| Parameter |
Value |
| Designation |
C/1999 J2 (Skiff) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2000-04-05T23:39:38.044800Z |
| Orbit solution date (soln_date, UTC) |
2025-07-31T12:12:22Z |
| Obs used |
978 |
| NEO |
- |
| M1 |
6.100 |
| K1 |
7.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-04-28.0000000 |
| e |
1.00112158 |
| q (au) |
7.109764 |
| a (au) |
-6339.047335 |
| i (deg) |
86.412859 |
| Ω (om, deg) |
50.042373 |
| ω (w, deg) |
127.138683 |
| M (ma, deg) |
0.000043 |
Magnitude
Scatter + Global Linear
$$
M_a = (-2.294 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
-2.294 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.502 |
| k |
1.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2000-04-06 |
2002-03-22 |
+20.3121 |
-17.666 |
| 2002-03-22 |
2003-05-29 |
+4.9690 |
-3.057 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
06:57:05.39 |
-75:19:40.1 |
HIP 33830 |
23.91 |
| 2026-06-01 12:00 |
06:57:13.49 |
-75:19:15.8 |
HIP 33830 |
23.87 |
| 2026-06-02 00:00 |
06:57:21.64 |
-75:18:51.8 |
HIP 33830 |
23.85 |
| 2026-06-02 12:00 |
06:57:29.82 |
-75:18:28.1 |
HIP 33830 |
23.84 |
| 2026-06-03 00:00 |
06:57:38.04 |
-75:18:04.6 |
HIP 33830 |
23.84 |
| 2026-06-03 12:00 |
06:57:46.30 |
-75:17:41.4 |
HIP 33830 |
23.85 |
| 2026-06-04 00:00 |
06:57:54.60 |
-75:17:18.4 |
HIP 33830 |
23.88 |
| 2026-06-04 12:00 |
06:58:02.94 |
-75:16:55.7 |
HIP 33830 |
23.92 |
| 2026-06-05 00:00 |
06:58:11.31 |
-75:16:33.3 |
HIP 33830 |
23.97 |
| 2026-06-05 12:00 |
06:58:19.72 |
-75:16:11.2 |
HIP 34119 |
23.55 |
| 2026-06-06 00:00 |
06:58:28.16 |
-75:15:49.3 |
HIP 34119 |
22.99 |
| 2026-06-06 12:00 |
06:58:36.64 |
-75:15:27.8 |
HIP 34119 |
22.42 |
| 2026-06-07 00:00 |
06:58:45.16 |
-75:15:06.5 |
HIP 34119 |
21.86 |
| 2026-06-07 12:00 |
06:58:53.71 |
-75:14:45.4 |
HIP 34119 |
21.31 |
| 2026-06-08 00:00 |
06:59:02.29 |
-75:14:24.7 |
HIP 34119 |
20.75 |
| 2026-06-08 12:00 |
06:59:10.91 |
-75:14:04.2 |
HIP 34119 |
20.20 |
| 2026-06-09 00:00 |
06:59:19.55 |
-75:13:44.1 |
HIP 34119 |
19.66 |
| 2026-06-09 12:00 |
06:59:28.23 |
-75:13:24.2 |
HIP 34119 |
19.11 |
| 2026-06-10 00:00 |
06:59:36.94 |
-75:13:04.5 |
HIP 34119 |
18.57 |
| 2026-06-10 12:00 |
06:59:45.69 |
-75:12:45.2 |
HIP 34119 |
18.03 |
| 2026-06-11 00:00 |
06:59:54.46 |
-75:12:26.2 |
HIP 34119 |
17.50 |
| 2026-06-11 12:00 |
07:00:03.26 |
-75:12:07.4 |
HIP 34119 |
16.98 |
| 2026-06-12 00:00 |
07:00:12.09 |
-75:11:49.0 |
HIP 34119 |
16.45 |
| 2026-06-12 12:00 |
07:00:20.95 |
-75:11:30.8 |
HIP 34119 |
15.94 |
| 2026-06-13 00:00 |
07:00:29.84 |
-75:11:12.9 |
HIP 34119 |
15.43 |
| 2026-06-13 12:00 |
07:00:38.76 |
-75:10:55.3 |
HIP 34119 |
14.93 |
| 2026-06-14 00:00 |
07:00:47.70 |
-75:10:38.0 |
HIP 34119 |
14.43 |
| 2026-06-14 12:00 |
07:00:56.67 |
-75:10:21.0 |
HIP 34119 |
13.94 |
| 2026-06-15 00:00 |
07:01:05.66 |
-75:10:04.3 |
HIP 34119 |
13.47 |
| 2026-06-15 12:00 |
07:01:14.68 |
-75:09:47.9 |
HIP 34119 |
13.00 |
| 2026-06-16 00:00 |
07:01:23.72 |
-75:09:31.7 |
HIP 34119 |
12.55 |
| 2026-06-16 12:00 |
07:01:32.79 |
-75:09:15.9 |
HIP 34119 |
12.10 |
| 2026-06-17 00:00 |
07:01:41.87 |
-75:09:00.4 |
HIP 34119 |
11.68 |
| 2026-06-17 12:00 |
07:01:50.98 |
-75:08:45.2 |
HIP 34119 |
11.27 |
| 2026-06-18 00:00 |
07:02:00.12 |
-75:08:30.3 |
HIP 34119 |
10.87 |
| 2026-06-18 12:00 |
07:02:09.27 |
-75:08:15.6 |
HIP 34119 |
10.50 |
| 2026-06-19 00:00 |
07:02:18.44 |
-75:08:01.3 |
HIP 34119 |
10.14 |
| 2026-06-19 12:00 |
07:02:27.64 |
-75:07:47.3 |
HIP 34119 |
9.81 |
| 2026-06-20 00:00 |
07:02:36.85 |
-75:07:33.6 |
HIP 34119 |
9.51 |
| 2026-06-20 12:00 |
07:02:46.08 |
-75:07:20.1 |
HIP 34119 |
9.23 |
| 2026-06-21 00:00 |
07:02:55.33 |
-75:07:07.0 |
HIP 34119 |
8.99 |
| 2026-06-21 12:00 |
07:03:04.59 |
-75:06:54.2 |
HIP 34119 |
8.78 |
| 2026-06-22 00:00 |
07:03:13.87 |
-75:06:41.7 |
HIP 34119 |
8.61 |