| Parameter |
Value |
| Designation |
238P/Read |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2022-06-05T10:21:50.189760Z |
| Orbit solution date (soln_date, UTC) |
2024-05-30T15:51:09Z |
| Obs used |
119 |
| NEO |
- |
| M1 |
8.300 |
| K1 |
29.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2022-09-15.0000000 |
| e |
0.25167358 |
| q (au) |
2.369349 |
| a (au) |
3.166197 |
| i (deg) |
1.264088 |
| Ω (om, deg) |
51.625454 |
| ω (w, deg) |
324.206807 |
| M (ma, deg) |
17.768666 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.654 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.654 |
| n |
6.000 |
| gf |
0.972 |
| gb |
-0.872 |
| k |
1.000 |
| δ90 |
8.980 |
| 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 |
| 2021-06-11 |
2021-11-26 |
+2.0364 |
+0.529 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
16:40:01.75 |
-22:18:27.4 |
HIP 81513 |
21.25 |
| 2026-03-26 12:00 |
16:40:05.41 |
-22:18:41.4 |
HIP 81513 |
22.00 |
| 2026-03-27 00:00 |
16:40:08.77 |
-22:18:54.9 |
HIP 81513 |
22.70 |
| 2026-03-27 12:00 |
16:40:11.84 |
-22:19:07.9 |
HIP 81513 |
23.35 |
| 2026-03-28 00:00 |
16:40:14.61 |
-22:19:20.4 |
HIP 81513 |
23.95 |
| 2026-03-28 12:00 |
16:40:17.09 |
-22:19:32.3 |
HIP 81513 |
24.50 |
| 2026-03-29 00:00 |
16:40:19.27 |
-22:19:43.6 |
HIP 81513 |
25.00 |
| 2026-03-29 12:00 |
16:40:21.15 |
-22:19:54.5 |
HIP 81513 |
25.44 |
| 2026-03-30 00:00 |
16:40:22.73 |
-22:20:04.8 |
HIP 81513 |
25.83 |
| 2026-03-30 12:00 |
16:40:24.02 |
-22:20:14.5 |
HIP 81513 |
26.16 |
| 2026-03-31 00:00 |
16:40:25.00 |
-22:20:23.8 |
HIP 81513 |
26.43 |
| 2026-03-31 12:00 |
16:40:25.68 |
-22:20:32.4 |
HIP 81513 |
26.64 |
| 2026-04-01 00:00 |
16:40:26.07 |
-22:20:40.6 |
HIP 81513 |
26.80 |
| 2026-04-01 12:00 |
16:40:26.14 |
-22:20:48.2 |
HIP 81513 |
26.90 |
| 2026-04-02 00:00 |
16:40:25.92 |
-22:20:55.2 |
HIP 81513 |
26.94 |
| 2026-04-02 12:00 |
16:40:25.39 |
-22:21:01.7 |
HIP 81513 |
26.92 |
| 2026-04-03 00:00 |
16:40:24.56 |
-22:21:07.6 |
HIP 81513 |
26.85 |
| 2026-04-03 12:00 |
16:40:23.43 |
-22:21:13.0 |
HIP 81513 |
26.72 |
| 2026-04-04 00:00 |
16:40:21.98 |
-22:21:17.9 |
HIP 81513 |
26.54 |
| 2026-04-04 12:00 |
16:40:20.23 |
-22:21:22.2 |
HIP 81513 |
26.31 |
| 2026-04-05 00:00 |
16:40:18.18 |
-22:21:25.9 |
HIP 81513 |
26.02 |
| 2026-04-05 12:00 |
16:40:15.82 |
-22:21:29.1 |
HIP 81513 |
25.68 |
| 2026-04-06 00:00 |
16:40:13.14 |
-22:21:31.7 |
HIP 81513 |
25.30 |
| 2026-04-06 12:00 |
16:40:10.16 |
-22:21:33.7 |
HIP 81513 |
24.87 |
| 2026-04-07 00:00 |
16:40:06.88 |
-22:21:35.2 |
HIP 81513 |
24.40 |
| 2026-04-07 12:00 |
16:40:03.28 |
-22:21:36.1 |
HIP 81513 |
23.90 |
| 2026-04-08 00:00 |
16:39:59.37 |
-22:21:36.4 |
HIP 81513 |
23.36 |
| 2026-04-08 12:00 |
16:39:55.15 |
-22:21:36.2 |
HIP 81513 |
22.80 |
| 2026-04-09 00:00 |
16:39:50.63 |
-22:21:35.4 |
HIP 81513 |
22.23 |
| 2026-04-09 12:00 |
16:39:45.79 |
-22:21:34.0 |
HIP 81513 |
21.64 |
| 2026-04-10 00:00 |
16:39:40.64 |
-22:21:32.0 |
HIP 81513 |
21.06 |
| 2026-04-10 12:00 |
16:39:35.18 |
-22:21:29.5 |
HIP 81513 |
20.49 |
| 2026-04-11 00:00 |
16:39:29.41 |
-22:21:26.3 |
HIP 81513 |
19.96 |
| 2026-04-11 12:00 |
16:39:23.33 |
-22:21:22.6 |
HIP 81513 |
19.47 |
| 2026-04-12 00:00 |
16:39:16.94 |
-22:21:18.3 |
HIP 81513 |
19.05 |
| 2026-04-12 12:00 |
16:39:10.24 |
-22:21:13.4 |
HIP 81513 |
18.72 |
| 2026-04-13 00:00 |
16:39:03.23 |
-22:21:07.9 |
HIP 81513 |
18.50 |
| 2026-04-13 12:00 |
16:38:55.91 |
-22:21:01.8 |
HIP 81513 |
18.41 |
| 2026-04-14 00:00 |
16:38:48.28 |
-22:20:55.1 |
HIP 81513 |
18.49 |
| 2026-04-14 12:00 |
16:38:40.34 |
-22:20:47.9 |
HIP 81513 |
18.74 |
| 2026-04-15 00:00 |
16:38:32.09 |
-22:20:40.0 |
HIP 81513 |
19.18 |
| 2026-04-15 12:00 |
16:38:23.53 |
-22:20:31.5 |
HIP 81513 |
19.81 |
| 2026-04-16 00:00 |
16:38:14.67 |
-22:20:22.4 |
HIP 81413 |
18.81 |