P/2015 W2 (Catalina)
| 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) |
| 2026-02-03 00:00 |
15:39:17.13 |
-29:36:47.8 |
HIP 76600 |
12.83 |
| 2026-02-03 12:00 |
15:39:21.68 |
-29:37:24.0 |
HIP 76600 |
13.04 |
| 2026-02-04 00:00 |
15:39:26.15 |
-29:38:00.0 |
HIP 76600 |
13.35 |
| 2026-02-04 12:00 |
15:39:30.53 |
-29:38:35.8 |
HIP 76600 |
13.73 |
| 2026-02-05 00:00 |
15:39:34.83 |
-29:39:11.3 |
HIP 76600 |
14.17 |
| 2026-02-05 12:00 |
15:39:39.03 |
-29:39:46.7 |
HIP 76600 |
14.67 |
| 2026-02-06 00:00 |
15:39:43.15 |
-29:40:21.9 |
HIP 76600 |
15.21 |
| 2026-02-06 12:00 |
15:39:47.18 |
-29:40:56.9 |
HIP 76600 |
15.79 |
| 2026-02-07 00:00 |
15:39:51.12 |
-29:41:31.7 |
HIP 76600 |
16.40 |
| 2026-02-07 12:00 |
15:39:54.97 |
-29:42:06.2 |
HIP 76754 |
16.96 |
| 2026-02-08 00:00 |
15:39:58.73 |
-29:42:40.6 |
HIP 76754 |
16.15 |
| 2026-02-08 12:00 |
15:40:02.41 |
-29:43:14.7 |
HIP 76754 |
15.38 |
| 2026-02-09 00:00 |
15:40:05.99 |
-29:43:48.7 |
HIP 76754 |
14.64 |
| 2026-02-09 12:00 |
15:40:09.48 |
-29:44:22.4 |
HIP 76754 |
13.93 |
| 2026-02-10 00:00 |
15:40:12.88 |
-29:44:55.9 |
HIP 76754 |
13.25 |
| 2026-02-10 12:00 |
15:40:16.18 |
-29:45:29.1 |
HIP 76754 |
12.62 |
| 2026-02-11 00:00 |
15:40:19.40 |
-29:46:02.2 |
HIP 76754 |
12.02 |
| 2026-02-11 12:00 |
15:40:22.52 |
-29:46:35.0 |
HIP 76754 |
11.46 |
| 2026-02-12 00:00 |
15:40:25.55 |
-29:47:07.6 |
HIP 76754 |
10.95 |
| 2026-02-12 12:00 |
15:40:28.49 |
-29:47:39.9 |
HIP 76754 |
10.49 |
| 2026-02-13 00:00 |
15:40:31.34 |
-29:48:12.1 |
HIP 76754 |
10.07 |
| 2026-02-13 12:00 |
15:40:34.09 |
-29:48:43.9 |
HIP 76754 |
9.69 |
| 2026-02-14 00:00 |
15:40:36.75 |
-29:49:15.6 |
HIP 76754 |
9.37 |
| 2026-02-14 12:00 |
15:40:39.31 |
-29:49:47.0 |
HIP 76754 |
9.10 |
| 2026-02-15 00:00 |
15:40:41.78 |
-29:50:18.2 |
HIP 76754 |
8.89 |
| 2026-02-15 12:00 |
15:40:44.16 |
-29:50:49.1 |
HIP 76754 |
8.72 |
| 2026-02-16 00:00 |
15:40:46.44 |
-29:51:19.7 |
HIP 76754 |
8.60 |
| 2026-02-16 12:00 |
15:40:48.62 |
-29:51:50.1 |
HIP 76754 |
8.52 |
| 2026-02-17 00:00 |
15:40:50.71 |
-29:52:20.3 |
HIP 76754 |
8.50 |
| 2026-02-17 12:00 |
15:40:52.70 |
-29:52:50.2 |
HIP 76754 |
8.51 |
| 2026-02-18 00:00 |
15:40:54.60 |
-29:53:19.9 |
HIP 76754 |
8.55 |
| 2026-02-18 12:00 |
15:40:56.41 |
-29:53:49.3 |
HIP 76754 |
8.63 |
| 2026-02-19 00:00 |
15:40:58.11 |
-29:54:18.4 |
HIP 76754 |
8.74 |
| 2026-02-19 12:00 |
15:40:59.72 |
-29:54:47.2 |
HIP 76754 |
8.86 |
| 2026-02-20 00:00 |
15:41:01.24 |
-29:55:15.8 |
HIP 76754 |
9.01 |
| 2026-02-20 12:00 |
15:41:02.65 |
-29:55:44.2 |
HIP 76754 |
9.17 |
| 2026-02-21 00:00 |
15:41:03.97 |
-29:56:12.2 |
HIP 76754 |
9.35 |
| 2026-02-21 12:00 |
15:41:05.20 |
-29:56:40.0 |
HIP 76754 |
9.53 |
| 2026-02-22 00:00 |
15:41:06.32 |
-29:57:07.5 |
HIP 76754 |
9.72 |
| 2026-02-22 12:00 |
15:41:07.35 |
-29:57:34.7 |
HIP 76754 |
9.91 |
| 2026-02-23 00:00 |
15:41:08.28 |
-29:58:01.7 |
HIP 76754 |
10.10 |
| 2026-02-23 12:00 |
15:41:09.12 |
-29:58:28.4 |
HIP 76754 |
10.28 |
| 2026-02-24 00:00 |
15:41:09.86 |
-29:58:54.7 |
HIP 76754 |
10.47 |