C/2008 P1 (Garradd)
| 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
$$
M_a = (10.383 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.383 |
| n |
2.000 |
| gf |
0.963 |
| gb |
-0.799 |
| k |
1.000 |
| δ90 |
9.998 |
| 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 |
-8.6794 |
+4.474 |
| 2009-07-23 |
2011-02-04 |
+5.2309 |
-3.080 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
11:51:39.76 |
+29:22:31.2 |
HIP 57976 |
24.88 |
| 2026-02-03 12:00 |
11:51:36.95 |
+29:22:59.0 |
HIP 57976 |
25.55 |
| 2026-02-04 00:00 |
11:51:34.11 |
+29:23:26.8 |
HIP 57976 |
26.23 |
| 2026-02-04 12:00 |
11:51:31.25 |
+29:23:54.5 |
HIP 57664 |
25.97 |
| 2026-02-05 00:00 |
11:51:28.36 |
+29:24:22.1 |
HIP 57664 |
25.25 |
| 2026-02-05 12:00 |
11:51:25.45 |
+29:24:49.7 |
HIP 57664 |
24.53 |
| 2026-02-06 00:00 |
11:51:22.52 |
+29:25:17.2 |
HIP 57664 |
23.81 |
| 2026-02-06 12:00 |
11:51:19.56 |
+29:25:44.7 |
HIP 57664 |
23.09 |
| 2026-02-07 00:00 |
11:51:16.58 |
+29:26:12.1 |
HIP 57664 |
22.38 |
| 2026-02-07 12:00 |
11:51:13.58 |
+29:26:39.4 |
HIP 57664 |
21.66 |
| 2026-02-08 00:00 |
11:51:10.56 |
+29:27:06.6 |
HIP 57664 |
20.94 |
| 2026-02-08 12:00 |
11:51:07.51 |
+29:27:33.8 |
HIP 57664 |
20.23 |
| 2026-02-09 00:00 |
11:51:04.44 |
+29:28:00.9 |
HIP 57664 |
19.51 |
| 2026-02-09 12:00 |
11:51:01.35 |
+29:28:27.9 |
HIP 57664 |
18.80 |
| 2026-02-10 00:00 |
11:50:58.24 |
+29:28:54.8 |
HIP 57664 |
18.10 |
| 2026-02-10 12:00 |
11:50:55.11 |
+29:29:21.7 |
HIP 57664 |
17.40 |
| 2026-02-11 00:00 |
11:50:51.95 |
+29:29:48.5 |
HIP 57664 |
16.70 |
| 2026-02-11 12:00 |
11:50:48.78 |
+29:30:15.1 |
HIP 57664 |
16.01 |
| 2026-02-12 00:00 |
11:50:45.58 |
+29:30:41.7 |
HIP 57664 |
15.33 |
| 2026-02-12 12:00 |
11:50:42.37 |
+29:31:08.2 |
HIP 57664 |
14.66 |
| 2026-02-13 00:00 |
11:50:39.13 |
+29:31:34.6 |
HIP 57664 |
14.01 |
| 2026-02-13 12:00 |
11:50:35.87 |
+29:32:00.8 |
HIP 57664 |
13.37 |
| 2026-02-14 00:00 |
11:50:32.60 |
+29:32:27.0 |
HIP 57664 |
12.74 |
| 2026-02-14 12:00 |
11:50:29.31 |
+29:32:53.1 |
HIP 57664 |
12.14 |
| 2026-02-15 00:00 |
11:50:25.99 |
+29:33:19.0 |
HIP 57664 |
11.56 |
| 2026-02-15 12:00 |
11:50:22.66 |
+29:33:44.9 |
HIP 57664 |
11.01 |
| 2026-02-16 00:00 |
11:50:19.31 |
+29:34:10.6 |
HIP 57664 |
10.50 |
| 2026-02-16 12:00 |
11:50:15.95 |
+29:34:36.2 |
HIP 57664 |
10.03 |
| 2026-02-17 00:00 |
11:50:12.56 |
+29:35:01.7 |
HIP 57664 |
9.60 |
| 2026-02-17 12:00 |
11:50:09.16 |
+29:35:27.1 |
HIP 57664 |
9.23 |
| 2026-02-18 00:00 |
11:50:05.74 |
+29:35:52.3 |
HIP 57664 |
8.92 |
| 2026-02-18 12:00 |
11:50:02.30 |
+29:36:17.4 |
HIP 57664 |
8.68 |
| 2026-02-19 00:00 |
11:49:58.85 |
+29:36:42.4 |
HIP 57664 |
8.52 |
| 2026-02-19 12:00 |
11:49:55.38 |
+29:37:07.2 |
HIP 57664 |
8.44 |
| 2026-02-20 00:00 |
11:49:51.90 |
+29:37:31.9 |
HIP 57664 |
8.44 |
| 2026-02-20 12:00 |
11:49:48.39 |
+29:37:56.5 |
HIP 57664 |
8.53 |
| 2026-02-21 00:00 |
11:49:44.88 |
+29:38:20.9 |
HIP 57664 |
8.69 |
| 2026-02-21 12:00 |
11:49:41.35 |
+29:38:45.2 |
HIP 57664 |
8.94 |
| 2026-02-22 00:00 |
11:49:37.80 |
+29:39:09.3 |
HIP 57664 |
9.26 |
| 2026-02-22 12:00 |
11:49:34.24 |
+29:39:33.3 |
HIP 57664 |
9.64 |
| 2026-02-23 00:00 |
11:49:30.67 |
+29:39:57.1 |
HIP 57664 |
10.09 |
| 2026-02-23 12:00 |
11:49:27.08 |
+29:40:20.8 |
HIP 57664 |
10.58 |
| 2026-02-24 00:00 |
11:49:23.48 |
+29:40:44.3 |
HIP 57664 |
11.12 |