| 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) |
| 2026-03-26 00:00 |
08:18:49.99 |
+53:33:19.9 |
HIP 40878 |
14.77 |
| 2026-03-26 12:00 |
08:18:47.88 |
+53:33:00.4 |
HIP 40878 |
15.11 |
| 2026-03-27 00:00 |
08:18:45.80 |
+53:32:40.8 |
HIP 40878 |
15.45 |
| 2026-03-27 12:00 |
08:18:43.76 |
+53:32:21.0 |
HIP 40878 |
15.79 |
| 2026-03-28 00:00 |
08:18:41.76 |
+53:32:01.1 |
HIP 40878 |
16.14 |
| 2026-03-28 12:00 |
08:18:39.79 |
+53:31:41.1 |
HIP 40878 |
16.48 |
| 2026-03-29 00:00 |
08:18:37.85 |
+53:31:20.9 |
HIP 40878 |
16.82 |
| 2026-03-29 12:00 |
08:18:35.96 |
+53:31:00.6 |
HIP 40878 |
17.17 |
| 2026-03-30 00:00 |
08:18:34.09 |
+53:30:40.2 |
HIP 40878 |
17.51 |
| 2026-03-30 12:00 |
08:18:32.27 |
+53:30:19.6 |
HIP 40878 |
17.85 |
| 2026-03-31 00:00 |
08:18:30.48 |
+53:29:58.9 |
HIP 40878 |
18.19 |
| 2026-03-31 12:00 |
08:18:28.73 |
+53:29:38.1 |
HIP 40878 |
18.53 |
| 2026-04-01 00:00 |
08:18:27.01 |
+53:29:17.1 |
HIP 40878 |
18.87 |
| 2026-04-01 12:00 |
08:18:25.33 |
+53:28:56.0 |
HIP 40878 |
19.21 |
| 2026-04-02 00:00 |
08:18:23.69 |
+53:28:34.9 |
HIP 40878 |
19.55 |
| 2026-04-02 12:00 |
08:18:22.08 |
+53:28:13.5 |
HIP 40878 |
19.89 |
| 2026-04-03 00:00 |
08:18:20.51 |
+53:27:52.1 |
HIP 40878 |
20.23 |
| 2026-04-03 12:00 |
08:18:18.98 |
+53:27:30.5 |
HIP 40878 |
20.56 |
| 2026-04-04 00:00 |
08:18:17.48 |
+53:27:08.9 |
HIP 40878 |
20.90 |
| 2026-04-04 12:00 |
08:18:16.02 |
+53:26:47.1 |
HIP 40878 |
21.23 |
| 2026-04-05 00:00 |
08:18:14.60 |
+53:26:25.2 |
HIP 40878 |
21.56 |
| 2026-04-05 12:00 |
08:18:13.21 |
+53:26:03.2 |
HIP 40878 |
21.89 |
| 2026-04-06 00:00 |
08:18:11.87 |
+53:25:41.1 |
HIP 40849 |
22.10 |
| 2026-04-06 12:00 |
08:18:10.55 |
+53:25:18.8 |
HIP 40849 |
22.03 |
| 2026-04-07 00:00 |
08:18:09.28 |
+53:24:56.5 |
HIP 40849 |
21.95 |
| 2026-04-07 12:00 |
08:18:08.04 |
+53:24:34.0 |
HIP 40849 |
21.88 |
| 2026-04-08 00:00 |
08:18:06.84 |
+53:24:11.5 |
HIP 40849 |
21.82 |
| 2026-04-08 12:00 |
08:18:05.68 |
+53:23:48.8 |
HIP 40849 |
21.75 |
| 2026-04-09 00:00 |
08:18:04.55 |
+53:23:26.1 |
HIP 40849 |
21.69 |
| 2026-04-09 12:00 |
08:18:03.46 |
+53:23:03.2 |
HIP 40849 |
21.63 |
| 2026-04-10 00:00 |
08:18:02.41 |
+53:22:40.3 |
HIP 40849 |
21.57 |
| 2026-04-10 12:00 |
08:18:01.40 |
+53:22:17.2 |
HIP 40849 |
21.51 |
| 2026-04-11 00:00 |
08:18:00.42 |
+53:21:54.1 |
HIP 40849 |
21.46 |
| 2026-04-11 12:00 |
08:17:59.49 |
+53:21:30.8 |
HIP 40849 |
21.41 |
| 2026-04-12 00:00 |
08:17:58.59 |
+53:21:07.5 |
HIP 40849 |
21.35 |
| 2026-04-12 12:00 |
08:17:57.72 |
+53:20:44.1 |
HIP 40849 |
21.31 |
| 2026-04-13 00:00 |
08:17:56.90 |
+53:20:20.5 |
HIP 40849 |
21.26 |
| 2026-04-13 12:00 |
08:17:56.11 |
+53:19:56.9 |
HIP 40849 |
21.22 |
| 2026-04-14 00:00 |
08:17:55.36 |
+53:19:33.3 |
HIP 40849 |
21.18 |
| 2026-04-14 12:00 |
08:17:54.65 |
+53:19:09.5 |
HIP 40849 |
21.14 |
| 2026-04-15 00:00 |
08:17:53.97 |
+53:18:45.6 |
HIP 40849 |
21.10 |
| 2026-04-15 12:00 |
08:17:53.34 |
+53:18:21.7 |
HIP 40849 |
21.06 |
| 2026-04-16 00:00 |
08:17:52.74 |
+53:17:57.7 |
HIP 40849 |
21.03 |