| 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) |
| 2026-05-12 00:00 |
08:40:22.56 |
-05:10:11.1 |
HIP 42461 |
23.57 |
| 2026-05-12 12:00 |
08:40:23.48 |
-05:09:54.5 |
HIP 42461 |
23.50 |
| 2026-05-13 00:00 |
08:40:24.42 |
-05:09:38.1 |
HIP 42461 |
23.44 |
| 2026-05-13 12:00 |
08:40:25.39 |
-05:09:21.8 |
HIP 42461 |
23.38 |
| 2026-05-14 00:00 |
08:40:26.39 |
-05:09:05.7 |
HIP 42461 |
23.35 |
| 2026-05-14 12:00 |
08:40:27.42 |
-05:08:49.8 |
HIP 42461 |
23.32 |
| 2026-05-15 00:00 |
08:40:28.47 |
-05:08:34.0 |
HIP 42461 |
23.31 |
| 2026-05-15 12:00 |
08:40:29.55 |
-05:08:18.4 |
HIP 42634 |
23.23 |
| 2026-05-16 00:00 |
08:40:30.66 |
-05:08:02.9 |
HIP 42634 |
22.87 |
| 2026-05-16 12:00 |
08:40:31.80 |
-05:07:47.6 |
HIP 42634 |
22.50 |
| 2026-05-17 00:00 |
08:40:32.97 |
-05:07:32.5 |
HIP 42634 |
22.14 |
| 2026-05-17 12:00 |
08:40:34.16 |
-05:07:17.5 |
HIP 42634 |
21.77 |
| 2026-05-18 00:00 |
08:40:35.39 |
-05:07:02.7 |
HIP 42634 |
21.41 |
| 2026-05-18 12:00 |
08:40:36.63 |
-05:06:48.1 |
HIP 42634 |
21.04 |
| 2026-05-19 00:00 |
08:40:37.91 |
-05:06:33.6 |
HIP 42634 |
20.67 |
| 2026-05-19 12:00 |
08:40:39.21 |
-05:06:19.4 |
HIP 42634 |
20.31 |
| 2026-05-20 00:00 |
08:40:40.54 |
-05:06:05.3 |
HIP 42634 |
19.94 |
| 2026-05-20 12:00 |
08:40:41.90 |
-05:05:51.3 |
HIP 42634 |
19.58 |
| 2026-05-21 00:00 |
08:40:43.29 |
-05:05:37.6 |
HIP 42634 |
19.22 |
| 2026-05-21 12:00 |
08:40:44.70 |
-05:05:24.0 |
HIP 42634 |
18.86 |
| 2026-05-22 00:00 |
08:40:46.13 |
-05:05:10.6 |
HIP 42634 |
18.50 |
| 2026-05-22 12:00 |
08:40:47.60 |
-05:04:57.3 |
HIP 42634 |
18.14 |
| 2026-05-23 00:00 |
08:40:49.09 |
-05:04:44.3 |
HIP 42634 |
17.79 |
| 2026-05-23 12:00 |
08:40:50.60 |
-05:04:31.4 |
HIP 42634 |
17.44 |
| 2026-05-24 00:00 |
08:40:52.15 |
-05:04:18.7 |
HIP 42634 |
17.09 |
| 2026-05-24 12:00 |
08:40:53.71 |
-05:04:06.2 |
HIP 42634 |
16.75 |
| 2026-05-25 00:00 |
08:40:55.31 |
-05:03:53.9 |
HIP 42634 |
16.42 |
| 2026-05-25 12:00 |
08:40:56.93 |
-05:03:41.7 |
HIP 42634 |
16.09 |
| 2026-05-26 00:00 |
08:40:58.57 |
-05:03:29.7 |
HIP 42634 |
15.77 |
| 2026-05-26 12:00 |
08:41:00.24 |
-05:03:17.9 |
HIP 42634 |
15.45 |
| 2026-05-27 00:00 |
08:41:01.93 |
-05:03:06.3 |
HIP 42634 |
15.15 |
| 2026-05-27 12:00 |
08:41:03.65 |
-05:02:54.9 |
HIP 42634 |
14.85 |
| 2026-05-28 00:00 |
08:41:05.40 |
-05:02:43.7 |
HIP 42634 |
14.57 |
| 2026-05-28 12:00 |
08:41:07.17 |
-05:02:32.6 |
HIP 42634 |
14.30 |
| 2026-05-29 00:00 |
08:41:08.96 |
-05:02:21.7 |
HIP 42634 |
14.04 |
| 2026-05-29 12:00 |
08:41:10.78 |
-05:02:11.0 |
HIP 42634 |
13.79 |
| 2026-05-30 00:00 |
08:41:12.62 |
-05:02:00.5 |
HIP 42634 |
13.56 |
| 2026-05-30 12:00 |
08:41:14.48 |
-05:01:50.2 |
HIP 42634 |
13.34 |
| 2026-05-31 00:00 |
08:41:16.37 |
-05:01:40.1 |
HIP 42634 |
13.15 |
| 2026-05-31 12:00 |
08:41:18.29 |
-05:01:30.2 |
HIP 42634 |
12.97 |
| 2026-06-01 00:00 |
08:41:20.23 |
-05:01:20.4 |
HIP 42634 |
12.82 |
| 2026-06-01 12:00 |
08:41:22.19 |
-05:01:10.8 |
HIP 42634 |
12.68 |
| 2026-06-02 00:00 |
08:41:24.17 |
-05:01:01.5 |
HIP 42634 |
12.57 |