| Parameter |
Value |
| Designation |
109P/Swift-Tuttle |
| Type |
P |
| Perihelion (tp_cal, UTC) |
1992-12-11T23:59:41.389440Z |
| Orbit solution date (soln_date, UTC) |
2001-10-09T15:34:49Z |
| Obs used |
652 |
| NEO |
Yes |
| M1 |
4.500 |
| K1 |
15.000 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
1995-10-10.0000000 |
| e |
0.96322576 |
| q (au) |
0.959516 |
| a (au) |
26.092069 |
| i (deg) |
113.453817 |
| Ω (om, deg) |
139.381192 |
| ω (w, deg) |
152.982168 |
| M (ma, deg) |
7.631696 |
Magnitude
Scatter + Global Linear
$$
M_a = (4.031 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
4.031 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.861 |
| 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 |
| 1992-01-03 |
1992-12-11 |
+4.1490 |
-0.126 |
| 1992-12-12 |
1993-03-09 |
+2.1256 |
-0.154 |
| 1993-03-09 |
1995-04-05 |
-0.7717 |
+0.720 |
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 |
09:42:43.47 |
-18:24:46.4 |
HIP 47537 |
17.94 |
| 2026-09-20 12:00 |
09:42:45.67 |
-18:25:06.5 |
HIP 47537 |
18.38 |
| 2026-09-21 00:00 |
09:42:47.85 |
-18:25:26.8 |
HIP 47537 |
18.81 |
| 2026-09-21 12:00 |
09:42:50.02 |
-18:25:47.1 |
HIP 47537 |
19.26 |
| 2026-09-22 00:00 |
09:42:52.17 |
-18:26:07.5 |
HIP 47537 |
19.71 |
| 2026-09-22 12:00 |
09:42:54.32 |
-18:26:28.1 |
HIP 47537 |
20.17 |
| 2026-09-23 00:00 |
09:42:56.45 |
-18:26:48.7 |
HIP 47537 |
20.63 |
| 2026-09-23 12:00 |
09:42:58.56 |
-18:27:09.4 |
HIP 47537 |
21.10 |
| 2026-09-24 00:00 |
09:43:00.67 |
-18:27:30.2 |
HIP 47537 |
21.56 |
| 2026-09-24 12:00 |
09:43:02.76 |
-18:27:51.0 |
HIP 47537 |
22.04 |
| 2026-09-25 00:00 |
09:43:04.84 |
-18:28:12.0 |
HIP 47537 |
22.51 |
| 2026-09-25 12:00 |
09:43:06.90 |
-18:28:33.1 |
HIP 47537 |
22.99 |
| 2026-09-26 00:00 |
09:43:08.95 |
-18:28:54.2 |
HIP 47537 |
23.47 |
| 2026-09-26 12:00 |
09:43:10.98 |
-18:29:15.4 |
HIP 47537 |
23.96 |
| 2026-09-27 00:00 |
09:43:13.00 |
-18:29:36.7 |
HIP 47537 |
24.44 |
| 2026-09-27 12:00 |
09:43:15.01 |
-18:29:58.1 |
HIP 47537 |
24.93 |
| 2026-09-28 00:00 |
09:43:17.00 |
-18:30:19.6 |
HIP 47537 |
25.42 |
| 2026-09-28 12:00 |
09:43:18.98 |
-18:30:41.1 |
HIP 47537 |
25.90 |
| 2026-09-29 00:00 |
09:43:20.94 |
-18:31:02.8 |
HIP 47537 |
26.39 |
| 2026-09-29 12:00 |
09:43:22.89 |
-18:31:24.5 |
HIP 47537 |
26.88 |
| 2026-09-30 00:00 |
09:43:24.82 |
-18:31:46.2 |
HIP 47537 |
27.37 |
| 2026-09-30 12:00 |
09:43:26.74 |
-18:32:08.1 |
HIP 47537 |
27.86 |
| 2026-10-01 00:00 |
09:43:28.64 |
-18:32:30.0 |
HIP 47537 |
28.35 |
| 2026-10-01 12:00 |
09:43:30.53 |
-18:32:52.0 |
HIP 47537 |
28.84 |
| 2026-10-02 00:00 |
09:43:32.40 |
-18:33:14.0 |
HIP 47537 |
29.33 |
| 2026-10-02 12:00 |
09:43:34.25 |
-18:33:36.1 |
HIP 47537 |
29.82 |
| 2026-10-03 00:00 |
09:43:36.09 |
-18:33:58.3 |
HIP 47537 |
30.31 |
| 2026-10-03 12:00 |
09:43:37.92 |
-18:34:20.5 |
HIP 47537 |
30.80 |
| 2026-10-04 00:00 |
09:43:39.72 |
-18:34:42.8 |
HIP 47905 |
31.18 |
| 2026-10-04 12:00 |
09:43:41.51 |
-18:35:05.2 |
HIP 47905 |
30.68 |
| 2026-10-05 00:00 |
09:43:43.29 |
-18:35:27.6 |
HIP 47905 |
30.19 |
| 2026-10-05 12:00 |
09:43:45.05 |
-18:35:50.1 |
HIP 47905 |
29.70 |
| 2026-10-06 00:00 |
09:43:46.79 |
-18:36:12.7 |
HIP 47905 |
29.22 |
| 2026-10-06 12:00 |
09:43:48.51 |
-18:36:35.2 |
HIP 47905 |
28.75 |
| 2026-10-07 00:00 |
09:43:50.22 |
-18:36:57.9 |
HIP 47905 |
28.28 |
| 2026-10-07 12:00 |
09:43:51.91 |
-18:37:20.6 |
HIP 47905 |
27.82 |
| 2026-10-08 00:00 |
09:43:53.58 |
-18:37:43.3 |
HIP 47905 |
27.37 |
| 2026-10-08 12:00 |
09:43:55.23 |
-18:38:06.1 |
HIP 47905 |
26.92 |
| 2026-10-09 00:00 |
09:43:56.87 |
-18:38:28.9 |
HIP 47905 |
26.49 |
| 2026-10-09 12:00 |
09:43:58.49 |
-18:38:51.8 |
HIP 47905 |
26.06 |
| 2026-10-10 00:00 |
09:44:00.09 |
-18:39:14.7 |
HIP 47905 |
25.64 |
| 2026-10-10 12:00 |
09:44:01.67 |
-18:39:37.7 |
HIP 47905 |
25.23 |
| 2026-10-11 00:00 |
09:44:03.23 |
-18:40:00.7 |
HIP 47905 |
24.82 |