| Parameter |
Value |
| Designation |
205P/Giacobini |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2015-05-14T00:01:56.562240Z |
| Orbit solution date (soln_date, UTC) |
2023-07-20T15:02:32Z |
| Obs used |
564 |
| NEO |
- |
| M1 |
14.000 |
| K1 |
9.750 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-02-19.0000000 |
| e |
0.56693106 |
| q (au) |
1.536180 |
| a (au) |
3.547195 |
| i (deg) |
15.287237 |
| Ω (om, deg) |
179.624626 |
| ω (w, deg) |
154.256561 |
| M (ma, deg) |
293.759426 |
Magnitude
Scatter + Global Linear
$$
M_a = (14.018 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
14.018 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.635 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2021-05-14 |
2021-11-14 |
+11.4692 |
-2.714 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
10:53:14.85 |
+05:21:46.7 |
HIP 53165 |
23.85 |
| 2026-06-01 12:00 |
10:53:20.51 |
+05:21:52.0 |
HIP 53165 |
24.56 |
| 2026-06-02 00:00 |
10:53:26.32 |
+05:21:56.3 |
HIP 53212 |
24.95 |
| 2026-06-02 12:00 |
10:53:32.30 |
+05:21:59.5 |
HIP 53212 |
25.40 |
| 2026-06-03 00:00 |
10:53:38.45 |
+05:22:01.5 |
HIP 53212 |
25.92 |
| 2026-06-03 12:00 |
10:53:44.75 |
+05:22:02.4 |
HIP 53212 |
26.52 |
| 2026-06-04 00:00 |
10:53:51.23 |
+05:22:02.2 |
HIP 53212 |
27.20 |
| 2026-06-04 12:00 |
10:53:57.86 |
+05:22:00.9 |
HIP 53212 |
27.96 |
| 2026-06-05 00:00 |
10:54:04.65 |
+05:21:58.4 |
HIP 53212 |
28.80 |
| 2026-06-05 12:00 |
10:54:11.60 |
+05:21:54.9 |
HIP 53212 |
29.72 |
| 2026-06-06 00:00 |
10:54:18.72 |
+05:21:50.3 |
HIP 53362 |
29.79 |
| 2026-06-06 12:00 |
10:54:25.99 |
+05:21:44.6 |
HIP 53362 |
29.53 |
| 2026-06-07 00:00 |
10:54:33.42 |
+05:21:37.8 |
HIP 53362 |
29.40 |
| 2026-06-07 12:00 |
10:54:41.01 |
+05:21:29.9 |
HIP 53485 |
27.84 |
| 2026-06-08 00:00 |
10:54:48.76 |
+05:21:20.9 |
HIP 53485 |
25.92 |
| 2026-06-08 12:00 |
10:54:56.66 |
+05:21:10.8 |
HIP 53485 |
23.96 |
| 2026-06-09 00:00 |
10:55:04.72 |
+05:20:59.7 |
HIP 53485 |
21.95 |
| 2026-06-09 12:00 |
10:55:12.93 |
+05:20:47.5 |
HIP 53485 |
19.91 |
| 2026-06-10 00:00 |
10:55:21.30 |
+05:20:34.2 |
HIP 53485 |
17.83 |
| 2026-06-10 12:00 |
10:55:29.82 |
+05:20:19.8 |
HIP 53485 |
15.72 |
| 2026-06-11 00:00 |
10:55:38.50 |
+05:20:04.4 |
HIP 53485 |
13.56 |
| 2026-06-11 12:00 |
10:55:47.33 |
+05:19:47.9 |
HIP 53485 |
11.38 |
| 2026-06-12 00:00 |
10:55:56.31 |
+05:19:30.3 |
HIP 53485 |
9.17 |
| 2026-06-12 12:00 |
10:56:05.44 |
+05:19:11.7 |
HIP 53485 |
6.94 |
| 2026-06-13 00:00 |
10:56:14.72 |
+05:18:52.1 |
HIP 53485 |
4.73 |
| 2026-06-13 12:00 |
10:56:24.15 |
+05:18:31.4 |
HIP 53485 |
2.71 |
| 2026-06-14 00:00 |
10:56:33.73 |
+05:18:09.6 |
HIP 53485 |
1.89 |
| 2026-06-14 12:00 |
10:56:43.46 |
+05:17:46.8 |
HIP 53485 |
3.40 |
| 2026-06-15 00:00 |
10:56:53.34 |
+05:17:23.0 |
HIP 53485 |
5.66 |
| 2026-06-15 12:00 |
10:57:03.36 |
+05:16:58.2 |
HIP 53485 |
8.08 |
| 2026-06-16 00:00 |
10:57:13.53 |
+05:16:32.3 |
HIP 53485 |
10.60 |
| 2026-06-16 12:00 |
10:57:23.84 |
+05:16:05.4 |
HIP 53485 |
13.17 |
| 2026-06-17 00:00 |
10:57:34.30 |
+05:15:37.5 |
HIP 53485 |
15.79 |
| 2026-06-17 12:00 |
10:57:44.90 |
+05:15:08.5 |
HIP 53485 |
18.45 |
| 2026-06-18 00:00 |
10:57:55.64 |
+05:14:38.6 |
HIP 53485 |
21.15 |
| 2026-06-18 12:00 |
10:58:06.53 |
+05:14:07.7 |
HIP 53485 |
23.90 |
| 2026-06-19 00:00 |
10:58:17.55 |
+05:13:35.8 |
HIP 53485 |
26.68 |
| 2026-06-19 12:00 |
10:58:28.72 |
+05:13:02.9 |
HIP 53485 |
29.51 |
| 2026-06-20 00:00 |
10:58:40.02 |
+05:12:29.0 |
HIP 53485 |
32.37 |
| 2026-06-20 12:00 |
10:58:51.46 |
+05:11:54.1 |
HIP 53856 |
33.87 |
| 2026-06-21 00:00 |
10:59:03.04 |
+05:11:18.3 |
HIP 53856 |
31.24 |
| 2026-06-21 12:00 |
10:59:14.75 |
+05:10:41.5 |
HIP 53856 |
28.65 |
| 2026-06-22 00:00 |
10:59:26.60 |
+05:10:03.7 |
HIP 53856 |
26.11 |