| Parameter |
Value |
| Designation |
C/2013 TW5 (Spacewatch) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2014-08-17T15:50:25.054080Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:41Z |
| Obs used |
421 |
| NEO |
- |
| M1 |
11.000 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-06-23.0000000 |
| e |
0.98693812 |
| q (au) |
5.830627 |
| a (au) |
446.385044 |
| i (deg) |
31.401407 |
| Ω (om, deg) |
319.703831 |
| ω (w, deg) |
190.375424 |
| M (ma, deg) |
359.994183 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.679 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.679 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.728 |
| k |
0.800 |
| δ90 |
9.998 |
| 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) |
| 2026-09-25 00:00 |
18:27:32.74 |
-45:36:22.9 |
HIP 90468 |
7.39 |
| 2026-09-25 12:00 |
18:27:33.24 |
-45:35:51.6 |
HIP 90468 |
7.90 |
| 2026-09-26 00:00 |
18:27:33.79 |
-45:35:20.4 |
HIP 90468 |
8.41 |
| 2026-09-26 12:00 |
18:27:34.40 |
-45:34:49.1 |
HIP 90468 |
8.92 |
| 2026-09-27 00:00 |
18:27:35.07 |
-45:34:17.8 |
HIP 90468 |
9.43 |
| 2026-09-27 12:00 |
18:27:35.80 |
-45:33:46.6 |
HIP 90468 |
9.95 |
| 2026-09-28 00:00 |
18:27:36.58 |
-45:33:15.3 |
HIP 90468 |
10.47 |
| 2026-09-28 12:00 |
18:27:37.42 |
-45:32:43.9 |
HIP 90468 |
10.99 |
| 2026-09-29 00:00 |
18:27:38.32 |
-45:32:12.6 |
HIP 90468 |
11.52 |
| 2026-09-29 12:00 |
18:27:39.27 |
-45:31:41.3 |
HIP 90468 |
12.04 |
| 2026-09-30 00:00 |
18:27:40.28 |
-45:31:10.0 |
HIP 90468 |
12.57 |
| 2026-09-30 12:00 |
18:27:41.35 |
-45:30:38.6 |
HIP 90468 |
13.10 |
| 2026-10-01 00:00 |
18:27:42.48 |
-45:30:07.3 |
HIP 90468 |
13.63 |
| 2026-10-01 12:00 |
18:27:43.66 |
-45:29:36.0 |
HIP 90468 |
14.17 |
| 2026-10-02 00:00 |
18:27:44.90 |
-45:29:04.6 |
HIP 90468 |
14.71 |
| 2026-10-02 12:00 |
18:27:46.20 |
-45:28:33.3 |
HIP 90468 |
15.25 |
| 2026-10-03 00:00 |
18:27:47.55 |
-45:28:02.0 |
HIP 90468 |
15.79 |
| 2026-10-03 12:00 |
18:27:48.96 |
-45:27:30.7 |
HIP 90468 |
16.34 |
| 2026-10-04 00:00 |
18:27:50.43 |
-45:26:59.4 |
HIP 90468 |
16.89 |
| 2026-10-04 12:00 |
18:27:51.95 |
-45:26:28.1 |
HIP 90468 |
17.45 |
| 2026-10-05 00:00 |
18:27:53.53 |
-45:25:56.8 |
HIP 90468 |
18.00 |
| 2026-10-05 12:00 |
18:27:55.17 |
-45:25:25.5 |
HIP 90468 |
18.56 |
| 2026-10-06 00:00 |
18:27:56.86 |
-45:24:54.3 |
HIP 90468 |
19.13 |
| 2026-10-06 12:00 |
18:27:58.61 |
-45:24:23.1 |
HIP 90468 |
19.70 |
| 2026-10-07 00:00 |
18:28:00.42 |
-45:23:51.8 |
HIP 90468 |
20.27 |
| 2026-10-07 12:00 |
18:28:02.28 |
-45:23:20.7 |
HIP 90468 |
20.84 |
| 2026-10-08 00:00 |
18:28:04.19 |
-45:22:49.5 |
HIP 90468 |
21.42 |
| 2026-10-08 12:00 |
18:28:06.17 |
-45:22:18.4 |
HIP 90468 |
22.01 |
| 2026-10-09 00:00 |
18:28:08.20 |
-45:21:47.3 |
HIP 90468 |
22.59 |
| 2026-10-09 12:00 |
18:28:10.28 |
-45:21:16.2 |
HIP 90468 |
23.19 |
| 2026-10-10 00:00 |
18:28:12.42 |
-45:20:45.2 |
HIP 90468 |
23.78 |
| 2026-10-10 12:00 |
18:28:14.62 |
-45:20:14.1 |
HIP 90468 |
24.38 |
| 2026-10-11 00:00 |
18:28:16.87 |
-45:19:43.2 |
HIP 90468 |
24.99 |
| 2026-10-11 12:00 |
18:28:19.17 |
-45:19:12.2 |
HIP 90468 |
25.59 |
| 2026-10-12 00:00 |
18:28:21.53 |
-45:18:41.3 |
HIP 90468 |
26.21 |
| 2026-10-12 12:00 |
18:28:23.94 |
-45:18:10.5 |
HIP 90468 |
26.82 |
| 2026-10-13 00:00 |
18:28:26.41 |
-45:17:39.7 |
HIP 90468 |
27.45 |
| 2026-10-13 12:00 |
18:28:28.94 |
-45:17:08.9 |
HIP 90468 |
28.07 |
| 2026-10-14 00:00 |
18:28:31.51 |
-45:16:38.2 |
HIP 90468 |
28.71 |
| 2026-10-14 12:00 |
18:28:34.14 |
-45:16:07.5 |
HIP 90468 |
29.34 |
| 2026-10-15 00:00 |
18:28:36.83 |
-45:15:36.9 |
HIP 90468 |
29.98 |
| 2026-10-15 12:00 |
18:28:39.56 |
-45:15:06.3 |
HIP 90468 |
30.63 |
| 2026-10-16 00:00 |
18:28:42.35 |
-45:14:35.8 |
HIP 90468 |
31.28 |