| Parameter |
Value |
| Designation |
177P/Barnard |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2006-08-28T16:23:52.091520Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:27:46Z |
| Obs used |
1702 |
| NEO |
Yes |
| M1 |
15.700 |
| K1 |
13.000 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2006-04-24.0000000 |
| e |
0.95444204 |
| q (au) |
1.107271 |
| a (au) |
24.304669 |
| i (deg) |
31.216459 |
| Ω (om, deg) |
272.067721 |
| ω (w, deg) |
60.453551 |
| M (ma, deg) |
358.957950 |
Magnitude
Scatter + Global Linear
$$
M_a = (15.195 + 4.041\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
15.195 |
| n |
4.041 |
| gf |
1.000 |
| gb |
-0.500 |
| 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
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2006-06-23 |
2006-08-28 |
+13.5160 |
-2.197 |
| 2006-08-28 |
2006-11-01 |
-5.2733 |
-2.545 |
| 2006-11-01 |
2006-12-11 |
+35.3909 |
-8.724 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-07-29 00:00 |
08:47:00.51 |
-05:04:53.5 |
HIP 43284 |
31.99 |
| 2026-07-29 12:00 |
08:47:03.99 |
-05:05:06.6 |
HIP 43284 |
31.10 |
| 2026-07-30 00:00 |
08:47:07.48 |
-05:05:19.9 |
HIP 43284 |
30.21 |
| 2026-07-30 12:00 |
08:47:10.96 |
-05:05:33.4 |
HIP 43284 |
29.31 |
| 2026-07-31 00:00 |
08:47:14.44 |
-05:05:47.0 |
HIP 43284 |
28.42 |
| 2026-07-31 12:00 |
08:47:17.93 |
-05:06:00.8 |
HIP 43284 |
27.52 |
| 2026-08-01 00:00 |
08:47:21.41 |
-05:06:14.8 |
HIP 43284 |
26.62 |
| 2026-08-01 12:00 |
08:47:24.89 |
-05:06:29.0 |
HIP 43284 |
25.72 |
| 2026-08-02 00:00 |
08:47:28.38 |
-05:06:43.3 |
HIP 43284 |
24.82 |
| 2026-08-02 12:00 |
08:47:31.86 |
-05:06:57.8 |
HIP 43284 |
23.92 |
| 2026-08-03 00:00 |
08:47:35.35 |
-05:07:12.5 |
HIP 43284 |
23.02 |
| 2026-08-03 12:00 |
08:47:38.83 |
-05:07:27.3 |
HIP 43284 |
22.12 |
| 2026-08-04 00:00 |
08:47:42.31 |
-05:07:42.3 |
HIP 43284 |
21.22 |
| 2026-08-04 12:00 |
08:47:45.79 |
-05:07:57.5 |
HIP 43284 |
20.32 |
| 2026-08-05 00:00 |
08:47:49.27 |
-05:08:12.9 |
HIP 43284 |
19.42 |
| 2026-08-05 12:00 |
08:47:52.75 |
-05:08:28.4 |
HIP 43284 |
18.51 |
| 2026-08-06 00:00 |
08:47:56.23 |
-05:08:44.0 |
HIP 43284 |
17.61 |
| 2026-08-06 12:00 |
08:47:59.70 |
-05:08:59.9 |
HIP 43284 |
16.70 |
| 2026-08-07 00:00 |
08:48:03.18 |
-05:09:15.8 |
HIP 43284 |
15.80 |
| 2026-08-07 12:00 |
08:48:06.65 |
-05:09:32.0 |
HIP 43284 |
14.90 |
| 2026-08-08 00:00 |
08:48:10.11 |
-05:09:48.3 |
HIP 43284 |
13.99 |
| 2026-08-08 12:00 |
08:48:13.58 |
-05:10:04.8 |
HIP 43284 |
13.09 |
| 2026-08-09 00:00 |
08:48:17.04 |
-05:10:21.4 |
HIP 43284 |
12.18 |
| 2026-08-09 12:00 |
08:48:20.50 |
-05:10:38.2 |
HIP 43284 |
11.28 |
| 2026-08-10 00:00 |
08:48:23.95 |
-05:10:55.2 |
HIP 43284 |
10.37 |
| 2026-08-10 12:00 |
08:48:27.41 |
-05:11:12.3 |
HIP 43284 |
9.46 |
| 2026-08-11 00:00 |
08:48:30.85 |
-05:11:29.6 |
HIP 43284 |
8.56 |
| 2026-08-11 12:00 |
08:48:34.30 |
-05:11:47.0 |
HIP 43284 |
7.65 |
| 2026-08-12 00:00 |
08:48:37.74 |
-05:12:04.6 |
HIP 43284 |
6.75 |
| 2026-08-12 12:00 |
08:48:41.17 |
-05:12:22.3 |
HIP 43284 |
5.85 |
| 2026-08-13 00:00 |
08:48:44.60 |
-05:12:40.2 |
HIP 43284 |
4.94 |
| 2026-08-13 12:00 |
08:48:48.02 |
-05:12:58.2 |
HIP 43284 |
4.04 |
| 2026-08-14 00:00 |
08:48:51.44 |
-05:13:16.4 |
HIP 43284 |
3.13 |
| 2026-08-14 12:00 |
08:48:54.86 |
-05:13:34.7 |
HIP 43284 |
2.23 |
| 2026-08-15 00:00 |
08:48:58.26 |
-05:13:53.2 |
HIP 43284 |
1.33 |
| 2026-08-15 12:00 |
08:49:01.66 |
-05:14:11.8 |
HIP 43284 |
0.43 |
| 2026-08-16 00:00 |
08:49:05.06 |
-05:14:30.6 |
HIP 43284 |
0.48 |
| 2026-08-16 12:00 |
08:49:08.45 |
-05:14:49.5 |
HIP 43284 |
1.38 |
| 2026-08-17 00:00 |
08:49:11.83 |
-05:15:08.5 |
HIP 43284 |
2.27 |
| 2026-08-17 12:00 |
08:49:15.20 |
-05:15:27.7 |
HIP 43284 |
3.17 |
| 2026-08-18 00:00 |
08:49:18.57 |
-05:15:47.0 |
HIP 43284 |
4.07 |
| 2026-08-18 12:00 |
08:49:21.93 |
-05:16:06.5 |
HIP 43284 |
4.97 |
| 2026-08-19 00:00 |
08:49:25.28 |
-05:16:26.1 |
HIP 43284 |
5.86 |