| 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) |
| 2026-05-12 00:00 |
19:45:16.69 |
-42:15:45.3 |
HIP 97205 |
9.81 |
| 2026-05-12 12:00 |
19:45:13.51 |
-42:16:28.3 |
HIP 97205 |
10.60 |
| 2026-05-13 00:00 |
19:45:10.28 |
-42:17:11.4 |
HIP 97205 |
11.41 |
| 2026-05-13 12:00 |
19:45:06.98 |
-42:17:54.5 |
HIP 97205 |
12.24 |
| 2026-05-14 00:00 |
19:45:03.62 |
-42:18:37.5 |
HIP 97205 |
13.09 |
| 2026-05-14 12:00 |
19:45:00.19 |
-42:19:20.6 |
HIP 97205 |
13.96 |
| 2026-05-15 00:00 |
19:44:56.70 |
-42:20:03.7 |
HIP 97205 |
14.84 |
| 2026-05-15 12:00 |
19:44:53.15 |
-42:20:46.7 |
HIP 97205 |
15.73 |
| 2026-05-16 00:00 |
19:44:49.53 |
-42:21:29.8 |
HIP 97205 |
16.64 |
| 2026-05-16 12:00 |
19:44:45.85 |
-42:22:12.8 |
HIP 97205 |
17.56 |
| 2026-05-17 00:00 |
19:44:42.11 |
-42:22:55.8 |
HIP 97194 |
18.29 |
| 2026-05-17 12:00 |
19:44:38.31 |
-42:23:38.8 |
HIP 97194 |
17.86 |
| 2026-05-18 00:00 |
19:44:34.45 |
-42:24:21.7 |
HIP 97194 |
17.49 |
| 2026-05-18 12:00 |
19:44:30.52 |
-42:25:04.7 |
HIP 97194 |
17.17 |
| 2026-05-19 00:00 |
19:44:26.53 |
-42:25:47.5 |
HIP 97194 |
16.92 |
| 2026-05-19 12:00 |
19:44:22.48 |
-42:26:30.4 |
HIP 97194 |
16.73 |
| 2026-05-20 00:00 |
19:44:18.38 |
-42:27:13.2 |
HIP 97194 |
16.60 |
| 2026-05-20 12:00 |
19:44:14.21 |
-42:27:56.0 |
HIP 97194 |
16.56 |
| 2026-05-21 00:00 |
19:44:09.98 |
-42:28:38.7 |
HIP 97194 |
16.58 |
| 2026-05-21 12:00 |
19:44:05.69 |
-42:29:21.4 |
HIP 97194 |
16.68 |
| 2026-05-22 00:00 |
19:44:01.35 |
-42:30:04.0 |
HIP 97194 |
16.86 |
| 2026-05-22 12:00 |
19:43:56.94 |
-42:30:46.6 |
HIP 97194 |
17.11 |
| 2026-05-23 00:00 |
19:43:52.48 |
-42:31:29.1 |
HIP 97038 |
16.73 |
| 2026-05-23 12:00 |
19:43:47.96 |
-42:32:11.6 |
HIP 97038 |
15.77 |
| 2026-05-24 00:00 |
19:43:43.38 |
-42:32:53.9 |
HIP 97038 |
14.82 |
| 2026-05-24 12:00 |
19:43:38.74 |
-42:33:36.2 |
HIP 97038 |
13.89 |
| 2026-05-25 00:00 |
19:43:34.05 |
-42:34:18.5 |
HIP 97038 |
12.99 |
| 2026-05-25 12:00 |
19:43:29.30 |
-42:35:00.6 |
HIP 97038 |
12.13 |
| 2026-05-26 00:00 |
19:43:24.49 |
-42:35:42.7 |
HIP 97038 |
11.31 |
| 2026-05-26 12:00 |
19:43:19.63 |
-42:36:24.7 |
HIP 97038 |
10.55 |
| 2026-05-27 00:00 |
19:43:14.71 |
-42:37:06.6 |
HIP 97038 |
9.86 |
| 2026-05-27 12:00 |
19:43:09.74 |
-42:37:48.5 |
HIP 97038 |
9.27 |
| 2026-05-28 00:00 |
19:43:04.72 |
-42:38:30.2 |
HIP 97038 |
8.79 |
| 2026-05-28 12:00 |
19:42:59.63 |
-42:39:11.9 |
HIP 97038 |
8.45 |
| 2026-05-29 00:00 |
19:42:54.50 |
-42:39:53.4 |
HIP 97038 |
8.27 |
| 2026-05-29 12:00 |
19:42:49.31 |
-42:40:34.8 |
HIP 97038 |
8.25 |
| 2026-05-30 00:00 |
19:42:44.07 |
-42:41:16.2 |
HIP 97038 |
8.42 |
| 2026-05-30 12:00 |
19:42:38.77 |
-42:41:57.4 |
HIP 97038 |
8.75 |
| 2026-05-31 00:00 |
19:42:33.43 |
-42:42:38.5 |
HIP 97038 |
9.23 |
| 2026-05-31 12:00 |
19:42:28.03 |
-42:43:19.6 |
HIP 97038 |
9.84 |
| 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 |