C/1999 XS87 (LINEAR)
| 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) |
| 2026-02-03 00:00 |
15:13:10.72 |
-26:58:22.8 |
HIP 74317 |
31.67 |
| 2026-02-03 12:00 |
15:13:11.57 |
-26:58:34.2 |
HIP 74317 |
31.69 |
| 2026-02-04 00:00 |
15:13:12.39 |
-26:58:45.5 |
HIP 74317 |
31.70 |
| 2026-02-04 12:00 |
15:13:13.17 |
-26:58:56.7 |
HIP 74317 |
31.71 |
| 2026-02-05 00:00 |
15:13:13.92 |
-26:59:07.7 |
HIP 74317 |
31.72 |
| 2026-02-05 12:00 |
15:13:14.62 |
-26:59:18.6 |
HIP 74317 |
31.73 |
| 2026-02-06 00:00 |
15:13:15.29 |
-26:59:29.4 |
HIP 74317 |
31.73 |
| 2026-02-06 12:00 |
15:13:15.93 |
-26:59:40.1 |
HIP 74317 |
31.73 |
| 2026-02-07 00:00 |
15:13:16.52 |
-26:59:50.7 |
HIP 74317 |
31.72 |
| 2026-02-07 12:00 |
15:13:17.08 |
-27:00:01.1 |
HIP 74317 |
31.72 |
| 2026-02-08 00:00 |
15:13:17.60 |
-27:00:11.4 |
HIP 74317 |
31.70 |
| 2026-02-08 12:00 |
15:13:18.09 |
-27:00:21.6 |
HIP 74317 |
31.69 |
| 2026-02-09 00:00 |
15:13:18.54 |
-27:00:31.6 |
HIP 74317 |
31.67 |
| 2026-02-09 12:00 |
15:13:18.95 |
-27:00:41.5 |
HIP 74317 |
31.64 |
| 2026-02-10 00:00 |
15:13:19.32 |
-27:00:51.3 |
HIP 74317 |
31.61 |
| 2026-02-10 12:00 |
15:13:19.66 |
-27:01:01.0 |
HIP 74317 |
31.58 |
| 2026-02-11 00:00 |
15:13:19.96 |
-27:01:10.5 |
HIP 74317 |
31.54 |
| 2026-02-11 12:00 |
15:13:20.22 |
-27:01:19.9 |
HIP 74317 |
31.50 |
| 2026-02-12 00:00 |
15:13:20.45 |
-27:01:29.2 |
HIP 74317 |
31.45 |
| 2026-02-12 12:00 |
15:13:20.64 |
-27:01:38.3 |
HIP 74317 |
31.40 |
| 2026-02-13 00:00 |
15:13:20.79 |
-27:01:47.3 |
HIP 74317 |
31.34 |
| 2026-02-13 12:00 |
15:13:20.90 |
-27:01:56.1 |
HIP 74317 |
31.28 |
| 2026-02-14 00:00 |
15:13:20.97 |
-27:02:04.9 |
HIP 74317 |
31.21 |
| 2026-02-14 12:00 |
15:13:21.01 |
-27:02:13.5 |
HIP 74317 |
31.14 |
| 2026-02-15 00:00 |
15:13:21.01 |
-27:02:21.9 |
HIP 74317 |
31.06 |
| 2026-02-15 12:00 |
15:13:20.98 |
-27:02:30.2 |
HIP 74317 |
30.98 |
| 2026-02-16 00:00 |
15:13:20.90 |
-27:02:38.4 |
HIP 74317 |
30.89 |
| 2026-02-16 12:00 |
15:13:20.79 |
-27:02:46.4 |
HIP 74317 |
30.80 |
| 2026-02-17 00:00 |
15:13:20.64 |
-27:02:54.3 |
HIP 74317 |
30.70 |
| 2026-02-17 12:00 |
15:13:20.45 |
-27:03:02.0 |
HIP 74317 |
30.59 |
| 2026-02-18 00:00 |
15:13:20.23 |
-27:03:09.7 |
HIP 74317 |
30.48 |
| 2026-02-18 12:00 |
15:13:19.97 |
-27:03:17.1 |
HIP 74317 |
30.37 |
| 2026-02-19 00:00 |
15:13:19.67 |
-27:03:24.4 |
HIP 74317 |
30.25 |
| 2026-02-19 12:00 |
15:13:19.33 |
-27:03:31.6 |
HIP 74317 |
30.12 |
| 2026-02-20 00:00 |
15:13:18.96 |
-27:03:38.6 |
HIP 74317 |
29.99 |
| 2026-02-20 12:00 |
15:13:18.54 |
-27:03:45.5 |
HIP 74317 |
29.85 |
| 2026-02-21 00:00 |
15:13:18.10 |
-27:03:52.3 |
HIP 74317 |
29.70 |
| 2026-02-21 12:00 |
15:13:17.61 |
-27:03:58.9 |
HIP 74317 |
29.56 |
| 2026-02-22 00:00 |
15:13:17.09 |
-27:04:05.3 |
HIP 74317 |
29.40 |
| 2026-02-22 12:00 |
15:13:16.53 |
-27:04:11.6 |
HIP 74317 |
29.24 |
| 2026-02-23 00:00 |
15:13:15.93 |
-27:04:17.8 |
HIP 74317 |
29.07 |
| 2026-02-23 12:00 |
15:13:15.30 |
-27:04:23.8 |
HIP 74317 |
28.90 |
| 2026-02-24 00:00 |
15:13:14.63 |
-27:04:29.6 |
HIP 74317 |
28.72 |