| 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) |
| 2026-07-29 00:00 |
09:47:38.62 |
-20:08:23.4 |
HIP 47915 |
29.67 |
| 2026-07-29 12:00 |
09:47:40.40 |
-20:08:25.3 |
HIP 47915 |
29.99 |
| 2026-07-30 00:00 |
09:47:42.19 |
-20:08:27.3 |
HIP 47915 |
30.31 |
| 2026-07-30 12:00 |
09:47:43.98 |
-20:08:29.5 |
HIP 47915 |
30.62 |
| 2026-07-31 00:00 |
09:47:45.78 |
-20:08:31.8 |
HIP 47915 |
30.95 |
| 2026-07-31 12:00 |
09:47:47.58 |
-20:08:34.2 |
HIP 47915 |
31.27 |
| 2026-08-01 00:00 |
09:47:49.39 |
-20:08:36.8 |
HIP 47915 |
31.59 |
| 2026-08-01 12:00 |
09:47:51.20 |
-20:08:39.6 |
HIP 47915 |
31.92 |
| 2026-08-02 00:00 |
09:47:53.01 |
-20:08:42.5 |
HIP 47915 |
32.25 |
| 2026-08-02 12:00 |
09:47:54.83 |
-20:08:45.5 |
HIP 47915 |
32.58 |
| 2026-08-03 00:00 |
09:47:56.65 |
-20:08:48.6 |
HIP 47915 |
32.91 |
| 2026-08-03 12:00 |
09:47:58.47 |
-20:08:52.0 |
HIP 47915 |
33.24 |
| 2026-08-04 00:00 |
09:48:00.30 |
-20:08:55.4 |
HIP 47915 |
33.58 |
| 2026-08-04 12:00 |
09:48:02.13 |
-20:08:59.0 |
HIP 48170 |
33.77 |
| 2026-08-05 00:00 |
09:48:03.97 |
-20:09:02.7 |
HIP 48170 |
33.64 |
| 2026-08-05 12:00 |
09:48:05.81 |
-20:09:06.6 |
HIP 48170 |
33.51 |
| 2026-08-06 00:00 |
09:48:07.65 |
-20:09:10.7 |
HIP 48170 |
33.39 |
| 2026-08-06 12:00 |
09:48:09.50 |
-20:09:14.8 |
HIP 48170 |
33.27 |
| 2026-08-07 00:00 |
09:48:11.35 |
-20:09:19.1 |
HIP 48170 |
33.17 |
| 2026-08-07 12:00 |
09:48:13.20 |
-20:09:23.6 |
HIP 48170 |
33.07 |
| 2026-08-08 00:00 |
09:48:15.05 |
-20:09:28.2 |
HIP 48170 |
32.98 |
| 2026-08-08 12:00 |
09:48:16.91 |
-20:09:32.9 |
HIP 48170 |
32.89 |
| 2026-08-09 00:00 |
09:48:18.77 |
-20:09:37.8 |
HIP 48170 |
32.82 |
| 2026-08-09 12:00 |
09:48:20.63 |
-20:09:42.8 |
HIP 48170 |
32.75 |
| 2026-08-10 00:00 |
09:48:22.49 |
-20:09:47.9 |
HIP 48170 |
32.69 |
| 2026-08-10 12:00 |
09:48:24.36 |
-20:09:53.2 |
HIP 48170 |
32.64 |
| 2026-08-11 00:00 |
09:48:26.23 |
-20:09:58.6 |
HIP 48170 |
32.59 |
| 2026-08-11 12:00 |
09:48:28.10 |
-20:10:04.2 |
HIP 48170 |
32.55 |
| 2026-08-12 00:00 |
09:48:29.97 |
-20:10:09.9 |
HIP 48170 |
32.53 |
| 2026-08-12 12:00 |
09:48:31.84 |
-20:10:15.8 |
HIP 48170 |
32.51 |
| 2026-08-13 00:00 |
09:48:33.71 |
-20:10:21.7 |
HIP 48170 |
32.50 |
| 2026-08-13 12:00 |
09:48:35.59 |
-20:10:27.9 |
HIP 48170 |
32.49 |
| 2026-08-14 00:00 |
09:48:37.46 |
-20:10:34.1 |
HIP 48170 |
32.50 |
| 2026-08-14 12:00 |
09:48:39.34 |
-20:10:40.5 |
HIP 48170 |
32.51 |
| 2026-08-15 00:00 |
09:48:41.22 |
-20:10:47.0 |
HIP 48170 |
32.54 |
| 2026-08-15 12:00 |
09:48:43.10 |
-20:10:53.7 |
HIP 48170 |
32.57 |
| 2026-08-16 00:00 |
09:48:44.98 |
-20:11:00.5 |
HIP 48170 |
32.61 |
| 2026-08-16 12:00 |
09:48:46.85 |
-20:11:07.4 |
HIP 48170 |
32.66 |
| 2026-08-17 00:00 |
09:48:48.73 |
-20:11:14.5 |
HIP 48170 |
32.71 |
| 2026-08-17 12:00 |
09:48:50.61 |
-20:11:21.7 |
HIP 48170 |
32.78 |
| 2026-08-18 00:00 |
09:48:52.49 |
-20:11:29.0 |
HIP 48170 |
32.85 |
| 2026-08-18 12:00 |
09:48:54.37 |
-20:11:36.4 |
HIP 48170 |
32.94 |
| 2026-08-19 00:00 |
09:48:56.25 |
-20:11:44.0 |
HIP 48170 |
33.03 |