| 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
$$
M_a = (13.645 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.645 |
| n |
6.000 |
| gf |
0.980 |
| gb |
-0.872 |
| k |
1.000 |
| δ90 |
9.541 |
| 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 |
+2.0338 |
+0.530 |
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 |
15:42:44.13 |
-20:17:01.2 |
HIP 76900 |
20.32 |
| 2026-07-29 12:00 |
15:42:47.61 |
-20:17:14.1 |
HIP 76900 |
20.49 |
| 2026-07-30 00:00 |
15:42:51.39 |
-20:17:28.0 |
HIP 76900 |
20.72 |
| 2026-07-30 12:00 |
15:42:55.48 |
-20:17:42.8 |
HIP 76900 |
21.01 |
| 2026-07-31 00:00 |
15:42:59.86 |
-20:17:58.6 |
HIP 76900 |
21.37 |
| 2026-07-31 12:00 |
15:43:04.55 |
-20:18:15.3 |
HIP 76900 |
21.80 |
| 2026-08-01 00:00 |
15:43:09.54 |
-20:18:32.9 |
HIP 76900 |
22.32 |
| 2026-08-01 12:00 |
15:43:14.82 |
-20:18:51.5 |
HIP 76900 |
22.93 |
| 2026-08-02 00:00 |
15:43:20.40 |
-20:19:11.0 |
HIP 76900 |
23.63 |
| 2026-08-02 12:00 |
15:43:26.28 |
-20:19:31.4 |
HIP 76900 |
24.43 |
| 2026-08-03 00:00 |
15:43:32.46 |
-20:19:52.8 |
HIP 77116 |
23.99 |
| 2026-08-03 12:00 |
15:43:38.93 |
-20:20:15.0 |
HIP 77116 |
23.19 |
| 2026-08-04 00:00 |
15:43:45.70 |
-20:20:38.2 |
HIP 77116 |
22.44 |
| 2026-08-04 12:00 |
15:43:52.76 |
-20:21:02.3 |
HIP 77116 |
21.77 |
| 2026-08-05 00:00 |
15:44:00.11 |
-20:21:27.3 |
HIP 77116 |
21.18 |
| 2026-08-05 12:00 |
15:44:07.76 |
-20:21:53.1 |
HIP 77116 |
20.72 |
| 2026-08-06 00:00 |
15:44:15.70 |
-20:22:19.9 |
HIP 77116 |
20.40 |
| 2026-08-06 12:00 |
15:44:23.93 |
-20:22:47.6 |
HIP 77116 |
20.26 |
| 2026-08-07 00:00 |
15:44:32.45 |
-20:23:16.1 |
HIP 77116 |
20.31 |
| 2026-08-07 12:00 |
15:44:41.26 |
-20:23:45.6 |
HIP 77116 |
20.58 |
| 2026-08-08 00:00 |
15:44:50.35 |
-20:24:15.9 |
HIP 77116 |
21.08 |
| 2026-08-08 12:00 |
15:44:59.74 |
-20:24:47.0 |
HIP 77116 |
21.81 |
| 2026-08-09 00:00 |
15:45:09.41 |
-20:25:19.1 |
HIP 77116 |
22.78 |
| 2026-08-09 12:00 |
15:45:19.37 |
-20:25:52.0 |
HIP 77116 |
23.97 |
| 2026-08-10 00:00 |
15:45:29.61 |
-20:26:25.7 |
HIP 77116 |
25.37 |
| 2026-08-10 12:00 |
15:45:40.14 |
-20:27:00.3 |
HIP 77338 |
23.49 |
| 2026-08-11 00:00 |
15:45:50.95 |
-20:27:35.8 |
HIP 77338 |
20.94 |
| 2026-08-11 12:00 |
15:46:02.05 |
-20:28:12.1 |
HIP 77338 |
18.33 |
| 2026-08-12 00:00 |
15:46:13.42 |
-20:28:49.2 |
HIP 77338 |
15.68 |
| 2026-08-12 12:00 |
15:46:25.08 |
-20:29:27.1 |
HIP 77338 |
13.00 |
| 2026-08-13 00:00 |
15:46:37.02 |
-20:30:05.8 |
HIP 77338 |
10.33 |
| 2026-08-13 12:00 |
15:46:49.23 |
-20:30:45.4 |
HIP 77338 |
7.73 |
| 2026-08-14 00:00 |
15:47:01.73 |
-20:31:25.7 |
HIP 77338 |
5.45 |
| 2026-08-14 12:00 |
15:47:14.49 |
-20:32:06.9 |
HIP 77338 |
4.19 |
| 2026-08-15 00:00 |
15:47:27.54 |
-20:32:48.8 |
HIP 77338 |
4.96 |
| 2026-08-15 12:00 |
15:47:40.85 |
-20:33:31.5 |
HIP 77338 |
7.21 |
| 2026-08-16 00:00 |
15:47:54.44 |
-20:34:15.0 |
HIP 77338 |
10.05 |
| 2026-08-16 12:00 |
15:48:08.30 |
-20:34:59.2 |
HIP 77428 |
11.76 |
| 2026-08-17 00:00 |
15:48:22.43 |
-20:35:44.2 |
HIP 77428 |
12.01 |
| 2026-08-17 12:00 |
15:48:36.83 |
-20:36:29.9 |
HIP 77428 |
13.19 |
| 2026-08-18 00:00 |
15:48:51.50 |
-20:37:16.4 |
HIP 77521 |
14.76 |
| 2026-08-18 12:00 |
15:49:06.43 |
-20:38:03.5 |
HIP 77521 |
11.68 |
| 2026-08-19 00:00 |
15:49:21.62 |
-20:38:51.4 |
HIP 77521 |
8.93 |