100P/Hartley 1
| 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 |
-1.000 |
| 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) |
| 2026-02-03 00:00 |
02:04:46.86 |
+17:09:23.5 |
HIP 9613 |
17.72 |
| 2026-02-03 12:00 |
02:04:57.00 |
+17:10:47.4 |
HIP 9613 |
19.97 |
| 2026-02-04 00:00 |
02:05:07.32 |
+17:12:12.1 |
HIP 9839 |
22.30 |
| 2026-02-04 12:00 |
02:05:17.81 |
+17:13:37.5 |
HIP 9839 |
20.49 |
| 2026-02-05 00:00 |
02:05:28.47 |
+17:15:03.8 |
HIP 9839 |
18.93 |
| 2026-02-05 12:00 |
02:05:39.31 |
+17:16:30.8 |
HIP 9839 |
17.69 |
| 2026-02-06 00:00 |
02:05:50.31 |
+17:17:58.7 |
HIP 9839 |
16.87 |
| 2026-02-06 12:00 |
02:06:01.49 |
+17:19:27.3 |
HIP 9839 |
16.56 |
| 2026-02-07 00:00 |
02:06:12.84 |
+17:20:56.7 |
HIP 9839 |
16.80 |
| 2026-02-07 12:00 |
02:06:24.36 |
+17:22:26.9 |
HIP 9839 |
17.60 |
| 2026-02-08 00:00 |
02:06:36.04 |
+17:23:57.8 |
HIP 9839 |
18.91 |
| 2026-02-08 12:00 |
02:06:47.89 |
+17:25:29.5 |
HIP 9777 |
20.44 |
| 2026-02-09 00:00 |
02:06:59.91 |
+17:27:02.0 |
HIP 9777 |
21.78 |
| 2026-02-09 12:00 |
02:07:12.09 |
+17:28:35.2 |
HIP 9777 |
23.53 |
| 2026-02-10 00:00 |
02:07:24.44 |
+17:30:09.2 |
HIP 10013 |
22.47 |
| 2026-02-10 12:00 |
02:07:36.95 |
+17:31:44.0 |
HIP 10013 |
19.25 |
| 2026-02-11 00:00 |
02:07:49.62 |
+17:33:19.4 |
HIP 10013 |
16.05 |
| 2026-02-11 12:00 |
02:08:02.45 |
+17:34:55.6 |
HIP 10013 |
12.93 |
| 2026-02-12 00:00 |
02:08:15.44 |
+17:36:32.6 |
HIP 10013 |
9.99 |
| 2026-02-12 12:00 |
02:08:28.60 |
+17:38:10.3 |
HIP 10013 |
7.51 |
| 2026-02-13 00:00 |
02:08:41.91 |
+17:39:48.7 |
HIP 10013 |
6.16 |
| 2026-02-13 12:00 |
02:08:55.37 |
+17:41:27.8 |
HIP 10013 |
6.71 |
| 2026-02-14 00:00 |
02:09:09.00 |
+17:43:07.6 |
HIP 10013 |
8.86 |
| 2026-02-14 12:00 |
02:09:22.78 |
+17:44:48.1 |
HIP 10013 |
11.81 |
| 2026-02-15 00:00 |
02:09:36.71 |
+17:46:29.4 |
HIP 10013 |
15.11 |
| 2026-02-15 12:00 |
02:09:50.80 |
+17:48:11.3 |
HIP 10013 |
18.61 |
| 2026-02-16 00:00 |
02:10:05.04 |
+17:49:54.0 |
HIP 10013 |
22.23 |
| 2026-02-16 12:00 |
02:10:19.43 |
+17:51:37.3 |
HIP 10013 |
25.93 |
| 2026-02-17 00:00 |
02:10:33.98 |
+17:53:21.3 |
HIP 10013 |
29.70 |
| 2026-02-17 12:00 |
02:10:48.67 |
+17:55:06.0 |
HIP 10295 |
26.12 |
| 2026-02-18 00:00 |
02:11:03.51 |
+17:56:51.3 |
HIP 10295 |
22.28 |
| 2026-02-18 12:00 |
02:11:18.50 |
+17:58:37.3 |
HIP 10295 |
18.47 |
| 2026-02-19 00:00 |
02:11:33.63 |
+18:00:24.0 |
HIP 10295 |
14.70 |
| 2026-02-19 12:00 |
02:11:48.91 |
+18:02:11.3 |
HIP 10295 |
11.07 |
| 2026-02-20 00:00 |
02:12:04.34 |
+18:03:59.3 |
HIP 10295 |
7.83 |
| 2026-02-20 12:00 |
02:12:19.90 |
+18:05:47.9 |
HIP 10295 |
5.78 |
| 2026-02-21 00:00 |
02:12:35.61 |
+18:07:37.1 |
HIP 10295 |
6.30 |
| 2026-02-21 12:00 |
02:12:51.46 |
+18:09:27.0 |
HIP 10295 |
8.99 |
| 2026-02-22 00:00 |
02:13:07.45 |
+18:11:17.5 |
HIP 10295 |
12.56 |
| 2026-02-22 12:00 |
02:13:23.58 |
+18:13:08.6 |
HIP 10295 |
16.47 |
| 2026-02-23 00:00 |
02:13:39.85 |
+18:15:00.3 |
HIP 10295 |
20.55 |
| 2026-02-23 12:00 |
02:13:56.25 |
+18:16:52.7 |
HIP 10295 |
24.73 |
| 2026-02-24 00:00 |
02:14:12.79 |
+18:18:45.6 |
HIP 10295 |
28.98 |