123P/West-Hartley
| Parameter |
Value |
| Designation |
123P/West-Hartley |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2019-02-04T16:07:06.352320Z |
| Orbit solution date (soln_date, UTC) |
2026-01-13T22:30:36Z |
| Obs used |
3382 |
| NEO |
- |
| M1 |
8.200 |
| K1 |
18.250 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-06-25.0000000 |
| e |
0.44921273 |
| q (au) |
2.126204 |
| a (au) |
3.860299 |
| i (deg) |
15.357040 |
| Ω (om, deg) |
46.509944 |
| ω (w, deg) |
102.958304 |
| M (ma, deg) |
235.941463 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.213 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.213 |
| n |
6.000 |
| gf |
0.998 |
| gb |
-0.927 |
| k |
1.000 |
| δ90 |
9.997 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
03:23:14.96 |
+28:01:05.2 |
HIP 15885 |
18.53 |
| 2026-02-03 12:00 |
03:23:29.90 |
+28:02:17.2 |
HIP 15885 |
15.75 |
| 2026-02-04 00:00 |
03:23:45.23 |
+28:03:30.2 |
HIP 15885 |
13.26 |
| 2026-02-04 12:00 |
03:24:00.97 |
+28:04:44.2 |
HIP 15885 |
11.33 |
| 2026-02-05 00:00 |
03:24:17.10 |
+28:05:59.1 |
HIP 15885 |
10.38 |
| 2026-02-05 12:00 |
03:24:33.62 |
+28:07:15.1 |
HIP 15885 |
10.76 |
| 2026-02-06 00:00 |
03:24:50.54 |
+28:08:31.9 |
HIP 15885 |
12.43 |
| 2026-02-06 12:00 |
03:25:07.85 |
+28:09:49.8 |
HIP 15885 |
15.03 |
| 2026-02-07 00:00 |
03:25:25.54 |
+28:11:08.5 |
HIP 15885 |
18.23 |
| 2026-02-07 12:00 |
03:25:43.63 |
+28:12:28.3 |
HIP 15885 |
21.80 |
| 2026-02-08 00:00 |
03:26:02.10 |
+28:13:48.9 |
HIP 15885 |
25.64 |
| 2026-02-08 12:00 |
03:26:20.95 |
+28:15:10.5 |
HIP 16042 |
27.93 |
| 2026-02-09 00:00 |
03:26:40.19 |
+28:16:33.1 |
HIP 16042 |
26.39 |
| 2026-02-09 12:00 |
03:26:59.81 |
+28:17:56.5 |
HIP 16042 |
25.55 |
| 2026-02-10 00:00 |
03:27:19.81 |
+28:19:20.8 |
HIP 16042 |
25.51 |
| 2026-02-10 12:00 |
03:27:40.19 |
+28:20:46.1 |
HIP 16042 |
26.33 |
| 2026-02-11 00:00 |
03:28:00.94 |
+28:22:12.3 |
HIP 16042 |
27.97 |
| 2026-02-11 12:00 |
03:28:22.07 |
+28:23:39.3 |
HIP 16042 |
30.34 |
| 2026-02-12 00:00 |
03:28:43.58 |
+28:25:07.2 |
HIP 16042 |
33.31 |
| 2026-02-12 12:00 |
03:29:05.46 |
+28:26:36.0 |
HIP 16042 |
36.77 |
| 2026-02-13 00:00 |
03:29:27.71 |
+28:28:05.7 |
HIP 16042 |
40.63 |
| 2026-02-13 12:00 |
03:29:50.33 |
+28:29:36.2 |
HIP 16513 |
37.59 |
| 2026-02-14 00:00 |
03:30:13.32 |
+28:31:07.6 |
HIP 16513 |
33.05 |
| 2026-02-14 12:00 |
03:30:36.67 |
+28:32:39.8 |
HIP 16513 |
28.69 |
| 2026-02-15 00:00 |
03:31:00.39 |
+28:34:12.8 |
HIP 16513 |
24.66 |
| 2026-02-15 12:00 |
03:31:24.47 |
+28:35:46.7 |
HIP 16513 |
21.22 |
| 2026-02-16 00:00 |
03:31:48.91 |
+28:37:21.4 |
HIP 16513 |
18.77 |
| 2026-02-16 12:00 |
03:32:13.72 |
+28:38:56.9 |
HIP 16513 |
17.80 |
| 2026-02-17 00:00 |
03:32:38.88 |
+28:40:33.2 |
HIP 16513 |
18.60 |
| 2026-02-17 12:00 |
03:33:04.40 |
+28:42:10.2 |
HIP 16513 |
21.05 |
| 2026-02-18 00:00 |
03:33:30.27 |
+28:43:48.0 |
HIP 16513 |
24.71 |
| 2026-02-18 12:00 |
03:33:56.50 |
+28:45:26.6 |
HIP 16513 |
29.17 |
| 2026-02-19 00:00 |
03:34:23.07 |
+28:47:06.0 |
HIP 16806 |
27.66 |
| 2026-02-19 12:00 |
03:34:50.00 |
+28:48:46.1 |
HIP 16806 |
21.59 |
| 2026-02-20 00:00 |
03:35:17.28 |
+28:50:26.9 |
HIP 16806 |
15.48 |
| 2026-02-20 12:00 |
03:35:44.90 |
+28:52:08.4 |
HIP 16806 |
9.44 |
| 2026-02-21 00:00 |
03:36:12.87 |
+28:53:50.7 |
HIP 16806 |
4.13 |
| 2026-02-21 12:00 |
03:36:41.17 |
+28:55:33.6 |
HIP 16806 |
5.13 |
| 2026-02-22 00:00 |
03:37:09.82 |
+28:57:17.2 |
HIP 16806 |
10.94 |
| 2026-02-22 12:00 |
03:37:38.81 |
+28:59:01.5 |
HIP 16806 |
17.33 |
| 2026-02-23 00:00 |
03:38:08.13 |
+29:00:46.4 |
HIP 16835 |
23.08 |
| 2026-02-23 12:00 |
03:38:37.79 |
+29:02:32.0 |
HIP 16835 |
27.98 |
| 2026-02-24 00:00 |
03:39:07.78 |
+29:04:18.2 |
HIP 17168 |
26.77 |