| Parameter |
Value |
| Designation |
132P/Helin-Roman-Alu 2 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-11-13T02:33:18.385920Z |
| Orbit solution date (soln_date, UTC) |
2025-11-23T22:26:53Z |
| Obs used |
1323 |
| NEO |
- |
| M1 |
10.200 |
| K1 |
22.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-10-04.0000000 |
| e |
0.56469630 |
| q (au) |
1.691775 |
| a (au) |
3.886424 |
| i (deg) |
5.382515 |
| Ω (om, deg) |
173.996571 |
| ω (w, deg) |
216.345515 |
| M (ma, deg) |
354.840671 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.038 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.038 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-1.000 |
| 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 |
| 2021-06-12 |
2021-08-13 |
-0.6116 |
+1.350 |
| 2021-08-13 |
2021-11-12 |
+29.4087 |
-7.185 |
| 2021-11-14 |
2022-04-02 |
-6.8747 |
+1.167 |
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 |
14:31:47.71 |
-09:57:55.2 |
HIP 71118 |
16.98 |
| 2026-05-12 12:00 |
14:31:31.69 |
-09:56:35.7 |
HIP 71118 |
19.05 |
| 2026-05-13 00:00 |
14:31:15.73 |
-09:55:16.6 |
HIP 71118 |
21.73 |
| 2026-05-13 12:00 |
14:30:59.81 |
-09:53:57.9 |
HIP 71118 |
24.81 |
| 2026-05-14 00:00 |
14:30:43.94 |
-09:52:39.6 |
HIP 71118 |
28.15 |
| 2026-05-14 12:00 |
14:30:28.12 |
-09:51:21.9 |
HIP 70784 |
29.95 |
| 2026-05-15 00:00 |
14:30:12.36 |
-09:50:04.5 |
HIP 70784 |
26.73 |
| 2026-05-15 12:00 |
14:29:56.66 |
-09:48:47.7 |
HIP 70784 |
23.79 |
| 2026-05-16 00:00 |
14:29:41.01 |
-09:47:31.4 |
HIP 70784 |
21.24 |
| 2026-05-16 12:00 |
14:29:25.43 |
-09:46:15.5 |
HIP 70784 |
19.21 |
| 2026-05-17 00:00 |
14:29:09.91 |
-09:45:00.2 |
HIP 70784 |
17.88 |
| 2026-05-17 12:00 |
14:28:54.46 |
-09:43:45.4 |
HIP 70784 |
17.40 |
| 2026-05-18 00:00 |
14:28:39.07 |
-09:42:31.1 |
HIP 70784 |
17.82 |
| 2026-05-18 12:00 |
14:28:23.76 |
-09:41:17.4 |
HIP 70784 |
19.07 |
| 2026-05-19 00:00 |
14:28:08.52 |
-09:40:04.2 |
HIP 70784 |
21.00 |
| 2026-05-19 12:00 |
14:27:53.35 |
-09:38:51.6 |
HIP 70784 |
23.42 |
| 2026-05-20 00:00 |
14:27:38.27 |
-09:37:39.5 |
HIP 70784 |
26.19 |
| 2026-05-20 12:00 |
14:27:23.26 |
-09:36:28.1 |
HIP 70784 |
29.20 |
| 2026-05-21 00:00 |
14:27:08.33 |
-09:35:17.2 |
HIP 70784 |
32.37 |
| 2026-05-21 12:00 |
14:26:53.49 |
-09:34:07.0 |
HIP 70784 |
35.67 |
| 2026-05-22 00:00 |
14:26:38.73 |
-09:32:57.3 |
HIP 70784 |
39.04 |
| 2026-05-22 12:00 |
14:26:24.06 |
-09:31:48.3 |
HIP 70784 |
42.46 |
| 2026-05-23 00:00 |
14:26:09.48 |
-09:30:39.9 |
HIP 70784 |
45.92 |
| 2026-05-23 12:00 |
14:25:54.99 |
-09:29:32.2 |
HIP 70688 |
48.78 |
| 2026-05-24 00:00 |
14:25:40.59 |
-09:28:25.0 |
HIP 70302 |
50.20 |
| 2026-05-24 12:00 |
14:25:26.28 |
-09:27:18.6 |
HIP 70302 |
46.78 |
| 2026-05-25 00:00 |
14:25:12.08 |
-09:26:12.8 |
HIP 70302 |
43.44 |
| 2026-05-25 12:00 |
14:24:57.97 |
-09:25:07.7 |
HIP 70302 |
40.18 |
| 2026-05-26 00:00 |
14:24:43.96 |
-09:24:03.2 |
HIP 70302 |
37.02 |
| 2026-05-26 12:00 |
14:24:30.05 |
-09:22:59.5 |
HIP 70302 |
33.97 |
| 2026-05-27 00:00 |
14:24:16.24 |
-09:21:56.4 |
HIP 70302 |
31.06 |
| 2026-05-27 12:00 |
14:24:02.54 |
-09:20:54.0 |
HIP 70302 |
28.33 |
| 2026-05-28 00:00 |
14:23:48.94 |
-09:19:52.3 |
HIP 70302 |
25.82 |
| 2026-05-28 12:00 |
14:23:35.45 |
-09:18:51.4 |
HIP 70302 |
23.58 |
| 2026-05-29 00:00 |
14:23:22.08 |
-09:17:51.2 |
HIP 70302 |
21.69 |
| 2026-05-29 12:00 |
14:23:08.81 |
-09:16:51.6 |
HIP 70302 |
20.23 |
| 2026-05-30 00:00 |
14:22:55.65 |
-09:15:52.9 |
HIP 70302 |
19.29 |
| 2026-05-30 12:00 |
14:22:42.61 |
-09:14:54.8 |
HIP 70302 |
18.92 |
| 2026-05-31 00:00 |
14:22:29.68 |
-09:13:57.5 |
HIP 70187 |
18.12 |
| 2026-05-31 12:00 |
14:22:16.87 |
-09:13:01.0 |
HIP 70187 |
16.62 |
| 2026-06-01 00:00 |
14:22:04.17 |
-09:12:05.2 |
HIP 70187 |
15.68 |
| 2026-06-01 12:00 |
14:21:51.60 |
-09:11:10.2 |
HIP 70187 |
15.39 |
| 2026-06-02 00:00 |
14:21:39.14 |
-09:10:16.0 |
HIP 70187 |
15.76 |