| Parameter |
Value |
| Designation |
C/1968 Y1 (Thomas) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1969-01-12T06:16:18.609600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:19Z |
| Obs used |
43 |
| NEO |
- |
| M1 |
5.800 |
| K1 |
10.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1969-02-14.0000000 |
| e |
0.99530224 |
| q (au) |
3.316098 |
| a (au) |
705.888695 |
| i (deg) |
45.229346 |
| Ω (om, deg) |
16.110035 |
| ω (w, deg) |
82.582846 |
| M (ma, deg) |
0.001721 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.454 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.454 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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 |
15:28:25.72 |
-57:57:47.7 |
HIP 75842 |
24.91 |
| 2026-09-20 12:00 |
15:28:27.27 |
-57:57:38.9 |
HIP 75842 |
24.98 |
| 2026-09-21 00:00 |
15:28:28.84 |
-57:57:30.2 |
HIP 75842 |
25.05 |
| 2026-09-21 12:00 |
15:28:30.43 |
-57:57:21.6 |
HIP 75842 |
25.11 |
| 2026-09-22 00:00 |
15:28:32.04 |
-57:57:13.1 |
HIP 75842 |
25.18 |
| 2026-09-22 12:00 |
15:28:33.66 |
-57:57:04.7 |
HIP 75842 |
25.24 |
| 2026-09-23 00:00 |
15:28:35.30 |
-57:56:56.4 |
HIP 75842 |
25.31 |
| 2026-09-23 12:00 |
15:28:36.96 |
-57:56:48.1 |
HIP 75842 |
25.38 |
| 2026-09-24 00:00 |
15:28:38.64 |
-57:56:40.0 |
HIP 75842 |
25.44 |
| 2026-09-24 12:00 |
15:28:40.34 |
-57:56:32.0 |
HIP 75842 |
25.51 |
| 2026-09-25 00:00 |
15:28:42.06 |
-57:56:24.1 |
HIP 75842 |
25.57 |
| 2026-09-25 12:00 |
15:28:43.79 |
-57:56:16.3 |
HIP 75842 |
25.64 |
| 2026-09-26 00:00 |
15:28:45.54 |
-57:56:08.5 |
HIP 75842 |
25.71 |
| 2026-09-26 12:00 |
15:28:47.31 |
-57:56:00.9 |
HIP 75842 |
25.78 |
| 2026-09-27 00:00 |
15:28:49.09 |
-57:55:53.4 |
HIP 75842 |
25.85 |
| 2026-09-27 12:00 |
15:28:50.89 |
-57:55:46.0 |
HIP 75842 |
25.91 |
| 2026-09-28 00:00 |
15:28:52.71 |
-57:55:38.7 |
HIP 75842 |
25.98 |
| 2026-09-28 12:00 |
15:28:54.55 |
-57:55:31.5 |
HIP 75842 |
26.05 |
| 2026-09-29 00:00 |
15:28:56.41 |
-57:55:24.4 |
HIP 75842 |
26.12 |
| 2026-09-29 12:00 |
15:28:58.28 |
-57:55:17.4 |
HIP 75842 |
26.19 |
| 2026-09-30 00:00 |
15:29:00.17 |
-57:55:10.5 |
HIP 75842 |
26.26 |
| 2026-09-30 12:00 |
15:29:02.07 |
-57:55:03.7 |
HIP 75842 |
26.34 |
| 2026-10-01 00:00 |
15:29:03.99 |
-57:54:57.0 |
HIP 75842 |
26.41 |
| 2026-10-01 12:00 |
15:29:05.93 |
-57:54:50.4 |
HIP 75842 |
26.48 |
| 2026-10-02 00:00 |
15:29:07.88 |
-57:54:44.0 |
HIP 75842 |
26.55 |
| 2026-10-02 12:00 |
15:29:09.85 |
-57:54:37.6 |
HIP 75842 |
26.63 |
| 2026-10-03 00:00 |
15:29:11.84 |
-57:54:31.4 |
HIP 75842 |
26.70 |
| 2026-10-03 12:00 |
15:29:13.84 |
-57:54:25.2 |
HIP 75842 |
26.78 |
| 2026-10-04 00:00 |
15:29:15.86 |
-57:54:19.2 |
HIP 75842 |
26.86 |
| 2026-10-04 12:00 |
15:29:17.89 |
-57:54:13.3 |
HIP 75842 |
26.93 |
| 2026-10-05 00:00 |
15:29:19.94 |
-57:54:07.4 |
HIP 75842 |
27.01 |
| 2026-10-05 12:00 |
15:29:22.01 |
-57:54:01.7 |
HIP 75842 |
27.09 |
| 2026-10-06 00:00 |
15:29:24.09 |
-57:53:56.1 |
HIP 75842 |
27.17 |
| 2026-10-06 12:00 |
15:29:26.18 |
-57:53:50.7 |
HIP 75842 |
27.25 |
| 2026-10-07 00:00 |
15:29:28.29 |
-57:53:45.3 |
HIP 75842 |
27.33 |
| 2026-10-07 12:00 |
15:29:30.42 |
-57:53:40.0 |
HIP 75842 |
27.42 |
| 2026-10-08 00:00 |
15:29:32.56 |
-57:53:34.9 |
HIP 75842 |
27.50 |
| 2026-10-08 12:00 |
15:29:34.71 |
-57:53:29.9 |
HIP 75842 |
27.58 |
| 2026-10-09 00:00 |
15:29:36.88 |
-57:53:24.9 |
HIP 75842 |
27.67 |
| 2026-10-09 12:00 |
15:29:39.07 |
-57:53:20.1 |
HIP 75842 |
27.76 |
| 2026-10-10 00:00 |
15:29:41.26 |
-57:53:15.4 |
HIP 75842 |
27.85 |
| 2026-10-10 12:00 |
15:29:43.48 |
-57:53:10.9 |
HIP 75842 |
27.93 |
| 2026-10-11 00:00 |
15:29:45.70 |
-57:53:06.4 |
HIP 75842 |
28.02 |