| Parameter |
Value |
| Designation |
C/1989 R1 (Helin-Roman) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
1989-08-20T06:57:23.126400Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:29:38Z |
| Obs used |
19 |
| NEO |
- |
| M1 |
- |
| K1 |
- |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1989-09-20.0000000 |
| e |
0.99999476 |
| q (au) |
1.324504 |
| a (au) |
252659.816775 |
| i (deg) |
128.133260 |
| Ω (om, deg) |
128.609412 |
| ω (w, deg) |
154.909426 |
| M (ma, deg) |
0.000000 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.756 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.756 |
| n |
2.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
09:45:06.53 |
-20:31:31.7 |
HIP 47856 |
9.03 |
| 2026-05-12 12:00 |
09:45:06.39 |
-20:31:14.3 |
HIP 47856 |
9.32 |
| 2026-05-13 00:00 |
09:45:06.27 |
-20:30:56.9 |
HIP 47856 |
9.61 |
| 2026-05-13 12:00 |
09:45:06.16 |
-20:30:39.5 |
HIP 47856 |
9.90 |
| 2026-05-14 00:00 |
09:45:06.08 |
-20:30:22.2 |
HIP 47856 |
10.18 |
| 2026-05-14 12:00 |
09:45:06.01 |
-20:30:05.0 |
HIP 47866 |
10.27 |
| 2026-05-15 00:00 |
09:45:05.95 |
-20:29:47.9 |
HIP 47866 |
10.01 |
| 2026-05-15 12:00 |
09:45:05.92 |
-20:29:30.9 |
HIP 47866 |
9.75 |
| 2026-05-16 00:00 |
09:45:05.90 |
-20:29:13.9 |
HIP 47866 |
9.48 |
| 2026-05-16 12:00 |
09:45:05.89 |
-20:28:57.0 |
HIP 47866 |
9.22 |
| 2026-05-17 00:00 |
09:45:05.91 |
-20:28:40.1 |
HIP 47866 |
8.96 |
| 2026-05-17 12:00 |
09:45:05.94 |
-20:28:23.4 |
HIP 47866 |
8.70 |
| 2026-05-18 00:00 |
09:45:05.98 |
-20:28:06.7 |
HIP 47866 |
8.45 |
| 2026-05-18 12:00 |
09:45:06.05 |
-20:27:50.1 |
HIP 47866 |
8.19 |
| 2026-05-19 00:00 |
09:45:06.13 |
-20:27:33.6 |
HIP 47866 |
7.93 |
| 2026-05-19 12:00 |
09:45:06.22 |
-20:27:17.2 |
HIP 47866 |
7.67 |
| 2026-05-20 00:00 |
09:45:06.33 |
-20:27:00.8 |
HIP 47866 |
7.42 |
| 2026-05-20 12:00 |
09:45:06.46 |
-20:26:44.6 |
HIP 47866 |
7.17 |
| 2026-05-21 00:00 |
09:45:06.61 |
-20:26:28.4 |
HIP 47866 |
6.91 |
| 2026-05-21 12:00 |
09:45:06.77 |
-20:26:12.3 |
HIP 47866 |
6.66 |
| 2026-05-22 00:00 |
09:45:06.95 |
-20:25:56.3 |
HIP 47866 |
6.41 |
| 2026-05-22 12:00 |
09:45:07.15 |
-20:25:40.4 |
HIP 47866 |
6.16 |
| 2026-05-23 00:00 |
09:45:07.36 |
-20:25:24.6 |
HIP 47866 |
5.90 |
| 2026-05-23 12:00 |
09:45:07.59 |
-20:25:08.8 |
HIP 47866 |
5.66 |
| 2026-05-24 00:00 |
09:45:07.83 |
-20:24:53.2 |
HIP 47866 |
5.41 |
| 2026-05-24 12:00 |
09:45:08.09 |
-20:24:37.6 |
HIP 47866 |
5.16 |
| 2026-05-25 00:00 |
09:45:08.37 |
-20:24:22.2 |
HIP 47866 |
4.91 |
| 2026-05-25 12:00 |
09:45:08.66 |
-20:24:06.8 |
HIP 47866 |
4.67 |
| 2026-05-26 00:00 |
09:45:08.97 |
-20:23:51.5 |
HIP 47866 |
4.42 |
| 2026-05-26 12:00 |
09:45:09.29 |
-20:23:36.3 |
HIP 47866 |
4.18 |
| 2026-05-27 00:00 |
09:45:09.63 |
-20:23:21.3 |
HIP 47866 |
3.93 |
| 2026-05-27 12:00 |
09:45:09.99 |
-20:23:06.3 |
HIP 47866 |
3.69 |
| 2026-05-28 00:00 |
09:45:10.36 |
-20:22:51.4 |
HIP 47866 |
3.45 |
| 2026-05-28 12:00 |
09:45:10.75 |
-20:22:36.6 |
HIP 47866 |
3.22 |
| 2026-05-29 00:00 |
09:45:11.15 |
-20:22:21.9 |
HIP 47866 |
2.98 |
| 2026-05-29 12:00 |
09:45:11.57 |
-20:22:07.3 |
HIP 47866 |
2.75 |
| 2026-05-30 00:00 |
09:45:12.01 |
-20:21:52.9 |
HIP 47866 |
2.53 |
| 2026-05-30 12:00 |
09:45:12.46 |
-20:21:38.5 |
HIP 47866 |
2.30 |
| 2026-05-31 00:00 |
09:45:12.93 |
-20:21:24.2 |
HIP 47866 |
2.09 |
| 2026-05-31 12:00 |
09:45:13.41 |
-20:21:10.0 |
HIP 47866 |
1.88 |
| 2026-06-01 00:00 |
09:45:13.91 |
-20:20:56.0 |
HIP 47866 |
1.69 |
| 2026-06-01 12:00 |
09:45:14.42 |
-20:20:42.0 |
HIP 47866 |
1.52 |
| 2026-06-02 00:00 |
09:45:14.95 |
-20:20:28.2 |
HIP 47866 |
1.37 |