| Parameter |
Value |
| Designation |
C/1990 E1 (Cernis-Kiuchi-Nakamura) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1990-03-17T07:48:46.033920Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:38Z |
| Obs used |
89 |
| NEO |
- |
| M1 |
7.100 |
| K1 |
39.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1990-04-01.0000000 |
| e |
1.00000000 |
| q (au) |
1.068341 |
| a (au) |
- |
| i (deg) |
48.142430 |
| Ω (om, deg) |
348.444903 |
| ω (w, deg) |
100.620374 |
| M (ma, deg) |
- |
Magnitude
Scatter + Global Linear
$$
M_a = (6.813 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
6.813 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 1990-03-17 |
1990-05-26 |
+18.7801 |
-0.670 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
15:35:23.99 |
-69:50:40.4 |
HIP 76184 |
18.28 |
| 2026-05-12 12:00 |
15:35:18.59 |
-69:50:38.6 |
HIP 76184 |
18.09 |
| 2026-05-13 00:00 |
15:35:13.18 |
-69:50:36.5 |
HIP 76184 |
17.91 |
| 2026-05-13 12:00 |
15:35:07.77 |
-69:50:34.2 |
HIP 76184 |
17.74 |
| 2026-05-14 00:00 |
15:35:02.36 |
-69:50:31.7 |
HIP 76184 |
17.58 |
| 2026-05-14 12:00 |
15:34:56.94 |
-69:50:29.1 |
HIP 76184 |
17.45 |
| 2026-05-15 00:00 |
15:34:51.52 |
-69:50:26.2 |
HIP 76184 |
17.32 |
| 2026-05-15 12:00 |
15:34:46.11 |
-69:50:23.1 |
HIP 76184 |
17.21 |
| 2026-05-16 00:00 |
15:34:40.69 |
-69:50:19.8 |
HIP 76184 |
17.12 |
| 2026-05-16 12:00 |
15:34:35.26 |
-69:50:16.2 |
HIP 76002 |
17.00 |
| 2026-05-17 00:00 |
15:34:29.84 |
-69:50:12.5 |
HIP 76002 |
16.53 |
| 2026-05-17 12:00 |
15:34:24.42 |
-69:50:08.6 |
HIP 76002 |
16.07 |
| 2026-05-18 00:00 |
15:34:19.00 |
-69:50:04.5 |
HIP 76002 |
15.60 |
| 2026-05-18 12:00 |
15:34:13.58 |
-69:50:00.1 |
HIP 76002 |
15.14 |
| 2026-05-19 00:00 |
15:34:08.17 |
-69:49:55.6 |
HIP 76002 |
14.67 |
| 2026-05-19 12:00 |
15:34:02.75 |
-69:49:50.8 |
HIP 76002 |
14.21 |
| 2026-05-20 00:00 |
15:33:57.34 |
-69:49:45.9 |
HIP 76002 |
13.74 |
| 2026-05-20 12:00 |
15:33:51.94 |
-69:49:40.7 |
HIP 76002 |
13.28 |
| 2026-05-21 00:00 |
15:33:46.53 |
-69:49:35.4 |
HIP 76002 |
12.82 |
| 2026-05-21 12:00 |
15:33:41.13 |
-69:49:29.8 |
HIP 76002 |
12.36 |
| 2026-05-22 00:00 |
15:33:35.74 |
-69:49:24.1 |
HIP 76002 |
11.90 |
| 2026-05-22 12:00 |
15:33:30.35 |
-69:49:18.1 |
HIP 76002 |
11.45 |
| 2026-05-23 00:00 |
15:33:24.96 |
-69:49:12.0 |
HIP 76002 |
10.99 |
| 2026-05-23 12:00 |
15:33:19.58 |
-69:49:05.6 |
HIP 76002 |
10.54 |
| 2026-05-24 00:00 |
15:33:14.21 |
-69:48:59.1 |
HIP 76002 |
10.09 |
| 2026-05-24 12:00 |
15:33:08.85 |
-69:48:52.3 |
HIP 76002 |
9.65 |
| 2026-05-25 00:00 |
15:33:03.49 |
-69:48:45.4 |
HIP 76002 |
9.21 |
| 2026-05-25 12:00 |
15:32:58.14 |
-69:48:38.2 |
HIP 76002 |
8.78 |
| 2026-05-26 00:00 |
15:32:52.80 |
-69:48:30.9 |
HIP 76002 |
8.35 |
| 2026-05-26 12:00 |
15:32:47.46 |
-69:48:23.4 |
HIP 76002 |
7.93 |
| 2026-05-27 00:00 |
15:32:42.14 |
-69:48:15.7 |
HIP 76002 |
7.51 |
| 2026-05-27 12:00 |
15:32:36.82 |
-69:48:07.7 |
HIP 76002 |
7.11 |
| 2026-05-28 00:00 |
15:32:31.52 |
-69:47:59.6 |
HIP 76002 |
6.72 |
| 2026-05-28 12:00 |
15:32:26.22 |
-69:47:51.3 |
HIP 76002 |
6.34 |
| 2026-05-29 00:00 |
15:32:20.94 |
-69:47:42.9 |
HIP 76002 |
5.97 |
| 2026-05-29 12:00 |
15:32:15.67 |
-69:47:34.2 |
HIP 76002 |
5.63 |
| 2026-05-30 00:00 |
15:32:10.41 |
-69:47:25.3 |
HIP 76002 |
5.31 |
| 2026-05-30 12:00 |
15:32:05.16 |
-69:47:16.2 |
HIP 76002 |
5.01 |
| 2026-05-31 00:00 |
15:31:59.92 |
-69:47:07.0 |
HIP 76002 |
4.75 |
| 2026-05-31 12:00 |
15:31:54.69 |
-69:46:57.6 |
HIP 76002 |
4.53 |
| 2026-06-01 00:00 |
15:31:49.48 |
-69:46:48.0 |
HIP 76002 |
4.35 |
| 2026-06-01 12:00 |
15:31:44.29 |
-69:46:38.2 |
HIP 76002 |
4.23 |
| 2026-06-02 00:00 |
15:31:39.10 |
-69:46:28.2 |
HIP 76002 |
4.15 |