| 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 |
0.975 |
| 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) |
| 2026-09-25 00:00 |
02:47:51.98 |
+13:54:39.0 |
HIP 12869 |
35.47 |
| 2026-09-25 12:00 |
02:47:38.99 |
+13:52:43.7 |
HIP 12869 |
32.45 |
| 2026-09-26 00:00 |
02:47:25.80 |
+13:50:47.6 |
HIP 12869 |
29.54 |
| 2026-09-26 12:00 |
02:47:12.43 |
+13:48:50.4 |
HIP 12869 |
26.80 |
| 2026-09-27 00:00 |
02:46:58.87 |
+13:46:52.3 |
HIP 12869 |
24.31 |
| 2026-09-27 12:00 |
02:46:45.12 |
+13:44:53.3 |
HIP 12869 |
22.17 |
| 2026-09-28 00:00 |
02:46:31.18 |
+13:42:53.3 |
HIP 12869 |
20.51 |
| 2026-09-28 12:00 |
02:46:17.07 |
+13:40:52.4 |
HIP 12869 |
19.51 |
| 2026-09-29 00:00 |
02:46:02.77 |
+13:38:50.6 |
HIP 12869 |
19.28 |
| 2026-09-29 12:00 |
02:45:48.29 |
+13:36:47.8 |
HIP 12869 |
19.88 |
| 2026-09-30 00:00 |
02:45:33.63 |
+13:34:44.2 |
HIP 12869 |
21.27 |
| 2026-09-30 12:00 |
02:45:18.79 |
+13:32:39.6 |
HIP 12844 |
22.90 |
| 2026-10-01 00:00 |
02:45:03.78 |
+13:30:34.2 |
HIP 12844 |
20.67 |
| 2026-10-01 12:00 |
02:44:48.59 |
+13:28:27.8 |
HIP 12738 |
19.02 |
| 2026-10-02 00:00 |
02:44:33.23 |
+13:26:20.6 |
HIP 12738 |
14.76 |
| 2026-10-02 12:00 |
02:44:17.70 |
+13:24:12.6 |
HIP 12738 |
10.48 |
| 2026-10-03 00:00 |
02:44:02.00 |
+13:22:03.6 |
HIP 12738 |
6.23 |
| 2026-10-03 12:00 |
02:43:46.13 |
+13:19:53.9 |
HIP 12738 |
2.51 |
| 2026-10-04 00:00 |
02:43:30.09 |
+13:17:43.2 |
HIP 12738 |
3.63 |
| 2026-10-04 12:00 |
02:43:13.89 |
+13:15:31.8 |
HIP 12738 |
7.78 |
| 2026-10-05 00:00 |
02:42:57.53 |
+13:13:19.5 |
HIP 12738 |
12.24 |
| 2026-10-05 12:00 |
02:42:41.01 |
+13:11:06.5 |
HIP 12738 |
16.79 |
| 2026-10-06 00:00 |
02:42:24.33 |
+13:08:52.6 |
HIP 12626 |
18.18 |
| 2026-10-06 12:00 |
02:42:07.50 |
+13:06:38.0 |
HIP 12626 |
16.05 |
| 2026-10-07 00:00 |
02:41:50.51 |
+13:04:22.6 |
HIP 12626 |
15.11 |
| 2026-10-07 12:00 |
02:41:33.37 |
+13:02:06.4 |
HIP 12626 |
15.62 |
| 2026-10-08 00:00 |
02:41:16.08 |
+12:59:49.5 |
HIP 12626 |
17.49 |
| 2026-10-08 12:00 |
02:40:58.65 |
+12:57:31.8 |
HIP 12626 |
20.36 |
| 2026-10-09 00:00 |
02:40:41.07 |
+12:55:13.5 |
HIP 12626 |
23.91 |
| 2026-10-09 12:00 |
02:40:23.35 |
+12:52:54.4 |
HIP 12626 |
27.90 |
| 2026-10-10 00:00 |
02:40:05.49 |
+12:50:34.7 |
HIP 12626 |
32.17 |
| 2026-10-10 12:00 |
02:39:47.50 |
+12:48:14.3 |
HIP 12626 |
36.65 |
| 2026-10-11 00:00 |
02:39:29.37 |
+12:45:53.2 |
HIP 12198 |
35.99 |
| 2026-10-11 12:00 |
02:39:11.11 |
+12:43:31.4 |
HIP 12198 |
32.37 |
| 2026-10-12 00:00 |
02:38:52.73 |
+12:41:09.1 |
HIP 12198 |
29.15 |
| 2026-10-12 12:00 |
02:38:34.22 |
+12:38:46.1 |
HIP 12252 |
25.55 |
| 2026-10-13 00:00 |
02:38:15.58 |
+12:36:22.5 |
HIP 12252 |
21.51 |
| 2026-10-13 12:00 |
02:37:56.83 |
+12:33:58.4 |
HIP 12252 |
18.02 |
| 2026-10-14 00:00 |
02:37:37.96 |
+12:31:33.7 |
HIP 12153 |
15.43 |
| 2026-10-14 12:00 |
02:37:18.98 |
+12:29:08.4 |
HIP 12153 |
10.32 |
| 2026-10-15 00:00 |
02:36:59.89 |
+12:26:42.6 |
HIP 12153 |
5.41 |
| 2026-10-15 12:00 |
02:36:40.69 |
+12:24:16.3 |
HIP 12153 |
2.70 |
| 2026-10-16 00:00 |
02:36:21.38 |
+12:21:49.4 |
HIP 12153 |
6.44 |