C/1999 J2 (Skiff)
| 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) |
| 2026-02-03 00:00 |
07:01:40.77 |
-77:40:44.7 |
HIP 34020 |
16.89 |
| 2026-02-03 12:00 |
07:01:28.63 |
-77:40:23.1 |
HIP 34020 |
17.46 |
| 2026-02-04 00:00 |
07:01:16.57 |
-77:40:01.2 |
HIP 34020 |
18.04 |
| 2026-02-04 12:00 |
07:01:04.57 |
-77:39:38.9 |
HIP 34020 |
18.64 |
| 2026-02-05 00:00 |
07:00:52.64 |
-77:39:16.3 |
HIP 34020 |
19.25 |
| 2026-02-05 12:00 |
07:00:40.78 |
-77:38:53.3 |
HIP 34020 |
19.87 |
| 2026-02-06 00:00 |
07:00:29.00 |
-77:38:30.0 |
HIP 34020 |
20.51 |
| 2026-02-06 12:00 |
07:00:17.28 |
-77:38:06.4 |
HIP 34020 |
21.15 |
| 2026-02-07 00:00 |
07:00:05.65 |
-77:37:42.4 |
HIP 33140 |
21.34 |
| 2026-02-07 12:00 |
06:59:54.08 |
-77:37:18.1 |
HIP 33140 |
20.97 |
| 2026-02-08 00:00 |
06:59:42.59 |
-77:36:53.5 |
HIP 33140 |
20.62 |
| 2026-02-08 12:00 |
06:59:31.18 |
-77:36:28.6 |
HIP 33140 |
20.31 |
| 2026-02-09 00:00 |
06:59:19.84 |
-77:36:03.3 |
HIP 33140 |
20.02 |
| 2026-02-09 12:00 |
06:59:08.59 |
-77:35:37.7 |
HIP 33140 |
19.76 |
| 2026-02-10 00:00 |
06:58:57.41 |
-77:35:11.8 |
HIP 33140 |
19.53 |
| 2026-02-10 12:00 |
06:58:46.31 |
-77:34:45.5 |
HIP 33140 |
19.33 |
| 2026-02-11 00:00 |
06:58:35.30 |
-77:34:19.0 |
HIP 33140 |
19.17 |
| 2026-02-11 12:00 |
06:58:24.36 |
-77:33:52.1 |
HIP 33140 |
19.03 |
| 2026-02-12 00:00 |
06:58:13.51 |
-77:33:25.0 |
HIP 33140 |
18.94 |
| 2026-02-12 12:00 |
06:58:02.74 |
-77:32:57.5 |
HIP 33140 |
18.87 |
| 2026-02-13 00:00 |
06:57:52.06 |
-77:32:29.7 |
HIP 33140 |
18.84 |
| 2026-02-13 12:00 |
06:57:41.46 |
-77:32:01.6 |
HIP 33140 |
18.85 |
| 2026-02-14 00:00 |
06:57:30.95 |
-77:31:33.2 |
HIP 33140 |
18.89 |
| 2026-02-14 12:00 |
06:57:20.52 |
-77:31:04.6 |
HIP 33140 |
18.97 |
| 2026-02-15 00:00 |
06:57:10.19 |
-77:30:35.6 |
HIP 33140 |
19.08 |
| 2026-02-15 12:00 |
06:56:59.94 |
-77:30:06.3 |
HIP 33140 |
19.22 |
| 2026-02-16 00:00 |
06:56:49.78 |
-77:29:36.8 |
HIP 33140 |
19.40 |
| 2026-02-16 12:00 |
06:56:39.71 |
-77:29:06.9 |
HIP 33140 |
19.61 |
| 2026-02-17 00:00 |
06:56:29.73 |
-77:28:36.8 |
HIP 33140 |
19.85 |
| 2026-02-17 12:00 |
06:56:19.84 |
-77:28:06.4 |
HIP 33140 |
20.12 |
| 2026-02-18 00:00 |
06:56:10.05 |
-77:27:35.7 |
HIP 33140 |
20.41 |
| 2026-02-18 12:00 |
06:56:00.35 |
-77:27:04.8 |
HIP 32884 |
20.67 |
| 2026-02-19 00:00 |
06:55:50.74 |
-77:26:33.6 |
HIP 32884 |
20.63 |
| 2026-02-19 12:00 |
06:55:41.23 |
-77:26:02.1 |
HIP 32884 |
20.62 |
| 2026-02-20 00:00 |
06:55:31.81 |
-77:25:30.3 |
HIP 32884 |
20.65 |
| 2026-02-20 12:00 |
06:55:22.49 |
-77:24:58.3 |
HIP 32884 |
20.70 |
| 2026-02-21 00:00 |
06:55:13.26 |
-77:24:26.0 |
HIP 32884 |
20.79 |
| 2026-02-21 12:00 |
06:55:04.13 |
-77:23:53.5 |
HIP 32884 |
20.91 |
| 2026-02-22 00:00 |
06:54:55.10 |
-77:23:20.7 |
HIP 32884 |
21.06 |
| 2026-02-22 12:00 |
06:54:46.16 |
-77:22:47.7 |
HIP 32884 |
21.24 |
| 2026-02-23 00:00 |
06:54:37.33 |
-77:22:14.4 |
HIP 32884 |
21.46 |
| 2026-02-23 12:00 |
06:54:28.59 |
-77:21:40.9 |
HIP 32884 |
21.69 |
| 2026-02-24 00:00 |
06:54:19.95 |
-77:21:07.1 |
HIP 32884 |
21.96 |