| Parameter |
Value |
| Designation |
C/1998 U1 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1998-05-02T12:00:10.497600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:57Z |
| Obs used |
122 |
| NEO |
- |
| M1 |
9.500 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1998-11-12.0000000 |
| e |
1.00043848 |
| q (au) |
3.975445 |
| a (au) |
-9066.409392 |
| i (deg) |
156.428505 |
| Ω (om, deg) |
210.457099 |
| ω (w, deg) |
124.645648 |
| M (ma, deg) |
0.000221 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.174 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.174 |
| n |
2.000 |
| gf |
0.858 |
| gb |
-0.501 |
| k |
1.000 |
| δ90 |
2.819 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
20:26:37.37 |
-43:48:43.2 |
HIP 100836 |
14.84 |
| 2026-07-29 12:00 |
20:26:33.86 |
-43:48:51.2 |
HIP 100836 |
15.03 |
| 2026-07-30 00:00 |
20:26:30.34 |
-43:48:59.0 |
HIP 100836 |
15.26 |
| 2026-07-30 12:00 |
20:26:26.83 |
-43:49:06.7 |
HIP 100836 |
15.50 |
| 2026-07-31 00:00 |
20:26:23.32 |
-43:49:14.2 |
HIP 100836 |
15.76 |
| 2026-07-31 12:00 |
20:26:19.81 |
-43:49:21.6 |
HIP 100836 |
16.05 |
| 2026-08-01 00:00 |
20:26:16.30 |
-43:49:28.9 |
HIP 100836 |
16.35 |
| 2026-08-01 12:00 |
20:26:12.79 |
-43:49:36.0 |
HIP 100836 |
16.67 |
| 2026-08-02 00:00 |
20:26:09.29 |
-43:49:42.9 |
HIP 100836 |
17.00 |
| 2026-08-02 12:00 |
20:26:05.79 |
-43:49:49.8 |
HIP 100836 |
17.35 |
| 2026-08-03 00:00 |
20:26:02.29 |
-43:49:56.4 |
HIP 100836 |
17.72 |
| 2026-08-03 12:00 |
20:25:58.79 |
-43:50:03.0 |
HIP 100836 |
18.09 |
| 2026-08-04 00:00 |
20:25:55.30 |
-43:50:09.4 |
HIP 100836 |
18.48 |
| 2026-08-04 12:00 |
20:25:51.81 |
-43:50:15.6 |
HIP 100836 |
18.88 |
| 2026-08-05 00:00 |
20:25:48.33 |
-43:50:21.7 |
HIP 100836 |
19.30 |
| 2026-08-05 12:00 |
20:25:44.85 |
-43:50:27.7 |
HIP 100836 |
19.72 |
| 2026-08-06 00:00 |
20:25:41.37 |
-43:50:33.5 |
HIP 100836 |
20.15 |
| 2026-08-06 12:00 |
20:25:37.90 |
-43:50:39.1 |
HIP 100836 |
20.58 |
| 2026-08-07 00:00 |
20:25:34.43 |
-43:50:44.7 |
HIP 100836 |
21.03 |
| 2026-08-07 12:00 |
20:25:30.97 |
-43:50:50.0 |
HIP 100836 |
21.48 |
| 2026-08-08 00:00 |
20:25:27.52 |
-43:50:55.2 |
HIP 100836 |
21.94 |
| 2026-08-08 12:00 |
20:25:24.07 |
-43:51:00.3 |
HIP 100836 |
22.40 |
| 2026-08-09 00:00 |
20:25:20.62 |
-43:51:05.2 |
HIP 100836 |
22.87 |
| 2026-08-09 12:00 |
20:25:17.19 |
-43:51:10.0 |
HIP 100836 |
23.35 |
| 2026-08-10 00:00 |
20:25:13.75 |
-43:51:14.6 |
HIP 100836 |
23.83 |
| 2026-08-10 12:00 |
20:25:10.33 |
-43:51:19.1 |
HIP 100836 |
24.31 |
| 2026-08-11 00:00 |
20:25:06.91 |
-43:51:23.4 |
HIP 100836 |
24.79 |
| 2026-08-11 12:00 |
20:25:03.50 |
-43:51:27.6 |
HIP 100528 |
24.63 |
| 2026-08-12 00:00 |
20:25:00.10 |
-43:51:31.6 |
HIP 100528 |
24.11 |
| 2026-08-12 12:00 |
20:24:56.71 |
-43:51:35.5 |
HIP 100528 |
23.60 |
| 2026-08-13 00:00 |
20:24:53.32 |
-43:51:39.2 |
HIP 100528 |
23.10 |
| 2026-08-13 12:00 |
20:24:49.94 |
-43:51:42.8 |
HIP 100528 |
22.60 |
| 2026-08-14 00:00 |
20:24:46.57 |
-43:51:46.2 |
HIP 100528 |
22.11 |
| 2026-08-14 12:00 |
20:24:43.21 |
-43:51:49.4 |
HIP 100528 |
21.62 |
| 2026-08-15 00:00 |
20:24:39.86 |
-43:51:52.5 |
HIP 100528 |
21.14 |
| 2026-08-15 12:00 |
20:24:36.52 |
-43:51:55.5 |
HIP 100528 |
20.67 |
| 2026-08-16 00:00 |
20:24:33.19 |
-43:51:58.3 |
HIP 100528 |
20.20 |
| 2026-08-16 12:00 |
20:24:29.86 |
-43:52:00.9 |
HIP 100528 |
19.74 |
| 2026-08-17 00:00 |
20:24:26.55 |
-43:52:03.4 |
HIP 100528 |
19.29 |
| 2026-08-17 12:00 |
20:24:23.25 |
-43:52:05.8 |
HIP 100528 |
18.85 |
| 2026-08-18 00:00 |
20:24:19.96 |
-43:52:08.0 |
HIP 100528 |
18.41 |
| 2026-08-18 12:00 |
20:24:16.68 |
-43:52:10.0 |
HIP 100528 |
17.99 |
| 2026-08-19 00:00 |
20:24:13.41 |
-43:52:11.9 |
HIP 100528 |
17.57 |