| Parameter |
Value |
| Designation |
C/2008 P1 (Garradd) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2009-07-22T22:51:56.433600Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:21Z |
| Obs used |
1345 |
| NEO |
- |
| M1 |
11.100 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2009-08-25.0000000 |
| e |
1.00167859 |
| q (au) |
3.896111 |
| a (au) |
-2321.061664 |
| i (deg) |
64.310315 |
| Ω (om, deg) |
357.676994 |
| ω (w, deg) |
11.865464 |
| M (ma, deg) |
0.000291 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.382 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.382 |
| n |
2.000 |
| gf |
0.971 |
| gb |
-0.955 |
| k |
1.000 |
| δ90 |
9.891 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2008-08-13 |
2009-07-21 |
-8.6915 |
+4.482 |
| 2009-07-23 |
2011-02-04 |
+5.2294 |
-3.081 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-05-12 00:00 |
11:40:40.97 |
+29:54:55.2 |
HIP 56942 |
8.56 |
| 2026-05-12 12:00 |
11:40:38.90 |
+29:54:40.6 |
HIP 56942 |
8.62 |
| 2026-05-13 00:00 |
11:40:36.85 |
+29:54:25.6 |
HIP 56942 |
8.72 |
| 2026-05-13 12:00 |
11:40:34.83 |
+29:54:10.5 |
HIP 56942 |
8.86 |
| 2026-05-14 00:00 |
11:40:32.84 |
+29:53:55.1 |
HIP 56942 |
9.02 |
| 2026-05-14 12:00 |
11:40:30.88 |
+29:53:39.5 |
HIP 56942 |
9.22 |
| 2026-05-15 00:00 |
11:40:28.95 |
+29:53:23.6 |
HIP 56942 |
9.44 |
| 2026-05-15 12:00 |
11:40:27.05 |
+29:53:07.5 |
HIP 56942 |
9.68 |
| 2026-05-16 00:00 |
11:40:25.17 |
+29:52:51.1 |
HIP 56942 |
9.95 |
| 2026-05-16 12:00 |
11:40:23.33 |
+29:52:34.6 |
HIP 56942 |
10.24 |
| 2026-05-17 00:00 |
11:40:21.51 |
+29:52:17.7 |
HIP 56942 |
10.54 |
| 2026-05-17 12:00 |
11:40:19.72 |
+29:52:00.7 |
HIP 56942 |
10.87 |
| 2026-05-18 00:00 |
11:40:17.96 |
+29:51:43.4 |
HIP 56942 |
11.20 |
| 2026-05-18 12:00 |
11:40:16.23 |
+29:51:25.9 |
HIP 56942 |
11.55 |
| 2026-05-19 00:00 |
11:40:14.53 |
+29:51:08.2 |
HIP 56942 |
11.91 |
| 2026-05-19 12:00 |
11:40:12.86 |
+29:50:50.2 |
HIP 56942 |
12.28 |
| 2026-05-20 00:00 |
11:40:11.22 |
+29:50:32.0 |
HIP 56942 |
12.66 |
| 2026-05-20 12:00 |
11:40:09.61 |
+29:50:13.6 |
HIP 56942 |
13.04 |
| 2026-05-21 00:00 |
11:40:08.03 |
+29:49:54.9 |
HIP 56942 |
13.44 |
| 2026-05-21 12:00 |
11:40:06.48 |
+29:49:36.1 |
HIP 56942 |
13.84 |
| 2026-05-22 00:00 |
11:40:04.96 |
+29:49:17.0 |
HIP 56942 |
14.24 |
| 2026-05-22 12:00 |
11:40:03.47 |
+29:48:57.7 |
HIP 56942 |
14.65 |
| 2026-05-23 00:00 |
11:40:02.00 |
+29:48:38.2 |
HIP 56942 |
15.06 |
| 2026-05-23 12:00 |
11:40:00.57 |
+29:48:18.4 |
HIP 56942 |
15.48 |
| 2026-05-24 00:00 |
11:39:59.17 |
+29:47:58.5 |
HIP 56942 |
15.89 |
| 2026-05-24 12:00 |
11:39:57.80 |
+29:47:38.3 |
HIP 56942 |
16.32 |
| 2026-05-25 00:00 |
11:39:56.46 |
+29:47:17.9 |
HIP 56942 |
16.74 |
| 2026-05-25 12:00 |
11:39:55.15 |
+29:46:57.4 |
HIP 56794 |
17.12 |
| 2026-05-26 00:00 |
11:39:53.87 |
+29:46:36.6 |
HIP 56794 |
16.81 |
| 2026-05-26 12:00 |
11:39:52.62 |
+29:46:15.6 |
HIP 56794 |
16.52 |
| 2026-05-27 00:00 |
11:39:51.40 |
+29:45:54.4 |
HIP 56794 |
16.24 |
| 2026-05-27 12:00 |
11:39:50.22 |
+29:45:33.0 |
HIP 56794 |
15.98 |
| 2026-05-28 00:00 |
11:39:49.06 |
+29:45:11.4 |
HIP 56794 |
15.73 |
| 2026-05-28 12:00 |
11:39:47.93 |
+29:44:49.6 |
HIP 56794 |
15.49 |
| 2026-05-29 00:00 |
11:39:46.84 |
+29:44:27.6 |
HIP 56794 |
15.27 |
| 2026-05-29 12:00 |
11:39:45.77 |
+29:44:05.4 |
HIP 56794 |
15.07 |
| 2026-05-30 00:00 |
11:39:44.73 |
+29:43:43.0 |
HIP 56794 |
14.88 |
| 2026-05-30 12:00 |
11:39:43.73 |
+29:43:20.4 |
HIP 56794 |
14.71 |
| 2026-05-31 00:00 |
11:39:42.76 |
+29:42:57.7 |
HIP 56794 |
14.56 |
| 2026-05-31 12:00 |
11:39:41.81 |
+29:42:34.7 |
HIP 56794 |
14.43 |
| 2026-06-01 00:00 |
11:39:40.90 |
+29:42:11.5 |
HIP 56794 |
14.32 |
| 2026-06-01 12:00 |
11:39:40.02 |
+29:41:48.2 |
HIP 56794 |
14.23 |
| 2026-06-02 00:00 |
11:39:39.17 |
+29:41:24.7 |
HIP 56794 |
14.15 |