| 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) |
| 2026-06-01 00:00 |
19:42:22.57 |
-42:44:00.5 |
HIP 97038 |
10.57 |
| 2026-06-01 12:00 |
19:42:17.07 |
-42:44:41.2 |
HIP 97038 |
11.39 |
| 2026-06-02 00:00 |
19:42:11.52 |
-42:45:21.9 |
HIP 97038 |
12.28 |
| 2026-06-02 12:00 |
19:42:05.91 |
-42:46:02.4 |
HIP 97038 |
13.24 |
| 2026-06-03 00:00 |
19:42:00.26 |
-42:46:42.8 |
HIP 97038 |
14.24 |
| 2026-06-03 12:00 |
19:41:54.56 |
-42:47:23.1 |
HIP 97038 |
15.29 |
| 2026-06-04 00:00 |
19:41:48.80 |
-42:48:03.2 |
HIP 97038 |
16.38 |
| 2026-06-04 12:00 |
19:41:43.00 |
-42:48:43.2 |
HIP 97038 |
17.49 |
| 2026-06-05 00:00 |
19:41:37.15 |
-42:49:23.1 |
HIP 97038 |
18.63 |
| 2026-06-05 12:00 |
19:41:31.25 |
-42:50:02.8 |
HIP 96869 |
18.40 |
| 2026-06-06 00:00 |
19:41:25.31 |
-42:50:42.4 |
HIP 96869 |
17.70 |
| 2026-06-06 12:00 |
19:41:19.31 |
-42:51:21.8 |
HIP 96869 |
17.08 |
| 2026-06-07 00:00 |
19:41:13.27 |
-42:52:01.1 |
HIP 96869 |
16.53 |
| 2026-06-07 12:00 |
19:41:07.19 |
-42:52:40.2 |
HIP 96869 |
16.07 |
| 2026-06-08 00:00 |
19:41:01.06 |
-42:53:19.1 |
HIP 96869 |
15.71 |
| 2026-06-08 12:00 |
19:40:54.88 |
-42:53:57.9 |
HIP 96869 |
15.45 |
| 2026-06-09 00:00 |
19:40:48.66 |
-42:54:36.6 |
HIP 96869 |
15.31 |
| 2026-06-09 12:00 |
19:40:42.39 |
-42:55:15.0 |
HIP 96869 |
15.28 |
| 2026-06-10 00:00 |
19:40:36.08 |
-42:55:53.3 |
HIP 96869 |
15.37 |
| 2026-06-10 12:00 |
19:40:29.72 |
-42:56:31.4 |
HIP 96869 |
15.58 |
| 2026-06-11 00:00 |
19:40:23.33 |
-42:57:09.4 |
HIP 96869 |
15.91 |
| 2026-06-11 12:00 |
19:40:16.89 |
-42:57:47.1 |
HIP 96869 |
16.34 |
| 2026-06-12 00:00 |
19:40:10.41 |
-42:58:24.7 |
HIP 96869 |
16.88 |
| 2026-06-12 12:00 |
19:40:03.88 |
-42:59:02.1 |
HIP 96869 |
17.51 |
| 2026-06-13 00:00 |
19:39:57.32 |
-42:59:39.3 |
HIP 96869 |
18.23 |
| 2026-06-13 12:00 |
19:39:50.72 |
-43:00:16.3 |
HIP 96869 |
19.02 |
| 2026-06-14 00:00 |
19:39:44.07 |
-43:00:53.1 |
HIP 96869 |
19.89 |
| 2026-06-14 12:00 |
19:39:37.39 |
-43:01:29.7 |
HIP 96869 |
20.81 |
| 2026-06-15 00:00 |
19:39:30.67 |
-43:02:06.2 |
HIP 96869 |
21.78 |
| 2026-06-15 12:00 |
19:39:23.91 |
-43:02:42.4 |
HIP 96529 |
21.80 |
| 2026-06-16 00:00 |
19:39:17.11 |
-43:03:18.4 |
HIP 96529 |
20.79 |
| 2026-06-16 12:00 |
19:39:10.28 |
-43:03:54.1 |
HIP 96529 |
19.81 |
| 2026-06-17 00:00 |
19:39:03.41 |
-43:04:29.7 |
HIP 96529 |
18.88 |
| 2026-06-17 12:00 |
19:38:56.50 |
-43:05:05.1 |
HIP 96529 |
18.00 |
| 2026-06-18 00:00 |
19:38:49.56 |
-43:05:40.2 |
HIP 96529 |
17.19 |
| 2026-06-18 12:00 |
19:38:42.59 |
-43:06:15.1 |
HIP 96529 |
16.44 |
| 2026-06-19 00:00 |
19:38:35.58 |
-43:06:49.8 |
HIP 96529 |
15.78 |
| 2026-06-19 12:00 |
19:38:28.54 |
-43:07:24.2 |
HIP 96529 |
15.21 |
| 2026-06-20 00:00 |
19:38:21.47 |
-43:07:58.5 |
HIP 96529 |
14.75 |
| 2026-06-20 12:00 |
19:38:14.36 |
-43:08:32.5 |
HIP 96529 |
14.40 |
| 2026-06-21 00:00 |
19:38:07.23 |
-43:09:06.2 |
HIP 96529 |
14.19 |
| 2026-06-21 12:00 |
19:38:00.06 |
-43:09:39.7 |
HIP 96529 |
14.11 |
| 2026-06-22 00:00 |
19:37:52.86 |
-43:10:13.0 |
HIP 96529 |
14.16 |