| Parameter |
Value |
| Designation |
C/2009 P1 (Garradd) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2011-12-23T16:15:40.786560Z |
| Orbit solution date (soln_date, UTC) |
2026-03-07T14:42:53Z |
| Obs used |
9048 |
| NEO |
- |
| M1 |
8.900 |
| 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) |
-1554.522037 |
| i (deg) |
106.177292 |
| Ω (om, deg) |
325.997229 |
| ω (w, deg) |
90.747065 |
| M (ma, deg) |
-0.000509 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.188 + 2.506\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.188 |
| n |
2.506 |
| gf |
1.000 |
| gb |
-0.551 |
| 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 |
+2.0997 |
-2.834 |
| 2011-06-07 |
2011-12-23 |
-2.4286 |
-0.161 |
| 2011-12-24 |
2012-06-08 |
-0.1237 |
-0.783 |
| 2012-06-08 |
2014-02-26 |
+9.1194 |
-5.086 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
06:52:13.23 |
-38:35:42.3 |
HIP 32992 |
2.57 |
| 2026-03-26 12:00 |
06:52:12.42 |
-38:34:54.7 |
HIP 32992 |
3.18 |
| 2026-03-27 00:00 |
06:52:11.66 |
-38:34:07.1 |
HIP 32992 |
3.85 |
| 2026-03-27 12:00 |
06:52:10.93 |
-38:33:19.6 |
HIP 32992 |
4.57 |
| 2026-03-28 00:00 |
06:52:10.25 |
-38:32:32.0 |
HIP 32992 |
5.30 |
| 2026-03-28 12:00 |
06:52:09.61 |
-38:31:44.5 |
HIP 32992 |
6.05 |
| 2026-03-29 00:00 |
06:52:09.01 |
-38:30:56.9 |
HIP 32992 |
6.81 |
| 2026-03-29 12:00 |
06:52:08.46 |
-38:30:09.4 |
HIP 32992 |
7.57 |
| 2026-03-30 00:00 |
06:52:07.94 |
-38:29:21.9 |
HIP 32992 |
8.34 |
| 2026-03-30 12:00 |
06:52:07.47 |
-38:28:34.4 |
HIP 32992 |
9.11 |
| 2026-03-31 00:00 |
06:52:07.03 |
-38:27:46.9 |
HIP 32992 |
9.88 |
| 2026-03-31 12:00 |
06:52:06.64 |
-38:26:59.4 |
HIP 32992 |
10.65 |
| 2026-04-01 00:00 |
06:52:06.29 |
-38:26:12.0 |
HIP 32992 |
11.42 |
| 2026-04-01 12:00 |
06:52:05.98 |
-38:25:24.6 |
HIP 32992 |
12.19 |
| 2026-04-02 00:00 |
06:52:05.72 |
-38:24:37.2 |
HIP 32930 |
12.92 |
| 2026-04-02 12:00 |
06:52:05.49 |
-38:23:49.9 |
HIP 32930 |
12.19 |
| 2026-04-03 00:00 |
06:52:05.30 |
-38:23:02.6 |
HIP 32930 |
11.47 |
| 2026-04-03 12:00 |
06:52:05.16 |
-38:22:15.4 |
HIP 32930 |
10.77 |
| 2026-04-04 00:00 |
06:52:05.06 |
-38:21:28.2 |
HIP 32930 |
10.08 |
| 2026-04-04 12:00 |
06:52:04.99 |
-38:20:41.1 |
HIP 32930 |
9.42 |
| 2026-04-05 00:00 |
06:52:04.97 |
-38:19:54.0 |
HIP 32930 |
8.78 |
| 2026-04-05 12:00 |
06:52:04.99 |
-38:19:07.0 |
HIP 32930 |
8.17 |
| 2026-04-06 00:00 |
06:52:05.05 |
-38:18:20.0 |
HIP 32930 |
7.60 |
| 2026-04-06 12:00 |
06:52:05.15 |
-38:17:33.1 |
HIP 32930 |
7.08 |
| 2026-04-07 00:00 |
06:52:05.29 |
-38:16:46.3 |
HIP 32930 |
6.61 |
| 2026-04-07 12:00 |
06:52:05.47 |
-38:15:59.6 |
HIP 32930 |
6.22 |
| 2026-04-08 00:00 |
06:52:05.69 |
-38:15:12.9 |
HIP 32930 |
5.91 |
| 2026-04-08 12:00 |
06:52:05.95 |
-38:14:26.3 |
HIP 32930 |
5.70 |
| 2026-04-09 00:00 |
06:52:06.25 |
-38:13:39.8 |
HIP 32930 |
5.61 |
| 2026-04-09 12:00 |
06:52:06.59 |
-38:12:53.4 |
HIP 32930 |
5.62 |
| 2026-04-10 00:00 |
06:52:06.98 |
-38:12:07.1 |
HIP 32930 |
5.75 |
| 2026-04-10 12:00 |
06:52:07.40 |
-38:11:20.8 |
HIP 32930 |
5.99 |
| 2026-04-11 00:00 |
06:52:07.86 |
-38:10:34.7 |
HIP 32930 |
6.31 |
| 2026-04-11 12:00 |
06:52:08.36 |
-38:09:48.7 |
HIP 32930 |
6.72 |
| 2026-04-12 00:00 |
06:52:08.90 |
-38:09:02.7 |
HIP 32930 |
7.20 |
| 2026-04-12 12:00 |
06:52:09.48 |
-38:08:16.9 |
HIP 32930 |
7.73 |
| 2026-04-13 00:00 |
06:52:10.10 |
-38:07:31.2 |
HIP 32930 |
8.30 |
| 2026-04-13 12:00 |
06:52:10.76 |
-38:06:45.6 |
HIP 32930 |
8.90 |
| 2026-04-14 00:00 |
06:52:11.46 |
-38:06:00.1 |
HIP 32930 |
9.54 |
| 2026-04-14 12:00 |
06:52:12.20 |
-38:05:14.7 |
HIP 32930 |
10.19 |
| 2026-04-15 00:00 |
06:52:12.98 |
-38:04:29.5 |
HIP 32930 |
10.87 |
| 2026-04-15 12:00 |
06:52:13.80 |
-38:03:44.4 |
HIP 32930 |
11.56 |
| 2026-04-16 00:00 |
06:52:14.65 |
-38:02:59.4 |
HIP 32994 |
12.13 |