C/1999 S2 (McNaught-Watson)
| Parameter |
Value |
| Designation |
C/1999 S2 (McNaught-Watson) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1997-11-22T14:49:59.252160Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:30:02Z |
| Obs used |
88 |
| NEO |
- |
| M1 |
8.000 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2000-03-17.0000000 |
| e |
1.00527083 |
| q (au) |
6.467743 |
| a (au) |
-1227.083165 |
| i (deg) |
65.820220 |
| Ω (om, deg) |
74.460976 |
| ω (w, deg) |
223.497414 |
| M (ma, deg) |
0.019384 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.223 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.223 |
| n |
2.000 |
| gf |
0.828 |
| gb |
-0.827 |
| k |
0.800 |
| δ90 |
9.796 |
| 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 |
04:47:07.12 |
+21:55:48.4 |
HIP 22291 |
19.21 |
| 2026-02-03 12:00 |
04:47:05.82 |
+21:55:49.2 |
HIP 22291 |
19.41 |
| 2026-02-04 00:00 |
04:47:04.54 |
+21:55:49.9 |
HIP 22291 |
19.60 |
| 2026-02-04 12:00 |
04:47:03.28 |
+21:55:50.7 |
HIP 22291 |
19.79 |
| 2026-02-05 00:00 |
04:47:02.04 |
+21:55:51.6 |
HIP 22291 |
19.98 |
| 2026-02-05 12:00 |
04:47:00.83 |
+21:55:52.4 |
HIP 22291 |
20.16 |
| 2026-02-06 00:00 |
04:46:59.63 |
+21:55:53.3 |
HIP 22291 |
20.35 |
| 2026-02-06 12:00 |
04:46:58.46 |
+21:55:54.3 |
HIP 22291 |
20.53 |
| 2026-02-07 00:00 |
04:46:57.31 |
+21:55:55.3 |
HIP 22291 |
20.71 |
| 2026-02-07 12:00 |
04:46:56.19 |
+21:55:56.3 |
HIP 22291 |
20.89 |
| 2026-02-08 00:00 |
04:46:55.08 |
+21:55:57.4 |
HIP 22291 |
21.07 |
| 2026-02-08 12:00 |
04:46:54.00 |
+21:55:58.5 |
HIP 22291 |
21.24 |
| 2026-02-09 00:00 |
04:46:52.94 |
+21:55:59.6 |
HIP 22291 |
21.41 |
| 2026-02-09 12:00 |
04:46:51.90 |
+21:56:00.8 |
HIP 22291 |
21.58 |
| 2026-02-10 00:00 |
04:46:50.89 |
+21:56:02.0 |
HIP 22291 |
21.74 |
| 2026-02-10 12:00 |
04:46:49.90 |
+21:56:03.3 |
HIP 22291 |
21.90 |
| 2026-02-11 00:00 |
04:46:48.93 |
+21:56:04.6 |
HIP 22291 |
22.06 |
| 2026-02-11 12:00 |
04:46:47.98 |
+21:56:05.9 |
HIP 22291 |
22.21 |
| 2026-02-12 00:00 |
04:46:47.06 |
+21:56:07.3 |
HIP 22291 |
22.37 |
| 2026-02-12 12:00 |
04:46:46.16 |
+21:56:08.7 |
HIP 22291 |
22.51 |
| 2026-02-13 00:00 |
04:46:45.28 |
+21:56:10.2 |
HIP 22291 |
22.66 |
| 2026-02-13 12:00 |
04:46:44.43 |
+21:56:11.7 |
HIP 22291 |
22.80 |
| 2026-02-14 00:00 |
04:46:43.60 |
+21:56:13.2 |
HIP 22291 |
22.93 |
| 2026-02-14 12:00 |
04:46:42.79 |
+21:56:14.8 |
HIP 22291 |
23.07 |
| 2026-02-15 00:00 |
04:46:42.01 |
+21:56:16.4 |
HIP 22291 |
23.19 |
| 2026-02-15 12:00 |
04:46:41.25 |
+21:56:18.1 |
HIP 22291 |
23.32 |
| 2026-02-16 00:00 |
04:46:40.51 |
+21:56:19.8 |
HIP 22291 |
23.44 |
| 2026-02-16 12:00 |
04:46:39.80 |
+21:56:21.5 |
HIP 22291 |
23.56 |
| 2026-02-17 00:00 |
04:46:39.11 |
+21:56:23.3 |
HIP 22291 |
23.67 |
| 2026-02-17 12:00 |
04:46:38.45 |
+21:56:25.2 |
HIP 22291 |
23.78 |
| 2026-02-18 00:00 |
04:46:37.80 |
+21:56:27.0 |
HIP 22291 |
23.88 |
| 2026-02-18 12:00 |
04:46:37.18 |
+21:56:28.9 |
HIP 22291 |
23.98 |
| 2026-02-19 00:00 |
04:46:36.59 |
+21:56:30.9 |
HIP 22291 |
24.07 |
| 2026-02-19 12:00 |
04:46:36.02 |
+21:56:32.9 |
HIP 22222 |
24.15 |
| 2026-02-20 00:00 |
04:46:35.47 |
+21:56:34.9 |
HIP 22222 |
24.13 |
| 2026-02-20 12:00 |
04:46:34.95 |
+21:56:37.0 |
HIP 22222 |
24.11 |
| 2026-02-21 00:00 |
04:46:34.45 |
+21:56:39.1 |
HIP 22222 |
24.08 |
| 2026-02-21 12:00 |
04:46:33.97 |
+21:56:41.2 |
HIP 22222 |
24.06 |
| 2026-02-22 00:00 |
04:46:33.52 |
+21:56:43.4 |
HIP 22222 |
24.04 |
| 2026-02-22 12:00 |
04:46:33.09 |
+21:56:45.6 |
HIP 22222 |
24.01 |
| 2026-02-23 00:00 |
04:46:32.69 |
+21:56:47.9 |
HIP 22222 |
23.99 |
| 2026-02-23 12:00 |
04:46:32.31 |
+21:56:50.2 |
HIP 22222 |
23.96 |
| 2026-02-24 00:00 |
04:46:31.95 |
+21:56:52.6 |
HIP 22222 |
23.93 |