| Parameter |
Value |
| Designation |
128P/Shoemaker-Holt 1 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2017-01-10T18:32:09.657600Z |
| Orbit solution date (soln_date, UTC) |
2026-03-09T08:49:55Z |
| Obs used |
847 |
| NEO |
- |
| M1 |
7.300 |
| K1 |
19.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2016-02-17.0000000 |
| e |
0.32145501 |
| q (au) |
3.055732 |
| a (au) |
4.503359 |
| i (deg) |
4.363922 |
| Ω (om, deg) |
214.293861 |
| ω (w, deg) |
210.579379 |
| M (ma, deg) |
326.092601 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.159 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.159 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.922 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
03:47:10.35 |
+18:44:28.7 |
HIP 17740 |
12.00 |
| 2026-06-01 12:00 |
03:47:59.76 |
+18:46:42.5 |
HIP 17740 |
6.94 |
| 2026-06-02 00:00 |
03:48:49.18 |
+18:48:55.5 |
HIP 17740 |
15.35 |
| 2026-06-02 12:00 |
03:49:38.62 |
+18:51:07.5 |
HIP 17961 |
26.37 |
| 2026-06-03 00:00 |
03:50:28.06 |
+18:53:18.5 |
HIP 17961 |
21.98 |
| 2026-06-03 12:00 |
03:51:17.52 |
+18:55:28.6 |
HIP 18110 |
14.46 |
| 2026-06-04 00:00 |
03:52:06.98 |
+18:57:37.8 |
HIP 18110 |
3.77 |
| 2026-06-04 12:00 |
03:52:56.45 |
+18:59:46.0 |
HIP 18110 |
10.10 |
| 2026-06-05 00:00 |
03:53:45.93 |
+19:01:53.2 |
HIP 18110 |
21.74 |
| 2026-06-05 12:00 |
03:54:35.41 |
+19:03:59.5 |
HIP 18347 |
21.73 |
| 2026-06-06 00:00 |
03:55:24.91 |
+19:06:04.9 |
HIP 18409 |
12.88 |
| 2026-06-06 12:00 |
03:56:14.41 |
+19:08:09.2 |
HIP 18409 |
5.70 |
| 2026-06-07 00:00 |
03:57:03.91 |
+19:10:12.6 |
HIP 18409 |
13.45 |
| 2026-06-07 12:00 |
03:57:53.42 |
+19:12:15.1 |
HIP 18409 |
24.72 |
| 2026-06-08 00:00 |
03:58:42.94 |
+19:14:16.5 |
HIP 18643 |
35.97 |
| 2026-06-08 12:00 |
03:59:32.46 |
+19:16:17.0 |
HIP 18784 |
33.61 |
| 2026-06-09 00:00 |
04:00:21.98 |
+19:18:16.5 |
HIP 18784 |
23.51 |
| 2026-06-09 12:00 |
04:01:11.51 |
+19:20:15.0 |
HIP 18784 |
16.05 |
| 2026-06-10 00:00 |
04:02:01.04 |
+19:22:12.5 |
HIP 18784 |
15.60 |
| 2026-06-10 12:00 |
04:02:50.57 |
+19:24:09.1 |
HIP 18946 |
11.84 |
| 2026-06-11 00:00 |
04:03:40.10 |
+19:26:04.6 |
HIP 18946 |
1.26 |
| 2026-06-11 12:00 |
04:04:29.63 |
+19:27:59.2 |
HIP 18946 |
11.96 |
| 2026-06-12 00:00 |
04:05:19.16 |
+19:29:52.7 |
HIP 19082 |
3.67 |
| 2026-06-12 12:00 |
04:06:08.69 |
+19:31:45.3 |
HIP 19082 |
11.42 |
| 2026-06-13 00:00 |
04:06:58.21 |
+19:33:36.8 |
HIP 19308 |
22.14 |
| 2026-06-13 12:00 |
04:07:47.74 |
+19:35:27.3 |
HIP 19308 |
11.73 |
| 2026-06-14 00:00 |
04:08:37.26 |
+19:37:16.8 |
HIP 19388 |
7.72 |
| 2026-06-14 12:00 |
04:09:26.77 |
+19:39:05.3 |
HIP 19388 |
4.71 |
| 2026-06-15 00:00 |
04:10:16.29 |
+19:40:52.8 |
HIP 19388 |
16.22 |
| 2026-06-15 12:00 |
04:11:05.79 |
+19:42:39.3 |
HIP 19669 |
26.42 |
| 2026-06-16 00:00 |
04:11:55.29 |
+19:44:24.7 |
HIP 19669 |
17.50 |
| 2026-06-16 12:00 |
04:12:44.78 |
+19:46:09.1 |
HIP 19669 |
13.86 |
| 2026-06-17 00:00 |
04:13:34.26 |
+19:47:52.5 |
HIP 19772 |
17.09 |
| 2026-06-17 12:00 |
04:14:23.73 |
+19:49:34.8 |
HIP 19772 |
14.81 |
| 2026-06-18 00:00 |
04:15:13.19 |
+19:51:16.1 |
HIP 19772 |
20.56 |
| 2026-06-18 12:00 |
04:16:02.64 |
+19:52:56.4 |
HIP 19975 |
18.53 |
| 2026-06-19 00:00 |
04:16:52.08 |
+19:54:35.6 |
HIP 19975 |
14.20 |
| 2026-06-19 12:00 |
04:17:41.51 |
+19:56:13.8 |
HIP 20130 |
18.05 |
| 2026-06-20 00:00 |
04:18:30.92 |
+19:57:51.0 |
HIP 20130 |
7.22 |
| 2026-06-20 12:00 |
04:19:20.32 |
+19:59:27.1 |
HIP 20175 |
3.46 |
| 2026-06-21 00:00 |
04:20:09.70 |
+20:01:02.1 |
HIP 20175 |
10.18 |
| 2026-06-21 12:00 |
04:20:59.07 |
+20:02:36.1 |
HIP 20175 |
21.66 |
| 2026-06-22 00:00 |
04:21:48.43 |
+20:04:09.1 |
HIP 20390 |
32.15 |