| Parameter |
Value |
| Designation |
C/2012 Y3 (McNaught) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2012-08-25T20:18:44.000640Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:32:30Z |
| Obs used |
150 |
| NEO |
- |
| M1 |
12.900 |
| K1 |
4.500 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2013-02-01.0000000 |
| e |
0.93994217 |
| q (au) |
1.764843 |
| a (au) |
29.385733 |
| i (deg) |
73.231907 |
| Ω (om, deg) |
122.707962 |
| ω (w, deg) |
235.694296 |
| M (ma, deg) |
0.984727 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.507 + 5.732\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.507 |
| n |
5.732 |
| gf |
0.999 |
| gb |
-1.000 |
| k |
0.800 |
| 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) |
| 2026-09-20 00:00 |
10:03:22.01 |
+46:18:30.9 |
HIP 49239 |
7.27 |
| 2026-09-20 12:00 |
10:03:27.34 |
+46:18:35.9 |
HIP 49239 |
7.75 |
| 2026-09-21 00:00 |
10:03:32.65 |
+46:18:41.2 |
HIP 49239 |
8.31 |
| 2026-09-21 12:00 |
10:03:37.94 |
+46:18:46.9 |
HIP 49239 |
8.94 |
| 2026-09-22 00:00 |
10:03:43.21 |
+46:18:52.9 |
HIP 49239 |
9.61 |
| 2026-09-22 12:00 |
10:03:48.45 |
+46:18:59.2 |
HIP 49239 |
10.32 |
| 2026-09-23 00:00 |
10:03:53.67 |
+46:19:05.8 |
HIP 49239 |
11.06 |
| 2026-09-23 12:00 |
10:03:58.87 |
+46:19:12.8 |
HIP 49239 |
11.82 |
| 2026-09-24 00:00 |
10:04:04.04 |
+46:19:20.1 |
HIP 49239 |
12.60 |
| 2026-09-24 12:00 |
10:04:09.18 |
+46:19:27.8 |
HIP 49239 |
13.40 |
| 2026-09-25 00:00 |
10:04:14.31 |
+46:19:35.7 |
HIP 49239 |
14.21 |
| 2026-09-25 12:00 |
10:04:19.40 |
+46:19:44.0 |
HIP 49239 |
15.02 |
| 2026-09-26 00:00 |
10:04:24.48 |
+46:19:52.7 |
HIP 49239 |
15.85 |
| 2026-09-26 12:00 |
10:04:29.52 |
+46:20:01.7 |
HIP 49239 |
16.68 |
| 2026-09-27 00:00 |
10:04:34.54 |
+46:20:11.0 |
HIP 49239 |
17.51 |
| 2026-09-27 12:00 |
10:04:39.54 |
+46:20:20.6 |
HIP 49239 |
18.35 |
| 2026-09-28 00:00 |
10:04:44.51 |
+46:20:30.6 |
HIP 49239 |
19.19 |
| 2026-09-28 12:00 |
10:04:49.45 |
+46:20:40.9 |
HIP 49239 |
20.03 |
| 2026-09-29 00:00 |
10:04:54.36 |
+46:20:51.5 |
HIP 49239 |
20.87 |
| 2026-09-29 12:00 |
10:04:59.25 |
+46:21:02.5 |
HIP 49239 |
21.71 |
| 2026-09-30 00:00 |
10:05:04.11 |
+46:21:13.8 |
HIP 49239 |
22.55 |
| 2026-09-30 12:00 |
10:05:08.94 |
+46:21:25.5 |
HIP 49239 |
23.39 |
| 2026-10-01 00:00 |
10:05:13.74 |
+46:21:37.5 |
HIP 49239 |
24.23 |
| 2026-10-01 12:00 |
10:05:18.52 |
+46:21:49.8 |
HIP 49576 |
24.89 |
| 2026-10-02 00:00 |
10:05:23.26 |
+46:22:02.4 |
HIP 49576 |
24.37 |
| 2026-10-02 12:00 |
10:05:27.98 |
+46:22:15.4 |
HIP 49576 |
23.87 |
| 2026-10-03 00:00 |
10:05:32.67 |
+46:22:28.7 |
HIP 49576 |
23.40 |
| 2026-10-03 12:00 |
10:05:37.32 |
+46:22:42.4 |
HIP 49576 |
22.96 |
| 2026-10-04 00:00 |
10:05:41.95 |
+46:22:56.4 |
HIP 49576 |
22.56 |
| 2026-10-04 12:00 |
10:05:46.55 |
+46:23:10.7 |
HIP 49576 |
22.18 |
| 2026-10-05 00:00 |
10:05:51.11 |
+46:23:25.4 |
HIP 49576 |
21.83 |
| 2026-10-05 12:00 |
10:05:55.64 |
+46:23:40.4 |
HIP 49576 |
21.52 |
| 2026-10-06 00:00 |
10:06:00.15 |
+46:23:55.7 |
HIP 49576 |
21.25 |
| 2026-10-06 12:00 |
10:06:04.62 |
+46:24:11.4 |
HIP 49576 |
21.01 |
| 2026-10-07 00:00 |
10:06:09.05 |
+46:24:27.4 |
HIP 49576 |
20.81 |
| 2026-10-07 12:00 |
10:06:13.46 |
+46:24:43.7 |
HIP 49576 |
20.64 |
| 2026-10-08 00:00 |
10:06:17.83 |
+46:25:00.4 |
HIP 49576 |
20.52 |
| 2026-10-08 12:00 |
10:06:22.17 |
+46:25:17.4 |
HIP 49576 |
20.43 |
| 2026-10-09 00:00 |
10:06:26.47 |
+46:25:34.7 |
HIP 49576 |
20.38 |
| 2026-10-09 12:00 |
10:06:30.74 |
+46:25:52.4 |
HIP 49576 |
20.37 |
| 2026-10-10 00:00 |
10:06:34.98 |
+46:26:10.4 |
HIP 49576 |
20.40 |
| 2026-10-10 12:00 |
10:06:39.18 |
+46:26:28.8 |
HIP 49576 |
20.47 |
| 2026-10-11 00:00 |
10:06:43.35 |
+46:26:47.4 |
HIP 49576 |
20.57 |