| Parameter |
Value |
| Designation |
278P/McNaught |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2013-08-02T10:27:33.508800Z |
| Orbit solution date (soln_date, UTC) |
2021-09-20T00:13:08Z |
| Obs used |
519 |
| NEO |
- |
| M1 |
12.600 |
| K1 |
13.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-06-08.0000000 |
| e |
0.43343798 |
| q (au) |
2.096064 |
| a (au) |
3.699620 |
| i (deg) |
6.683671 |
| Ω (om, deg) |
15.492573 |
| ω (w, deg) |
237.922750 |
| M (ma, deg) |
93.431156 |
Magnitude
Scatter + Global Linear
$$
M_a = (10.947 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
10.947 |
| n |
6.000 |
| gf |
0.999 |
| gb |
-0.946 |
| 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) |
| 2026-03-26 00:00 |
07:41:49.65 |
+28:10:13.3 |
HIP 37407 |
18.89 |
| 2026-03-26 12:00 |
07:41:50.76 |
+28:09:10.8 |
HIP 37407 |
18.34 |
| 2026-03-27 00:00 |
07:41:52.16 |
+28:08:07.7 |
HIP 37407 |
17.88 |
| 2026-03-27 12:00 |
07:41:53.86 |
+28:07:03.9 |
HIP 37407 |
17.52 |
| 2026-03-28 00:00 |
07:41:55.86 |
+28:05:59.4 |
HIP 37407 |
17.28 |
| 2026-03-28 12:00 |
07:41:58.14 |
+28:04:54.4 |
HIP 37407 |
17.17 |
| 2026-03-29 00:00 |
07:42:00.72 |
+28:03:48.7 |
HIP 37407 |
17.19 |
| 2026-03-29 12:00 |
07:42:03.59 |
+28:02:42.4 |
HIP 37407 |
17.36 |
| 2026-03-30 00:00 |
07:42:06.74 |
+28:01:35.5 |
HIP 37407 |
17.68 |
| 2026-03-30 12:00 |
07:42:10.19 |
+28:00:28.0 |
HIP 37407 |
18.14 |
| 2026-03-31 00:00 |
07:42:13.92 |
+27:59:19.9 |
HIP 37407 |
18.76 |
| 2026-03-31 12:00 |
07:42:17.94 |
+27:58:11.3 |
HIP 37407 |
19.52 |
| 2026-04-01 00:00 |
07:42:22.24 |
+27:57:02.0 |
HIP 37407 |
20.42 |
| 2026-04-01 12:00 |
07:42:26.82 |
+27:55:52.1 |
HIP 37407 |
21.45 |
| 2026-04-02 00:00 |
07:42:31.69 |
+27:54:41.7 |
HIP 37407 |
22.60 |
| 2026-04-02 12:00 |
07:42:36.84 |
+27:53:30.7 |
HIP 37407 |
23.87 |
| 2026-04-03 00:00 |
07:42:42.27 |
+27:52:19.1 |
HIP 37407 |
25.24 |
| 2026-04-03 12:00 |
07:42:47.98 |
+27:51:07.0 |
HIP 37407 |
26.71 |
| 2026-04-04 00:00 |
07:42:53.96 |
+27:49:54.3 |
HIP 37407 |
28.28 |
| 2026-04-04 12:00 |
07:43:00.22 |
+27:48:41.0 |
HIP 37407 |
29.93 |
| 2026-04-05 00:00 |
07:43:06.76 |
+27:47:27.2 |
HIP 37407 |
31.66 |
| 2026-04-05 12:00 |
07:43:13.57 |
+27:46:12.8 |
HIP 37826 |
31.76 |
| 2026-04-06 00:00 |
07:43:20.66 |
+27:44:57.9 |
HIP 37826 |
31.05 |
| 2026-04-06 12:00 |
07:43:28.02 |
+27:43:42.4 |
HIP 37826 |
30.41 |
| 2026-04-07 00:00 |
07:43:35.65 |
+27:42:26.4 |
HIP 37826 |
29.86 |
| 2026-04-07 12:00 |
07:43:43.55 |
+27:41:09.9 |
HIP 37826 |
29.41 |
| 2026-04-08 00:00 |
07:43:51.72 |
+27:39:52.8 |
HIP 37826 |
29.09 |
| 2026-04-08 12:00 |
07:44:00.15 |
+27:38:35.2 |
HIP 37826 |
28.90 |
| 2026-04-09 00:00 |
07:44:08.85 |
+27:37:17.1 |
HIP 37826 |
28.87 |
| 2026-04-09 12:00 |
07:44:17.82 |
+27:35:58.4 |
HIP 37826 |
29.00 |
| 2026-04-10 00:00 |
07:44:27.05 |
+27:34:39.2 |
HIP 37826 |
29.30 |
| 2026-04-10 12:00 |
07:44:36.55 |
+27:33:19.5 |
HIP 37826 |
29.80 |
| 2026-04-11 00:00 |
07:44:46.30 |
+27:31:59.3 |
HIP 37826 |
30.48 |
| 2026-04-11 12:00 |
07:44:56.32 |
+27:30:38.5 |
HIP 37826 |
31.35 |
| 2026-04-12 00:00 |
07:45:06.60 |
+27:29:17.2 |
HIP 37826 |
32.41 |
| 2026-04-12 12:00 |
07:45:17.13 |
+27:27:55.4 |
HIP 37826 |
33.66 |
| 2026-04-13 00:00 |
07:45:27.92 |
+27:26:33.1 |
HIP 37826 |
35.08 |
| 2026-04-13 12:00 |
07:45:38.97 |
+27:25:10.3 |
HIP 37826 |
36.66 |
| 2026-04-14 00:00 |
07:45:50.27 |
+27:23:47.0 |
HIP 37826 |
38.41 |
| 2026-04-14 12:00 |
07:46:01.83 |
+27:22:23.1 |
HIP 37886 |
38.90 |
| 2026-04-15 00:00 |
07:46:13.64 |
+27:20:58.8 |
HIP 37886 |
37.72 |
| 2026-04-15 12:00 |
07:46:25.69 |
+27:19:33.9 |
HIP 37886 |
36.76 |
| 2026-04-16 00:00 |
07:46:38.00 |
+27:18:08.5 |
HIP 37886 |
36.03 |