| Parameter |
Value |
| Designation |
C/2009 E1 (Itagaki) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2009-04-07T22:05:17.583360Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:29Z |
| Obs used |
562 |
| NEO |
- |
| M1 |
13.500 |
| K1 |
16.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-04-29.0000000 |
| e |
0.98507270 |
| q (au) |
0.599722 |
| a (au) |
40.176157 |
| i (deg) |
127.453383 |
| Ω (om, deg) |
105.962011 |
| ω (w, deg) |
48.955232 |
| M (ma, deg) |
0.081586 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.399 + 5.843\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.399 |
| n |
5.843 |
| gf |
0.999 |
| gb |
-0.662 |
| 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 |
| 2008-03-20 |
2009-03-20 |
-20.1855 |
-2.656 |
| 2009-03-20 |
2009-04-06 |
+18.5279 |
+1.854 |
| 2009-04-08 |
2009-05-09 |
+5.8500 |
-2.134 |
| 2009-05-09 |
2009-05-27 |
-15.6182 |
-2.738 |
| 2009-05-27 |
2009-06-21 |
+20.5841 |
-3.922 |
| 2009-06-21 |
2009-07-04 |
+33.7456 |
-7.368 |
| 2009-07-04 |
2009-08-19 |
-24.8681 |
+6.863 |
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 |
17:12:01.70 |
-52:33:09.3 |
HIP 84085 |
7.44 |
| 2026-06-01 12:00 |
17:11:55.69 |
-52:33:10.7 |
HIP 84085 |
6.81 |
| 2026-06-02 00:00 |
17:11:49.68 |
-52:33:11.8 |
HIP 84085 |
6.24 |
| 2026-06-02 12:00 |
17:11:43.66 |
-52:33:12.7 |
HIP 84085 |
5.75 |
| 2026-06-03 00:00 |
17:11:37.64 |
-52:33:13.3 |
HIP 84085 |
5.37 |
| 2026-06-03 12:00 |
17:11:31.61 |
-52:33:13.7 |
HIP 84085 |
5.13 |
| 2026-06-04 00:00 |
17:11:25.57 |
-52:33:13.9 |
HIP 84051 |
4.59 |
| 2026-06-04 12:00 |
17:11:19.53 |
-52:33:13.8 |
HIP 84051 |
3.82 |
| 2026-06-05 00:00 |
17:11:13.48 |
-52:33:13.4 |
HIP 84051 |
3.12 |
| 2026-06-05 12:00 |
17:11:07.43 |
-52:33:12.8 |
HIP 84051 |
2.57 |
| 2026-06-06 00:00 |
17:11:01.38 |
-52:33:12.0 |
HIP 84051 |
2.27 |
| 2026-06-06 12:00 |
17:10:55.32 |
-52:33:10.9 |
HIP 84051 |
2.31 |
| 2026-06-07 00:00 |
17:10:49.26 |
-52:33:09.6 |
HIP 84051 |
2.69 |
| 2026-06-07 12:00 |
17:10:43.20 |
-52:33:08.0 |
HIP 84051 |
3.29 |
| 2026-06-08 00:00 |
17:10:37.13 |
-52:33:06.2 |
HIP 84051 |
4.01 |
| 2026-06-08 12:00 |
17:10:31.07 |
-52:33:04.1 |
HIP 84051 |
4.80 |
| 2026-06-09 00:00 |
17:10:25.00 |
-52:33:01.8 |
HIP 84051 |
5.63 |
| 2026-06-09 12:00 |
17:10:18.93 |
-52:32:59.2 |
HIP 84051 |
6.48 |
| 2026-06-10 00:00 |
17:10:12.87 |
-52:32:56.4 |
HIP 84051 |
7.35 |
| 2026-06-10 12:00 |
17:10:06.80 |
-52:32:53.3 |
HIP 83964 |
7.46 |
| 2026-06-11 00:00 |
17:10:00.73 |
-52:32:50.0 |
HIP 83964 |
7.22 |
| 2026-06-11 12:00 |
17:09:54.67 |
-52:32:46.4 |
HIP 83964 |
7.09 |
| 2026-06-12 00:00 |
17:09:48.61 |
-52:32:42.6 |
HIP 83964 |
7.09 |
| 2026-06-12 12:00 |
17:09:42.55 |
-52:32:38.6 |
HIP 83964 |
7.21 |
| 2026-06-13 00:00 |
17:09:36.50 |
-52:32:34.3 |
HIP 83964 |
7.45 |
| 2026-06-13 12:00 |
17:09:30.44 |
-52:32:29.8 |
HIP 83964 |
7.79 |
| 2026-06-14 00:00 |
17:09:24.40 |
-52:32:25.0 |
HIP 83964 |
8.23 |
| 2026-06-14 12:00 |
17:09:18.35 |
-52:32:20.0 |
HIP 83964 |
8.74 |
| 2026-06-15 00:00 |
17:09:12.31 |
-52:32:14.7 |
HIP 83964 |
9.32 |
| 2026-06-15 12:00 |
17:09:06.28 |
-52:32:09.2 |
HIP 83964 |
9.96 |
| 2026-06-16 00:00 |
17:09:00.26 |
-52:32:03.5 |
HIP 83964 |
10.64 |
| 2026-06-16 12:00 |
17:08:54.24 |
-52:31:57.5 |
HIP 83964 |
11.35 |
| 2026-06-17 00:00 |
17:08:48.22 |
-52:31:51.2 |
HIP 83964 |
12.10 |
| 2026-06-17 12:00 |
17:08:42.22 |
-52:31:44.8 |
HIP 83964 |
12.86 |
| 2026-06-18 00:00 |
17:08:36.22 |
-52:31:38.1 |
HIP 83964 |
13.65 |
| 2026-06-18 12:00 |
17:08:30.24 |
-52:31:31.1 |
HIP 83964 |
14.46 |
| 2026-06-19 00:00 |
17:08:24.26 |
-52:31:24.0 |
HIP 83964 |
15.28 |
| 2026-06-19 12:00 |
17:08:18.29 |
-52:31:16.5 |
HIP 83964 |
16.11 |
| 2026-06-20 00:00 |
17:08:12.33 |
-52:31:08.9 |
HIP 83964 |
16.95 |
| 2026-06-20 12:00 |
17:08:06.38 |
-52:31:01.0 |
HIP 83964 |
17.79 |
| 2026-06-21 00:00 |
17:08:00.45 |
-52:30:52.9 |
HIP 83671 |
17.63 |
| 2026-06-21 12:00 |
17:07:54.52 |
-52:30:44.6 |
HIP 83671 |
16.73 |
| 2026-06-22 00:00 |
17:07:48.61 |
-52:30:36.0 |
HIP 83671 |
15.85 |