161P/Hartley-IRAS
| Parameter |
Value |
| Designation |
161P/Hartley-IRAS |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2005-06-20T20:24:46.189440Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:27:43Z |
| Obs used |
335 |
| NEO |
Yes |
| M1 |
11.500 |
| K1 |
11.500 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2004-07-04.0000000 |
| e |
0.83508810 |
| q (au) |
1.274829 |
| a (au) |
7.730366 |
| i (deg) |
95.698050 |
| Ω (om, deg) |
1.398165 |
| ω (w, deg) |
47.091452 |
| M (ma, deg) |
343.865252 |
Magnitude
Scatter + Global Linear
$$
M_a = (9.254 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
9.254 |
| n |
6.000 |
| gf |
1.000 |
| gb |
-0.998 |
| 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
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
01:49:07.39 |
-55:03:44.7 |
HIP 8687 |
23.46 |
| 2026-02-03 12:00 |
01:49:00.83 |
-54:54:04.8 |
HIP 8687 |
24.03 |
| 2026-02-04 00:00 |
01:48:54.73 |
-54:44:25.0 |
HIP 8541 |
19.50 |
| 2026-02-04 12:00 |
01:48:49.08 |
-54:34:45.4 |
HIP 8541 |
13.13 |
| 2026-02-05 00:00 |
01:48:43.87 |
-54:25:05.9 |
HIP 8541 |
12.29 |
| 2026-02-05 12:00 |
01:48:39.10 |
-54:15:26.6 |
HIP 8541 |
17.78 |
| 2026-02-06 00:00 |
01:48:34.76 |
-54:05:47.6 |
HIP 8578 |
18.66 |
| 2026-02-06 12:00 |
01:48:30.84 |
-53:56:08.8 |
HIP 8578 |
19.04 |
| 2026-02-07 00:00 |
01:48:27.35 |
-53:46:30.2 |
HIP 8578 |
23.70 |
| 2026-02-07 12:00 |
01:48:24.27 |
-53:36:52.0 |
HIP 8456 |
19.16 |
| 2026-02-08 00:00 |
01:48:21.60 |
-53:27:14.1 |
HIP 8456 |
10.58 |
| 2026-02-08 12:00 |
01:48:19.33 |
-53:17:36.5 |
HIP 8456 |
6.46 |
| 2026-02-09 00:00 |
01:48:17.46 |
-53:07:59.4 |
HIP 8462 |
10.53 |
| 2026-02-09 12:00 |
01:48:15.99 |
-52:58:22.6 |
HIP 8462 |
8.16 |
| 2026-02-10 00:00 |
01:48:14.90 |
-52:48:46.3 |
HIP 8462 |
14.35 |
| 2026-02-10 12:00 |
01:48:14.19 |
-52:39:10.4 |
HIP 8430 |
12.55 |
| 2026-02-11 00:00 |
01:48:13.85 |
-52:29:34.9 |
HIP 8430 |
4.69 |
| 2026-02-11 12:00 |
01:48:13.89 |
-52:20:00.0 |
HIP 8430 |
8.37 |
| 2026-02-12 00:00 |
01:48:14.30 |
-52:10:25.6 |
HIP 8430 |
17.34 |
| 2026-02-12 12:00 |
01:48:15.07 |
-52:00:51.8 |
HIP 8317 |
15.78 |
| 2026-02-13 00:00 |
01:48:16.19 |
-51:51:18.5 |
HIP 8317 |
9.97 |
| 2026-02-13 12:00 |
01:48:17.66 |
-51:41:45.8 |
HIP 8440 |
6.28 |
| 2026-02-14 00:00 |
01:48:19.48 |
-51:32:13.7 |
HIP 8449 |
6.22 |
| 2026-02-14 12:00 |
01:48:21.65 |
-51:22:42.3 |
HIP 8449 |
13.12 |
| 2026-02-15 00:00 |
01:48:24.15 |
-51:13:11.5 |
HIP 8449 |
22.05 |
| 2026-02-15 12:00 |
01:48:26.98 |
-51:03:41.4 |
HIP 8240 |
26.65 |
| 2026-02-16 00:00 |
01:48:30.14 |
-50:54:12.0 |
HIP 8240 |
23.35 |
| 2026-02-16 12:00 |
01:48:33.62 |
-50:44:43.4 |
HIP 8445 |
15.99 |
| 2026-02-17 00:00 |
01:48:37.42 |
-50:35:15.4 |
HIP 8445 |
6.66 |
| 2026-02-17 12:00 |
01:48:41.54 |
-50:25:48.3 |
HIP 8445 |
3.59 |
| 2026-02-18 00:00 |
01:48:45.97 |
-50:16:21.9 |
HIP 8445 |
12.67 |
| 2026-02-18 12:00 |
01:48:50.70 |
-50:06:56.3 |
HIP 8562 |
18.36 |
| 2026-02-19 00:00 |
01:48:55.73 |
-49:57:31.5 |
HIP 8286 |
22.27 |
| 2026-02-19 12:00 |
01:49:01.06 |
-49:48:07.6 |
HIP 8290 |
23.33 |
| 2026-02-20 00:00 |
01:49:06.68 |
-49:38:44.6 |
HIP 8290 |
22.33 |
| 2026-02-20 12:00 |
01:49:12.59 |
-49:29:22.4 |
HIP 8290 |
25.16 |
| 2026-02-21 00:00 |
01:49:18.78 |
-49:20:01.1 |
HIP 8290 |
30.76 |
| 2026-02-21 12:00 |
01:49:25.26 |
-49:10:40.8 |
HIP 8741 |
36.21 |
| 2026-02-22 00:00 |
01:49:32.00 |
-49:01:21.3 |
HIP 8733 |
35.14 |
| 2026-02-22 12:00 |
01:49:39.02 |
-48:52:02.8 |
HIP 8733 |
29.42 |
| 2026-02-23 00:00 |
01:49:46.31 |
-48:42:45.3 |
HIP 8733 |
25.87 |
| 2026-02-23 12:00 |
01:49:53.86 |
-48:33:28.8 |
HIP 8364 |
24.10 |
| 2026-02-24 00:00 |
01:50:01.67 |
-48:24:13.2 |
HIP 8364 |
22.57 |