| 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) |
| 2026-09-20 00:00 |
07:26:27.34 |
-75:48:04.2 |
HIP 36097 |
12.69 |
| 2026-09-20 12:00 |
07:26:30.54 |
-75:48:39.1 |
HIP 36097 |
13.29 |
| 2026-09-21 00:00 |
07:26:33.66 |
-75:49:14.2 |
HIP 36097 |
13.89 |
| 2026-09-21 12:00 |
07:26:36.69 |
-75:49:49.3 |
HIP 36097 |
14.49 |
| 2026-09-22 00:00 |
07:26:39.64 |
-75:50:24.7 |
HIP 36097 |
15.10 |
| 2026-09-22 12:00 |
07:26:42.51 |
-75:51:00.1 |
HIP 36097 |
15.70 |
| 2026-09-23 00:00 |
07:26:45.30 |
-75:51:35.6 |
HIP 36097 |
16.31 |
| 2026-09-23 12:00 |
07:26:48.00 |
-75:52:11.3 |
HIP 36097 |
16.92 |
| 2026-09-24 00:00 |
07:26:50.62 |
-75:52:47.1 |
HIP 36097 |
17.54 |
| 2026-09-24 12:00 |
07:26:53.16 |
-75:53:22.9 |
HIP 36097 |
18.15 |
| 2026-09-25 00:00 |
07:26:55.61 |
-75:53:58.9 |
HIP 36097 |
18.77 |
| 2026-09-25 12:00 |
07:26:57.97 |
-75:54:35.1 |
HIP 36097 |
19.38 |
| 2026-09-26 00:00 |
07:27:00.25 |
-75:55:11.3 |
HIP 36097 |
20.00 |
| 2026-09-26 12:00 |
07:27:02.45 |
-75:55:47.6 |
HIP 36097 |
20.62 |
| 2026-09-27 00:00 |
07:27:04.56 |
-75:56:24.0 |
HIP 36097 |
21.24 |
| 2026-09-27 12:00 |
07:27:06.58 |
-75:57:00.5 |
HIP 36097 |
21.86 |
| 2026-09-28 00:00 |
07:27:08.51 |
-75:57:37.1 |
HIP 36097 |
22.48 |
| 2026-09-28 12:00 |
07:27:10.36 |
-75:58:13.8 |
HIP 36097 |
23.10 |
| 2026-09-29 00:00 |
07:27:12.12 |
-75:58:50.6 |
HIP 36097 |
23.72 |
| 2026-09-29 12:00 |
07:27:13.79 |
-75:59:27.4 |
HIP 36097 |
24.35 |
| 2026-09-30 00:00 |
07:27:15.37 |
-76:00:04.4 |
HIP 36097 |
24.97 |
| 2026-09-30 12:00 |
07:27:16.87 |
-76:00:41.4 |
HIP 36097 |
25.59 |
| 2026-10-01 00:00 |
07:27:18.27 |
-76:01:18.6 |
HIP 36097 |
26.22 |
| 2026-10-01 12:00 |
07:27:19.59 |
-76:01:55.8 |
HIP 36097 |
26.84 |
| 2026-10-02 00:00 |
07:27:20.81 |
-76:02:33.0 |
HIP 36097 |
27.47 |
| 2026-10-02 12:00 |
07:27:21.95 |
-76:03:10.4 |
HIP 36097 |
28.09 |
| 2026-10-03 00:00 |
07:27:22.99 |
-76:03:47.8 |
HIP 36097 |
28.72 |
| 2026-10-03 12:00 |
07:27:23.95 |
-76:04:25.3 |
HIP 36097 |
29.34 |
| 2026-10-04 00:00 |
07:27:24.81 |
-76:05:02.8 |
HIP 36097 |
29.97 |
| 2026-10-04 12:00 |
07:27:25.57 |
-76:05:40.4 |
HIP 36097 |
30.60 |
| 2026-10-05 00:00 |
07:27:26.25 |
-76:06:18.1 |
HIP 36097 |
31.22 |
| 2026-10-05 12:00 |
07:27:26.83 |
-76:06:55.8 |
HIP 36097 |
31.85 |
| 2026-10-06 00:00 |
07:27:27.32 |
-76:07:33.6 |
HIP 36097 |
32.48 |
| 2026-10-06 12:00 |
07:27:27.72 |
-76:08:11.5 |
HIP 36094 |
32.32 |
| 2026-10-07 00:00 |
07:27:28.02 |
-76:08:49.3 |
HIP 36094 |
31.70 |
| 2026-10-07 12:00 |
07:27:28.22 |
-76:09:27.2 |
HIP 36094 |
31.07 |
| 2026-10-08 00:00 |
07:27:28.33 |
-76:10:05.2 |
HIP 36094 |
30.45 |
| 2026-10-08 12:00 |
07:27:28.35 |
-76:10:43.2 |
HIP 36094 |
29.82 |
| 2026-10-09 00:00 |
07:27:28.27 |
-76:11:21.2 |
HIP 36094 |
29.20 |
| 2026-10-09 12:00 |
07:27:28.09 |
-76:11:59.3 |
HIP 36094 |
28.57 |
| 2026-10-10 00:00 |
07:27:27.82 |
-76:12:37.4 |
HIP 36094 |
27.94 |
| 2026-10-10 12:00 |
07:27:27.45 |
-76:13:15.5 |
HIP 36094 |
27.31 |
| 2026-10-11 00:00 |
07:27:26.99 |
-76:13:53.7 |
HIP 36094 |
26.68 |