| Parameter |
Value |
| Designation |
161P/Hartley-IRAS |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2005-06-22T21:34:52.124160Z |
| Orbit solution date (soln_date, UTC) |
2026-09-21T07:12:14Z |
| Obs used |
622 |
| NEO |
Yes |
| M1 |
14.700 |
| K1 |
6.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2014-09-09.0000000 |
| e |
0.83613587 |
| q (au) |
1.264836 |
| a (au) |
7.718810 |
| i (deg) |
95.632456 |
| Ω (om, deg) |
1.283059 |
| ω (w, deg) |
46.983552 |
| M (ma, deg) |
154.659523 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.580 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.580 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.502 |
| 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
Finding Chart
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-09-20 00:00 |
01:19:07.03 |
-14:50:53.2 |
HIP 6164 |
0.76 |
| 2026-09-20 12:00 |
01:14:58.77 |
-14:37:22.4 |
HIP 5756 |
21.47 |
| 2026-09-21 00:00 |
01:10:44.25 |
-14:23:09.7 |
HIP 5475 |
9.28 |
| 2026-09-21 12:00 |
01:06:23.49 |
-14:08:13.8 |
HIP 5191 |
9.56 |
| 2026-09-22 00:00 |
01:01:56.54 |
-13:52:33.5 |
HIP 4821 |
15.32 |
| 2026-09-22 12:00 |
00:57:23.49 |
-13:36:07.8 |
HIP 4594 |
21.07 |
| 2026-09-23 00:00 |
00:52:44.44 |
-13:18:55.7 |
HIP 4066 |
10.29 |
| 2026-09-23 12:00 |
00:47:59.50 |
-13:00:56.4 |
HIP 3783 |
24.36 |
| 2026-09-24 00:00 |
00:43:08.84 |
-12:42:09.3 |
HIP 3255 |
24.45 |
| 2026-09-24 12:00 |
00:38:12.64 |
-12:22:34.0 |
HIP 3028 |
13.20 |
| 2026-09-25 00:00 |
00:33:11.11 |
-12:02:10.3 |
HIP 2532 |
22.05 |
| 2026-09-25 12:00 |
00:28:04.52 |
-11:40:58.2 |
HIP 2215 |
1.74 |
| 2026-09-26 00:00 |
00:22:53.12 |
-11:18:58.2 |
HIP 1832 |
5.14 |
| 2026-09-26 12:00 |
00:17:37.23 |
-10:56:10.8 |
HIP 1509 |
17.27 |
| 2026-09-27 00:00 |
00:12:17.19 |
-10:32:37.0 |
HIP 899 |
26.85 |
| 2026-09-27 12:00 |
00:06:53.36 |
-10:08:18.0 |
HIP 462 |
37.25 |
| 2026-09-28 00:00 |
00:01:26.13 |
-09:43:15.4 |
HIP 118 |
17.53 |
| 2026-09-28 12:00 |
23:55:55.93 |
-09:17:31.0 |
HIP 118020 |
13.93 |
| 2026-09-29 00:00 |
23:50:23.19 |
-08:51:07.0 |
HIP 117743 |
35.09 |
| 2026-09-29 12:00 |
23:44:48.37 |
-08:24:06.0 |
HIP 117127 |
3.98 |
| 2026-09-30 00:00 |
23:39:11.94 |
-07:56:30.7 |
HIP 116834 |
24.01 |
| 2026-09-30 12:00 |
23:33:34.41 |
-07:28:24.2 |
HIP 116388 |
25.40 |
| 2026-10-01 00:00 |
23:27:56.26 |
-06:59:49.7 |
HIP 115958 |
26.66 |
| 2026-10-01 12:00 |
23:22:17.99 |
-06:30:50.8 |
HIP 115260 |
24.47 |
| 2026-10-02 00:00 |
23:16:40.11 |
-06:01:31.1 |
HIP 114795 |
22.43 |
| 2026-10-02 12:00 |
23:11:03.12 |
-05:31:54.4 |
HIP 114493 |
26.21 |
| 2026-10-03 00:00 |
23:05:27.51 |
-05:02:04.6 |
HIP 113965 |
12.67 |
| 2026-10-03 12:00 |
22:59:53.76 |
-04:32:05.7 |
HIP 113537 |
10.70 |
| 2026-10-04 00:00 |
22:54:22.33 |
-04:02:01.5 |
HIP 113091 |
24.17 |
| 2026-10-04 12:00 |
22:48:53.67 |
-03:31:56.0 |
HIP 112669 |
8.86 |
| 2026-10-05 00:00 |
22:43:28.21 |
-03:01:52.9 |
HIP 112271 |
15.42 |
| 2026-10-05 12:00 |
22:38:06.34 |
-02:31:56.0 |
HIP 111741 |
21.98 |
| 2026-10-06 00:00 |
22:32:48.43 |
-02:02:08.7 |
HIP 111394 |
33.36 |
| 2026-10-06 12:00 |
22:27:34.83 |
-01:32:34.5 |
HIP 110848 |
6.26 |
| 2026-10-07 00:00 |
22:22:25.86 |
-01:03:16.4 |
HIP 110461 |
20.10 |
| 2026-10-07 12:00 |
22:17:21.80 |
-00:34:17.4 |
HIP 110113 |
18.77 |
| 2026-10-08 00:00 |
22:12:22.89 |
-00:05:40.2 |
HIP 109578 |
17.85 |
| 2026-10-08 12:00 |
22:07:29.38 |
+00:22:33.0 |
HIP 109186 |
12.98 |
| 2026-10-09 00:00 |
22:02:41.43 |
+00:50:19.9 |
HIP 108691 |
27.90 |
| 2026-10-09 12:00 |
21:57:59.22 |
+01:17:38.6 |
HIP 108496 |
31.21 |
| 2026-10-10 00:00 |
21:53:22.88 |
+01:44:27.6 |
HIP 107941 |
21.51 |
| 2026-10-10 12:00 |
21:48:52.52 |
+02:10:45.4 |
HIP 107679 |
13.35 |
| 2026-10-11 00:00 |
21:44:28.20 |
+02:36:31.0 |
HIP 107367 |
23.55 |