| Parameter |
Value |
| Designation |
C/2013 E2 (Iwamoto) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2013-03-09T00:45:46.535040Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:32Z |
| Obs used |
1159 |
| NEO |
- |
| M1 |
10.800 |
| K1 |
6.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-08-12.0000000 |
| e |
0.99393505 |
| q (au) |
1.413322 |
| a (au) |
233.031227 |
| i (deg) |
21.857721 |
| Ω (om, deg) |
182.470545 |
| ω (w, deg) |
95.823644 |
| M (ma, deg) |
0.043213 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.451 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.451 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-0.751 |
| k |
0.996 |
| 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 |
| 2013-03-10 |
2013-06-03 |
+5.4065 |
-1.965 |
| 2013-06-03 |
2014-02-02 |
-0.2753 |
-0.072 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
05:01:00.62 |
+02:23:19.1 |
HIP 23417 |
24.23 |
| 2026-07-29 12:00 |
05:01:03.27 |
+02:23:07.2 |
HIP 23417 |
23.68 |
| 2026-07-30 00:00 |
05:01:05.90 |
+02:22:55.2 |
HIP 23417 |
23.13 |
| 2026-07-30 12:00 |
05:01:08.51 |
+02:22:43.0 |
HIP 23417 |
22.60 |
| 2026-07-31 00:00 |
05:01:11.09 |
+02:22:30.7 |
HIP 23417 |
22.08 |
| 2026-07-31 12:00 |
05:01:13.64 |
+02:22:18.3 |
HIP 23417 |
21.57 |
| 2026-08-01 00:00 |
05:01:16.17 |
+02:22:05.7 |
HIP 23417 |
21.06 |
| 2026-08-01 12:00 |
05:01:18.68 |
+02:21:52.9 |
HIP 23417 |
20.57 |
| 2026-08-02 00:00 |
05:01:21.16 |
+02:21:40.1 |
HIP 23417 |
20.09 |
| 2026-08-02 12:00 |
05:01:23.62 |
+02:21:27.0 |
HIP 23417 |
19.62 |
| 2026-08-03 00:00 |
05:01:26.05 |
+02:21:13.9 |
HIP 23417 |
19.16 |
| 2026-08-03 12:00 |
05:01:28.46 |
+02:21:00.6 |
HIP 23417 |
18.71 |
| 2026-08-04 00:00 |
05:01:30.84 |
+02:20:47.1 |
HIP 23417 |
18.27 |
| 2026-08-04 12:00 |
05:01:33.20 |
+02:20:33.5 |
HIP 23417 |
17.84 |
| 2026-08-05 00:00 |
05:01:35.53 |
+02:20:19.8 |
HIP 23417 |
17.43 |
| 2026-08-05 12:00 |
05:01:37.84 |
+02:20:05.9 |
HIP 23417 |
17.03 |
| 2026-08-06 00:00 |
05:01:40.12 |
+02:19:51.9 |
HIP 23417 |
16.64 |
| 2026-08-06 12:00 |
05:01:42.37 |
+02:19:37.8 |
HIP 23417 |
16.27 |
| 2026-08-07 00:00 |
05:01:44.60 |
+02:19:23.5 |
HIP 23417 |
15.91 |
| 2026-08-07 12:00 |
05:01:46.80 |
+02:19:09.1 |
HIP 23417 |
15.56 |
| 2026-08-08 00:00 |
05:01:48.97 |
+02:18:54.5 |
HIP 23417 |
15.23 |
| 2026-08-08 12:00 |
05:01:51.12 |
+02:18:39.9 |
HIP 23417 |
14.92 |
| 2026-08-09 00:00 |
05:01:53.23 |
+02:18:25.0 |
HIP 23417 |
14.61 |
| 2026-08-09 12:00 |
05:01:55.33 |
+02:18:10.1 |
HIP 23417 |
14.33 |
| 2026-08-10 00:00 |
05:01:57.39 |
+02:17:55.0 |
HIP 23417 |
14.06 |
| 2026-08-10 12:00 |
05:01:59.43 |
+02:17:39.8 |
HIP 23417 |
13.81 |
| 2026-08-11 00:00 |
05:02:01.44 |
+02:17:24.5 |
HIP 23417 |
13.57 |
| 2026-08-11 12:00 |
05:02:03.42 |
+02:17:09.0 |
HIP 23417 |
13.35 |
| 2026-08-12 00:00 |
05:02:05.37 |
+02:16:53.4 |
HIP 23417 |
13.15 |
| 2026-08-12 12:00 |
05:02:07.30 |
+02:16:37.7 |
HIP 23417 |
12.96 |
| 2026-08-13 00:00 |
05:02:09.19 |
+02:16:21.8 |
HIP 23417 |
12.79 |
| 2026-08-13 12:00 |
05:02:11.06 |
+02:16:05.9 |
HIP 23417 |
12.64 |
| 2026-08-14 00:00 |
05:02:12.90 |
+02:15:49.8 |
HIP 23417 |
12.51 |
| 2026-08-14 12:00 |
05:02:14.71 |
+02:15:33.5 |
HIP 23417 |
12.39 |
| 2026-08-15 00:00 |
05:02:16.49 |
+02:15:17.2 |
HIP 23417 |
12.29 |
| 2026-08-15 12:00 |
05:02:18.24 |
+02:15:00.7 |
HIP 23417 |
12.20 |
| 2026-08-16 00:00 |
05:02:19.96 |
+02:14:44.2 |
HIP 23448 |
11.96 |
| 2026-08-16 12:00 |
05:02:21.66 |
+02:14:27.5 |
HIP 23448 |
11.63 |
| 2026-08-17 00:00 |
05:02:23.32 |
+02:14:10.7 |
HIP 23448 |
11.32 |
| 2026-08-17 12:00 |
05:02:24.95 |
+02:13:53.7 |
HIP 23448 |
11.02 |
| 2026-08-18 00:00 |
05:02:26.56 |
+02:13:36.7 |
HIP 23448 |
10.73 |
| 2026-08-18 12:00 |
05:02:28.13 |
+02:13:19.6 |
HIP 23448 |
10.46 |
| 2026-08-19 00:00 |
05:02:29.68 |
+02:13:02.3 |
HIP 23448 |
10.19 |