| Parameter |
Value |
| Designation |
323P/SOHO |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2021-01-17T15:09:04.803840Z |
| Orbit solution date (soln_date, UTC) |
2025-02-20T14:38:09Z |
| Obs used |
171 |
| NEO |
Yes |
| M1 |
23.400 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2021-03-03.0000000 |
| e |
0.98481410 |
| q (au) |
0.039207 |
| a (au) |
2.581828 |
| i (deg) |
5.369972 |
| Ω (om, deg) |
324.229171 |
| ω (w, deg) |
353.174495 |
| M (ma, deg) |
10.541190 |
Magnitude
Scatter + Global Linear
$$
M_a = (20.000 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
20.000 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.500 |
| 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 |
| 2025-01-27 |
2025-02-08 |
-17.3579 |
+3.208 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
09:38:00.74 |
+14:53:32.7 |
HIP 47211 |
24.02 |
| 2026-09-20 12:00 |
09:38:17.94 |
+14:52:08.0 |
HIP 47211 |
27.28 |
| 2026-09-21 00:00 |
09:38:35.06 |
+14:50:43.7 |
HIP 47368 |
26.35 |
| 2026-09-21 12:00 |
09:38:52.09 |
+14:49:19.8 |
HIP 47368 |
24.18 |
| 2026-09-22 00:00 |
09:39:09.04 |
+14:47:56.2 |
HIP 47368 |
22.65 |
| 2026-09-22 12:00 |
09:39:25.92 |
+14:46:32.9 |
HIP 47368 |
21.88 |
| 2026-09-23 00:00 |
09:39:42.70 |
+14:45:10.0 |
HIP 47368 |
21.95 |
| 2026-09-23 12:00 |
09:39:59.41 |
+14:43:47.4 |
HIP 47368 |
22.83 |
| 2026-09-24 00:00 |
09:40:16.03 |
+14:42:25.2 |
HIP 47368 |
24.43 |
| 2026-09-24 12:00 |
09:40:32.56 |
+14:41:03.3 |
HIP 47597 |
26.00 |
| 2026-09-25 00:00 |
09:40:49.01 |
+14:39:41.9 |
HIP 47597 |
22.44 |
| 2026-09-25 12:00 |
09:41:05.37 |
+14:38:20.8 |
HIP 47597 |
19.16 |
| 2026-09-26 00:00 |
09:41:21.64 |
+14:37:00.1 |
HIP 47597 |
16.30 |
| 2026-09-26 12:00 |
09:41:37.82 |
+14:35:39.7 |
HIP 47597 |
14.12 |
| 2026-09-27 00:00 |
09:41:53.92 |
+14:34:19.8 |
HIP 47597 |
12.93 |
| 2026-09-27 12:00 |
09:42:09.92 |
+14:33:00.3 |
HIP 47597 |
12.99 |
| 2026-09-28 00:00 |
09:42:25.83 |
+14:31:41.1 |
HIP 47597 |
14.27 |
| 2026-09-28 12:00 |
09:42:41.66 |
+14:30:22.4 |
HIP 47597 |
16.47 |
| 2026-09-29 00:00 |
09:42:57.39 |
+14:29:04.1 |
HIP 47597 |
19.26 |
| 2026-09-29 12:00 |
09:43:13.02 |
+14:27:46.2 |
HIP 47597 |
22.40 |
| 2026-09-30 00:00 |
09:43:28.56 |
+14:26:28.7 |
HIP 47723 |
25.45 |
| 2026-09-30 12:00 |
09:43:44.01 |
+14:25:11.7 |
HIP 47723 |
23.89 |
| 2026-10-01 00:00 |
09:43:59.36 |
+14:23:55.0 |
HIP 47723 |
22.92 |
| 2026-10-01 12:00 |
09:44:14.61 |
+14:22:38.9 |
HIP 47723 |
22.61 |
| 2026-10-02 00:00 |
09:44:29.77 |
+14:21:23.2 |
HIP 47723 |
22.96 |
| 2026-10-02 12:00 |
09:44:44.83 |
+14:20:07.9 |
HIP 47723 |
23.93 |
| 2026-10-03 00:00 |
09:44:59.78 |
+14:18:53.1 |
HIP 47723 |
25.45 |
| 2026-10-03 12:00 |
09:45:14.64 |
+14:17:38.8 |
HIP 47994 |
27.40 |
| 2026-10-04 00:00 |
09:45:29.39 |
+14:16:24.9 |
HIP 47994 |
23.62 |
| 2026-10-04 12:00 |
09:45:44.05 |
+14:15:11.5 |
HIP 47994 |
19.87 |
| 2026-10-05 00:00 |
09:45:58.59 |
+14:13:58.6 |
HIP 47994 |
16.14 |
| 2026-10-05 12:00 |
09:46:13.04 |
+14:12:46.2 |
HIP 47994 |
12.45 |
| 2026-10-06 00:00 |
09:46:27.37 |
+14:11:34.3 |
HIP 47994 |
8.78 |
| 2026-10-06 12:00 |
09:46:41.60 |
+14:10:22.9 |
HIP 47994 |
5.16 |
| 2026-10-07 00:00 |
09:46:55.73 |
+14:09:12.1 |
HIP 47994 |
1.70 |
| 2026-10-07 12:00 |
09:47:09.74 |
+14:08:01.7 |
HIP 47994 |
2.29 |
| 2026-10-08 00:00 |
09:47:23.64 |
+14:06:51.9 |
HIP 47994 |
5.75 |
| 2026-10-08 12:00 |
09:47:37.43 |
+14:05:42.6 |
HIP 47994 |
9.27 |
| 2026-10-09 00:00 |
09:47:51.11 |
+14:04:33.9 |
HIP 47994 |
12.76 |
| 2026-10-09 12:00 |
09:48:04.68 |
+14:03:25.7 |
HIP 47994 |
16.24 |
| 2026-10-10 00:00 |
09:48:18.13 |
+14:02:18.1 |
HIP 47994 |
19.69 |
| 2026-10-10 12:00 |
09:48:31.47 |
+14:01:11.0 |
HIP 48152 |
17.45 |
| 2026-10-11 00:00 |
09:48:44.69 |
+14:00:04.6 |
HIP 48152 |
15.55 |