| 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) |
| 2026-05-12 00:00 |
15:26:20.82 |
-29:53:05.3 |
HIP 75547 |
13.76 |
| 2026-05-12 12:00 |
15:26:11.00 |
-29:52:32.3 |
HIP 75547 |
13.84 |
| 2026-05-13 00:00 |
15:26:01.18 |
-29:51:59.1 |
HIP 75547 |
14.26 |
| 2026-05-13 12:00 |
15:25:51.36 |
-29:51:25.5 |
HIP 75547 |
15.01 |
| 2026-05-14 00:00 |
15:25:41.53 |
-29:50:51.5 |
HIP 75547 |
16.03 |
| 2026-05-14 12:00 |
15:25:31.70 |
-29:50:17.3 |
HIP 75547 |
17.27 |
| 2026-05-15 00:00 |
15:25:21.87 |
-29:49:42.7 |
HIP 75547 |
18.70 |
| 2026-05-15 12:00 |
15:25:12.04 |
-29:49:07.8 |
HIP 75547 |
20.28 |
| 2026-05-16 00:00 |
15:25:02.21 |
-29:48:32.6 |
HIP 75547 |
21.96 |
| 2026-05-16 12:00 |
15:24:52.39 |
-29:47:57.1 |
HIP 75547 |
23.74 |
| 2026-05-17 00:00 |
15:24:42.57 |
-29:47:21.3 |
HIP 75547 |
25.59 |
| 2026-05-17 12:00 |
15:24:32.75 |
-29:46:45.2 |
HIP 75547 |
27.49 |
| 2026-05-18 00:00 |
15:24:22.94 |
-29:46:08.8 |
HIP 75547 |
29.44 |
| 2026-05-18 12:00 |
15:24:13.14 |
-29:45:32.1 |
HIP 75550 |
31.18 |
| 2026-05-19 00:00 |
15:24:03.35 |
-29:44:55.1 |
HIP 75272 |
29.74 |
| 2026-05-19 12:00 |
15:23:53.56 |
-29:44:17.8 |
HIP 75272 |
28.05 |
| 2026-05-20 00:00 |
15:23:43.79 |
-29:43:40.3 |
HIP 75272 |
26.43 |
| 2026-05-20 12:00 |
15:23:34.03 |
-29:43:02.4 |
HIP 75272 |
24.91 |
| 2026-05-21 00:00 |
15:23:24.28 |
-29:42:24.3 |
HIP 75272 |
23.49 |
| 2026-05-21 12:00 |
15:23:14.55 |
-29:41:46.0 |
HIP 75272 |
22.19 |
| 2026-05-22 00:00 |
15:23:04.83 |
-29:41:07.4 |
HIP 75272 |
21.05 |
| 2026-05-22 12:00 |
15:22:55.13 |
-29:40:28.5 |
HIP 75272 |
20.08 |
| 2026-05-23 00:00 |
15:22:45.45 |
-29:39:49.3 |
HIP 75272 |
19.31 |
| 2026-05-23 12:00 |
15:22:35.79 |
-29:39:10.0 |
HIP 75272 |
18.76 |
| 2026-05-24 00:00 |
15:22:26.14 |
-29:38:30.3 |
HIP 75272 |
18.46 |
| 2026-05-24 12:00 |
15:22:16.52 |
-29:37:50.5 |
HIP 75272 |
18.42 |
| 2026-05-25 00:00 |
15:22:06.91 |
-29:37:10.3 |
HIP 75272 |
18.62 |
| 2026-05-25 12:00 |
15:21:57.33 |
-29:36:30.0 |
HIP 75272 |
19.08 |
| 2026-05-26 00:00 |
15:21:47.78 |
-29:35:49.4 |
HIP 75272 |
19.76 |
| 2026-05-26 12:00 |
15:21:38.25 |
-29:35:08.7 |
HIP 75272 |
20.65 |
| 2026-05-27 00:00 |
15:21:28.74 |
-29:34:27.6 |
HIP 75272 |
21.71 |
| 2026-05-27 12:00 |
15:21:19.26 |
-29:33:46.4 |
HIP 75272 |
22.93 |
| 2026-05-28 00:00 |
15:21:09.81 |
-29:33:05.0 |
HIP 75272 |
24.27 |
| 2026-05-28 12:00 |
15:21:00.38 |
-29:32:23.4 |
HIP 75272 |
25.72 |
| 2026-05-29 00:00 |
15:20:50.99 |
-29:31:41.5 |
HIP 75272 |
27.26 |
| 2026-05-29 12:00 |
15:20:41.62 |
-29:30:59.5 |
HIP 75272 |
28.87 |
| 2026-05-30 00:00 |
15:20:32.29 |
-29:30:17.2 |
HIP 74949 |
27.05 |
| 2026-05-30 12:00 |
15:20:22.99 |
-29:29:34.8 |
HIP 74949 |
25.05 |
| 2026-05-31 00:00 |
15:20:13.72 |
-29:28:52.2 |
HIP 74949 |
23.06 |
| 2026-05-31 12:00 |
15:20:04.49 |
-29:28:09.5 |
HIP 74949 |
21.12 |
| 2026-06-01 00:00 |
15:19:55.29 |
-29:27:26.5 |
HIP 74949 |
19.21 |
| 2026-06-01 12:00 |
15:19:46.12 |
-29:26:43.4 |
HIP 74949 |
17.36 |
| 2026-06-02 00:00 |
15:19:37.00 |
-29:26:00.1 |
HIP 74949 |
15.58 |