C/1999 S4 (LINEAR)
| Parameter |
Value |
| Designation |
C/1999 S4 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2000-07-26T03:54:28.607040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:02Z |
| Obs used |
1230 |
| NEO |
- |
| M1 |
9.600 |
| K1 |
6.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-02-13.0000000 |
| e |
1.00010829 |
| q (au) |
0.765089 |
| a (au) |
-7064.946187 |
| i (deg) |
149.384928 |
| Ω (om, deg) |
83.180585 |
| ω (w, deg) |
151.049994 |
| M (ma, deg) |
-0.000272 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.703 + 2.930\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.703 |
| n |
2.930 |
| gf |
0.800 |
| gb |
-0.588 |
| k |
0.800 |
| δ90 |
1.000 |
| 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 |
| 1999-09-27 |
1999-12-05 |
+5.1833 |
-3.118 |
| 1999-12-05 |
2000-06-22 |
+2.2171 |
-1.141 |
| 2000-06-22 |
2000-07-26 |
-14.5391 |
-1.393 |
| 2000-07-26 |
2000-08-30 |
+15.4677 |
+2.517 |
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 |
07:58:36.39 |
-00:39:22.0 |
HIP 38915 |
11.51 |
| 2026-02-03 12:00 |
07:58:33.92 |
-00:39:10.8 |
HIP 38915 |
10.94 |
| 2026-02-04 00:00 |
07:58:31.46 |
-00:38:59.4 |
HIP 38915 |
10.38 |
| 2026-02-04 12:00 |
07:58:29.01 |
-00:38:48.0 |
HIP 38915 |
9.83 |
| 2026-02-05 00:00 |
07:58:26.56 |
-00:38:36.4 |
HIP 38915 |
9.30 |
| 2026-02-05 12:00 |
07:58:24.12 |
-00:38:24.8 |
HIP 38915 |
8.78 |
| 2026-02-06 00:00 |
07:58:21.69 |
-00:38:13.1 |
HIP 38915 |
8.28 |
| 2026-02-06 12:00 |
07:58:19.26 |
-00:38:01.3 |
HIP 38915 |
7.81 |
| 2026-02-07 00:00 |
07:58:16.84 |
-00:37:49.3 |
HIP 38915 |
7.36 |
| 2026-02-07 12:00 |
07:58:14.43 |
-00:37:37.3 |
HIP 38915 |
6.94 |
| 2026-02-08 00:00 |
07:58:12.03 |
-00:37:25.3 |
HIP 38915 |
6.57 |
| 2026-02-08 12:00 |
07:58:09.64 |
-00:37:13.1 |
HIP 38915 |
6.23 |
| 2026-02-09 00:00 |
07:58:07.25 |
-00:37:00.8 |
HIP 38915 |
5.95 |
| 2026-02-09 12:00 |
07:58:04.88 |
-00:36:48.4 |
HIP 38915 |
5.72 |
| 2026-02-10 00:00 |
07:58:02.51 |
-00:36:36.0 |
HIP 38915 |
5.56 |
| 2026-02-10 12:00 |
07:58:00.15 |
-00:36:23.5 |
HIP 38915 |
5.47 |
| 2026-02-11 00:00 |
07:57:57.80 |
-00:36:10.9 |
HIP 38915 |
5.45 |
| 2026-02-11 12:00 |
07:57:55.46 |
-00:35:58.2 |
HIP 38915 |
5.51 |
| 2026-02-12 00:00 |
07:57:53.13 |
-00:35:45.4 |
HIP 38915 |
5.63 |
| 2026-02-12 12:00 |
07:57:50.81 |
-00:35:32.5 |
HIP 38915 |
5.82 |
| 2026-02-13 00:00 |
07:57:48.50 |
-00:35:19.6 |
HIP 38915 |
6.07 |
| 2026-02-13 12:00 |
07:57:46.20 |
-00:35:06.6 |
HIP 38885 |
5.92 |
| 2026-02-14 00:00 |
07:57:43.92 |
-00:34:53.5 |
HIP 38885 |
5.57 |
| 2026-02-14 12:00 |
07:57:41.64 |
-00:34:40.3 |
HIP 38885 |
5.26 |
| 2026-02-15 00:00 |
07:57:39.37 |
-00:34:27.0 |
HIP 38885 |
5.01 |
| 2026-02-15 12:00 |
07:57:37.11 |
-00:34:13.7 |
HIP 38885 |
4.83 |
| 2026-02-16 00:00 |
07:57:34.86 |
-00:34:00.3 |
HIP 38885 |
4.72 |
| 2026-02-16 12:00 |
07:57:32.63 |
-00:33:46.8 |
HIP 38885 |
4.69 |
| 2026-02-17 00:00 |
07:57:30.41 |
-00:33:33.3 |
HIP 38885 |
4.73 |
| 2026-02-17 12:00 |
07:57:28.19 |
-00:33:19.7 |
HIP 38885 |
4.86 |
| 2026-02-18 00:00 |
07:57:25.99 |
-00:33:06.0 |
HIP 38885 |
5.05 |
| 2026-02-18 12:00 |
07:57:23.81 |
-00:32:52.2 |
HIP 38885 |
5.31 |
| 2026-02-19 00:00 |
07:57:21.63 |
-00:32:38.4 |
HIP 38885 |
5.61 |
| 2026-02-19 12:00 |
07:57:19.47 |
-00:32:24.5 |
HIP 38885 |
5.96 |
| 2026-02-20 00:00 |
07:57:17.32 |
-00:32:10.5 |
HIP 38885 |
6.35 |
| 2026-02-20 12:00 |
07:57:15.18 |
-00:31:56.5 |
HIP 38885 |
6.76 |
| 2026-02-21 00:00 |
07:57:13.05 |
-00:31:42.5 |
HIP 38885 |
7.20 |
| 2026-02-21 12:00 |
07:57:10.94 |
-00:31:28.3 |
HIP 38885 |
7.65 |
| 2026-02-22 00:00 |
07:57:08.84 |
-00:31:14.1 |
HIP 38885 |
8.12 |
| 2026-02-22 12:00 |
07:57:06.76 |
-00:30:59.9 |
HIP 38885 |
8.60 |
| 2026-02-23 00:00 |
07:57:04.68 |
-00:30:45.5 |
HIP 38885 |
9.09 |
| 2026-02-23 12:00 |
07:57:02.63 |
-00:30:31.2 |
HIP 38885 |
9.59 |
| 2026-02-24 00:00 |
07:57:00.58 |
-00:30:16.7 |
HIP 38885 |
10.10 |