C/2009 P1 (Garradd)
| Parameter |
Value |
| Designation |
C/2009 P1 (Garradd) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-12-23T16:15:40.821120Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:31:33Z |
| Obs used |
9044 |
| NEO |
- |
| M1 |
8.800 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2011-11-22.0000000 |
| e |
1.00099744 |
| q (au) |
1.550536 |
| a (au) |
-1554.512313 |
| i (deg) |
106.177292 |
| Ω (om, deg) |
325.997228 |
| ω (w, deg) |
90.747065 |
| M (ma, deg) |
-0.000509 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.185 + 2.513\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.185 |
| n |
2.513 |
| gf |
1.000 |
| gb |
-0.552 |
| k |
0.800 |
| δ90 |
10.000 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2008-09-27 |
2011-06-07 |
+2.0779 |
-2.821 |
| 2011-06-07 |
2011-12-23 |
-2.3690 |
-0.177 |
| 2011-12-24 |
2012-06-08 |
-0.1339 |
-0.780 |
| 2012-06-08 |
2014-02-26 |
+9.1067 |
-5.082 |
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 |
06:57:01.61 |
-39:43:59.4 |
HIP 33549 |
20.68 |
| 2026-02-03 12:00 |
06:56:57.10 |
-39:43:32.8 |
HIP 33549 |
21.61 |
| 2026-02-04 00:00 |
06:56:52.61 |
-39:43:05.8 |
HIP 33549 |
22.54 |
| 2026-02-04 12:00 |
06:56:48.15 |
-39:42:38.5 |
HIP 33549 |
23.48 |
| 2026-02-05 00:00 |
06:56:43.71 |
-39:42:10.8 |
HIP 33549 |
24.43 |
| 2026-02-05 12:00 |
06:56:39.29 |
-39:41:42.7 |
HIP 33549 |
25.37 |
| 2026-02-06 00:00 |
06:56:34.90 |
-39:41:14.2 |
HIP 33549 |
26.32 |
| 2026-02-06 12:00 |
06:56:30.54 |
-39:40:45.4 |
HIP 33161 |
27.18 |
| 2026-02-07 00:00 |
06:56:26.21 |
-39:40:16.2 |
HIP 33161 |
26.27 |
| 2026-02-07 12:00 |
06:56:21.90 |
-39:39:46.7 |
HIP 33161 |
25.37 |
| 2026-02-08 00:00 |
06:56:17.62 |
-39:39:16.8 |
HIP 33161 |
24.48 |
| 2026-02-08 12:00 |
06:56:13.36 |
-39:38:46.6 |
HIP 33161 |
23.60 |
| 2026-02-09 00:00 |
06:56:09.14 |
-39:38:16.0 |
HIP 33161 |
22.73 |
| 2026-02-09 12:00 |
06:56:04.94 |
-39:37:45.0 |
HIP 33161 |
21.88 |
| 2026-02-10 00:00 |
06:56:00.77 |
-39:37:13.7 |
HIP 33161 |
21.03 |
| 2026-02-10 12:00 |
06:55:56.63 |
-39:36:42.1 |
HIP 33161 |
20.21 |
| 2026-02-11 00:00 |
06:55:52.52 |
-39:36:10.1 |
HIP 33161 |
19.40 |
| 2026-02-11 12:00 |
06:55:48.44 |
-39:35:37.8 |
HIP 33161 |
18.60 |
| 2026-02-12 00:00 |
06:55:44.38 |
-39:35:05.2 |
HIP 33161 |
17.83 |
| 2026-02-12 12:00 |
06:55:40.36 |
-39:34:32.2 |
HIP 33161 |
17.09 |
| 2026-02-13 00:00 |
06:55:36.37 |
-39:33:58.9 |
HIP 33161 |
16.37 |
| 2026-02-13 12:00 |
06:55:32.41 |
-39:33:25.3 |
HIP 33161 |
15.68 |
| 2026-02-14 00:00 |
06:55:28.48 |
-39:32:51.3 |
HIP 33161 |
15.03 |
| 2026-02-14 12:00 |
06:55:24.58 |
-39:32:17.0 |
HIP 33161 |
14.42 |
| 2026-02-15 00:00 |
06:55:20.71 |
-39:31:42.5 |
HIP 33161 |
13.85 |
| 2026-02-15 12:00 |
06:55:16.88 |
-39:31:07.6 |
HIP 33161 |
13.33 |
| 2026-02-16 00:00 |
06:55:13.07 |
-39:30:32.4 |
HIP 33161 |
12.87 |
| 2026-02-16 12:00 |
06:55:09.30 |
-39:29:56.9 |
HIP 33161 |
12.47 |
| 2026-02-17 00:00 |
06:55:05.57 |
-39:29:21.1 |
HIP 33161 |
12.13 |
| 2026-02-17 12:00 |
06:55:01.86 |
-39:28:45.0 |
HIP 33161 |
11.87 |
| 2026-02-18 00:00 |
06:54:58.19 |
-39:28:08.6 |
HIP 33161 |
11.68 |
| 2026-02-18 12:00 |
06:54:54.55 |
-39:27:31.9 |
HIP 33161 |
11.58 |
| 2026-02-19 00:00 |
06:54:50.95 |
-39:26:54.9 |
HIP 33161 |
11.56 |
| 2026-02-19 12:00 |
06:54:47.38 |
-39:26:17.7 |
HIP 33161 |
11.62 |
| 2026-02-20 00:00 |
06:54:43.84 |
-39:25:40.2 |
HIP 33161 |
11.75 |
| 2026-02-20 12:00 |
06:54:40.34 |
-39:25:02.4 |
HIP 33161 |
11.97 |
| 2026-02-21 00:00 |
06:54:36.88 |
-39:24:24.3 |
HIP 33161 |
12.26 |
| 2026-02-21 12:00 |
06:54:33.45 |
-39:23:45.9 |
HIP 33161 |
12.62 |
| 2026-02-22 00:00 |
06:54:30.05 |
-39:23:07.3 |
HIP 33161 |
13.03 |
| 2026-02-22 12:00 |
06:54:26.69 |
-39:22:28.5 |
HIP 33161 |
13.51 |
| 2026-02-23 00:00 |
06:54:23.37 |
-39:21:49.3 |
HIP 33161 |
14.03 |
| 2026-02-23 12:00 |
06:54:20.08 |
-39:21:10.0 |
HIP 33161 |
14.60 |
| 2026-02-24 00:00 |
06:54:16.83 |
-39:20:30.4 |
HIP 33161 |
15.20 |