| Parameter |
Value |
| Designation |
C/1998 Y1 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1998-11-21T13:57:33.661440Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:57Z |
| Obs used |
131 |
| NEO |
- |
| M1 |
14.000 |
| K1 |
10.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1999-01-13.0000000 |
| e |
0.92389938 |
| q (au) |
1.746990 |
| a (au) |
22.956311 |
| i (deg) |
28.108156 |
| Ω (om, deg) |
98.858723 |
| ω (w, deg) |
339.843627 |
| M (ma, deg) |
0.469715 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.201 + 5.443\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.201 |
| n |
5.443 |
| gf |
0.906 |
| gb |
-0.901 |
| k |
1.000 |
| δ90 |
5.356 |
| 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) |
| 2026-09-20 00:00 |
16:41:06.28 |
-08:20:10.7 |
HIP 81663 |
2.92 |
| 2026-09-20 12:00 |
16:41:07.30 |
-08:20:24.6 |
HIP 81663 |
3.26 |
| 2026-09-21 00:00 |
16:41:08.35 |
-08:20:38.5 |
HIP 81663 |
3.60 |
| 2026-09-21 12:00 |
16:41:09.42 |
-08:20:52.5 |
HIP 81663 |
3.95 |
| 2026-09-22 00:00 |
16:41:10.51 |
-08:21:06.4 |
HIP 81663 |
4.31 |
| 2026-09-22 12:00 |
16:41:11.63 |
-08:21:20.4 |
HIP 81663 |
4.67 |
| 2026-09-23 00:00 |
16:41:12.78 |
-08:21:34.4 |
HIP 81663 |
5.04 |
| 2026-09-23 12:00 |
16:41:13.95 |
-08:21:48.4 |
HIP 81663 |
5.41 |
| 2026-09-24 00:00 |
16:41:15.15 |
-08:22:02.4 |
HIP 81663 |
5.78 |
| 2026-09-24 12:00 |
16:41:16.37 |
-08:22:16.4 |
HIP 81663 |
6.17 |
| 2026-09-25 00:00 |
16:41:17.62 |
-08:22:30.4 |
HIP 81663 |
6.55 |
| 2026-09-25 12:00 |
16:41:18.89 |
-08:22:44.5 |
HIP 81663 |
6.95 |
| 2026-09-26 00:00 |
16:41:20.19 |
-08:22:58.5 |
HIP 81663 |
7.34 |
| 2026-09-26 12:00 |
16:41:21.51 |
-08:23:12.6 |
HIP 81663 |
7.74 |
| 2026-09-27 00:00 |
16:41:22.85 |
-08:23:26.7 |
HIP 81663 |
8.15 |
| 2026-09-27 12:00 |
16:41:24.22 |
-08:23:40.7 |
HIP 81663 |
8.56 |
| 2026-09-28 00:00 |
16:41:25.62 |
-08:23:54.8 |
HIP 81663 |
8.98 |
| 2026-09-28 12:00 |
16:41:27.04 |
-08:24:08.9 |
HIP 81663 |
9.40 |
| 2026-09-29 00:00 |
16:41:28.48 |
-08:24:23.0 |
HIP 81663 |
9.83 |
| 2026-09-29 12:00 |
16:41:29.95 |
-08:24:37.1 |
HIP 81663 |
10.26 |
| 2026-09-30 00:00 |
16:41:31.44 |
-08:24:51.2 |
HIP 81663 |
10.70 |
| 2026-09-30 12:00 |
16:41:32.95 |
-08:25:05.3 |
HIP 81663 |
11.14 |
| 2026-10-01 00:00 |
16:41:34.49 |
-08:25:19.4 |
HIP 81663 |
11.58 |
| 2026-10-01 12:00 |
16:41:36.06 |
-08:25:33.5 |
HIP 81663 |
12.04 |
| 2026-10-02 00:00 |
16:41:37.64 |
-08:25:47.6 |
HIP 81663 |
12.49 |
| 2026-10-02 12:00 |
16:41:39.26 |
-08:26:01.7 |
HIP 81663 |
12.95 |
| 2026-10-03 00:00 |
16:41:40.89 |
-08:26:15.8 |
HIP 81663 |
13.42 |
| 2026-10-03 12:00 |
16:41:42.55 |
-08:26:29.8 |
HIP 81663 |
13.89 |
| 2026-10-04 00:00 |
16:41:44.23 |
-08:26:43.9 |
HIP 81663 |
14.36 |
| 2026-10-04 12:00 |
16:41:45.93 |
-08:26:58.0 |
HIP 81663 |
14.84 |
| 2026-10-05 00:00 |
16:41:47.66 |
-08:27:12.1 |
HIP 81663 |
15.33 |
| 2026-10-05 12:00 |
16:41:49.41 |
-08:27:26.1 |
HIP 81663 |
15.82 |
| 2026-10-06 00:00 |
16:41:51.19 |
-08:27:40.2 |
HIP 81663 |
16.31 |
| 2026-10-06 12:00 |
16:41:52.98 |
-08:27:54.3 |
HIP 81663 |
16.81 |
| 2026-10-07 00:00 |
16:41:54.80 |
-08:28:08.3 |
HIP 81663 |
17.32 |
| 2026-10-07 12:00 |
16:41:56.64 |
-08:28:22.3 |
HIP 81663 |
17.83 |
| 2026-10-08 00:00 |
16:41:58.51 |
-08:28:36.3 |
HIP 81663 |
18.34 |
| 2026-10-08 12:00 |
16:42:00.40 |
-08:28:50.3 |
HIP 81663 |
18.86 |
| 2026-10-09 00:00 |
16:42:02.30 |
-08:29:04.3 |
HIP 81663 |
19.38 |
| 2026-10-09 12:00 |
16:42:04.24 |
-08:29:18.3 |
HIP 81663 |
19.91 |
| 2026-10-10 00:00 |
16:42:06.19 |
-08:29:32.2 |
HIP 81663 |
20.44 |
| 2026-10-10 12:00 |
16:42:08.16 |
-08:29:46.2 |
HIP 81663 |
20.98 |
| 2026-10-11 00:00 |
16:42:10.16 |
-08:30:00.1 |
HIP 81663 |
21.52 |