| 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 |
0.998 |
| 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
14:21:26.81 |
-09:09:22.5 |
HIP 70187 |
16.73 |
| 2026-06-03 00:00 |
14:21:14.60 |
-09:08:29.8 |
HIP 70187 |
18.19 |
| 2026-06-03 12:00 |
14:21:02.51 |
-09:07:37.9 |
HIP 70187 |
20.01 |
| 2026-06-04 00:00 |
14:20:50.55 |
-09:06:46.8 |
HIP 70187 |
22.10 |
| 2026-06-04 12:00 |
14:20:38.72 |
-09:05:56.5 |
HIP 70187 |
24.36 |
| 2026-06-05 00:00 |
14:20:27.02 |
-09:05:07.0 |
HIP 70060 |
23.99 |
| 2026-06-05 12:00 |
14:20:15.44 |
-09:04:18.3 |
HIP 70060 |
22.99 |
| 2026-06-06 00:00 |
14:20:04.00 |
-09:03:30.5 |
HIP 70060 |
22.35 |
| 2026-06-06 12:00 |
14:19:52.68 |
-09:02:43.4 |
HIP 70060 |
22.10 |
| 2026-06-07 00:00 |
14:19:41.51 |
-09:01:57.2 |
HIP 70060 |
22.22 |
| 2026-06-07 12:00 |
14:19:30.46 |
-09:01:11.8 |
HIP 70060 |
22.71 |
| 2026-06-08 00:00 |
14:19:19.55 |
-09:00:27.3 |
HIP 70060 |
23.52 |
| 2026-06-08 12:00 |
14:19:08.78 |
-08:59:43.6 |
HIP 70060 |
24.61 |
| 2026-06-09 00:00 |
14:18:58.14 |
-08:59:00.7 |
HIP 69823 |
23.70 |
| 2026-06-09 12:00 |
14:18:47.65 |
-08:58:18.7 |
HIP 69823 |
21.21 |
| 2026-06-10 00:00 |
14:18:37.29 |
-08:57:37.6 |
HIP 69823 |
18.81 |
| 2026-06-10 12:00 |
14:18:27.08 |
-08:56:57.3 |
HIP 69823 |
16.51 |
| 2026-06-11 00:00 |
14:18:17.01 |
-08:56:17.9 |
HIP 69823 |
14.35 |
| 2026-06-11 12:00 |
14:18:07.08 |
-08:55:39.3 |
HIP 69823 |
12.37 |
| 2026-06-12 00:00 |
14:17:57.29 |
-08:55:01.6 |
HIP 69823 |
10.65 |
| 2026-06-12 12:00 |
14:17:47.65 |
-08:54:24.8 |
HIP 69823 |
9.30 |
| 2026-06-13 00:00 |
14:17:38.16 |
-08:53:48.9 |
HIP 69823 |
8.47 |
| 2026-06-13 12:00 |
14:17:28.81 |
-08:53:13.9 |
HIP 69823 |
8.27 |
| 2026-06-14 00:00 |
14:17:19.62 |
-08:52:39.8 |
HIP 69773 |
7.64 |
| 2026-06-14 12:00 |
14:17:10.57 |
-08:52:06.5 |
HIP 69773 |
5.48 |
| 2026-06-15 00:00 |
14:17:01.68 |
-08:51:34.2 |
HIP 69773 |
3.53 |
| 2026-06-15 12:00 |
14:16:52.93 |
-08:51:02.8 |
HIP 69773 |
2.27 |
| 2026-06-16 00:00 |
14:16:44.34 |
-08:50:32.2 |
HIP 69773 |
2.75 |
| 2026-06-16 12:00 |
14:16:35.90 |
-08:50:02.6 |
HIP 69773 |
4.38 |
| 2026-06-17 00:00 |
14:16:27.61 |
-08:49:33.9 |
HIP 69773 |
6.29 |
| 2026-06-17 12:00 |
14:16:19.48 |
-08:49:06.1 |
HIP 69773 |
8.25 |
| 2026-06-18 00:00 |
14:16:11.50 |
-08:48:39.2 |
HIP 69773 |
10.20 |
| 2026-06-18 12:00 |
14:16:03.68 |
-08:48:13.2 |
HIP 69773 |
12.14 |
| 2026-06-19 00:00 |
14:15:56.02 |
-08:47:48.2 |
HIP 69773 |
14.05 |
| 2026-06-19 12:00 |
14:15:48.51 |
-08:47:24.0 |
HIP 69773 |
15.92 |
| 2026-06-20 00:00 |
14:15:41.16 |
-08:47:00.8 |
HIP 69773 |
17.76 |
| 2026-06-20 12:00 |
14:15:33.97 |
-08:46:38.4 |
HIP 69773 |
19.56 |
| 2026-06-21 00:00 |
14:15:26.93 |
-08:46:17.0 |
HIP 69773 |
21.32 |
| 2026-06-21 12:00 |
14:15:20.06 |
-08:45:56.5 |
HIP 69541 |
22.97 |
| 2026-06-22 00:00 |
14:15:13.34 |
-08:45:37.0 |
HIP 69541 |
21.51 |