| Parameter |
Value |
| Designation |
100P/Hartley 1 |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2016-04-02T02:13:28.588800Z |
| Orbit solution date (soln_date, UTC) |
2025-07-31T12:12:40Z |
| Obs used |
644 |
| NEO |
- |
| M1 |
9.900 |
| K1 |
23.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-04-02.0000000 |
| e |
0.41375811 |
| q (au) |
2.009747 |
| a (au) |
3.428188 |
| i (deg) |
25.584071 |
| Ω (om, deg) |
37.764478 |
| ω (w, deg) |
181.874834 |
| M (ma, deg) |
303.154223 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.868 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.868 |
| n |
6.000 |
| 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 |
| 2022-01-26 |
2022-08-15 |
+10.8671 |
-3.807 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-06-01 00:00 |
03:33:39.50 |
+25:56:10.9 |
HIP 16429 |
31.52 |
| 2026-06-01 12:00 |
03:34:07.68 |
+25:58:38.5 |
HIP 16429 |
38.30 |
| 2026-06-02 00:00 |
03:34:35.85 |
+26:01:06.1 |
HIP 16879 |
34.87 |
| 2026-06-02 12:00 |
03:35:04.01 |
+26:03:33.5 |
HIP 16879 |
28.79 |
| 2026-06-03 00:00 |
03:35:32.17 |
+26:06:00.9 |
HIP 16879 |
23.11 |
| 2026-06-03 12:00 |
03:36:00.33 |
+26:08:28.2 |
HIP 16879 |
18.21 |
| 2026-06-04 00:00 |
03:36:28.47 |
+26:10:55.5 |
HIP 16879 |
14.87 |
| 2026-06-04 12:00 |
03:36:56.62 |
+26:13:22.6 |
HIP 16879 |
14.24 |
| 2026-06-05 00:00 |
03:37:24.75 |
+26:15:49.7 |
HIP 16879 |
16.62 |
| 2026-06-05 12:00 |
03:37:52.87 |
+26:18:16.7 |
HIP 16879 |
21.00 |
| 2026-06-06 00:00 |
03:38:20.99 |
+26:20:43.6 |
HIP 16879 |
26.41 |
| 2026-06-06 12:00 |
03:38:49.09 |
+26:23:10.4 |
HIP 16879 |
32.33 |
| 2026-06-07 00:00 |
03:39:17.19 |
+26:25:37.1 |
HIP 17140 |
30.40 |
| 2026-06-07 12:00 |
03:39:45.27 |
+26:28:03.8 |
HIP 17140 |
25.98 |
| 2026-06-08 00:00 |
03:40:13.34 |
+26:30:30.4 |
HIP 17140 |
22.74 |
| 2026-06-08 12:00 |
03:40:41.40 |
+26:32:56.8 |
HIP 17140 |
21.21 |
| 2026-06-09 00:00 |
03:41:09.45 |
+26:35:23.2 |
HIP 17324 |
17.98 |
| 2026-06-09 12:00 |
03:41:37.48 |
+26:37:49.6 |
HIP 17324 |
12.19 |
| 2026-06-10 00:00 |
03:42:05.50 |
+26:40:15.8 |
HIP 17324 |
8.03 |
| 2026-06-10 12:00 |
03:42:33.50 |
+26:42:41.9 |
HIP 17324 |
8.40 |
| 2026-06-11 00:00 |
03:43:01.49 |
+26:45:08.0 |
HIP 17324 |
12.92 |
| 2026-06-11 12:00 |
03:43:29.46 |
+26:47:33.9 |
HIP 17324 |
18.79 |
| 2026-06-12 00:00 |
03:43:57.41 |
+26:49:59.8 |
HIP 17324 |
25.08 |
| 2026-06-12 12:00 |
03:44:25.35 |
+26:52:25.6 |
HIP 17407 |
30.84 |
| 2026-06-13 00:00 |
03:44:53.26 |
+26:54:51.3 |
HIP 17592 |
30.64 |
| 2026-06-13 12:00 |
03:45:21.16 |
+26:57:16.9 |
HIP 17592 |
25.59 |
| 2026-06-14 00:00 |
03:45:49.03 |
+26:59:42.5 |
HIP 17592 |
21.43 |
| 2026-06-14 12:00 |
03:46:16.88 |
+27:02:07.9 |
HIP 17592 |
18.78 |
| 2026-06-15 00:00 |
03:46:44.71 |
+27:04:33.2 |
HIP 17592 |
18.29 |
| 2026-06-15 12:00 |
03:47:12.52 |
+27:06:58.5 |
HIP 17592 |
20.11 |
| 2026-06-16 00:00 |
03:47:40.30 |
+27:09:23.6 |
HIP 17592 |
23.70 |
| 2026-06-16 12:00 |
03:48:08.06 |
+27:11:48.7 |
HIP 17592 |
28.41 |
| 2026-06-17 00:00 |
03:48:35.79 |
+27:14:13.7 |
HIP 17924 |
21.99 |
| 2026-06-17 12:00 |
03:49:03.49 |
+27:16:38.6 |
HIP 17924 |
15.59 |
| 2026-06-18 00:00 |
03:49:31.16 |
+27:19:03.3 |
HIP 17924 |
9.48 |
| 2026-06-18 12:00 |
03:49:58.81 |
+27:21:28.0 |
HIP 17924 |
4.89 |
| 2026-06-19 00:00 |
03:50:26.43 |
+27:23:52.6 |
HIP 17924 |
6.70 |
| 2026-06-19 12:00 |
03:50:54.01 |
+27:26:17.1 |
HIP 17924 |
12.34 |
| 2026-06-20 00:00 |
03:51:21.57 |
+27:28:41.5 |
HIP 17924 |
18.60 |
| 2026-06-20 12:00 |
03:51:49.09 |
+27:31:05.9 |
HIP 17924 |
25.01 |
| 2026-06-21 00:00 |
03:52:16.58 |
+27:33:30.1 |
HIP 17924 |
31.47 |
| 2026-06-21 12:00 |
03:52:44.04 |
+27:35:54.2 |
HIP 18119 |
32.33 |
| 2026-06-22 00:00 |
03:53:11.47 |
+27:38:18.3 |
HIP 18208 |
31.13 |