| Parameter |
Value |
| Designation |
C/2018 X2 (Fitzsimmons) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2019-07-08T12:50:12.180480Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:48Z |
| Obs used |
390 |
| NEO |
- |
| M1 |
10.600 |
| K1 |
12.750 |
| PC |
0.030 |
| Discovery observation (MPC, UTC) |
2018-12-08T11:10:09.696000Z |
| Discovery magnitude (MPC) |
19.10 c |
| Discovery observatory (MPC) |
T05 · ATLAS-HKO, Haleakala |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2019-02-10.0000000 |
| e |
0.98628022 |
| q (au) |
2.125879 |
| a (au) |
154.949983 |
| i (deg) |
23.068234 |
| Ω (om, deg) |
340.833210 |
| ω (w, deg) |
162.047045 |
| M (ma, deg) |
359.924099 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.225 + 5.892\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.225 |
| n |
5.892 |
| gf |
0.996 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
2.692 |
| 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 |
19:33:42.92 |
-41:57:40.3 |
HIP 96099 |
21.57 |
| 2026-06-01 12:00 |
19:33:37.13 |
-41:58:09.8 |
HIP 96099 |
20.46 |
| 2026-06-02 00:00 |
19:33:31.29 |
-41:58:39.0 |
HIP 96099 |
19.36 |
| 2026-06-02 12:00 |
19:33:25.40 |
-41:59:08.1 |
HIP 96099 |
18.26 |
| 2026-06-03 00:00 |
19:33:19.46 |
-41:59:37.1 |
HIP 96099 |
17.17 |
| 2026-06-03 12:00 |
19:33:13.46 |
-42:00:05.9 |
HIP 96099 |
16.09 |
| 2026-06-04 00:00 |
19:33:07.42 |
-42:00:34.5 |
HIP 96099 |
15.03 |
| 2026-06-04 12:00 |
19:33:01.33 |
-42:01:02.9 |
HIP 96099 |
13.99 |
| 2026-06-05 00:00 |
19:32:55.18 |
-42:01:31.2 |
HIP 96099 |
12.99 |
| 2026-06-05 12:00 |
19:32:48.99 |
-42:01:59.4 |
HIP 96099 |
12.02 |
| 2026-06-06 00:00 |
19:32:42.75 |
-42:02:27.3 |
HIP 96099 |
11.11 |
| 2026-06-06 12:00 |
19:32:36.46 |
-42:02:55.1 |
HIP 96099 |
10.27 |
| 2026-06-07 00:00 |
19:32:30.12 |
-42:03:22.7 |
HIP 96041 |
9.21 |
| 2026-06-07 12:00 |
19:32:23.74 |
-42:03:50.1 |
HIP 96041 |
7.95 |
| 2026-06-08 00:00 |
19:32:17.31 |
-42:04:17.3 |
HIP 96041 |
6.68 |
| 2026-06-08 12:00 |
19:32:10.84 |
-42:04:44.3 |
HIP 96041 |
5.42 |
| 2026-06-09 00:00 |
19:32:04.32 |
-42:05:11.2 |
HIP 96041 |
4.16 |
| 2026-06-09 12:00 |
19:31:57.75 |
-42:05:37.8 |
HIP 96041 |
2.91 |
| 2026-06-10 00:00 |
19:31:51.14 |
-42:06:04.3 |
HIP 96041 |
1.74 |
| 2026-06-10 12:00 |
19:31:44.49 |
-42:06:30.5 |
HIP 96041 |
0.96 |
| 2026-06-11 00:00 |
19:31:37.79 |
-42:06:56.5 |
HIP 96041 |
1.51 |
| 2026-06-11 12:00 |
19:31:31.05 |
-42:07:22.4 |
HIP 96041 |
2.66 |
| 2026-06-12 00:00 |
19:31:24.27 |
-42:07:48.0 |
HIP 96041 |
3.93 |
| 2026-06-12 12:00 |
19:31:17.45 |
-42:08:13.4 |
HIP 96041 |
5.23 |
| 2026-06-13 00:00 |
19:31:10.59 |
-42:08:38.6 |
HIP 96041 |
6.55 |
| 2026-06-13 12:00 |
19:31:03.69 |
-42:09:03.6 |
HIP 96041 |
7.88 |
| 2026-06-14 00:00 |
19:30:56.75 |
-42:09:28.3 |
HIP 96041 |
9.22 |
| 2026-06-14 12:00 |
19:30:49.77 |
-42:09:52.8 |
HIP 96041 |
10.57 |
| 2026-06-15 00:00 |
19:30:42.75 |
-42:10:17.1 |
HIP 96041 |
11.93 |
| 2026-06-15 12:00 |
19:30:35.70 |
-42:10:41.2 |
HIP 96041 |
13.29 |
| 2026-06-16 00:00 |
19:30:28.61 |
-42:11:05.0 |
HIP 96041 |
14.65 |
| 2026-06-16 12:00 |
19:30:21.48 |
-42:11:28.6 |
HIP 96041 |
16.03 |
| 2026-06-17 00:00 |
19:30:14.32 |
-42:11:51.9 |
HIP 96041 |
17.40 |
| 2026-06-17 12:00 |
19:30:07.13 |
-42:12:15.0 |
HIP 96041 |
18.79 |
| 2026-06-18 00:00 |
19:29:59.90 |
-42:12:37.9 |
HIP 96041 |
20.18 |
| 2026-06-18 12:00 |
19:29:52.64 |
-42:13:00.5 |
HIP 96041 |
21.57 |
| 2026-06-19 00:00 |
19:29:45.34 |
-42:13:22.8 |
HIP 96041 |
22.97 |
| 2026-06-19 12:00 |
19:29:38.02 |
-42:13:44.9 |
HIP 96041 |
24.37 |
| 2026-06-20 00:00 |
19:29:30.66 |
-42:14:06.7 |
HIP 96041 |
25.77 |
| 2026-06-20 12:00 |
19:29:23.28 |
-42:14:28.3 |
HIP 95701 |
25.22 |
| 2026-06-21 00:00 |
19:29:15.86 |
-42:14:49.6 |
HIP 95701 |
24.08 |
| 2026-06-21 12:00 |
19:29:08.42 |
-42:15:10.7 |
HIP 95701 |
22.96 |
| 2026-06-22 00:00 |
19:29:00.95 |
-42:15:31.5 |
HIP 95701 |
21.88 |