| Parameter |
Value |
| Designation |
C/1885 X1 (Fabry) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1886-04-06T10:56:04.807680Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:28:53Z |
| Obs used |
46 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1886-01-18.0000000 |
| e |
1.00038711 |
| q (au) |
0.642383 |
| a (au) |
-1659.415920 |
| i (deg) |
82.629776 |
| Ω (om, deg) |
37.962462 |
| ω (w, deg) |
126.588976 |
| M (ma, deg) |
-0.001144 |
Magnitude
Scatter + Global Linear
$$
M_a = (H_0 + n\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
- |
| n |
- |
| gf |
- |
| gb |
- |
| k |
- |
| δ90 |
- |
| 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 |
03:20:10.57 |
-45:01:26.0 |
HIP 15473 |
8.69 |
| 2026-05-12 12:00 |
03:20:11.62 |
-45:01:24.2 |
HIP 15473 |
8.86 |
| 2026-05-13 00:00 |
03:20:12.68 |
-45:01:22.5 |
HIP 15548 |
8.89 |
| 2026-05-13 12:00 |
03:20:13.73 |
-45:01:20.9 |
HIP 15548 |
8.89 |
| 2026-05-14 00:00 |
03:20:14.78 |
-45:01:19.4 |
HIP 15548 |
8.89 |
| 2026-05-14 12:00 |
03:20:15.83 |
-45:01:18.0 |
HIP 15548 |
8.90 |
| 2026-05-15 00:00 |
03:20:16.89 |
-45:01:16.7 |
HIP 15548 |
8.91 |
| 2026-05-15 12:00 |
03:20:17.94 |
-45:01:15.4 |
HIP 15548 |
8.92 |
| 2026-05-16 00:00 |
03:20:18.99 |
-45:01:14.3 |
HIP 15548 |
8.94 |
| 2026-05-16 12:00 |
03:20:20.04 |
-45:01:13.2 |
HIP 15548 |
8.95 |
| 2026-05-17 00:00 |
03:20:21.09 |
-45:01:12.2 |
HIP 15548 |
8.97 |
| 2026-05-17 12:00 |
03:20:22.14 |
-45:01:11.4 |
HIP 15548 |
9.00 |
| 2026-05-18 00:00 |
03:20:23.19 |
-45:01:10.6 |
HIP 15548 |
9.02 |
| 2026-05-18 12:00 |
03:20:24.24 |
-45:01:09.8 |
HIP 15548 |
9.05 |
| 2026-05-19 00:00 |
03:20:25.29 |
-45:01:09.2 |
HIP 15548 |
9.08 |
| 2026-05-19 12:00 |
03:20:26.34 |
-45:01:08.7 |
HIP 15548 |
9.11 |
| 2026-05-20 00:00 |
03:20:27.38 |
-45:01:08.2 |
HIP 15548 |
9.14 |
| 2026-05-20 12:00 |
03:20:28.43 |
-45:01:07.9 |
HIP 15548 |
9.18 |
| 2026-05-21 00:00 |
03:20:29.48 |
-45:01:07.6 |
HIP 15548 |
9.21 |
| 2026-05-21 12:00 |
03:20:30.52 |
-45:01:07.4 |
HIP 15548 |
9.25 |
| 2026-05-22 00:00 |
03:20:31.56 |
-45:01:07.3 |
HIP 15548 |
9.29 |
| 2026-05-22 12:00 |
03:20:32.60 |
-45:01:07.3 |
HIP 15548 |
9.34 |
| 2026-05-23 00:00 |
03:20:33.64 |
-45:01:07.4 |
HIP 15548 |
9.38 |
| 2026-05-23 12:00 |
03:20:34.68 |
-45:01:07.6 |
HIP 15548 |
9.43 |
| 2026-05-24 00:00 |
03:20:35.72 |
-45:01:07.9 |
HIP 15548 |
9.48 |
| 2026-05-24 12:00 |
03:20:36.75 |
-45:01:08.2 |
HIP 15548 |
9.53 |
| 2026-05-25 00:00 |
03:20:37.79 |
-45:01:08.6 |
HIP 15548 |
9.58 |
| 2026-05-25 12:00 |
03:20:38.82 |
-45:01:09.2 |
HIP 15548 |
9.64 |
| 2026-05-26 00:00 |
03:20:39.85 |
-45:01:09.8 |
HIP 15548 |
9.69 |
| 2026-05-26 12:00 |
03:20:40.88 |
-45:01:10.5 |
HIP 15548 |
9.75 |
| 2026-05-27 00:00 |
03:20:41.90 |
-45:01:11.3 |
HIP 15548 |
9.81 |
| 2026-05-27 12:00 |
03:20:42.93 |
-45:01:12.1 |
HIP 15548 |
9.87 |
| 2026-05-28 00:00 |
03:20:43.95 |
-45:01:13.1 |
HIP 15548 |
9.93 |
| 2026-05-28 12:00 |
03:20:44.97 |
-45:01:14.1 |
HIP 15548 |
10.00 |
| 2026-05-29 00:00 |
03:20:45.99 |
-45:01:15.3 |
HIP 15548 |
10.06 |
| 2026-05-29 12:00 |
03:20:47.00 |
-45:01:16.5 |
HIP 15548 |
10.13 |
| 2026-05-30 00:00 |
03:20:48.02 |
-45:01:17.8 |
HIP 15548 |
10.19 |
| 2026-05-30 12:00 |
03:20:49.03 |
-45:01:19.2 |
HIP 15548 |
10.26 |
| 2026-05-31 00:00 |
03:20:50.04 |
-45:01:20.6 |
HIP 15548 |
10.33 |
| 2026-05-31 12:00 |
03:20:51.04 |
-45:01:22.2 |
HIP 15548 |
10.40 |
| 2026-06-01 00:00 |
03:20:52.05 |
-45:01:23.9 |
HIP 15548 |
10.48 |
| 2026-06-01 12:00 |
03:20:53.05 |
-45:01:25.6 |
HIP 15548 |
10.55 |
| 2026-06-02 00:00 |
03:20:54.05 |
-45:01:27.4 |
HIP 15548 |
10.63 |