8P/Tuttle
| 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
$$
M_a = (10.014 + 5.507\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.014 |
| n |
5.507 |
| gf |
0.998 |
| gb |
-1.000 |
| k |
0.996 |
| 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 |
-14.7328 |
-0.879 |
| 2021-10-15 |
2021-08-27 |
+8.0581 |
-2.802 |
| 2021-08-27 |
2022-03-19 |
-2.3685 |
+0.975 |
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 |
18:50:28.34 |
-10:53:54.2 |
HIP 92453 |
6.47 |
| 2026-02-03 12:00 |
18:50:39.14 |
-10:53:01.2 |
HIP 92453 |
7.82 |
| 2026-02-04 00:00 |
18:50:49.89 |
-10:52:07.8 |
HIP 92453 |
9.80 |
| 2026-02-04 12:00 |
18:51:00.60 |
-10:51:14.3 |
HIP 92453 |
12.10 |
| 2026-02-05 00:00 |
18:51:11.25 |
-10:50:20.4 |
HIP 92453 |
14.56 |
| 2026-02-05 12:00 |
18:51:21.86 |
-10:49:26.4 |
HIP 92453 |
17.10 |
| 2026-02-06 00:00 |
18:51:32.41 |
-10:48:32.1 |
HIP 92453 |
19.69 |
| 2026-02-06 12:00 |
18:51:42.91 |
-10:47:37.5 |
HIP 92453 |
22.32 |
| 2026-02-07 00:00 |
18:51:53.35 |
-10:46:42.7 |
HIP 92453 |
24.95 |
| 2026-02-07 12:00 |
18:52:03.75 |
-10:45:47.6 |
HIP 92453 |
27.60 |
| 2026-02-08 00:00 |
18:52:14.09 |
-10:44:52.3 |
HIP 92453 |
30.25 |
| 2026-02-08 12:00 |
18:52:24.37 |
-10:43:56.8 |
HIP 92453 |
32.89 |
| 2026-02-09 00:00 |
18:52:34.60 |
-10:43:01.0 |
HIP 92694 |
31.38 |
| 2026-02-09 12:00 |
18:52:44.78 |
-10:42:05.0 |
HIP 92694 |
29.78 |
| 2026-02-10 00:00 |
18:52:54.89 |
-10:41:08.7 |
HIP 92694 |
28.35 |
| 2026-02-10 12:00 |
18:53:04.96 |
-10:40:12.2 |
HIP 92694 |
27.10 |
| 2026-02-11 00:00 |
18:53:14.96 |
-10:39:15.5 |
HIP 92838 |
25.87 |
| 2026-02-11 12:00 |
18:53:24.90 |
-10:38:18.6 |
HIP 92838 |
23.25 |
| 2026-02-12 00:00 |
18:53:34.79 |
-10:37:21.4 |
HIP 92838 |
20.64 |
| 2026-02-12 12:00 |
18:53:44.62 |
-10:36:24.0 |
HIP 92838 |
18.05 |
| 2026-02-13 00:00 |
18:53:54.38 |
-10:35:26.4 |
HIP 92838 |
15.48 |
| 2026-02-13 12:00 |
18:54:04.09 |
-10:34:28.5 |
HIP 92838 |
12.92 |
| 2026-02-14 00:00 |
18:54:13.73 |
-10:33:30.5 |
HIP 92838 |
10.38 |
| 2026-02-14 12:00 |
18:54:23.31 |
-10:32:32.2 |
HIP 92838 |
7.87 |
| 2026-02-15 00:00 |
18:54:32.83 |
-10:31:33.7 |
HIP 92838 |
5.40 |
| 2026-02-15 12:00 |
18:54:42.29 |
-10:30:35.0 |
HIP 92838 |
3.07 |
| 2026-02-16 00:00 |
18:54:51.68 |
-10:29:36.1 |
HIP 92838 |
1.56 |
| 2026-02-16 12:00 |
18:55:01.00 |
-10:28:36.9 |
HIP 92838 |
2.83 |
| 2026-02-17 00:00 |
18:55:10.26 |
-10:27:37.6 |
HIP 92838 |
5.09 |
| 2026-02-17 12:00 |
18:55:19.46 |
-10:26:38.1 |
HIP 92838 |
7.48 |
| 2026-02-18 00:00 |
18:55:28.59 |
-10:25:38.3 |
HIP 92838 |
9.90 |
| 2026-02-18 12:00 |
18:55:37.65 |
-10:24:38.4 |
HIP 92838 |
12.32 |
| 2026-02-19 00:00 |
18:55:46.64 |
-10:23:38.3 |
HIP 92838 |
14.73 |
| 2026-02-19 12:00 |
18:55:55.57 |
-10:22:37.9 |
HIP 92838 |
17.14 |
| 2026-02-20 00:00 |
18:56:04.42 |
-10:21:37.4 |
HIP 92838 |
19.53 |
| 2026-02-20 12:00 |
18:56:13.21 |
-10:20:36.7 |
HIP 92838 |
21.91 |
| 2026-02-21 00:00 |
18:56:21.93 |
-10:19:35.8 |
HIP 92838 |
24.28 |
| 2026-02-21 12:00 |
18:56:30.57 |
-10:18:34.7 |
HIP 93076 |
23.82 |
| 2026-02-22 00:00 |
18:56:39.15 |
-10:17:33.5 |
HIP 93076 |
21.66 |
| 2026-02-22 12:00 |
18:56:47.65 |
-10:16:32.0 |
HIP 93076 |
19.55 |
| 2026-02-23 00:00 |
18:56:56.08 |
-10:15:30.4 |
HIP 93076 |
17.51 |
| 2026-02-23 12:00 |
18:57:04.44 |
-10:14:28.7 |
HIP 93076 |
15.55 |
| 2026-02-24 00:00 |
18:57:12.72 |
-10:13:26.7 |
HIP 93076 |
13.71 |