| 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) |
| 2026-07-29 00:00 |
18:31:49.35 |
-06:37:55.6 |
HIP 90976 |
29.23 |
| 2026-07-29 12:00 |
18:31:38.96 |
-06:38:08.7 |
HIP 90976 |
31.31 |
| 2026-07-30 00:00 |
18:31:28.64 |
-06:38:22.2 |
HIP 90847 |
32.34 |
| 2026-07-30 12:00 |
18:31:18.38 |
-06:38:36.0 |
HIP 90847 |
33.23 |
| 2026-07-31 00:00 |
18:31:08.18 |
-06:38:50.1 |
HIP 90847 |
34.29 |
| 2026-07-31 12:00 |
18:30:58.05 |
-06:39:04.6 |
HIP 90847 |
35.50 |
| 2026-08-01 00:00 |
18:30:47.99 |
-06:39:19.4 |
HIP 90847 |
36.84 |
| 2026-08-01 12:00 |
18:30:38.00 |
-06:39:34.5 |
HIP 90847 |
38.29 |
| 2026-08-02 00:00 |
18:30:28.08 |
-06:39:49.9 |
HIP 90617 |
38.47 |
| 2026-08-02 12:00 |
18:30:18.22 |
-06:40:05.7 |
HIP 90652 |
37.76 |
| 2026-08-03 00:00 |
18:30:08.44 |
-06:40:21.8 |
HIP 90652 |
37.14 |
| 2026-08-03 12:00 |
18:29:58.72 |
-06:40:38.2 |
HIP 90652 |
36.66 |
| 2026-08-04 00:00 |
18:29:49.08 |
-06:40:54.9 |
HIP 90652 |
36.33 |
| 2026-08-04 12:00 |
18:29:39.51 |
-06:41:11.9 |
HIP 90652 |
36.16 |
| 2026-08-05 00:00 |
18:29:30.02 |
-06:41:29.3 |
HIP 90652 |
36.13 |
| 2026-08-05 12:00 |
18:29:20.60 |
-06:41:46.9 |
HIP 90652 |
36.25 |
| 2026-08-06 00:00 |
18:29:11.25 |
-06:42:04.8 |
HIP 90652 |
36.51 |
| 2026-08-06 12:00 |
18:29:01.98 |
-06:42:23.1 |
HIP 90512 |
36.02 |
| 2026-08-07 00:00 |
18:28:52.79 |
-06:42:41.6 |
HIP 90512 |
35.51 |
| 2026-08-07 12:00 |
18:28:43.67 |
-06:43:00.4 |
HIP 90512 |
35.15 |
| 2026-08-08 00:00 |
18:28:34.64 |
-06:43:19.6 |
HIP 90512 |
34.94 |
| 2026-08-08 12:00 |
18:28:25.68 |
-06:43:39.0 |
HIP 90512 |
34.89 |
| 2026-08-09 00:00 |
18:28:16.80 |
-06:43:58.6 |
HIP 90512 |
34.99 |
| 2026-08-09 12:00 |
18:28:08.01 |
-06:44:18.6 |
HIP 90379 |
33.72 |
| 2026-08-10 00:00 |
18:27:59.29 |
-06:44:38.8 |
HIP 90379 |
31.95 |
| 2026-08-10 12:00 |
18:27:50.66 |
-06:44:59.3 |
HIP 90379 |
30.24 |
| 2026-08-11 00:00 |
18:27:42.11 |
-06:45:20.1 |
HIP 90379 |
28.61 |
| 2026-08-11 12:00 |
18:27:33.65 |
-06:45:41.1 |
HIP 90379 |
27.06 |
| 2026-08-12 00:00 |
18:27:25.27 |
-06:46:02.4 |
HIP 90379 |
25.59 |
| 2026-08-12 12:00 |
18:27:16.98 |
-06:46:24.0 |
HIP 90379 |
24.23 |
| 2026-08-13 00:00 |
18:27:08.77 |
-06:46:45.7 |
HIP 90379 |
22.99 |
| 2026-08-13 12:00 |
18:27:00.65 |
-06:47:07.8 |
HIP 90379 |
21.87 |
| 2026-08-14 00:00 |
18:26:52.62 |
-06:47:30.1 |
HIP 90379 |
20.89 |
| 2026-08-14 12:00 |
18:26:44.68 |
-06:47:52.6 |
HIP 90379 |
20.08 |
| 2026-08-15 00:00 |
18:26:36.82 |
-06:48:15.3 |
HIP 90379 |
19.44 |
| 2026-08-15 12:00 |
18:26:29.06 |
-06:48:38.3 |
HIP 90379 |
18.97 |
| 2026-08-16 00:00 |
18:26:21.38 |
-06:49:01.5 |
HIP 90379 |
18.70 |
| 2026-08-16 12:00 |
18:26:13.80 |
-06:49:25.0 |
HIP 90379 |
18.62 |
| 2026-08-17 00:00 |
18:26:06.30 |
-06:49:48.6 |
HIP 90379 |
18.73 |
| 2026-08-17 12:00 |
18:25:58.90 |
-06:50:12.5 |
HIP 90379 |
19.02 |
| 2026-08-18 00:00 |
18:25:51.59 |
-06:50:36.6 |
HIP 90379 |
19.46 |
| 2026-08-18 12:00 |
18:25:44.38 |
-06:51:00.8 |
HIP 90379 |
20.06 |
| 2026-08-19 00:00 |
18:25:37.26 |
-06:51:25.3 |
HIP 90238 |
18.98 |