| 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) |
| 2026-03-26 00:00 |
19:45:19.65 |
-41:15:16.5 |
HIP 97137 |
12.21 |
| 2026-03-26 12:00 |
19:45:22.63 |
-41:15:47.4 |
HIP 97137 |
12.98 |
| 2026-03-27 00:00 |
19:45:25.55 |
-41:16:18.6 |
HIP 97137 |
13.73 |
| 2026-03-27 12:00 |
19:45:28.41 |
-41:16:49.9 |
HIP 97137 |
14.48 |
| 2026-03-28 00:00 |
19:45:31.21 |
-41:17:21.5 |
HIP 97137 |
15.22 |
| 2026-03-28 12:00 |
19:45:33.95 |
-41:17:53.3 |
HIP 97137 |
15.96 |
| 2026-03-29 00:00 |
19:45:36.63 |
-41:18:25.3 |
HIP 97137 |
16.69 |
| 2026-03-29 12:00 |
19:45:39.24 |
-41:18:57.6 |
HIP 97137 |
17.42 |
| 2026-03-30 00:00 |
19:45:41.80 |
-41:19:30.0 |
HIP 97137 |
18.14 |
| 2026-03-30 12:00 |
19:45:44.29 |
-41:20:02.7 |
HIP 97137 |
18.86 |
| 2026-03-31 00:00 |
19:45:46.72 |
-41:20:35.5 |
HIP 97137 |
19.56 |
| 2026-03-31 12:00 |
19:45:49.09 |
-41:21:08.6 |
HIP 97137 |
20.27 |
| 2026-04-01 00:00 |
19:45:51.39 |
-41:21:41.9 |
HIP 97137 |
20.96 |
| 2026-04-01 12:00 |
19:45:53.64 |
-41:22:15.3 |
HIP 97131 |
21.52 |
| 2026-04-02 00:00 |
19:45:55.82 |
-41:22:49.0 |
HIP 97131 |
21.46 |
| 2026-04-02 12:00 |
19:45:57.93 |
-41:23:22.9 |
HIP 97131 |
21.42 |
| 2026-04-03 00:00 |
19:45:59.99 |
-41:23:56.9 |
HIP 97131 |
21.38 |
| 2026-04-03 12:00 |
19:46:01.98 |
-41:24:31.2 |
HIP 97131 |
21.36 |
| 2026-04-04 00:00 |
19:46:03.91 |
-41:25:05.7 |
HIP 97131 |
21.34 |
| 2026-04-04 12:00 |
19:46:05.77 |
-41:25:40.3 |
HIP 97131 |
21.33 |
| 2026-04-05 00:00 |
19:46:07.57 |
-41:26:15.2 |
HIP 97131 |
21.34 |
| 2026-04-05 12:00 |
19:46:09.31 |
-41:26:50.2 |
HIP 97131 |
21.35 |
| 2026-04-06 00:00 |
19:46:10.98 |
-41:27:25.5 |
HIP 97131 |
21.37 |
| 2026-04-06 12:00 |
19:46:12.59 |
-41:28:00.9 |
HIP 97131 |
21.40 |
| 2026-04-07 00:00 |
19:46:14.13 |
-41:28:36.5 |
HIP 97131 |
21.44 |
| 2026-04-07 12:00 |
19:46:15.61 |
-41:29:12.3 |
HIP 97131 |
21.48 |
| 2026-04-08 00:00 |
19:46:17.03 |
-41:29:48.3 |
HIP 97131 |
21.53 |
| 2026-04-08 12:00 |
19:46:18.38 |
-41:30:24.4 |
HIP 97131 |
21.59 |
| 2026-04-09 00:00 |
19:46:19.66 |
-41:31:00.8 |
HIP 97131 |
21.66 |
| 2026-04-09 12:00 |
19:46:20.88 |
-41:31:37.3 |
HIP 97131 |
21.73 |
| 2026-04-10 00:00 |
19:46:22.03 |
-41:32:14.0 |
HIP 97131 |
21.81 |
| 2026-04-10 12:00 |
19:46:23.12 |
-41:32:50.8 |
HIP 97131 |
21.90 |
| 2026-04-11 00:00 |
19:46:24.14 |
-41:33:27.9 |
HIP 97131 |
21.99 |
| 2026-04-11 12:00 |
19:46:25.09 |
-41:34:05.1 |
HIP 97131 |
22.08 |
| 2026-04-12 00:00 |
19:46:25.98 |
-41:34:42.5 |
HIP 97131 |
22.19 |
| 2026-04-12 12:00 |
19:46:26.81 |
-41:35:20.0 |
HIP 97131 |
22.30 |
| 2026-04-13 00:00 |
19:46:27.56 |
-41:35:57.7 |
HIP 97131 |
22.41 |
| 2026-04-13 12:00 |
19:46:28.25 |
-41:36:35.6 |
HIP 97131 |
22.53 |
| 2026-04-14 00:00 |
19:46:28.88 |
-41:37:13.7 |
HIP 97131 |
22.66 |
| 2026-04-14 12:00 |
19:46:29.43 |
-41:37:51.9 |
HIP 97131 |
22.79 |
| 2026-04-15 00:00 |
19:46:29.92 |
-41:38:30.2 |
HIP 97131 |
22.92 |
| 2026-04-15 12:00 |
19:46:30.34 |
-41:39:08.7 |
HIP 97131 |
23.06 |
| 2026-04-16 00:00 |
19:46:30.70 |
-41:39:47.4 |
HIP 97131 |
23.21 |