| Parameter |
Value |
| Designation |
C/1999 K2 (Ferris) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1999-04-10T12:51:40.688640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:00Z |
| Obs used |
101 |
| NEO |
- |
| M1 |
7.000 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1999-06-24.0000000 |
| e |
0.96579603 |
| q (au) |
5.290256 |
| a (au) |
154.667896 |
| i (deg) |
82.190925 |
| Ω (om, deg) |
300.318118 |
| ω (w, deg) |
4.570397 |
| M (ma, deg) |
0.038155 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.566 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.566 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.664 |
| 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) |
| 2026-09-20 00:00 |
08:32:29.84 |
+52:03:37.8 |
HIP 42020 |
17.32 |
| 2026-09-20 12:00 |
08:32:32.32 |
+52:03:47.1 |
HIP 42020 |
17.13 |
| 2026-09-21 00:00 |
08:32:34.77 |
+52:03:56.6 |
HIP 42020 |
16.96 |
| 2026-09-21 12:00 |
08:32:37.20 |
+52:04:06.2 |
HIP 42020 |
16.80 |
| 2026-09-22 00:00 |
08:32:39.59 |
+52:04:16.0 |
HIP 42020 |
16.65 |
| 2026-09-22 12:00 |
08:32:41.97 |
+52:04:25.9 |
HIP 42020 |
16.51 |
| 2026-09-23 00:00 |
08:32:44.31 |
+52:04:36.1 |
HIP 42020 |
16.39 |
| 2026-09-23 12:00 |
08:32:46.63 |
+52:04:46.4 |
HIP 42020 |
16.29 |
| 2026-09-24 00:00 |
08:32:48.92 |
+52:04:56.8 |
HIP 42020 |
16.19 |
| 2026-09-24 12:00 |
08:32:51.18 |
+52:05:07.4 |
HIP 42020 |
16.12 |
| 2026-09-25 00:00 |
08:32:53.41 |
+52:05:18.2 |
HIP 42020 |
16.05 |
| 2026-09-25 12:00 |
08:32:55.61 |
+52:05:29.1 |
HIP 42020 |
16.00 |
| 2026-09-26 00:00 |
08:32:57.79 |
+52:05:40.2 |
HIP 42020 |
15.96 |
| 2026-09-26 12:00 |
08:32:59.93 |
+52:05:51.5 |
HIP 42020 |
15.94 |
| 2026-09-27 00:00 |
08:33:02.05 |
+52:06:02.9 |
HIP 42020 |
15.93 |
| 2026-09-27 12:00 |
08:33:04.14 |
+52:06:14.4 |
HIP 42020 |
15.93 |
| 2026-09-28 00:00 |
08:33:06.20 |
+52:06:26.2 |
HIP 42020 |
15.95 |
| 2026-09-28 12:00 |
08:33:08.23 |
+52:06:38.1 |
HIP 42020 |
15.98 |
| 2026-09-29 00:00 |
08:33:10.23 |
+52:06:50.1 |
HIP 42020 |
16.02 |
| 2026-09-29 12:00 |
08:33:12.20 |
+52:07:02.3 |
HIP 42020 |
16.08 |
| 2026-09-30 00:00 |
08:33:14.14 |
+52:07:14.6 |
HIP 42020 |
16.14 |
| 2026-09-30 12:00 |
08:33:16.05 |
+52:07:27.1 |
HIP 42020 |
16.22 |
| 2026-10-01 00:00 |
08:33:17.92 |
+52:07:39.8 |
HIP 42020 |
16.32 |
| 2026-10-01 12:00 |
08:33:19.77 |
+52:07:52.6 |
HIP 42020 |
16.42 |
| 2026-10-02 00:00 |
08:33:21.59 |
+52:08:05.5 |
HIP 42020 |
16.53 |
| 2026-10-02 12:00 |
08:33:23.38 |
+52:08:18.6 |
HIP 42020 |
16.65 |
| 2026-10-03 00:00 |
08:33:25.14 |
+52:08:31.9 |
HIP 42020 |
16.79 |
| 2026-10-03 12:00 |
08:33:26.86 |
+52:08:45.3 |
HIP 42125 |
16.68 |
| 2026-10-04 00:00 |
08:33:28.56 |
+52:08:58.9 |
HIP 42125 |
16.38 |
| 2026-10-04 12:00 |
08:33:30.22 |
+52:09:12.5 |
HIP 42125 |
16.09 |
| 2026-10-05 00:00 |
08:33:31.85 |
+52:09:26.4 |
HIP 42125 |
15.80 |
| 2026-10-05 12:00 |
08:33:33.45 |
+52:09:40.4 |
HIP 42125 |
15.52 |
| 2026-10-06 00:00 |
08:33:35.01 |
+52:09:54.5 |
HIP 42125 |
15.25 |
| 2026-10-06 12:00 |
08:33:36.55 |
+52:10:08.8 |
HIP 42125 |
14.98 |
| 2026-10-07 00:00 |
08:33:38.05 |
+52:10:23.2 |
HIP 42125 |
14.73 |
| 2026-10-07 12:00 |
08:33:39.52 |
+52:10:37.8 |
HIP 42125 |
14.48 |
| 2026-10-08 00:00 |
08:33:40.96 |
+52:10:52.5 |
HIP 42125 |
14.23 |
| 2026-10-08 12:00 |
08:33:42.36 |
+52:11:07.3 |
HIP 42125 |
14.00 |
| 2026-10-09 00:00 |
08:33:43.73 |
+52:11:22.3 |
HIP 42125 |
13.78 |
| 2026-10-09 12:00 |
08:33:45.07 |
+52:11:37.4 |
HIP 42125 |
13.56 |
| 2026-10-10 00:00 |
08:33:46.37 |
+52:11:52.6 |
HIP 42125 |
13.36 |
| 2026-10-10 12:00 |
08:33:47.64 |
+52:12:08.0 |
HIP 42125 |
13.16 |
| 2026-10-11 00:00 |
08:33:48.88 |
+52:12:23.5 |
HIP 42125 |
12.98 |