| 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) |
| 2026-03-26 00:00 |
01:23:02.52 |
+10:30:45.0 |
HIP 6442 |
9.75 |
| 2026-03-26 12:00 |
01:23:26.52 |
+10:32:29.9 |
HIP 6442 |
14.77 |
| 2026-03-27 00:00 |
01:23:50.56 |
+10:34:14.9 |
HIP 6484 |
18.05 |
| 2026-03-27 12:00 |
01:24:14.62 |
+10:36:00.0 |
HIP 6484 |
19.95 |
| 2026-03-28 00:00 |
01:24:38.70 |
+10:37:45.2 |
HIP 6484 |
23.37 |
| 2026-03-28 12:00 |
01:25:02.81 |
+10:39:30.6 |
HIP 6695 |
20.33 |
| 2026-03-29 00:00 |
01:25:26.94 |
+10:41:16.1 |
HIP 6695 |
18.52 |
| 2026-03-29 12:00 |
01:25:51.09 |
+10:43:01.6 |
HIP 6695 |
18.69 |
| 2026-03-30 00:00 |
01:26:15.27 |
+10:44:47.3 |
HIP 6695 |
20.80 |
| 2026-03-30 12:00 |
01:26:39.47 |
+10:46:33.1 |
HIP 6695 |
24.34 |
| 2026-03-31 00:00 |
01:27:03.69 |
+10:48:18.9 |
HIP 6695 |
28.81 |
| 2026-03-31 12:00 |
01:27:27.93 |
+10:50:04.8 |
HIP 6764 |
32.61 |
| 2026-04-01 00:00 |
01:27:52.19 |
+10:51:50.8 |
HIP 6919 |
31.55 |
| 2026-04-01 12:00 |
01:28:16.47 |
+10:53:36.9 |
HIP 6919 |
30.18 |
| 2026-04-02 00:00 |
01:28:40.77 |
+10:55:23.0 |
HIP 7014 |
26.06 |
| 2026-04-02 12:00 |
01:29:05.09 |
+10:57:09.3 |
HIP 7014 |
19.88 |
| 2026-04-03 00:00 |
01:29:29.42 |
+10:58:55.5 |
HIP 7014 |
13.75 |
| 2026-04-03 12:00 |
01:29:53.78 |
+11:00:41.8 |
HIP 7014 |
7.75 |
| 2026-04-04 00:00 |
01:30:18.15 |
+11:02:28.2 |
HIP 7014 |
2.99 |
| 2026-04-04 12:00 |
01:30:42.53 |
+11:04:14.6 |
HIP 7014 |
5.97 |
| 2026-04-05 00:00 |
01:31:06.94 |
+11:06:01.0 |
HIP 7014 |
11.84 |
| 2026-04-05 12:00 |
01:31:31.36 |
+11:07:47.5 |
HIP 7117 |
14.69 |
| 2026-04-06 00:00 |
01:31:55.79 |
+11:09:34.0 |
HIP 7117 |
16.52 |
| 2026-04-06 12:00 |
01:32:20.24 |
+11:11:20.5 |
HIP 7117 |
20.21 |
| 2026-04-07 00:00 |
01:32:44.70 |
+11:13:07.1 |
HIP 7277 |
23.74 |
| 2026-04-07 12:00 |
01:33:09.17 |
+11:14:53.6 |
HIP 7277 |
22.28 |
| 2026-04-08 00:00 |
01:33:33.66 |
+11:16:40.2 |
HIP 7277 |
22.54 |
| 2026-04-08 12:00 |
01:33:58.16 |
+11:18:26.8 |
HIP 7397 |
21.82 |
| 2026-04-09 00:00 |
01:34:22.67 |
+11:20:13.4 |
HIP 7397 |
15.57 |
| 2026-04-09 12:00 |
01:34:47.19 |
+11:22:00.0 |
HIP 7397 |
9.36 |
| 2026-04-10 00:00 |
01:35:11.72 |
+11:23:46.5 |
HIP 7397 |
3.33 |
| 2026-04-10 12:00 |
01:35:36.27 |
+11:25:33.0 |
HIP 7397 |
3.64 |
| 2026-04-11 00:00 |
01:36:00.82 |
+11:27:19.6 |
HIP 7397 |
9.70 |
| 2026-04-11 12:00 |
01:36:25.38 |
+11:29:06.1 |
HIP 7397 |
15.92 |
| 2026-04-12 00:00 |
01:36:49.95 |
+11:30:52.5 |
HIP 7397 |
22.18 |
| 2026-04-12 12:00 |
01:37:14.52 |
+11:32:39.0 |
HIP 7575 |
26.72 |
| 2026-04-13 00:00 |
01:37:39.11 |
+11:34:25.3 |
HIP 7575 |
24.54 |
| 2026-04-13 12:00 |
01:38:03.70 |
+11:36:11.7 |
HIP 7575 |
23.86 |
| 2026-04-14 00:00 |
01:38:28.29 |
+11:37:58.0 |
HIP 7575 |
24.81 |
| 2026-04-14 12:00 |
01:38:52.89 |
+11:39:44.2 |
HIP 7797 |
24.91 |
| 2026-04-15 00:00 |
01:39:17.49 |
+11:41:30.4 |
HIP 7797 |
18.92 |
| 2026-04-15 12:00 |
01:39:42.10 |
+11:43:16.5 |
HIP 7797 |
13.19 |
| 2026-04-16 00:00 |
01:40:06.71 |
+11:45:02.5 |
HIP 7797 |
8.31 |