26P/Grigg-Skjellerup
| Parameter |
Value |
| Designation |
26P/Grigg-Skjellerup |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2013-07-06T00:05:12.914880Z |
| Orbit solution date (soln_date, UTC) |
2024-10-11T15:43:03Z |
| Obs used |
511 |
| NEO |
Yes |
| M1 |
16.500 |
| K1 |
5.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2012-03-31.0000000 |
| e |
0.63966796 |
| q (au) |
1.089725 |
| a (au) |
3.024224 |
| i (deg) |
22.455114 |
| Ω (om, deg) |
211.633966 |
| ω (w, deg) |
1.896086 |
| M (ma, deg) |
273.417838 |
Magnitude
Scatter + Global Linear
$$
M_a = (13.785 + 4.946\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
13.785 |
| n |
4.946 |
| gf |
0.998 |
| gb |
-0.927 |
| k |
0.996 |
| δ90 |
1.000 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
00:46:41.34 |
+08:03:39.5 |
HIP 3666 |
15.13 |
| 2026-02-03 12:00 |
00:46:58.83 |
+08:04:35.9 |
HIP 3666 |
13.94 |
| 2026-02-04 00:00 |
00:47:16.41 |
+08:05:33.1 |
HIP 3666 |
14.10 |
| 2026-02-04 12:00 |
00:47:34.11 |
+08:06:31.2 |
HIP 3666 |
15.59 |
| 2026-02-05 00:00 |
00:47:51.90 |
+08:07:30.2 |
HIP 3666 |
18.12 |
| 2026-02-05 12:00 |
00:48:09.80 |
+08:08:29.9 |
HIP 3666 |
21.32 |
| 2026-02-06 00:00 |
00:48:27.80 |
+08:09:30.5 |
HIP 3862 |
20.60 |
| 2026-02-06 12:00 |
00:48:45.90 |
+08:10:31.9 |
HIP 3862 |
17.94 |
| 2026-02-07 00:00 |
00:49:04.10 |
+08:11:34.1 |
HIP 3862 |
16.17 |
| 2026-02-07 12:00 |
00:49:22.40 |
+08:12:37.0 |
HIP 3862 |
15.63 |
| 2026-02-08 00:00 |
00:49:40.80 |
+08:13:40.8 |
HIP 3862 |
16.46 |
| 2026-02-08 12:00 |
00:49:59.30 |
+08:14:45.3 |
HIP 3968 |
16.20 |
| 2026-02-09 00:00 |
00:50:17.89 |
+08:15:50.7 |
HIP 3968 |
11.52 |
| 2026-02-09 12:00 |
00:50:36.58 |
+08:16:56.7 |
HIP 3968 |
6.86 |
| 2026-02-10 00:00 |
00:50:55.37 |
+08:18:03.6 |
HIP 3968 |
2.54 |
| 2026-02-10 12:00 |
00:51:14.25 |
+08:19:11.2 |
HIP 3968 |
3.42 |
| 2026-02-11 00:00 |
00:51:33.22 |
+08:20:19.5 |
HIP 3968 |
7.97 |
| 2026-02-11 12:00 |
00:51:52.28 |
+08:21:28.5 |
HIP 3968 |
12.75 |
| 2026-02-12 00:00 |
00:52:11.44 |
+08:22:38.3 |
HIP 3968 |
17.59 |
| 2026-02-12 12:00 |
00:52:30.69 |
+08:23:48.8 |
HIP 4094 |
16.12 |
| 2026-02-13 00:00 |
00:52:50.02 |
+08:25:00.1 |
HIP 4094 |
15.52 |
| 2026-02-13 12:00 |
00:53:09.45 |
+08:26:12.0 |
HIP 4094 |
16.44 |
| 2026-02-14 00:00 |
00:53:28.97 |
+08:27:24.6 |
HIP 4094 |
18.68 |
| 2026-02-14 12:00 |
00:53:48.57 |
+08:28:37.9 |
HIP 4094 |
21.86 |
| 2026-02-15 00:00 |
00:54:08.26 |
+08:29:51.9 |
HIP 4094 |
25.64 |
| 2026-02-15 12:00 |
00:54:28.03 |
+08:31:06.6 |
HIP 4094 |
29.81 |
| 2026-02-16 00:00 |
00:54:47.89 |
+08:32:21.9 |
HIP 4399 |
27.32 |
| 2026-02-16 12:00 |
00:55:07.83 |
+08:33:37.9 |
HIP 4399 |
23.83 |
| 2026-02-17 00:00 |
00:55:27.86 |
+08:34:54.5 |
HIP 4399 |
21.00 |
| 2026-02-17 12:00 |
00:55:47.97 |
+08:36:11.8 |
HIP 4399 |
19.15 |
| 2026-02-18 00:00 |
00:56:08.16 |
+08:37:29.7 |
HIP 4399 |
18.58 |
| 2026-02-18 12:00 |
00:56:28.43 |
+08:38:48.3 |
HIP 4399 |
19.42 |
| 2026-02-19 00:00 |
00:56:48.78 |
+08:40:07.4 |
HIP 4399 |
21.53 |
| 2026-02-19 12:00 |
00:57:09.20 |
+08:41:27.2 |
HIP 4399 |
24.60 |
| 2026-02-20 00:00 |
00:57:29.71 |
+08:42:47.6 |
HIP 4399 |
28.32 |
| 2026-02-20 12:00 |
00:57:50.29 |
+08:44:08.5 |
HIP 4503 |
31.59 |
| 2026-02-21 00:00 |
00:58:10.95 |
+08:45:30.1 |
HIP 4503 |
33.68 |
| 2026-02-21 12:00 |
00:58:31.68 |
+08:46:52.2 |
HIP 4503 |
36.43 |
| 2026-02-22 00:00 |
00:58:52.49 |
+08:48:14.9 |
HIP 4752 |
32.92 |
| 2026-02-22 12:00 |
00:59:13.37 |
+08:49:38.1 |
HIP 4752 |
27.91 |
| 2026-02-23 00:00 |
00:59:34.32 |
+08:51:01.9 |
HIP 4752 |
23.04 |
| 2026-02-23 12:00 |
00:59:55.34 |
+08:52:26.2 |
HIP 4752 |
18.42 |
| 2026-02-24 00:00 |
01:00:16.43 |
+08:53:51.1 |
HIP 4752 |
14.34 |