| 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) |
| 2026-07-29 00:00 |
14:14:24.69 |
-09:02:25.1 |
HIP 69463 |
27.80 |
| 2026-07-29 12:00 |
14:14:29.95 |
-09:03:09.4 |
HIP 69463 |
29.18 |
| 2026-07-30 00:00 |
14:14:35.36 |
-09:03:54.4 |
HIP 69694 |
27.76 |
| 2026-07-30 12:00 |
14:14:40.91 |
-09:04:40.1 |
HIP 69694 |
26.24 |
| 2026-07-31 00:00 |
14:14:46.62 |
-09:05:26.5 |
HIP 69694 |
24.69 |
| 2026-07-31 12:00 |
14:14:52.47 |
-09:06:13.6 |
HIP 69694 |
23.11 |
| 2026-08-01 00:00 |
14:14:58.46 |
-09:07:01.5 |
HIP 69694 |
21.51 |
| 2026-08-01 12:00 |
14:15:04.60 |
-09:07:50.0 |
HIP 69694 |
19.89 |
| 2026-08-02 00:00 |
14:15:10.89 |
-09:08:39.2 |
HIP 69694 |
18.26 |
| 2026-08-02 12:00 |
14:15:17.32 |
-09:09:29.1 |
HIP 69694 |
16.63 |
| 2026-08-03 00:00 |
14:15:23.89 |
-09:10:19.6 |
HIP 69694 |
14.99 |
| 2026-08-03 12:00 |
14:15:30.61 |
-09:11:10.9 |
HIP 69694 |
13.39 |
| 2026-08-04 00:00 |
14:15:37.47 |
-09:12:02.8 |
HIP 69694 |
11.83 |
| 2026-08-04 12:00 |
14:15:44.47 |
-09:12:55.4 |
HIP 69694 |
10.36 |
| 2026-08-05 00:00 |
14:15:51.62 |
-09:13:48.6 |
HIP 69694 |
9.06 |
| 2026-08-05 12:00 |
14:15:58.90 |
-09:14:42.6 |
HIP 69694 |
8.03 |
| 2026-08-06 00:00 |
14:16:06.33 |
-09:15:37.1 |
HIP 69694 |
7.41 |
| 2026-08-06 12:00 |
14:16:13.90 |
-09:16:32.3 |
HIP 69694 |
7.33 |
| 2026-08-07 00:00 |
14:16:21.60 |
-09:17:28.2 |
HIP 69694 |
7.85 |
| 2026-08-07 12:00 |
14:16:29.45 |
-09:18:24.7 |
HIP 69694 |
8.88 |
| 2026-08-08 00:00 |
14:16:37.44 |
-09:19:21.9 |
HIP 69694 |
10.29 |
| 2026-08-08 12:00 |
14:16:45.56 |
-09:20:19.6 |
HIP 69694 |
11.97 |
| 2026-08-09 00:00 |
14:16:53.82 |
-09:21:18.0 |
HIP 69694 |
13.84 |
| 2026-08-09 12:00 |
14:17:02.22 |
-09:22:17.1 |
HIP 69694 |
15.84 |
| 2026-08-10 00:00 |
14:17:10.76 |
-09:23:16.7 |
HIP 69694 |
17.95 |
| 2026-08-10 12:00 |
14:17:19.43 |
-09:24:17.0 |
HIP 69920 |
17.97 |
| 2026-08-11 00:00 |
14:17:28.24 |
-09:25:17.9 |
HIP 69920 |
15.81 |
| 2026-08-11 12:00 |
14:17:37.19 |
-09:26:19.3 |
HIP 69920 |
13.70 |
| 2026-08-12 00:00 |
14:17:46.27 |
-09:27:21.4 |
HIP 69920 |
11.69 |
| 2026-08-12 12:00 |
14:17:55.48 |
-09:28:24.1 |
HIP 69920 |
9.86 |
| 2026-08-13 00:00 |
14:18:04.83 |
-09:29:27.3 |
HIP 69920 |
8.36 |
| 2026-08-13 12:00 |
14:18:14.31 |
-09:30:31.2 |
HIP 69920 |
7.43 |
| 2026-08-14 00:00 |
14:18:23.93 |
-09:31:35.6 |
HIP 69920 |
7.34 |
| 2026-08-14 12:00 |
14:18:33.67 |
-09:32:40.6 |
HIP 69920 |
8.13 |
| 2026-08-15 00:00 |
14:18:43.55 |
-09:33:46.1 |
HIP 69920 |
9.63 |
| 2026-08-15 12:00 |
14:18:53.55 |
-09:34:52.2 |
HIP 69920 |
11.58 |
| 2026-08-16 00:00 |
14:19:03.69 |
-09:35:58.9 |
HIP 69920 |
13.81 |
| 2026-08-16 12:00 |
14:19:13.95 |
-09:37:06.1 |
HIP 69920 |
16.22 |
| 2026-08-17 00:00 |
14:19:24.35 |
-09:38:13.8 |
HIP 69920 |
18.76 |
| 2026-08-17 12:00 |
14:19:34.87 |
-09:39:22.1 |
HIP 69920 |
21.39 |
| 2026-08-18 00:00 |
14:19:45.51 |
-09:40:30.9 |
HIP 69920 |
24.10 |
| 2026-08-18 12:00 |
14:19:56.29 |
-09:41:40.3 |
HIP 69920 |
26.87 |
| 2026-08-19 00:00 |
14:20:07.18 |
-09:42:50.1 |
HIP 70187 |
27.39 |