| 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) |
| 2026-03-26 00:00 |
08:41:09.10 |
-05:44:30.8 |
HIP 42674 |
12.92 |
| 2026-03-26 12:00 |
08:41:07.25 |
-05:44:06.2 |
HIP 42674 |
13.05 |
| 2026-03-27 00:00 |
08:41:05.42 |
-05:43:41.5 |
HIP 42674 |
13.20 |
| 2026-03-27 12:00 |
08:41:03.61 |
-05:43:16.8 |
HIP 42674 |
13.38 |
| 2026-03-28 00:00 |
08:41:01.84 |
-05:42:52.1 |
HIP 42674 |
13.57 |
| 2026-03-28 12:00 |
08:41:00.09 |
-05:42:27.4 |
HIP 42674 |
13.78 |
| 2026-03-29 00:00 |
08:40:58.37 |
-05:42:02.8 |
HIP 42674 |
14.00 |
| 2026-03-29 12:00 |
08:40:56.68 |
-05:41:38.1 |
HIP 42674 |
14.24 |
| 2026-03-30 00:00 |
08:40:55.01 |
-05:41:13.5 |
HIP 42674 |
14.50 |
| 2026-03-30 12:00 |
08:40:53.38 |
-05:40:48.9 |
HIP 42674 |
14.76 |
| 2026-03-31 00:00 |
08:40:51.77 |
-05:40:24.3 |
HIP 42674 |
15.04 |
| 2026-03-31 12:00 |
08:40:50.19 |
-05:39:59.7 |
HIP 42674 |
15.32 |
| 2026-04-01 00:00 |
08:40:48.64 |
-05:39:35.2 |
HIP 42674 |
15.62 |
| 2026-04-01 12:00 |
08:40:47.12 |
-05:39:10.6 |
HIP 42674 |
15.92 |
| 2026-04-02 00:00 |
08:40:45.62 |
-05:38:46.1 |
HIP 42674 |
16.23 |
| 2026-04-02 12:00 |
08:40:44.16 |
-05:38:21.7 |
HIP 42674 |
16.54 |
| 2026-04-03 00:00 |
08:40:42.72 |
-05:37:57.2 |
HIP 42674 |
16.86 |
| 2026-04-03 12:00 |
08:40:41.31 |
-05:37:32.8 |
HIP 42674 |
17.19 |
| 2026-04-04 00:00 |
08:40:39.93 |
-05:37:08.4 |
HIP 42674 |
17.51 |
| 2026-04-04 12:00 |
08:40:38.58 |
-05:36:44.1 |
HIP 42674 |
17.84 |
| 2026-04-05 00:00 |
08:40:37.26 |
-05:36:19.8 |
HIP 42674 |
18.17 |
| 2026-04-05 12:00 |
08:40:35.97 |
-05:35:55.5 |
HIP 42674 |
18.51 |
| 2026-04-06 00:00 |
08:40:34.70 |
-05:35:31.3 |
HIP 42674 |
18.84 |
| 2026-04-06 12:00 |
08:40:33.47 |
-05:35:07.1 |
HIP 42674 |
19.18 |
| 2026-04-07 00:00 |
08:40:32.26 |
-05:34:42.9 |
HIP 42674 |
19.51 |
| 2026-04-07 12:00 |
08:40:31.09 |
-05:34:18.8 |
HIP 42674 |
19.84 |
| 2026-04-08 00:00 |
08:40:29.94 |
-05:33:54.8 |
HIP 42674 |
20.18 |
| 2026-04-08 12:00 |
08:40:28.82 |
-05:33:30.8 |
HIP 42674 |
20.51 |
| 2026-04-09 00:00 |
08:40:27.74 |
-05:33:06.9 |
HIP 42674 |
20.84 |
| 2026-04-09 12:00 |
08:40:26.68 |
-05:32:43.0 |
HIP 42674 |
21.17 |
| 2026-04-10 00:00 |
08:40:25.65 |
-05:32:19.1 |
HIP 42674 |
21.50 |
| 2026-04-10 12:00 |
08:40:24.65 |
-05:31:55.3 |
HIP 42674 |
21.83 |
| 2026-04-11 00:00 |
08:40:23.68 |
-05:31:31.6 |
HIP 42674 |
22.15 |
| 2026-04-11 12:00 |
08:40:22.75 |
-05:31:08.0 |
HIP 42674 |
22.47 |
| 2026-04-12 00:00 |
08:40:21.84 |
-05:30:44.4 |
HIP 42674 |
22.79 |
| 2026-04-12 12:00 |
08:40:20.96 |
-05:30:20.9 |
HIP 42674 |
23.10 |
| 2026-04-13 00:00 |
08:40:20.11 |
-05:29:57.4 |
HIP 42674 |
23.42 |
| 2026-04-13 12:00 |
08:40:19.29 |
-05:29:34.0 |
HIP 42674 |
23.72 |
| 2026-04-14 00:00 |
08:40:18.50 |
-05:29:10.7 |
HIP 42674 |
24.03 |
| 2026-04-14 12:00 |
08:40:17.75 |
-05:28:47.4 |
HIP 42674 |
24.33 |
| 2026-04-15 00:00 |
08:40:17.02 |
-05:28:24.3 |
HIP 42674 |
24.63 |
| 2026-04-15 12:00 |
08:40:16.32 |
-05:28:01.2 |
HIP 42674 |
24.92 |
| 2026-04-16 00:00 |
08:40:15.66 |
-05:27:38.2 |
HIP 42674 |
25.21 |