132P/Helin-Roman-Alu 2
| 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) |
| 2026-02-03 00:00 |
14:58:00.62 |
-13:04:46.8 |
HIP 73291 |
21.30 |
| 2026-02-03 12:00 |
14:58:07.16 |
-13:04:50.3 |
HIP 73291 |
20.64 |
| 2026-02-04 00:00 |
14:58:13.55 |
-13:04:53.0 |
HIP 73291 |
20.08 |
| 2026-02-04 12:00 |
14:58:19.79 |
-13:04:55.0 |
HIP 73291 |
19.62 |
| 2026-02-05 00:00 |
14:58:25.88 |
-13:04:56.2 |
HIP 73291 |
19.27 |
| 2026-02-05 12:00 |
14:58:31.82 |
-13:04:56.7 |
HIP 73291 |
19.03 |
| 2026-02-06 00:00 |
14:58:37.59 |
-13:04:56.5 |
HIP 73291 |
18.88 |
| 2026-02-06 12:00 |
14:58:43.22 |
-13:04:55.5 |
HIP 73291 |
18.82 |
| 2026-02-07 00:00 |
14:58:48.69 |
-13:04:53.7 |
HIP 73291 |
18.85 |
| 2026-02-07 12:00 |
14:58:54.00 |
-13:04:51.2 |
HIP 73291 |
18.95 |
| 2026-02-08 00:00 |
14:58:59.15 |
-13:04:47.9 |
HIP 73291 |
19.12 |
| 2026-02-08 12:00 |
14:59:04.14 |
-13:04:43.9 |
HIP 73291 |
19.35 |
| 2026-02-09 00:00 |
14:59:08.98 |
-13:04:39.1 |
HIP 73291 |
19.63 |
| 2026-02-09 12:00 |
14:59:13.66 |
-13:04:33.5 |
HIP 73291 |
19.94 |
| 2026-02-10 00:00 |
14:59:18.17 |
-13:04:27.2 |
HIP 73291 |
20.29 |
| 2026-02-10 12:00 |
14:59:22.53 |
-13:04:20.2 |
HIP 73291 |
20.66 |
| 2026-02-11 00:00 |
14:59:26.72 |
-13:04:12.3 |
HIP 73291 |
21.05 |
| 2026-02-11 12:00 |
14:59:30.75 |
-13:04:03.8 |
HIP 73291 |
21.44 |
| 2026-02-12 00:00 |
14:59:34.62 |
-13:03:54.4 |
HIP 73291 |
21.85 |
| 2026-02-12 12:00 |
14:59:38.32 |
-13:03:44.3 |
HIP 73291 |
22.25 |
| 2026-02-13 00:00 |
14:59:41.86 |
-13:03:33.4 |
HIP 73291 |
22.64 |
| 2026-02-13 12:00 |
14:59:45.23 |
-13:03:21.7 |
HIP 73291 |
23.03 |
| 2026-02-14 00:00 |
14:59:48.44 |
-13:03:09.3 |
HIP 73291 |
23.40 |
| 2026-02-14 12:00 |
14:59:51.48 |
-13:02:56.1 |
HIP 73291 |
23.76 |
| 2026-02-15 00:00 |
14:59:54.36 |
-13:02:42.2 |
HIP 73291 |
24.10 |
| 2026-02-15 12:00 |
14:59:57.07 |
-13:02:27.5 |
HIP 73291 |
24.42 |
| 2026-02-16 00:00 |
14:59:59.61 |
-13:02:12.0 |
HIP 73291 |
24.71 |
| 2026-02-16 12:00 |
15:00:01.98 |
-13:01:55.7 |
HIP 73291 |
24.98 |
| 2026-02-17 00:00 |
15:00:04.18 |
-13:01:38.7 |
HIP 73291 |
25.22 |
| 2026-02-17 12:00 |
15:00:06.22 |
-13:01:20.9 |
HIP 73291 |
25.44 |
| 2026-02-18 00:00 |
15:00:08.08 |
-13:01:02.3 |
HIP 73291 |
25.62 |
| 2026-02-18 12:00 |
15:00:09.77 |
-13:00:43.0 |
HIP 73291 |
25.77 |
| 2026-02-19 00:00 |
15:00:11.30 |
-13:00:22.9 |
HIP 73291 |
25.89 |
| 2026-02-19 12:00 |
15:00:12.65 |
-13:00:02.1 |
HIP 73291 |
25.98 |
| 2026-02-20 00:00 |
15:00:13.83 |
-12:59:40.4 |
HIP 73291 |
26.03 |
| 2026-02-20 12:00 |
15:00:14.84 |
-12:59:18.0 |
HIP 73508 |
25.88 |
| 2026-02-21 00:00 |
15:00:15.68 |
-12:58:54.9 |
HIP 73508 |
25.46 |
| 2026-02-21 12:00 |
15:00:16.35 |
-12:58:31.0 |
HIP 73508 |
25.06 |
| 2026-02-22 00:00 |
15:00:16.84 |
-12:58:06.3 |
HIP 73508 |
24.68 |
| 2026-02-22 12:00 |
15:00:17.16 |
-12:57:40.9 |
HIP 73508 |
24.32 |
| 2026-02-23 00:00 |
15:00:17.31 |
-12:57:14.7 |
HIP 73508 |
23.99 |
| 2026-02-23 12:00 |
15:00:17.29 |
-12:56:47.7 |
HIP 73508 |
23.68 |
| 2026-02-24 00:00 |
15:00:17.09 |
-12:56:20.0 |
HIP 73508 |
23.40 |