| Parameter |
Value |
| Designation |
191P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2007-09-13T14:40:41.669760Z |
| Orbit solution date (soln_date, UTC) |
2024-10-05T23:12:39Z |
| Obs used |
787 |
| NEO |
- |
| M1 |
13.800 |
| K1 |
8.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2010-02-25.0000000 |
| e |
0.42072245 |
| q (au) |
2.046442 |
| a (au) |
3.532749 |
| i (deg) |
8.759005 |
| Ω (om, deg) |
106.503897 |
| ω (w, deg) |
274.213416 |
| M (ma, deg) |
132.906520 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.851 + 4.652\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.851 |
| n |
4.652 |
| gf |
0.910 |
| gb |
-0.898 |
| k |
1.000 |
| δ90 |
6.023 |
| 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) |
| 2026-09-25 00:00 |
16:35:25.86 |
-20:00:45.7 |
HIP 81173 |
9.98 |
| 2026-09-25 12:00 |
16:35:49.49 |
-20:02:17.3 |
HIP 81325 |
12.62 |
| 2026-09-26 00:00 |
16:36:13.31 |
-20:03:48.8 |
HIP 81325 |
7.27 |
| 2026-09-26 12:00 |
16:36:37.31 |
-20:05:20.4 |
HIP 81325 |
3.69 |
| 2026-09-27 00:00 |
16:37:01.49 |
-20:06:52.0 |
HIP 81325 |
6.56 |
| 2026-09-27 12:00 |
16:37:25.85 |
-20:08:23.5 |
HIP 81325 |
11.94 |
| 2026-09-28 00:00 |
16:37:50.40 |
-20:09:55.0 |
HIP 81325 |
17.71 |
| 2026-09-28 12:00 |
16:38:15.12 |
-20:11:26.5 |
HIP 81325 |
23.61 |
| 2026-09-29 00:00 |
16:38:40.03 |
-20:12:58.0 |
HIP 81632 |
29.22 |
| 2026-09-29 12:00 |
16:39:05.11 |
-20:14:29.4 |
HIP 81632 |
23.24 |
| 2026-09-30 00:00 |
16:39:30.37 |
-20:16:00.7 |
HIP 81632 |
17.28 |
| 2026-09-30 12:00 |
16:39:55.81 |
-20:17:32.0 |
HIP 81632 |
11.45 |
| 2026-10-01 00:00 |
16:40:21.42 |
-20:19:03.3 |
HIP 81632 |
6.27 |
| 2026-10-01 12:00 |
16:40:47.21 |
-20:20:34.5 |
HIP 81632 |
4.94 |
| 2026-10-02 00:00 |
16:41:13.17 |
-20:22:05.6 |
HIP 81632 |
9.38 |
| 2026-10-02 12:00 |
16:41:39.31 |
-20:23:36.6 |
HIP 81632 |
15.21 |
| 2026-10-03 00:00 |
16:42:05.62 |
-20:25:07.6 |
HIP 81785 |
14.18 |
| 2026-10-03 12:00 |
16:42:32.10 |
-20:26:38.4 |
HIP 81785 |
15.80 |
| 2026-10-04 00:00 |
16:42:58.75 |
-20:28:09.2 |
HIP 81887 |
16.41 |
| 2026-10-04 12:00 |
16:43:25.57 |
-20:29:39.8 |
HIP 81887 |
12.46 |
| 2026-10-05 00:00 |
16:43:52.57 |
-20:31:10.4 |
HIP 81887 |
11.18 |
| 2026-10-05 12:00 |
16:44:19.73 |
-20:32:40.8 |
HIP 81887 |
13.41 |
| 2026-10-06 00:00 |
16:44:47.07 |
-20:34:11.1 |
HIP 81887 |
17.93 |
| 2026-10-06 12:00 |
16:45:14.57 |
-20:35:41.3 |
HIP 81887 |
23.47 |
| 2026-10-07 00:00 |
16:45:42.23 |
-20:37:11.4 |
HIP 81887 |
29.49 |
| 2026-10-07 12:00 |
16:46:10.07 |
-20:38:41.3 |
HIP 82244 |
33.92 |
| 2026-10-08 00:00 |
16:46:38.06 |
-20:40:11.0 |
HIP 82244 |
27.68 |
| 2026-10-08 12:00 |
16:47:06.23 |
-20:41:40.6 |
HIP 82244 |
21.70 |
| 2026-10-09 00:00 |
16:47:34.55 |
-20:43:10.0 |
HIP 82244 |
16.32 |
| 2026-10-09 12:00 |
16:48:03.04 |
-20:44:39.3 |
HIP 82244 |
12.39 |
| 2026-10-10 00:00 |
16:48:31.69 |
-20:46:08.4 |
HIP 82244 |
11.59 |
| 2026-10-10 12:00 |
16:49:00.50 |
-20:47:37.3 |
HIP 82244 |
14.49 |
| 2026-10-11 00:00 |
16:49:29.47 |
-20:49:06.0 |
HIP 82244 |
19.55 |
| 2026-10-11 12:00 |
16:49:58.60 |
-20:50:34.5 |
HIP 82244 |
25.53 |
| 2026-10-12 00:00 |
16:50:27.89 |
-20:52:02.8 |
HIP 82306 |
31.91 |
| 2026-10-12 12:00 |
16:50:57.33 |
-20:53:31.0 |
HIP 82519 |
29.71 |
| 2026-10-13 00:00 |
16:51:26.93 |
-20:54:58.9 |
HIP 82519 |
25.79 |
| 2026-10-13 12:00 |
16:51:56.68 |
-20:56:26.5 |
HIP 82519 |
23.39 |
| 2026-10-14 00:00 |
16:52:26.59 |
-20:57:54.0 |
HIP 82519 |
23.04 |
| 2026-10-14 12:00 |
16:52:56.65 |
-20:59:21.2 |
HIP 82519 |
24.83 |
| 2026-10-15 00:00 |
16:53:26.86 |
-21:00:48.2 |
HIP 82760 |
23.84 |
| 2026-10-15 12:00 |
16:53:57.22 |
-21:02:14.9 |
HIP 82760 |
19.41 |
| 2026-10-16 00:00 |
16:54:27.73 |
-21:03:41.4 |
HIP 82760 |
17.03 |