| Parameter |
Value |
| Designation |
C/1998 U5 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1998-12-21T18:14:25.114560Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:57Z |
| Obs used |
406 |
| NEO |
- |
| M1 |
11.000 |
| K1 |
15.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1998-12-01.0000000 |
| e |
0.98797943 |
| q (au) |
1.236453 |
| a (au) |
102.861449 |
| i (deg) |
131.764750 |
| Ω (om, deg) |
66.650605 |
| ω (w, deg) |
51.134275 |
| M (ma, deg) |
359.980387 |
Magnitude
Scatter + Global Linear
$$
M_a = (8.137 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
8.137 |
| 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 |
| 1998-10-30 |
1998-12-21 |
+23.4645 |
-2.542 |
| 1998-12-21 |
1999-05-11 |
-3.5652 |
+0.381 |
| 1999-05-11 |
1999-12-09 |
-44.9953 |
+16.194 |
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 |
13:57:05.16 |
-39:30:55.8 |
HIP 68202 |
13.46 |
| 2026-05-12 12:00 |
13:57:02.15 |
-39:30:39.5 |
HIP 68202 |
13.60 |
| 2026-05-13 00:00 |
13:56:59.16 |
-39:30:23.0 |
HIP 68047 |
13.07 |
| 2026-05-13 12:00 |
13:56:56.18 |
-39:30:06.4 |
HIP 68047 |
12.43 |
| 2026-05-14 00:00 |
13:56:53.21 |
-39:29:49.8 |
HIP 68047 |
11.79 |
| 2026-05-14 12:00 |
13:56:50.25 |
-39:29:33.0 |
HIP 68047 |
11.16 |
| 2026-05-15 00:00 |
13:56:47.30 |
-39:29:16.1 |
HIP 68047 |
10.52 |
| 2026-05-15 12:00 |
13:56:44.35 |
-39:28:59.2 |
HIP 68047 |
9.89 |
| 2026-05-16 00:00 |
13:56:41.43 |
-39:28:42.1 |
HIP 68047 |
9.26 |
| 2026-05-16 12:00 |
13:56:38.51 |
-39:28:24.9 |
HIP 68047 |
8.62 |
| 2026-05-17 00:00 |
13:56:35.60 |
-39:28:07.6 |
HIP 68047 |
7.99 |
| 2026-05-17 12:00 |
13:56:32.70 |
-39:27:50.3 |
HIP 68047 |
7.36 |
| 2026-05-18 00:00 |
13:56:29.82 |
-39:27:32.8 |
HIP 68047 |
6.74 |
| 2026-05-18 12:00 |
13:56:26.95 |
-39:27:15.2 |
HIP 68047 |
6.11 |
| 2026-05-19 00:00 |
13:56:24.09 |
-39:26:57.6 |
HIP 68047 |
5.48 |
| 2026-05-19 12:00 |
13:56:21.24 |
-39:26:39.8 |
HIP 68047 |
4.86 |
| 2026-05-20 00:00 |
13:56:18.41 |
-39:26:22.0 |
HIP 68047 |
4.24 |
| 2026-05-20 12:00 |
13:56:15.59 |
-39:26:04.1 |
HIP 68047 |
3.62 |
| 2026-05-21 00:00 |
13:56:12.78 |
-39:25:46.1 |
HIP 68047 |
3.00 |
| 2026-05-21 12:00 |
13:56:09.99 |
-39:25:28.0 |
HIP 68047 |
2.39 |
| 2026-05-22 00:00 |
13:56:07.21 |
-39:25:09.8 |
HIP 68047 |
1.78 |
| 2026-05-22 12:00 |
13:56:04.44 |
-39:24:51.5 |
HIP 68047 |
1.18 |
| 2026-05-23 00:00 |
13:56:01.69 |
-39:24:33.2 |
HIP 68047 |
0.62 |
| 2026-05-23 12:00 |
13:55:58.95 |
-39:24:14.8 |
HIP 68047 |
0.35 |
| 2026-05-24 00:00 |
13:55:56.23 |
-39:23:56.3 |
HIP 68047 |
0.78 |
| 2026-05-24 12:00 |
13:55:53.52 |
-39:23:37.8 |
HIP 68047 |
1.35 |
| 2026-05-25 00:00 |
13:55:50.82 |
-39:23:19.1 |
HIP 68047 |
1.95 |
| 2026-05-25 12:00 |
13:55:48.14 |
-39:23:00.4 |
HIP 68047 |
2.55 |
| 2026-05-26 00:00 |
13:55:45.48 |
-39:22:41.6 |
HIP 68047 |
3.15 |
| 2026-05-26 12:00 |
13:55:42.83 |
-39:22:22.8 |
HIP 68047 |
3.74 |
| 2026-05-27 00:00 |
13:55:40.19 |
-39:22:03.9 |
HIP 68047 |
4.34 |
| 2026-05-27 12:00 |
13:55:37.57 |
-39:21:44.9 |
HIP 68047 |
4.94 |
| 2026-05-28 00:00 |
13:55:34.97 |
-39:21:25.9 |
HIP 68047 |
5.53 |
| 2026-05-28 12:00 |
13:55:32.38 |
-39:21:06.8 |
HIP 68047 |
6.12 |
| 2026-05-29 00:00 |
13:55:29.81 |
-39:20:47.6 |
HIP 68047 |
6.71 |
| 2026-05-29 12:00 |
13:55:27.25 |
-39:20:28.4 |
HIP 68047 |
7.30 |
| 2026-05-30 00:00 |
13:55:24.71 |
-39:20:09.1 |
HIP 68047 |
7.89 |
| 2026-05-30 12:00 |
13:55:22.19 |
-39:19:49.7 |
HIP 68047 |
8.47 |
| 2026-05-31 00:00 |
13:55:19.69 |
-39:19:30.4 |
HIP 68047 |
9.06 |
| 2026-05-31 12:00 |
13:55:17.20 |
-39:19:10.9 |
HIP 68047 |
9.64 |
| 2026-06-01 00:00 |
13:55:14.72 |
-39:18:51.4 |
HIP 68047 |
10.22 |
| 2026-06-01 12:00 |
13:55:12.27 |
-39:18:31.9 |
HIP 68047 |
10.79 |
| 2026-06-02 00:00 |
13:55:09.83 |
-39:18:12.3 |
HIP 68047 |
11.36 |