| 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) |
| 2026-09-20 00:00 |
08:52:34.85 |
-05:41:08.4 |
HIP 43498 |
22.60 |
| 2026-09-20 12:00 |
08:52:37.28 |
-05:41:34.2 |
HIP 43498 |
22.69 |
| 2026-09-21 00:00 |
08:52:39.69 |
-05:42:00.0 |
HIP 43498 |
22.79 |
| 2026-09-21 12:00 |
08:52:42.08 |
-05:42:25.8 |
HIP 43498 |
22.92 |
| 2026-09-22 00:00 |
08:52:44.44 |
-05:42:51.6 |
HIP 43498 |
23.06 |
| 2026-09-22 12:00 |
08:52:46.79 |
-05:43:17.6 |
HIP 43498 |
23.22 |
| 2026-09-23 00:00 |
08:52:49.11 |
-05:43:43.5 |
HIP 43498 |
23.39 |
| 2026-09-23 12:00 |
08:52:51.41 |
-05:44:09.5 |
HIP 43498 |
23.59 |
| 2026-09-24 00:00 |
08:52:53.70 |
-05:44:35.5 |
HIP 43498 |
23.79 |
| 2026-09-24 12:00 |
08:52:55.96 |
-05:45:01.6 |
HIP 43498 |
24.02 |
| 2026-09-25 00:00 |
08:52:58.19 |
-05:45:27.7 |
HIP 43498 |
24.25 |
| 2026-09-25 12:00 |
08:53:00.41 |
-05:45:53.8 |
HIP 43498 |
24.50 |
| 2026-09-26 00:00 |
08:53:02.60 |
-05:46:19.9 |
HIP 43498 |
24.76 |
| 2026-09-26 12:00 |
08:53:04.78 |
-05:46:46.1 |
HIP 43498 |
25.04 |
| 2026-09-27 00:00 |
08:53:06.93 |
-05:47:12.3 |
HIP 43498 |
25.32 |
| 2026-09-27 12:00 |
08:53:09.05 |
-05:47:38.6 |
HIP 43648 |
25.37 |
| 2026-09-28 00:00 |
08:53:11.16 |
-05:48:04.8 |
HIP 43648 |
24.86 |
| 2026-09-28 12:00 |
08:53:13.24 |
-05:48:31.1 |
HIP 43648 |
24.36 |
| 2026-09-29 00:00 |
08:53:15.30 |
-05:48:57.4 |
HIP 43648 |
23.87 |
| 2026-09-29 12:00 |
08:53:17.33 |
-05:49:23.7 |
HIP 43648 |
23.39 |
| 2026-09-30 00:00 |
08:53:19.34 |
-05:49:50.1 |
HIP 43648 |
22.92 |
| 2026-09-30 12:00 |
08:53:21.33 |
-05:50:16.4 |
HIP 43648 |
22.46 |
| 2026-10-01 00:00 |
08:53:23.30 |
-05:50:42.8 |
HIP 43648 |
22.00 |
| 2026-10-01 12:00 |
08:53:25.24 |
-05:51:09.2 |
HIP 43648 |
21.56 |
| 2026-10-02 00:00 |
08:53:27.16 |
-05:51:35.6 |
HIP 43648 |
21.13 |
| 2026-10-02 12:00 |
08:53:29.05 |
-05:52:02.0 |
HIP 43648 |
20.71 |
| 2026-10-03 00:00 |
08:53:30.92 |
-05:52:28.4 |
HIP 43648 |
20.30 |
| 2026-10-03 12:00 |
08:53:32.76 |
-05:52:54.8 |
HIP 43648 |
19.90 |
| 2026-10-04 00:00 |
08:53:34.58 |
-05:53:21.2 |
HIP 43648 |
19.51 |
| 2026-10-04 12:00 |
08:53:36.38 |
-05:53:47.6 |
HIP 43648 |
19.14 |
| 2026-10-05 00:00 |
08:53:38.15 |
-05:54:14.0 |
HIP 43648 |
18.78 |
| 2026-10-05 12:00 |
08:53:39.90 |
-05:54:40.5 |
HIP 43648 |
18.43 |
| 2026-10-06 00:00 |
08:53:41.62 |
-05:55:06.9 |
HIP 43648 |
18.09 |
| 2026-10-06 12:00 |
08:53:43.31 |
-05:55:33.3 |
HIP 43648 |
17.77 |
| 2026-10-07 00:00 |
08:53:44.98 |
-05:55:59.7 |
HIP 43648 |
17.46 |
| 2026-10-07 12:00 |
08:53:46.63 |
-05:56:26.1 |
HIP 43648 |
17.16 |
| 2026-10-08 00:00 |
08:53:48.24 |
-05:56:52.5 |
HIP 43648 |
16.88 |
| 2026-10-08 12:00 |
08:53:49.84 |
-05:57:18.9 |
HIP 43648 |
16.62 |
| 2026-10-09 00:00 |
08:53:51.40 |
-05:57:45.2 |
HIP 43648 |
16.36 |
| 2026-10-09 12:00 |
08:53:52.94 |
-05:58:11.6 |
HIP 43648 |
16.13 |
| 2026-10-10 00:00 |
08:53:54.46 |
-05:58:37.9 |
HIP 43648 |
15.90 |
| 2026-10-10 12:00 |
08:53:55.94 |
-05:59:04.2 |
HIP 43648 |
15.70 |
| 2026-10-11 00:00 |
08:53:57.40 |
-05:59:30.5 |
HIP 43648 |
15.50 |