| Parameter |
Value |
| Designation |
C/2015 X2 (Catalina) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-12-20T17:13:10.505280Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:18Z |
| Obs used |
43 |
| NEO |
- |
| M1 |
16.100 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-12-12.0000000 |
| e |
0.87907924 |
| q (au) |
1.904555 |
| a (au) |
15.750441 |
| i (deg) |
72.458476 |
| Ω (om, deg) |
101.094124 |
| ω (w, deg) |
42.018183 |
| M (ma, deg) |
359.862546 |
Magnitude
Scatter + Global Linear
$$
M_a = (18.961 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
18.961 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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 |
19:18:50.02 |
-43:27:51.9 |
HIP 94953 |
22.18 |
| 2026-09-20 12:00 |
19:18:47.63 |
-43:27:33.0 |
HIP 94953 |
21.98 |
| 2026-09-21 00:00 |
19:18:45.30 |
-43:27:13.9 |
HIP 94953 |
21.79 |
| 2026-09-21 12:00 |
19:18:43.04 |
-43:26:54.6 |
HIP 94953 |
21.61 |
| 2026-09-22 00:00 |
19:18:40.85 |
-43:26:35.2 |
HIP 94953 |
21.42 |
| 2026-09-22 12:00 |
19:18:38.72 |
-43:26:15.5 |
HIP 94953 |
21.25 |
| 2026-09-23 00:00 |
19:18:36.67 |
-43:25:55.8 |
HIP 94953 |
21.07 |
| 2026-09-23 12:00 |
19:18:34.67 |
-43:25:35.9 |
HIP 94953 |
20.90 |
| 2026-09-24 00:00 |
19:18:32.75 |
-43:25:15.8 |
HIP 94953 |
20.74 |
| 2026-09-24 12:00 |
19:18:30.89 |
-43:24:55.5 |
HIP 94953 |
20.57 |
| 2026-09-25 00:00 |
19:18:29.10 |
-43:24:35.1 |
HIP 94953 |
20.41 |
| 2026-09-25 12:00 |
19:18:27.38 |
-43:24:14.6 |
HIP 94953 |
20.25 |
| 2026-09-26 00:00 |
19:18:25.72 |
-43:23:53.9 |
HIP 94953 |
20.09 |
| 2026-09-26 12:00 |
19:18:24.14 |
-43:23:33.1 |
HIP 94953 |
19.93 |
| 2026-09-27 00:00 |
19:18:22.62 |
-43:23:12.1 |
HIP 94953 |
19.77 |
| 2026-09-27 12:00 |
19:18:21.16 |
-43:22:51.0 |
HIP 94953 |
19.61 |
| 2026-09-28 00:00 |
19:18:19.78 |
-43:22:29.8 |
HIP 94953 |
19.46 |
| 2026-09-28 12:00 |
19:18:18.46 |
-43:22:08.4 |
HIP 94953 |
19.30 |
| 2026-09-29 00:00 |
19:18:17.21 |
-43:21:46.9 |
HIP 94953 |
19.14 |
| 2026-09-29 12:00 |
19:18:16.03 |
-43:21:25.2 |
HIP 94953 |
18.98 |
| 2026-09-30 00:00 |
19:18:14.92 |
-43:21:03.4 |
HIP 94953 |
18.82 |
| 2026-09-30 12:00 |
19:18:13.87 |
-43:20:41.5 |
HIP 94953 |
18.65 |
| 2026-10-01 00:00 |
19:18:12.89 |
-43:20:19.5 |
HIP 94953 |
18.49 |
| 2026-10-01 12:00 |
19:18:11.98 |
-43:19:57.4 |
HIP 94953 |
18.32 |
| 2026-10-02 00:00 |
19:18:11.14 |
-43:19:35.1 |
HIP 94953 |
18.15 |
| 2026-10-02 12:00 |
19:18:10.37 |
-43:19:12.7 |
HIP 94953 |
17.98 |
| 2026-10-03 00:00 |
19:18:09.66 |
-43:18:50.2 |
HIP 94953 |
17.81 |
| 2026-10-03 12:00 |
19:18:09.02 |
-43:18:27.6 |
HIP 94953 |
17.63 |
| 2026-10-04 00:00 |
19:18:08.45 |
-43:18:04.9 |
HIP 94953 |
17.45 |
| 2026-10-04 12:00 |
19:18:07.95 |
-43:17:42.0 |
HIP 94953 |
17.26 |
| 2026-10-05 00:00 |
19:18:07.52 |
-43:17:19.1 |
HIP 94953 |
17.07 |
| 2026-10-05 12:00 |
19:18:07.16 |
-43:16:56.0 |
HIP 94953 |
16.88 |
| 2026-10-06 00:00 |
19:18:06.86 |
-43:16:32.9 |
HIP 94953 |
16.68 |
| 2026-10-06 12:00 |
19:18:06.63 |
-43:16:09.6 |
HIP 94953 |
16.48 |
| 2026-10-07 00:00 |
19:18:06.47 |
-43:15:46.3 |
HIP 94953 |
16.28 |
| 2026-10-07 12:00 |
19:18:06.38 |
-43:15:22.9 |
HIP 94953 |
16.07 |
| 2026-10-08 00:00 |
19:18:06.36 |
-43:14:59.3 |
HIP 94953 |
15.86 |
| 2026-10-08 12:00 |
19:18:06.40 |
-43:14:35.7 |
HIP 94953 |
15.64 |
| 2026-10-09 00:00 |
19:18:06.52 |
-43:14:12.0 |
HIP 94953 |
15.42 |
| 2026-10-09 12:00 |
19:18:06.70 |
-43:13:48.2 |
HIP 94953 |
15.19 |
| 2026-10-10 00:00 |
19:18:06.95 |
-43:13:24.3 |
HIP 94953 |
14.96 |
| 2026-10-10 12:00 |
19:18:07.27 |
-43:13:00.4 |
HIP 94953 |
14.72 |
| 2026-10-11 00:00 |
19:18:07.65 |
-43:12:36.3 |
HIP 94953 |
14.48 |