| Parameter |
Value |
| Designation |
C/1999 XS87 (LINEAR) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1999-08-06T14:30:32.385600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:02Z |
| Obs used |
98 |
| NEO |
- |
| M1 |
13.700 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-01-09.0000000 |
| e |
0.84057497 |
| q (au) |
2.771840 |
| a (au) |
17.386476 |
| i (deg) |
14.846408 |
| Ω (om, deg) |
266.729359 |
| ω (w, deg) |
151.354533 |
| M (ma, deg) |
2.112638 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.066 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.066 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.759 |
| k |
0.800 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
15:11:31.08 |
-27:05:35.3 |
HIP 74317 |
13.90 |
| 2026-03-26 12:00 |
15:11:28.39 |
-27:05:31.5 |
HIP 74317 |
13.91 |
| 2026-03-27 00:00 |
15:11:25.68 |
-27:05:27.6 |
HIP 74317 |
13.94 |
| 2026-03-27 12:00 |
15:11:22.94 |
-27:05:23.4 |
HIP 74317 |
14.01 |
| 2026-03-28 00:00 |
15:11:20.17 |
-27:05:19.1 |
HIP 74317 |
14.11 |
| 2026-03-28 12:00 |
15:11:17.37 |
-27:05:14.7 |
HIP 74317 |
14.24 |
| 2026-03-29 00:00 |
15:11:14.55 |
-27:05:10.1 |
HIP 74317 |
14.39 |
| 2026-03-29 12:00 |
15:11:11.70 |
-27:05:05.4 |
HIP 74317 |
14.58 |
| 2026-03-30 00:00 |
15:11:08.83 |
-27:05:00.4 |
HIP 74317 |
14.79 |
| 2026-03-30 12:00 |
15:11:05.93 |
-27:04:55.4 |
HIP 74317 |
15.04 |
| 2026-03-31 00:00 |
15:11:03.01 |
-27:04:50.1 |
HIP 74317 |
15.31 |
| 2026-03-31 12:00 |
15:11:00.06 |
-27:04:44.7 |
HIP 74317 |
15.61 |
| 2026-04-01 00:00 |
15:10:57.08 |
-27:04:39.2 |
HIP 74317 |
15.93 |
| 2026-04-01 12:00 |
15:10:54.09 |
-27:04:33.5 |
HIP 74317 |
16.28 |
| 2026-04-02 00:00 |
15:10:51.06 |
-27:04:27.6 |
HIP 74317 |
16.66 |
| 2026-04-02 12:00 |
15:10:48.02 |
-27:04:21.6 |
HIP 74317 |
17.06 |
| 2026-04-03 00:00 |
15:10:44.95 |
-27:04:15.5 |
HIP 74317 |
17.48 |
| 2026-04-03 12:00 |
15:10:41.85 |
-27:04:09.1 |
HIP 74317 |
17.92 |
| 2026-04-04 00:00 |
15:10:38.74 |
-27:04:02.7 |
HIP 74317 |
18.39 |
| 2026-04-04 12:00 |
15:10:35.60 |
-27:03:56.0 |
HIP 74317 |
18.87 |
| 2026-04-05 00:00 |
15:10:32.43 |
-27:03:49.2 |
HIP 74317 |
19.37 |
| 2026-04-05 12:00 |
15:10:29.25 |
-27:03:42.3 |
HIP 74317 |
19.89 |
| 2026-04-06 00:00 |
15:10:26.04 |
-27:03:35.2 |
HIP 74317 |
20.43 |
| 2026-04-06 12:00 |
15:10:22.81 |
-27:03:27.9 |
HIP 74317 |
20.98 |
| 2026-04-07 00:00 |
15:10:19.56 |
-27:03:20.5 |
HIP 74317 |
21.55 |
| 2026-04-07 12:00 |
15:10:16.29 |
-27:03:13.0 |
HIP 74317 |
22.14 |
| 2026-04-08 00:00 |
15:10:12.99 |
-27:03:05.3 |
HIP 74317 |
22.74 |
| 2026-04-08 12:00 |
15:10:09.68 |
-27:02:57.4 |
HIP 74317 |
23.35 |
| 2026-04-09 00:00 |
15:10:06.34 |
-27:02:49.4 |
HIP 74317 |
23.97 |
| 2026-04-09 12:00 |
15:10:02.99 |
-27:02:41.3 |
HIP 74317 |
24.61 |
| 2026-04-10 00:00 |
15:09:59.61 |
-27:02:32.9 |
HIP 74317 |
25.26 |
| 2026-04-10 12:00 |
15:09:56.22 |
-27:02:24.5 |
HIP 74317 |
25.92 |
| 2026-04-11 00:00 |
15:09:52.80 |
-27:02:15.9 |
HIP 74317 |
26.59 |
| 2026-04-11 12:00 |
15:09:49.37 |
-27:02:07.1 |
HIP 74317 |
27.27 |
| 2026-04-12 00:00 |
15:09:45.92 |
-27:01:58.2 |
HIP 74317 |
27.96 |
| 2026-04-12 12:00 |
15:09:42.44 |
-27:01:49.2 |
HIP 74317 |
28.66 |
| 2026-04-13 00:00 |
15:09:38.95 |
-27:01:40.0 |
HIP 74317 |
29.37 |
| 2026-04-13 12:00 |
15:09:35.45 |
-27:01:30.6 |
HIP 74317 |
30.09 |
| 2026-04-14 00:00 |
15:09:31.92 |
-27:01:21.2 |
HIP 74317 |
30.81 |
| 2026-04-14 12:00 |
15:09:28.38 |
-27:01:11.5 |
HIP 74317 |
31.55 |
| 2026-04-15 00:00 |
15:09:24.82 |
-27:01:01.7 |
HIP 74131 |
31.78 |
| 2026-04-15 12:00 |
15:09:21.24 |
-27:00:51.8 |
HIP 74131 |
31.48 |
| 2026-04-16 00:00 |
15:09:17.65 |
-27:00:41.8 |
HIP 74131 |
31.19 |