| Parameter |
Value |
| Designation |
117P/Helin-Roman-Alu 1 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2014-03-27T04:27:16.583040Z |
| Orbit solution date (soln_date, UTC) |
2026-03-09T08:47:52Z |
| Obs used |
6500 |
| NEO |
- |
| M1 |
5.700 |
| K1 |
15.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-02-26.0000000 |
| e |
0.25383563 |
| q (au) |
3.056348 |
| a (au) |
4.096078 |
| i (deg) |
8.697534 |
| Ω (om, deg) |
58.898113 |
| ω (w, deg) |
222.686727 |
| M (ma, deg) |
356.530072 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.689 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.689 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.923 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
06:06:19.07 |
+27:50:08.8 |
HIP 28920 |
5.98 |
| 2026-06-01 12:00 |
06:06:47.64 |
+27:50:10.5 |
HIP 28920 |
9.22 |
| 2026-06-02 00:00 |
06:07:16.24 |
+27:50:12.0 |
HIP 29044 |
5.41 |
| 2026-06-02 12:00 |
06:07:44.89 |
+27:50:13.2 |
HIP 29044 |
1.76 |
| 2026-06-03 00:00 |
06:08:13.56 |
+27:50:14.3 |
HIP 29044 |
7.56 |
| 2026-06-03 12:00 |
06:08:42.28 |
+27:50:15.2 |
HIP 29044 |
13.85 |
| 2026-06-04 00:00 |
06:09:11.02 |
+27:50:15.8 |
HIP 29044 |
20.19 |
| 2026-06-04 12:00 |
06:09:39.80 |
+27:50:16.2 |
HIP 29044 |
26.54 |
| 2026-06-05 00:00 |
06:10:08.62 |
+27:50:16.4 |
HIP 29044 |
32.90 |
| 2026-06-05 12:00 |
06:10:37.46 |
+27:50:16.4 |
HIP 29044 |
39.27 |
| 2026-06-06 00:00 |
06:11:06.34 |
+27:50:16.2 |
HIP 29510 |
35.12 |
| 2026-06-06 12:00 |
06:11:35.25 |
+27:50:15.8 |
HIP 29510 |
30.83 |
| 2026-06-07 00:00 |
06:12:04.20 |
+27:50:15.2 |
HIP 29510 |
27.36 |
| 2026-06-07 12:00 |
06:12:33.17 |
+27:50:14.3 |
HIP 29510 |
25.07 |
| 2026-06-08 00:00 |
06:13:02.17 |
+27:50:13.3 |
HIP 29510 |
24.31 |
| 2026-06-08 12:00 |
06:13:31.20 |
+27:50:12.0 |
HIP 29628 |
19.56 |
| 2026-06-09 00:00 |
06:14:00.26 |
+27:50:10.5 |
HIP 29668 |
13.63 |
| 2026-06-09 12:00 |
06:14:29.34 |
+27:50:08.8 |
HIP 29668 |
7.57 |
| 2026-06-10 00:00 |
06:14:58.45 |
+27:50:06.9 |
HIP 29668 |
3.41 |
| 2026-06-10 12:00 |
06:15:27.59 |
+27:50:04.7 |
HIP 29749 |
6.23 |
| 2026-06-11 00:00 |
06:15:56.76 |
+27:50:02.4 |
HIP 29749 |
1.73 |
| 2026-06-11 12:00 |
06:16:25.94 |
+27:49:59.8 |
HIP 29749 |
7.10 |
| 2026-06-12 00:00 |
06:16:55.16 |
+27:49:57.0 |
HIP 29749 |
13.46 |
| 2026-06-12 12:00 |
06:17:24.39 |
+27:49:54.0 |
HIP 29927 |
13.11 |
| 2026-06-13 00:00 |
06:17:53.65 |
+27:49:50.7 |
HIP 29927 |
10.65 |
| 2026-06-13 12:00 |
06:18:22.93 |
+27:49:47.3 |
HIP 29927 |
11.78 |
| 2026-06-14 00:00 |
06:18:52.23 |
+27:49:43.6 |
HIP 29927 |
15.74 |
| 2026-06-14 12:00 |
06:19:21.55 |
+27:49:39.7 |
HIP 29927 |
21.00 |
| 2026-06-15 00:00 |
06:19:50.89 |
+27:49:35.6 |
HIP 30101 |
26.66 |
| 2026-06-15 12:00 |
06:20:20.25 |
+27:49:31.3 |
HIP 30101 |
26.65 |
| 2026-06-16 00:00 |
06:20:49.62 |
+27:49:26.7 |
HIP 30331 |
27.89 |
| 2026-06-16 12:00 |
06:21:19.02 |
+27:49:22.0 |
HIP 30331 |
21.96 |
| 2026-06-17 00:00 |
06:21:48.43 |
+27:49:17.0 |
HIP 30331 |
16.46 |
| 2026-06-17 12:00 |
06:22:17.85 |
+27:49:11.8 |
HIP 30354 |
11.87 |
| 2026-06-18 00:00 |
06:22:47.29 |
+27:49:06.3 |
HIP 30354 |
6.64 |
| 2026-06-18 12:00 |
06:23:16.74 |
+27:49:00.7 |
HIP 30354 |
5.68 |
| 2026-06-19 00:00 |
06:23:46.20 |
+27:48:54.9 |
HIP 30354 |
10.26 |
| 2026-06-19 12:00 |
06:24:15.67 |
+27:48:48.8 |
HIP 30354 |
16.22 |
| 2026-06-20 00:00 |
06:24:45.16 |
+27:48:42.5 |
HIP 30525 |
13.59 |
| 2026-06-20 12:00 |
06:25:14.66 |
+27:48:36.0 |
HIP 30525 |
13.74 |
| 2026-06-21 00:00 |
06:25:44.16 |
+27:48:29.3 |
HIP 30618 |
12.34 |
| 2026-06-21 12:00 |
06:26:13.68 |
+27:48:22.3 |
HIP 30618 |
11.73 |
| 2026-06-22 00:00 |
06:26:43.20 |
+27:48:15.2 |
HIP 30618 |
14.43 |