191P/McNaught
| 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
$$
M_a = (11.838 + 4.649\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.838 |
| n |
4.649 |
| gf |
0.918 |
| gb |
-0.898 |
| k |
1.000 |
| δ90 |
6.580 |
| 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 |
16:45:02.27 |
-17:18:30.5 |
HIP 82102 |
17.48 |
| 2026-02-03 12:00 |
16:45:25.12 |
-17:19:05.0 |
HIP 82102 |
11.99 |
| 2026-02-04 00:00 |
16:45:47.86 |
-17:19:38.9 |
HIP 82102 |
6.55 |
| 2026-02-04 12:00 |
16:46:10.48 |
-17:20:12.3 |
HIP 82102 |
1.20 |
| 2026-02-05 00:00 |
16:46:32.98 |
-17:20:45.2 |
HIP 82102 |
4.33 |
| 2026-02-05 12:00 |
16:46:55.37 |
-17:21:17.5 |
HIP 82102 |
9.68 |
| 2026-02-06 00:00 |
16:47:17.63 |
-17:21:49.3 |
HIP 82102 |
15.01 |
| 2026-02-06 12:00 |
16:47:39.78 |
-17:22:20.6 |
HIP 82102 |
20.32 |
| 2026-02-07 00:00 |
16:48:01.80 |
-17:22:51.4 |
HIP 82120 |
24.52 |
| 2026-02-07 12:00 |
16:48:23.69 |
-17:23:21.6 |
HIP 82120 |
28.88 |
| 2026-02-08 00:00 |
16:48:45.46 |
-17:23:51.3 |
HIP 82120 |
33.47 |
| 2026-02-08 12:00 |
16:49:07.10 |
-17:24:20.5 |
HIP 82120 |
38.19 |
| 2026-02-09 00:00 |
16:49:28.62 |
-17:24:49.1 |
HIP 82331 |
38.52 |
| 2026-02-09 12:00 |
16:49:50.01 |
-17:25:17.3 |
HIP 82331 |
39.52 |
| 2026-02-10 00:00 |
16:50:11.26 |
-17:25:44.9 |
HIP 82331 |
41.12 |
| 2026-02-10 12:00 |
16:50:32.38 |
-17:26:12.0 |
HIP 82393 |
41.97 |
| 2026-02-11 00:00 |
16:50:53.37 |
-17:26:38.6 |
HIP 82393 |
42.51 |
| 2026-02-11 12:00 |
16:51:14.23 |
-17:27:04.7 |
HIP 82393 |
43.62 |
| 2026-02-12 00:00 |
16:51:34.95 |
-17:27:30.2 |
HIP 82393 |
45.25 |
| 2026-02-12 12:00 |
16:51:55.53 |
-17:27:55.3 |
HIP 82665 |
42.14 |
| 2026-02-13 00:00 |
16:52:15.98 |
-17:28:19.8 |
HIP 82665 |
38.64 |
| 2026-02-13 12:00 |
16:52:36.28 |
-17:28:43.9 |
HIP 82665 |
35.50 |
| 2026-02-14 00:00 |
16:52:56.45 |
-17:29:07.4 |
HIP 82665 |
32.79 |
| 2026-02-14 12:00 |
16:53:16.47 |
-17:29:30.4 |
HIP 82665 |
30.63 |
| 2026-02-15 00:00 |
16:53:36.35 |
-17:29:53.0 |
HIP 82665 |
29.12 |
| 2026-02-15 12:00 |
16:53:56.08 |
-17:30:15.0 |
HIP 82665 |
28.34 |
| 2026-02-16 00:00 |
16:54:15.66 |
-17:30:36.6 |
HIP 82665 |
28.33 |
| 2026-02-16 12:00 |
16:54:35.10 |
-17:30:57.6 |
HIP 82665 |
29.08 |
| 2026-02-17 00:00 |
16:54:54.39 |
-17:31:18.2 |
HIP 82665 |
30.52 |
| 2026-02-17 12:00 |
16:55:13.53 |
-17:31:38.3 |
HIP 82956 |
32.44 |
| 2026-02-18 00:00 |
16:55:32.52 |
-17:31:57.9 |
HIP 82956 |
28.54 |
| 2026-02-18 12:00 |
16:55:51.35 |
-17:32:17.0 |
HIP 82956 |
24.89 |
| 2026-02-19 00:00 |
16:56:10.03 |
-17:32:35.7 |
HIP 82956 |
21.59 |
| 2026-02-19 12:00 |
16:56:28.55 |
-17:32:53.9 |
HIP 82956 |
18.79 |
| 2026-02-20 00:00 |
16:56:46.92 |
-17:33:11.6 |
HIP 82956 |
16.74 |
| 2026-02-20 12:00 |
16:57:05.13 |
-17:33:28.8 |
HIP 82956 |
15.68 |
| 2026-02-21 00:00 |
16:57:23.18 |
-17:33:45.6 |
HIP 82956 |
15.80 |
| 2026-02-21 12:00 |
16:57:41.07 |
-17:34:01.9 |
HIP 82956 |
17.02 |
| 2026-02-22 00:00 |
16:57:58.80 |
-17:34:17.7 |
HIP 82956 |
19.13 |
| 2026-02-22 12:00 |
16:58:16.36 |
-17:34:33.1 |
HIP 82956 |
21.83 |
| 2026-02-23 00:00 |
16:58:33.76 |
-17:34:48.1 |
HIP 82956 |
24.92 |
| 2026-02-23 12:00 |
16:58:51.00 |
-17:35:02.6 |
HIP 82956 |
28.26 |
| 2026-02-24 00:00 |
16:59:08.07 |
-17:35:16.6 |
HIP 82956 |
31.74 |