| 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 |
0.960 |
| gb |
-0.747 |
| k |
1.000 |
| δ90 |
9.885 |
| 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) |
| 2026-07-29 00:00 |
11:41:16.88 |
+28:43:36.4 |
HIP 57035 |
9.03 |
| 2026-07-29 12:00 |
11:41:19.25 |
+28:43:03.1 |
HIP 57035 |
9.26 |
| 2026-07-30 00:00 |
11:41:21.65 |
+28:42:29.9 |
HIP 57035 |
9.54 |
| 2026-07-30 12:00 |
11:41:24.06 |
+28:41:56.8 |
HIP 57035 |
9.88 |
| 2026-07-31 00:00 |
11:41:26.49 |
+28:41:23.6 |
HIP 57035 |
10.25 |
| 2026-07-31 12:00 |
11:41:28.95 |
+28:40:50.5 |
HIP 57035 |
10.67 |
| 2026-08-01 00:00 |
11:41:31.43 |
+28:40:17.4 |
HIP 57035 |
11.12 |
| 2026-08-01 12:00 |
11:41:33.92 |
+28:39:44.3 |
HIP 57035 |
11.61 |
| 2026-08-02 00:00 |
11:41:36.44 |
+28:39:11.3 |
HIP 57035 |
12.13 |
| 2026-08-02 12:00 |
11:41:38.98 |
+28:38:38.3 |
HIP 57035 |
12.67 |
| 2026-08-03 00:00 |
11:41:41.53 |
+28:38:05.3 |
HIP 57035 |
13.24 |
| 2026-08-03 12:00 |
11:41:44.11 |
+28:37:32.4 |
HIP 57035 |
13.82 |
| 2026-08-04 00:00 |
11:41:46.70 |
+28:36:59.5 |
HIP 57035 |
14.43 |
| 2026-08-04 12:00 |
11:41:49.32 |
+28:36:26.6 |
HIP 57035 |
15.05 |
| 2026-08-05 00:00 |
11:41:51.95 |
+28:35:53.8 |
HIP 57035 |
15.69 |
| 2026-08-05 12:00 |
11:41:54.61 |
+28:35:21.1 |
HIP 57035 |
16.35 |
| 2026-08-06 00:00 |
11:41:57.28 |
+28:34:48.3 |
HIP 57035 |
17.01 |
| 2026-08-06 12:00 |
11:41:59.97 |
+28:34:15.7 |
HIP 57035 |
17.69 |
| 2026-08-07 00:00 |
11:42:02.68 |
+28:33:43.1 |
HIP 57035 |
18.38 |
| 2026-08-07 12:00 |
11:42:05.41 |
+28:33:10.5 |
HIP 57035 |
19.07 |
| 2026-08-08 00:00 |
11:42:08.15 |
+28:32:38.0 |
HIP 57035 |
19.78 |
| 2026-08-08 12:00 |
11:42:10.92 |
+28:32:05.5 |
HIP 57035 |
20.50 |
| 2026-08-09 00:00 |
11:42:13.70 |
+28:31:33.1 |
HIP 57035 |
21.22 |
| 2026-08-09 12:00 |
11:42:16.50 |
+28:31:00.8 |
HIP 57035 |
21.95 |
| 2026-08-10 00:00 |
11:42:19.32 |
+28:30:28.5 |
HIP 57035 |
22.68 |
| 2026-08-10 12:00 |
11:42:22.15 |
+28:29:56.3 |
HIP 57035 |
23.42 |
| 2026-08-11 00:00 |
11:42:25.00 |
+28:29:24.1 |
HIP 57035 |
24.17 |
| 2026-08-11 12:00 |
11:42:27.87 |
+28:28:52.0 |
HIP 57035 |
24.93 |
| 2026-08-12 00:00 |
11:42:30.76 |
+28:28:20.0 |
HIP 57035 |
25.68 |
| 2026-08-12 12:00 |
11:42:33.66 |
+28:27:48.1 |
HIP 57035 |
26.45 |
| 2026-08-13 00:00 |
11:42:36.57 |
+28:27:16.2 |
HIP 57160 |
26.04 |
| 2026-08-13 12:00 |
11:42:39.51 |
+28:26:44.4 |
HIP 57160 |
25.30 |
| 2026-08-14 00:00 |
11:42:42.46 |
+28:26:12.7 |
HIP 57160 |
24.57 |
| 2026-08-14 12:00 |
11:42:45.42 |
+28:25:41.0 |
HIP 57160 |
23.85 |
| 2026-08-15 00:00 |
11:42:48.40 |
+28:25:09.5 |
HIP 57160 |
23.13 |
| 2026-08-15 12:00 |
11:42:51.40 |
+28:24:38.0 |
HIP 57160 |
22.42 |
| 2026-08-16 00:00 |
11:42:54.41 |
+28:24:06.6 |
HIP 57160 |
21.72 |
| 2026-08-16 12:00 |
11:42:57.44 |
+28:23:35.2 |
HIP 57160 |
21.04 |
| 2026-08-17 00:00 |
11:43:00.48 |
+28:23:04.0 |
HIP 57160 |
20.36 |
| 2026-08-17 12:00 |
11:43:03.53 |
+28:22:32.9 |
HIP 57160 |
19.70 |
| 2026-08-18 00:00 |
11:43:06.60 |
+28:22:01.8 |
HIP 57160 |
19.06 |
| 2026-08-18 12:00 |
11:43:09.68 |
+28:21:30.9 |
HIP 57160 |
18.44 |
| 2026-08-19 00:00 |
11:43:12.78 |
+28:21:00.0 |
HIP 57160 |
17.83 |