| 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) |
| 2026-06-01 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 |
| 2026-06-02 12:00 |
08:41:26.18 |
-05:00:52.3 |
HIP 42634 |
12.49 |
| 2026-06-03 00:00 |
08:41:28.21 |
-05:00:43.3 |
HIP 42634 |
12.43 |
| 2026-06-03 12:00 |
08:41:30.26 |
-05:00:34.5 |
HIP 42634 |
12.39 |
| 2026-06-04 00:00 |
08:41:32.34 |
-05:00:25.9 |
HIP 42634 |
12.39 |
| 2026-06-04 12:00 |
08:41:34.44 |
-05:00:17.5 |
HIP 42634 |
12.41 |
| 2026-06-05 00:00 |
08:41:36.56 |
-05:00:09.2 |
HIP 42634 |
12.46 |
| 2026-06-05 12:00 |
08:41:38.71 |
-05:00:01.2 |
HIP 42634 |
12.54 |
| 2026-06-06 00:00 |
08:41:40.88 |
-04:59:53.4 |
HIP 42634 |
12.65 |
| 2026-06-06 12:00 |
08:41:43.06 |
-04:59:45.7 |
HIP 42634 |
12.79 |
| 2026-06-07 00:00 |
08:41:45.28 |
-04:59:38.3 |
HIP 42634 |
12.95 |
| 2026-06-07 12:00 |
08:41:47.51 |
-04:59:31.0 |
HIP 42634 |
13.15 |
| 2026-06-08 00:00 |
08:41:49.76 |
-04:59:24.0 |
HIP 42634 |
13.37 |
| 2026-06-08 12:00 |
08:41:52.04 |
-04:59:17.1 |
HIP 42634 |
13.61 |
| 2026-06-09 00:00 |
08:41:54.34 |
-04:59:10.4 |
HIP 42634 |
13.89 |
| 2026-06-09 12:00 |
08:41:56.66 |
-04:59:04.0 |
HIP 42634 |
14.18 |
| 2026-06-10 00:00 |
08:41:59.00 |
-04:58:57.7 |
HIP 42634 |
14.51 |
| 2026-06-10 12:00 |
08:42:01.36 |
-04:58:51.6 |
HIP 42634 |
14.85 |
| 2026-06-11 00:00 |
08:42:03.74 |
-04:58:45.7 |
HIP 42634 |
15.22 |
| 2026-06-11 12:00 |
08:42:06.15 |
-04:58:40.1 |
HIP 42634 |
15.60 |
| 2026-06-12 00:00 |
08:42:08.57 |
-04:58:34.6 |
HIP 42634 |
16.01 |
| 2026-06-12 12:00 |
08:42:11.01 |
-04:58:29.3 |
HIP 42634 |
16.43 |
| 2026-06-13 00:00 |
08:42:13.48 |
-04:58:24.2 |
HIP 42634 |
16.88 |
| 2026-06-13 12:00 |
08:42:15.96 |
-04:58:19.4 |
HIP 42634 |
17.34 |
| 2026-06-14 00:00 |
08:42:18.47 |
-04:58:14.7 |
HIP 42634 |
17.81 |
| 2026-06-14 12:00 |
08:42:20.99 |
-04:58:10.2 |
HIP 42634 |
18.30 |
| 2026-06-15 00:00 |
08:42:23.53 |
-04:58:06.0 |
HIP 42634 |
18.81 |
| 2026-06-15 12:00 |
08:42:26.09 |
-04:58:01.9 |
HIP 42634 |
19.33 |
| 2026-06-16 00:00 |
08:42:28.68 |
-04:57:58.0 |
HIP 42634 |
19.86 |
| 2026-06-16 12:00 |
08:42:31.28 |
-04:57:54.4 |
HIP 42634 |
20.40 |
| 2026-06-17 00:00 |
08:42:33.90 |
-04:57:50.9 |
HIP 42759 |
20.78 |
| 2026-06-17 12:00 |
08:42:36.53 |
-04:57:47.7 |
HIP 42759 |
20.62 |
| 2026-06-18 00:00 |
08:42:39.19 |
-04:57:44.6 |
HIP 42759 |
20.48 |
| 2026-06-18 12:00 |
08:42:41.86 |
-04:57:41.8 |
HIP 42759 |
20.36 |
| 2026-06-19 00:00 |
08:42:44.55 |
-04:57:39.1 |
HIP 42759 |
20.27 |
| 2026-06-19 12:00 |
08:42:47.26 |
-04:57:36.7 |
HIP 42759 |
20.20 |
| 2026-06-20 00:00 |
08:42:49.99 |
-04:57:34.5 |
HIP 42759 |
20.16 |
| 2026-06-20 12:00 |
08:42:52.73 |
-04:57:32.4 |
HIP 42759 |
20.15 |
| 2026-06-21 00:00 |
08:42:55.50 |
-04:57:30.6 |
HIP 42759 |
20.16 |
| 2026-06-21 12:00 |
08:42:58.27 |
-04:57:29.0 |
HIP 42759 |
20.20 |
| 2026-06-22 00:00 |
08:43:01.07 |
-04:57:27.6 |
HIP 42759 |
20.26 |