| 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 |
-0.500 |
| 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) |
| 2026-05-12 00:00 |
06:52:20.69 |
-75:39:15.0 |
HIP 32828 |
7.53 |
| 2026-05-12 12:00 |
06:52:26.71 |
-75:38:41.2 |
HIP 32828 |
8.15 |
| 2026-05-13 00:00 |
06:52:32.80 |
-75:38:07.5 |
HIP 32828 |
8.78 |
| 2026-05-13 12:00 |
06:52:38.95 |
-75:37:34.1 |
HIP 32828 |
9.42 |
| 2026-05-14 00:00 |
06:52:45.16 |
-75:37:00.9 |
HIP 32828 |
10.06 |
| 2026-05-14 12:00 |
06:52:51.43 |
-75:36:28.0 |
HIP 32828 |
10.71 |
| 2026-05-15 00:00 |
06:52:57.77 |
-75:35:55.2 |
HIP 32828 |
11.36 |
| 2026-05-15 12:00 |
06:53:04.16 |
-75:35:22.6 |
HIP 32828 |
12.02 |
| 2026-05-16 00:00 |
06:53:10.62 |
-75:34:50.3 |
HIP 32828 |
12.68 |
| 2026-05-16 12:00 |
06:53:17.13 |
-75:34:18.2 |
HIP 32828 |
13.34 |
| 2026-05-17 00:00 |
06:53:23.71 |
-75:33:46.3 |
HIP 32828 |
14.00 |
| 2026-05-17 12:00 |
06:53:30.34 |
-75:33:14.6 |
HIP 32828 |
14.66 |
| 2026-05-18 00:00 |
06:53:37.04 |
-75:32:43.1 |
HIP 32828 |
15.32 |
| 2026-05-18 12:00 |
06:53:43.79 |
-75:32:11.9 |
HIP 32828 |
15.99 |
| 2026-05-19 00:00 |
06:53:50.59 |
-75:31:40.9 |
HIP 32828 |
16.65 |
| 2026-05-19 12:00 |
06:53:57.45 |
-75:31:10.2 |
HIP 32828 |
17.32 |
| 2026-05-20 00:00 |
06:54:04.37 |
-75:30:39.6 |
HIP 32828 |
17.98 |
| 2026-05-20 12:00 |
06:54:11.34 |
-75:30:09.3 |
HIP 32828 |
18.65 |
| 2026-05-21 00:00 |
06:54:18.37 |
-75:29:39.3 |
HIP 32828 |
19.31 |
| 2026-05-21 12:00 |
06:54:25.45 |
-75:29:09.4 |
HIP 32828 |
19.98 |
| 2026-05-22 00:00 |
06:54:32.58 |
-75:28:39.8 |
HIP 32828 |
20.65 |
| 2026-05-22 12:00 |
06:54:39.77 |
-75:28:10.5 |
HIP 32828 |
21.31 |
| 2026-05-23 00:00 |
06:54:47.00 |
-75:27:41.4 |
HIP 32828 |
21.97 |
| 2026-05-23 12:00 |
06:54:54.29 |
-75:27:12.5 |
HIP 32828 |
22.64 |
| 2026-05-24 00:00 |
06:55:01.63 |
-75:26:43.9 |
HIP 32828 |
23.30 |
| 2026-05-24 12:00 |
06:55:09.02 |
-75:26:15.5 |
HIP 32828 |
23.96 |
| 2026-05-25 00:00 |
06:55:16.45 |
-75:25:47.4 |
HIP 32828 |
24.63 |
| 2026-05-25 12:00 |
06:55:23.94 |
-75:25:19.5 |
HIP 32828 |
25.29 |
| 2026-05-26 00:00 |
06:55:31.47 |
-75:24:51.9 |
HIP 33830 |
25.26 |
| 2026-05-26 12:00 |
06:55:39.05 |
-75:24:24.5 |
HIP 33830 |
25.09 |
| 2026-05-27 00:00 |
06:55:46.68 |
-75:23:57.3 |
HIP 33830 |
24.92 |
| 2026-05-27 12:00 |
06:55:54.35 |
-75:23:30.5 |
HIP 33830 |
24.77 |
| 2026-05-28 00:00 |
06:56:02.07 |
-75:23:03.8 |
HIP 33830 |
24.63 |
| 2026-05-28 12:00 |
06:56:09.83 |
-75:22:37.5 |
HIP 33830 |
24.49 |
| 2026-05-29 00:00 |
06:56:17.64 |
-75:22:11.4 |
HIP 33830 |
24.37 |
| 2026-05-29 12:00 |
06:56:25.49 |
-75:21:45.5 |
HIP 33830 |
24.27 |
| 2026-05-30 00:00 |
06:56:33.39 |
-75:21:19.9 |
HIP 33830 |
24.17 |
| 2026-05-30 12:00 |
06:56:41.32 |
-75:20:54.6 |
HIP 33830 |
24.09 |
| 2026-05-31 00:00 |
06:56:49.30 |
-75:20:29.5 |
HIP 33830 |
24.01 |
| 2026-05-31 12:00 |
06:56:57.33 |
-75:20:04.7 |
HIP 33830 |
23.95 |
| 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 |