| 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) |
| 2026-09-20 00:00 |
15:01:18.62 |
-25:57:53.5 |
HIP 73532 |
15.21 |
| 2026-09-20 12:00 |
15:01:21.55 |
-25:57:57.3 |
HIP 73532 |
14.90 |
| 2026-09-21 00:00 |
15:01:24.51 |
-25:58:01.2 |
HIP 73532 |
14.61 |
| 2026-09-21 12:00 |
15:01:27.50 |
-25:58:05.3 |
HIP 73532 |
14.34 |
| 2026-09-22 00:00 |
15:01:30.51 |
-25:58:09.5 |
HIP 73532 |
14.10 |
| 2026-09-22 12:00 |
15:01:33.54 |
-25:58:13.9 |
HIP 73532 |
13.88 |
| 2026-09-23 00:00 |
15:01:36.60 |
-25:58:18.4 |
HIP 73532 |
13.69 |
| 2026-09-23 12:00 |
15:01:39.69 |
-25:58:23.1 |
HIP 73532 |
13.53 |
| 2026-09-24 00:00 |
15:01:42.80 |
-25:58:27.9 |
HIP 73532 |
13.40 |
| 2026-09-24 12:00 |
15:01:45.93 |
-25:58:32.9 |
HIP 73532 |
13.30 |
| 2026-09-25 00:00 |
15:01:49.09 |
-25:58:38.0 |
HIP 73532 |
13.24 |
| 2026-09-25 12:00 |
15:01:52.27 |
-25:58:43.2 |
HIP 73532 |
13.21 |
| 2026-09-26 00:00 |
15:01:55.47 |
-25:58:48.6 |
HIP 73532 |
13.23 |
| 2026-09-26 12:00 |
15:01:58.70 |
-25:58:54.1 |
HIP 73532 |
13.28 |
| 2026-09-27 00:00 |
15:02:01.95 |
-25:58:59.8 |
HIP 73532 |
13.37 |
| 2026-09-27 12:00 |
15:02:05.22 |
-25:59:05.6 |
HIP 73532 |
13.50 |
| 2026-09-28 00:00 |
15:02:08.52 |
-25:59:11.5 |
HIP 73532 |
13.67 |
| 2026-09-28 12:00 |
15:02:11.84 |
-25:59:17.6 |
HIP 73532 |
13.88 |
| 2026-09-29 00:00 |
15:02:15.18 |
-25:59:23.9 |
HIP 73532 |
14.12 |
| 2026-09-29 12:00 |
15:02:18.54 |
-25:59:30.2 |
HIP 73532 |
14.40 |
| 2026-09-30 00:00 |
15:02:21.92 |
-25:59:36.7 |
HIP 73532 |
14.72 |
| 2026-09-30 12:00 |
15:02:25.33 |
-25:59:43.3 |
HIP 73532 |
15.07 |
| 2026-10-01 00:00 |
15:02:28.76 |
-25:59:50.1 |
HIP 73532 |
15.45 |
| 2026-10-01 12:00 |
15:02:32.21 |
-25:59:57.0 |
HIP 73532 |
15.86 |
| 2026-10-02 00:00 |
15:02:35.68 |
-26:00:04.1 |
HIP 73532 |
16.30 |
| 2026-10-02 12:00 |
15:02:39.18 |
-26:00:11.3 |
HIP 73532 |
16.77 |
| 2026-10-03 00:00 |
15:02:42.69 |
-26:00:18.6 |
HIP 73532 |
17.26 |
| 2026-10-03 12:00 |
15:02:46.22 |
-26:00:26.0 |
HIP 73532 |
17.78 |
| 2026-10-04 00:00 |
15:02:49.78 |
-26:00:33.6 |
HIP 73532 |
18.32 |
| 2026-10-04 12:00 |
15:02:53.36 |
-26:00:41.3 |
HIP 73532 |
18.88 |
| 2026-10-05 00:00 |
15:02:56.95 |
-26:00:49.2 |
HIP 73532 |
19.46 |
| 2026-10-05 12:00 |
15:03:00.57 |
-26:00:57.2 |
HIP 73532 |
20.07 |
| 2026-10-06 00:00 |
15:03:04.20 |
-26:01:05.3 |
HIP 73532 |
20.68 |
| 2026-10-06 12:00 |
15:03:07.86 |
-26:01:13.5 |
HIP 73532 |
21.32 |
| 2026-10-07 00:00 |
15:03:11.53 |
-26:01:21.9 |
HIP 73532 |
21.97 |
| 2026-10-07 12:00 |
15:03:15.22 |
-26:01:30.4 |
HIP 73532 |
22.64 |
| 2026-10-08 00:00 |
15:03:18.94 |
-26:01:39.1 |
HIP 73532 |
23.32 |
| 2026-10-08 12:00 |
15:03:22.67 |
-26:01:47.8 |
HIP 73532 |
24.01 |
| 2026-10-09 00:00 |
15:03:26.42 |
-26:01:56.7 |
HIP 73532 |
24.72 |
| 2026-10-09 12:00 |
15:03:30.18 |
-26:02:05.7 |
HIP 73532 |
25.44 |
| 2026-10-10 00:00 |
15:03:33.97 |
-26:02:14.9 |
HIP 73532 |
26.17 |
| 2026-10-10 12:00 |
15:03:37.77 |
-26:02:24.2 |
HIP 73532 |
26.91 |
| 2026-10-11 00:00 |
15:03:41.59 |
-26:02:33.6 |
HIP 73532 |
27.66 |