| 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) |
| 2026-07-29 00:00 |
15:09:22.02 |
-28:06:01.2 |
HIP 74149 |
16.20 |
| 2026-07-29 12:00 |
15:09:21.41 |
-28:05:29.8 |
HIP 74149 |
16.67 |
| 2026-07-30 00:00 |
15:09:20.89 |
-28:04:58.8 |
HIP 74149 |
17.15 |
| 2026-07-30 12:00 |
15:09:20.46 |
-28:04:28.1 |
HIP 74149 |
17.64 |
| 2026-07-31 00:00 |
15:09:20.12 |
-28:03:57.7 |
HIP 74149 |
18.12 |
| 2026-07-31 12:00 |
15:09:19.88 |
-28:03:27.7 |
HIP 74149 |
18.60 |
| 2026-08-01 00:00 |
15:09:19.72 |
-28:02:57.9 |
HIP 74149 |
19.08 |
| 2026-08-01 12:00 |
15:09:19.66 |
-28:02:28.5 |
HIP 74149 |
19.56 |
| 2026-08-02 00:00 |
15:09:19.68 |
-28:01:59.4 |
HIP 74149 |
20.04 |
| 2026-08-02 12:00 |
15:09:19.80 |
-28:01:30.7 |
HIP 74149 |
20.52 |
| 2026-08-03 00:00 |
15:09:20.00 |
-28:01:02.2 |
HIP 74149 |
20.99 |
| 2026-08-03 12:00 |
15:09:20.30 |
-28:00:34.1 |
HIP 74149 |
21.47 |
| 2026-08-04 00:00 |
15:09:20.69 |
-28:00:06.4 |
HIP 74149 |
21.94 |
| 2026-08-04 12:00 |
15:09:21.17 |
-27:59:38.9 |
HIP 74149 |
22.41 |
| 2026-08-05 00:00 |
15:09:21.74 |
-27:59:11.9 |
HIP 74149 |
22.87 |
| 2026-08-05 12:00 |
15:09:22.40 |
-27:58:45.1 |
HIP 74149 |
23.34 |
| 2026-08-06 00:00 |
15:09:23.16 |
-27:58:18.7 |
HIP 74149 |
23.80 |
| 2026-08-06 12:00 |
15:09:24.00 |
-27:57:52.6 |
HIP 74149 |
24.26 |
| 2026-08-07 00:00 |
15:09:24.93 |
-27:57:26.9 |
HIP 74149 |
24.72 |
| 2026-08-07 12:00 |
15:09:25.96 |
-27:57:01.6 |
HIP 74149 |
25.17 |
| 2026-08-08 00:00 |
15:09:27.07 |
-27:56:36.5 |
HIP 74149 |
25.63 |
| 2026-08-08 12:00 |
15:09:28.28 |
-27:56:11.9 |
HIP 74149 |
26.08 |
| 2026-08-09 00:00 |
15:09:29.57 |
-27:55:47.6 |
HIP 74149 |
26.54 |
| 2026-08-09 12:00 |
15:09:30.96 |
-27:55:23.6 |
HIP 74149 |
26.99 |
| 2026-08-10 00:00 |
15:09:32.44 |
-27:55:00.0 |
HIP 74149 |
27.45 |
| 2026-08-10 12:00 |
15:09:34.00 |
-27:54:36.7 |
HIP 74149 |
27.91 |
| 2026-08-11 00:00 |
15:09:35.66 |
-27:54:13.8 |
HIP 74149 |
28.36 |
| 2026-08-11 12:00 |
15:09:37.41 |
-27:53:51.3 |
HIP 74149 |
28.82 |
| 2026-08-12 00:00 |
15:09:39.24 |
-27:53:29.1 |
HIP 74149 |
29.28 |
| 2026-08-12 12:00 |
15:09:41.17 |
-27:53:07.3 |
HIP 74149 |
29.75 |
| 2026-08-13 00:00 |
15:09:43.18 |
-27:52:45.9 |
HIP 74149 |
30.21 |
| 2026-08-13 12:00 |
15:09:45.29 |
-27:52:24.8 |
HIP 74149 |
30.68 |
| 2026-08-14 00:00 |
15:09:47.48 |
-27:52:04.1 |
HIP 74149 |
31.16 |
| 2026-08-14 12:00 |
15:09:49.77 |
-27:51:43.7 |
HIP 74318 |
31.57 |
| 2026-08-15 00:00 |
15:09:52.14 |
-27:51:23.7 |
HIP 74318 |
30.97 |
| 2026-08-15 12:00 |
15:09:54.60 |
-27:51:04.1 |
HIP 74318 |
30.37 |
| 2026-08-16 00:00 |
15:09:57.15 |
-27:50:44.9 |
HIP 74318 |
29.76 |
| 2026-08-16 12:00 |
15:09:59.79 |
-27:50:26.0 |
HIP 74318 |
29.14 |
| 2026-08-17 00:00 |
15:10:02.51 |
-27:50:07.5 |
HIP 74318 |
28.52 |
| 2026-08-17 12:00 |
15:10:05.32 |
-27:49:49.3 |
HIP 74318 |
27.89 |
| 2026-08-18 00:00 |
15:10:08.22 |
-27:49:31.6 |
HIP 74318 |
27.26 |
| 2026-08-18 12:00 |
15:10:11.21 |
-27:49:14.2 |
HIP 74318 |
26.62 |
| 2026-08-19 00:00 |
15:10:14.28 |
-27:48:57.1 |
HIP 74318 |
25.99 |