C/1998 U5 (LINEAR)
| 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 |
1999-05-23 |
-4.9497 |
+0.556 |
| 1999-05-23 |
1999-12-09 |
-52.6648 |
+20.427 |
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 |
14:05:07.47 |
-39:32:52.0 |
HIP 68831 |
17.71 |
| 2026-02-03 12:00 |
14:05:06.82 |
-39:33:07.4 |
HIP 68831 |
17.99 |
| 2026-02-04 00:00 |
14:05:06.13 |
-39:33:22.7 |
HIP 68831 |
18.28 |
| 2026-02-04 12:00 |
14:05:05.42 |
-39:33:37.9 |
HIP 68831 |
18.56 |
| 2026-02-05 00:00 |
14:05:04.69 |
-39:33:52.9 |
HIP 68831 |
18.85 |
| 2026-02-05 12:00 |
14:05:03.92 |
-39:34:07.9 |
HIP 68831 |
19.13 |
| 2026-02-06 00:00 |
14:05:03.13 |
-39:34:22.7 |
HIP 68831 |
19.42 |
| 2026-02-06 12:00 |
14:05:02.31 |
-39:34:37.3 |
HIP 68831 |
19.70 |
| 2026-02-07 00:00 |
14:05:01.47 |
-39:34:51.8 |
HIP 68831 |
19.99 |
| 2026-02-07 12:00 |
14:05:00.60 |
-39:35:06.2 |
HIP 68772 |
19.75 |
| 2026-02-08 00:00 |
14:04:59.70 |
-39:35:20.5 |
HIP 68772 |
19.47 |
| 2026-02-08 12:00 |
14:04:58.78 |
-39:35:34.6 |
HIP 68772 |
19.20 |
| 2026-02-09 00:00 |
14:04:57.83 |
-39:35:48.6 |
HIP 68772 |
18.93 |
| 2026-02-09 12:00 |
14:04:56.85 |
-39:36:02.5 |
HIP 68772 |
18.66 |
| 2026-02-10 00:00 |
14:04:55.85 |
-39:36:16.2 |
HIP 68772 |
18.39 |
| 2026-02-10 12:00 |
14:04:54.82 |
-39:36:29.8 |
HIP 68772 |
18.13 |
| 2026-02-11 00:00 |
14:04:53.76 |
-39:36:43.2 |
HIP 68772 |
17.86 |
| 2026-02-11 12:00 |
14:04:52.68 |
-39:36:56.5 |
HIP 68772 |
17.60 |
| 2026-02-12 00:00 |
14:04:51.57 |
-39:37:09.7 |
HIP 68772 |
17.35 |
| 2026-02-12 12:00 |
14:04:50.44 |
-39:37:22.7 |
HIP 68772 |
17.09 |
| 2026-02-13 00:00 |
14:04:49.28 |
-39:37:35.6 |
HIP 68772 |
16.84 |
| 2026-02-13 12:00 |
14:04:48.09 |
-39:37:48.3 |
HIP 68772 |
16.59 |
| 2026-02-14 00:00 |
14:04:46.88 |
-39:38:00.9 |
HIP 68772 |
16.35 |
| 2026-02-14 12:00 |
14:04:45.64 |
-39:38:13.3 |
HIP 68772 |
16.10 |
| 2026-02-15 00:00 |
14:04:44.37 |
-39:38:25.6 |
HIP 68772 |
15.87 |
| 2026-02-15 12:00 |
14:04:43.08 |
-39:38:37.8 |
HIP 68772 |
15.64 |
| 2026-02-16 00:00 |
14:04:41.77 |
-39:38:49.7 |
HIP 68772 |
15.41 |
| 2026-02-16 12:00 |
14:04:40.43 |
-39:39:01.6 |
HIP 68772 |
15.19 |
| 2026-02-17 00:00 |
14:04:39.06 |
-39:39:13.3 |
HIP 68772 |
14.98 |
| 2026-02-17 12:00 |
14:04:37.67 |
-39:39:24.8 |
HIP 68772 |
14.77 |
| 2026-02-18 00:00 |
14:04:36.25 |
-39:39:36.1 |
HIP 68772 |
14.57 |
| 2026-02-18 12:00 |
14:04:34.81 |
-39:39:47.4 |
HIP 68772 |
14.37 |
| 2026-02-19 00:00 |
14:04:33.34 |
-39:39:58.4 |
HIP 68772 |
14.19 |
| 2026-02-19 12:00 |
14:04:31.85 |
-39:40:09.3 |
HIP 68772 |
14.01 |
| 2026-02-20 00:00 |
14:04:30.33 |
-39:40:20.1 |
HIP 68772 |
13.84 |
| 2026-02-20 12:00 |
14:04:28.79 |
-39:40:30.6 |
HIP 68772 |
13.68 |
| 2026-02-21 00:00 |
14:04:27.22 |
-39:40:41.1 |
HIP 68772 |
13.53 |
| 2026-02-21 12:00 |
14:04:25.63 |
-39:40:51.3 |
HIP 68772 |
13.40 |
| 2026-02-22 00:00 |
14:04:24.02 |
-39:41:01.4 |
HIP 68772 |
13.27 |
| 2026-02-22 12:00 |
14:04:22.38 |
-39:41:11.4 |
HIP 68772 |
13.15 |
| 2026-02-23 00:00 |
14:04:20.71 |
-39:41:21.1 |
HIP 68772 |
13.05 |
| 2026-02-23 12:00 |
14:04:19.02 |
-39:41:30.7 |
HIP 68772 |
12.96 |
| 2026-02-24 00:00 |
14:04:17.31 |
-39:41:40.2 |
HIP 68653 |
12.68 |