| Parameter |
Value |
| Designation |
8P/Tuttle |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2008-01-27T00:25:56.539200Z |
| Orbit solution date (soln_date, UTC) |
2022-05-02T08:47:13Z |
| Obs used |
1768 |
| NEO |
Yes |
| M1 |
14.600 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2008-08-23.0000000 |
| e |
0.81978762 |
| q (au) |
1.027263 |
| a (au) |
5.700291 |
| i (deg) |
54.981969 |
| Ω (om, deg) |
270.342162 |
| ω (w, deg) |
207.511518 |
| M (ma, deg) |
15.134474 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.885 + 4.854\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.885 |
| n |
4.854 |
| gf |
1.000 |
| gb |
-0.500 |
| k |
1.000 |
| 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 |
| 2020-06-21 |
2021-10-15 |
-12.4684 |
-1.024 |
| 2021-10-15 |
2021-08-27 |
+7.6790 |
-2.670 |
| 2021-08-27 |
2022-03-19 |
-2.4327 |
+1.020 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
18:21:29.82 |
-07:21:34.7 |
HIP 90030 |
13.15 |
| 2026-09-20 12:00 |
18:21:29.33 |
-07:22:04.0 |
HIP 90030 |
12.94 |
| 2026-09-21 00:00 |
18:21:28.95 |
-07:22:33.3 |
HIP 90030 |
12.73 |
| 2026-09-21 12:00 |
18:21:28.67 |
-07:23:02.5 |
HIP 90030 |
12.51 |
| 2026-09-22 00:00 |
18:21:28.50 |
-07:23:31.6 |
HIP 90030 |
12.29 |
| 2026-09-22 12:00 |
18:21:28.43 |
-07:24:00.7 |
HIP 90030 |
12.06 |
| 2026-09-23 00:00 |
18:21:28.47 |
-07:24:29.7 |
HIP 90030 |
11.82 |
| 2026-09-23 12:00 |
18:21:28.60 |
-07:24:58.6 |
HIP 90030 |
11.58 |
| 2026-09-24 00:00 |
18:21:28.84 |
-07:25:27.5 |
HIP 90030 |
11.32 |
| 2026-09-24 12:00 |
18:21:29.19 |
-07:25:56.3 |
HIP 90030 |
11.06 |
| 2026-09-25 00:00 |
18:21:29.63 |
-07:26:25.0 |
HIP 90030 |
10.80 |
| 2026-09-25 12:00 |
18:21:30.18 |
-07:26:53.6 |
HIP 90030 |
10.52 |
| 2026-09-26 00:00 |
18:21:30.83 |
-07:27:22.2 |
HIP 90030 |
10.24 |
| 2026-09-26 12:00 |
18:21:31.58 |
-07:27:50.6 |
HIP 90030 |
9.95 |
| 2026-09-27 00:00 |
18:21:32.43 |
-07:28:19.0 |
HIP 90030 |
9.65 |
| 2026-09-27 12:00 |
18:21:33.38 |
-07:28:47.2 |
HIP 90030 |
9.35 |
| 2026-09-28 00:00 |
18:21:34.44 |
-07:29:15.4 |
HIP 90030 |
9.04 |
| 2026-09-28 12:00 |
18:21:35.60 |
-07:29:43.5 |
HIP 90030 |
8.73 |
| 2026-09-29 00:00 |
18:21:36.85 |
-07:30:11.4 |
HIP 90030 |
8.42 |
| 2026-09-29 12:00 |
18:21:38.21 |
-07:30:39.3 |
HIP 90030 |
8.12 |
| 2026-09-30 00:00 |
18:21:39.66 |
-07:31:07.0 |
HIP 90030 |
7.81 |
| 2026-09-30 12:00 |
18:21:41.22 |
-07:31:34.6 |
HIP 90030 |
7.52 |
| 2026-10-01 00:00 |
18:21:42.88 |
-07:32:02.1 |
HIP 90030 |
7.24 |
| 2026-10-01 12:00 |
18:21:44.63 |
-07:32:29.5 |
HIP 90030 |
6.98 |
| 2026-10-02 00:00 |
18:21:46.49 |
-07:32:56.8 |
HIP 90030 |
6.75 |
| 2026-10-02 12:00 |
18:21:48.44 |
-07:33:23.9 |
HIP 90030 |
6.55 |
| 2026-10-03 00:00 |
18:21:50.50 |
-07:33:50.9 |
HIP 90030 |
6.39 |
| 2026-10-03 12:00 |
18:21:52.65 |
-07:34:17.8 |
HIP 90030 |
6.28 |
| 2026-10-04 00:00 |
18:21:54.90 |
-07:34:44.6 |
HIP 90030 |
6.23 |
| 2026-10-04 12:00 |
18:21:57.25 |
-07:35:11.2 |
HIP 90030 |
6.24 |
| 2026-10-05 00:00 |
18:21:59.70 |
-07:35:37.6 |
HIP 90030 |
6.33 |
| 2026-10-05 12:00 |
18:22:02.24 |
-07:36:03.9 |
HIP 90030 |
6.50 |
| 2026-10-06 00:00 |
18:22:04.89 |
-07:36:30.1 |
HIP 90030 |
6.74 |
| 2026-10-06 12:00 |
18:22:07.63 |
-07:36:56.1 |
HIP 90030 |
7.05 |
| 2026-10-07 00:00 |
18:22:10.46 |
-07:37:21.9 |
HIP 90030 |
7.44 |
| 2026-10-07 12:00 |
18:22:13.40 |
-07:37:47.6 |
HIP 90030 |
7.89 |
| 2026-10-08 00:00 |
18:22:16.43 |
-07:38:13.1 |
HIP 90030 |
8.41 |
| 2026-10-08 12:00 |
18:22:19.55 |
-07:38:38.5 |
HIP 90030 |
8.98 |
| 2026-10-09 00:00 |
18:22:22.78 |
-07:39:03.7 |
HIP 90030 |
9.60 |
| 2026-10-09 12:00 |
18:22:26.09 |
-07:39:28.7 |
HIP 90030 |
10.28 |
| 2026-10-10 00:00 |
18:22:29.51 |
-07:39:53.5 |
HIP 90030 |
10.99 |
| 2026-10-10 12:00 |
18:22:33.01 |
-07:40:18.2 |
HIP 90030 |
11.74 |
| 2026-10-11 00:00 |
18:22:36.61 |
-07:40:42.6 |
HIP 90030 |
12.54 |