| Parameter |
Value |
| Designation |
C/1985 T1 (Thiele) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1985-12-19T05:04:22.480320Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:33Z |
| Obs used |
133 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
13.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1985-12-16.0000000 |
| e |
0.98328249 |
| q (au) |
1.317141 |
| a (au) |
78.788093 |
| i (deg) |
139.069283 |
| Ω (om, deg) |
53.012812 |
| ω (w, deg) |
53.000230 |
| M (ma, deg) |
359.995474 |
Magnitude
Scatter + Global Linear
$$
M_a = (6.369 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.369 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.998 |
| k |
1.000 |
| 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) |
| 2026-03-26 00:00 |
12:37:06.83 |
-31:18:24.6 |
HIP 61603 |
14.36 |
| 2026-03-26 12:00 |
12:37:04.58 |
-31:18:15.4 |
HIP 61603 |
14.64 |
| 2026-03-27 00:00 |
12:37:02.33 |
-31:18:06.2 |
HIP 61603 |
14.93 |
| 2026-03-27 12:00 |
12:37:00.08 |
-31:17:56.8 |
HIP 61603 |
15.24 |
| 2026-03-28 00:00 |
12:36:57.83 |
-31:17:47.3 |
HIP 61603 |
15.56 |
| 2026-03-28 12:00 |
12:36:55.57 |
-31:17:37.7 |
HIP 61603 |
15.89 |
| 2026-03-29 00:00 |
12:36:53.32 |
-31:17:27.9 |
HIP 61603 |
16.24 |
| 2026-03-29 12:00 |
12:36:51.06 |
-31:17:18.0 |
HIP 61603 |
16.59 |
| 2026-03-30 00:00 |
12:36:48.81 |
-31:17:08.0 |
HIP 61603 |
16.95 |
| 2026-03-30 12:00 |
12:36:46.55 |
-31:16:57.9 |
HIP 61603 |
17.33 |
| 2026-03-31 00:00 |
12:36:44.30 |
-31:16:47.6 |
HIP 61603 |
17.71 |
| 2026-03-31 12:00 |
12:36:42.04 |
-31:16:37.2 |
HIP 61603 |
18.10 |
| 2026-04-01 00:00 |
12:36:39.79 |
-31:16:26.7 |
HIP 61478 |
18.15 |
| 2026-04-01 12:00 |
12:36:37.54 |
-31:16:16.1 |
HIP 61478 |
18.02 |
| 2026-04-02 00:00 |
12:36:35.28 |
-31:16:05.4 |
HIP 61478 |
17.91 |
| 2026-04-02 12:00 |
12:36:33.03 |
-31:15:54.5 |
HIP 61478 |
17.81 |
| 2026-04-03 00:00 |
12:36:30.78 |
-31:15:43.5 |
HIP 61478 |
17.73 |
| 2026-04-03 12:00 |
12:36:28.53 |
-31:15:32.4 |
HIP 61478 |
17.66 |
| 2026-04-04 00:00 |
12:36:26.28 |
-31:15:21.2 |
HIP 61478 |
17.61 |
| 2026-04-04 12:00 |
12:36:24.03 |
-31:15:09.9 |
HIP 61478 |
17.58 |
| 2026-04-05 00:00 |
12:36:21.78 |
-31:14:58.4 |
HIP 61478 |
17.56 |
| 2026-04-05 12:00 |
12:36:19.54 |
-31:14:46.8 |
HIP 61478 |
17.56 |
| 2026-04-06 00:00 |
12:36:17.30 |
-31:14:35.2 |
HIP 61478 |
17.58 |
| 2026-04-06 12:00 |
12:36:15.05 |
-31:14:23.4 |
HIP 61478 |
17.62 |
| 2026-04-07 00:00 |
12:36:12.82 |
-31:14:11.5 |
HIP 61478 |
17.67 |
| 2026-04-07 12:00 |
12:36:10.58 |
-31:13:59.5 |
HIP 61478 |
17.74 |
| 2026-04-08 00:00 |
12:36:08.35 |
-31:13:47.3 |
HIP 61478 |
17.83 |
| 2026-04-08 12:00 |
12:36:06.12 |
-31:13:35.1 |
HIP 61478 |
17.93 |
| 2026-04-09 00:00 |
12:36:03.89 |
-31:13:22.8 |
HIP 61478 |
18.05 |
| 2026-04-09 12:00 |
12:36:01.66 |
-31:13:10.3 |
HIP 61478 |
18.18 |
| 2026-04-10 00:00 |
12:35:59.44 |
-31:12:57.8 |
HIP 61478 |
18.33 |
| 2026-04-10 12:00 |
12:35:57.22 |
-31:12:45.1 |
HIP 61399 |
18.34 |
| 2026-04-11 00:00 |
12:35:55.01 |
-31:12:32.3 |
HIP 61399 |
18.13 |
| 2026-04-11 12:00 |
12:35:52.80 |
-31:12:19.5 |
HIP 61399 |
17.94 |
| 2026-04-12 00:00 |
12:35:50.59 |
-31:12:06.5 |
HIP 61399 |
17.77 |
| 2026-04-12 12:00 |
12:35:48.39 |
-31:11:53.4 |
HIP 61399 |
17.60 |
| 2026-04-13 00:00 |
12:35:46.19 |
-31:11:40.3 |
HIP 61399 |
17.46 |
| 2026-04-13 12:00 |
12:35:43.99 |
-31:11:27.0 |
HIP 61399 |
17.33 |
| 2026-04-14 00:00 |
12:35:41.80 |
-31:11:13.6 |
HIP 61399 |
17.22 |
| 2026-04-14 12:00 |
12:35:39.62 |
-31:11:00.2 |
HIP 61399 |
17.12 |
| 2026-04-15 00:00 |
12:35:37.44 |
-31:10:46.6 |
HIP 61399 |
17.04 |
| 2026-04-15 12:00 |
12:35:35.26 |
-31:10:33.0 |
HIP 61399 |
16.98 |
| 2026-04-16 00:00 |
12:35:33.09 |
-31:10:19.2 |
HIP 61399 |
16.93 |