |
-27:46:51.0 |
HIP 74934 |
12.61 |
| 2026-09-30 12:00 |
15:19:19.12 |
-27:47:04.1 |
HIP 74934 |
13.45 |
| 2026-10-01 00:00 |
15:19:28.40 |
-27:47:17.5 |
HIP 74934 |
14.54 |
| 2026-10-01 12:00 |
15:19:37.74 |
-27:47:31.2 |
HIP 74934 |
15.83 |
| 2026-10-02 00:00 |
15:19:47.14 |
-27:47:45.3 |
HIP 74934 |
17.28 |
| 2026-10-02 12:00 |
15:19:56.58 |
-27:47:59.6 |
HIP 74934 |
18.86 |
| 2026-10-03 00:00 |
15:20:06.08 |
-27:48:14.3 |
HIP 74934 |
20.54 |
| 2026-10-03 12:00 |
15:20:15.64 |
-27:48:29.2 |
HIP 75162 |
18.74 |
| 2026-10-04 00:00 |
15:20:25.24 |
-27:48:44.5 |
HIP 75162 |
16.68 |
| 2026-10-04 12:00 |
15:20:34.90 |
-27:49:00.0 |
HIP 75162 |
14.63 |
| 2026-10-05 00:00 |
15:20:44.61 |
-27:49:15.9 |
HIP 75162 |
12.60 |
| 2026-10-05 12:00 |
15:20:54.37 |
-27:49:32.0 |
HIP 75162 |
10.62 |
| 2026-10-06 00:00 |
15:21:04.19 |
-27:49:48.5 |
HIP 75162 |
8.71 |
| 2026-10-06 12:00 |
15:21:14.05 |
-27:50:05.2 |
HIP 75162 |
6.96 |
| 2026-10-07 00:00 |
15:21:23.96 |
-27:50:22.3 |
HIP 75162 |
5.53 |
| 2026-10-07 12:00 |
15:21:33.93 |
-27:50:39.6 |
HIP 75162 |
4.73 |
| 2026-10-08 00:00 |
15:21:43.94 |
-27:50:57.2 |
HIP 75162 |
4.91 |
| 2026-10-08 12:00 |
15:21:54.00 |
-27:51:15.1 |
HIP 75162 |
5.98 |
| 2026-10-09 00:00 |
15:22:04.11 |
-27:51:33.3 |
HIP 75162 |
7.60 |
| 2026-10-09 12:00 |
15:22:14.26 |
-27:51:51.7 |
HIP 75162 |
9.48 |
| 2026-10-10 00:00 |
15:22:24.46 |
-27:52:10.5 |
HIP 75162 |
11.51 |
| 2026-10-10 12:00 |
15:22:34.71 |
-27:52:29.5 |
HIP 75162 |
13.63 |
| 2026-10-11 00:00 |
15:22:45.01 |
-27:52:48.8 |
HIP 75343 |
13.71 |