117P/Helin-Roman-Alu 1
| Parameter |
Value |
| Designation |
117P/Helin-Roman-Alu 1 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2014-03-27T04:28:33.893760Z |
| Orbit solution date (soln_date, UTC) |
2026-01-08T08:29:29Z |
| Obs used |
6498 |
| NEO |
- |
| M1 |
5.700 |
| K1 |
15.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-02-25.0000000 |
| e |
0.25383482 |
| q (au) |
3.056347 |
| a (au) |
4.096074 |
| i (deg) |
8.697539 |
| Ω (om, deg) |
58.898137 |
| ω (w, deg) |
222.686887 |
| M (ma, deg) |
356.411068 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.690 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.690 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.925 |
| 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) |
| 2026-02-03 00:00 |
05:03:47.48 |
+27:29:19.2 |
HIP 23570 |
4.63 |
| 2026-02-03 12:00 |
05:03:42.10 |
+27:29:07.3 |
HIP 23570 |
5.72 |
| 2026-02-04 00:00 |
05:03:36.95 |
+27:28:55.6 |
HIP 23570 |
6.79 |
| 2026-02-04 12:00 |
05:03:32.03 |
+27:28:44.0 |
HIP 23570 |
7.85 |
| 2026-02-05 00:00 |
05:03:27.35 |
+27:28:32.6 |
HIP 23570 |
8.86 |
| 2026-02-05 12:00 |
05:03:22.90 |
+27:28:21.3 |
HIP 23570 |
9.84 |
| 2026-02-06 00:00 |
05:03:18.69 |
+27:28:10.3 |
HIP 23570 |
10.77 |
| 2026-02-06 12:00 |
05:03:14.71 |
+27:27:59.4 |
HIP 23570 |
11.66 |
| 2026-02-07 00:00 |
05:03:10.97 |
+27:27:48.6 |
HIP 23570 |
12.50 |
| 2026-02-07 12:00 |
05:03:07.46 |
+27:27:38.1 |
HIP 23570 |
13.29 |
| 2026-02-08 00:00 |
05:03:04.19 |
+27:27:27.7 |
HIP 23570 |
14.03 |
| 2026-02-08 12:00 |
05:03:01.15 |
+27:27:17.6 |
HIP 23570 |
14.72 |
| 2026-02-09 00:00 |
05:02:58.35 |
+27:27:07.6 |
HIP 23570 |
15.36 |
| 2026-02-09 12:00 |
05:02:55.79 |
+27:26:57.8 |
HIP 23570 |
15.95 |
| 2026-02-10 00:00 |
05:02:53.46 |
+27:26:48.3 |
HIP 23570 |
16.49 |
| 2026-02-10 12:00 |
05:02:51.36 |
+27:26:38.9 |
HIP 23570 |
16.98 |
| 2026-02-11 00:00 |
05:02:49.50 |
+27:26:29.8 |
HIP 23570 |
17.42 |
| 2026-02-11 12:00 |
05:02:47.88 |
+27:26:20.8 |
HIP 23570 |
17.81 |
| 2026-02-12 00:00 |
05:02:46.49 |
+27:26:12.1 |
HIP 23570 |
18.15 |
| 2026-02-12 12:00 |
05:02:45.34 |
+27:26:03.6 |
HIP 23570 |
18.44 |
| 2026-02-13 00:00 |
05:02:44.42 |
+27:25:55.3 |
HIP 23570 |
18.68 |
| 2026-02-13 12:00 |
05:02:43.73 |
+27:25:47.3 |
HIP 23570 |
18.87 |
| 2026-02-14 00:00 |
05:02:43.28 |
+27:25:39.4 |
HIP 23570 |
19.01 |
| 2026-02-14 12:00 |
05:02:43.07 |
+27:25:31.8 |
HIP 23570 |
19.09 |
| 2026-02-15 00:00 |
05:02:43.08 |
+27:25:24.5 |
HIP 23570 |
19.14 |
| 2026-02-15 12:00 |
05:02:43.33 |
+27:25:17.3 |
HIP 23570 |
19.13 |
| 2026-02-16 00:00 |
05:02:43.82 |
+27:25:10.4 |
HIP 23570 |
19.07 |
| 2026-02-16 12:00 |
05:02:44.54 |
+27:25:03.8 |
HIP 23570 |
18.96 |
| 2026-02-17 00:00 |
05:02:45.49 |
+27:24:57.4 |
HIP 23570 |
18.81 |
| 2026-02-17 12:00 |
05:02:46.67 |
+27:24:51.2 |
HIP 23570 |
18.61 |
| 2026-02-18 00:00 |
05:02:48.08 |
+27:24:45.3 |
HIP 23570 |
18.36 |
| 2026-02-18 12:00 |
05:02:49.72 |
+27:24:39.6 |
HIP 23570 |
18.07 |
| 2026-02-19 00:00 |
05:02:51.60 |
+27:24:34.2 |
HIP 23570 |
17.73 |
| 2026-02-19 12:00 |
05:02:53.70 |
+27:24:29.0 |
HIP 23570 |
17.35 |
| 2026-02-20 00:00 |
05:02:56.03 |
+27:24:24.0 |
HIP 23570 |
16.93 |
| 2026-02-20 12:00 |
05:02:58.60 |
+27:24:19.4 |
HIP 23570 |
16.47 |
| 2026-02-21 00:00 |
05:03:01.38 |
+27:24:14.9 |
HIP 23570 |
15.96 |
| 2026-02-21 12:00 |
05:03:04.40 |
+27:24:10.7 |
HIP 23570 |
15.43 |
| 2026-02-22 00:00 |
05:03:07.64 |
+27:24:06.8 |
HIP 23570 |
14.85 |
| 2026-02-22 12:00 |
05:03:11.11 |
+27:24:03.1 |
HIP 23570 |
14.25 |
| 2026-02-23 00:00 |
05:03:14.81 |
+27:23:59.7 |
HIP 23570 |
13.63 |
| 2026-02-23 12:00 |
05:03:18.72 |
+27:23:56.5 |
HIP 23570 |
12.98 |
| 2026-02-24 00:00 |
05:03:22.86 |
+27:23:53.6 |
HIP 23570 |
12.32 |