C/2017 D2 (Barros)
| Parameter |
Value |
| Designation |
C/2017 D2 (Barros) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2017-07-14T12:49:04.209600Z |
| Orbit solution date (soln_date, UTC) |
2024-12-12T17:11:30Z |
| Obs used |
433 |
| NEO |
- |
| M1 |
13.600 |
| K1 |
5.250 |
| PC |
- |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-08-10.0000000 |
| e |
0.99819913 |
| q (au) |
2.485874 |
| a (au) |
1380.371396 |
| i (deg) |
31.265640 |
| Ω (om, deg) |
331.042014 |
| ω (w, deg) |
334.339752 |
| M (ma, deg) |
0.000509 |
Magnitude
Scatter + Global Linear
$$
M_a = (12.809 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
12.809 |
| n |
2.000 |
| 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 |
| 2017-02-23 |
2017-07-07 |
-12.4888 |
+4.968 |
| 2017-07-16 |
2018-10-10 |
+1.2813 |
-0.500 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-02-03 00:00 |
05:42:30.02 |
+52:26:58.3 |
HIP 26974 |
8.93 |
| 2026-02-03 12:00 |
05:42:24.67 |
+52:26:23.5 |
HIP 26974 |
9.88 |
| 2026-02-04 00:00 |
05:42:19.39 |
+52:25:48.5 |
HIP 26974 |
10.83 |
| 2026-02-04 12:00 |
05:42:14.17 |
+52:25:13.3 |
HIP 26974 |
11.77 |
| 2026-02-05 00:00 |
05:42:09.03 |
+52:24:37.8 |
HIP 26974 |
12.72 |
| 2026-02-05 12:00 |
05:42:03.95 |
+52:24:02.2 |
HIP 26974 |
13.66 |
| 2026-02-06 00:00 |
05:41:58.94 |
+52:23:26.3 |
HIP 26974 |
14.60 |
| 2026-02-06 12:00 |
05:41:54.01 |
+52:22:50.2 |
HIP 26769 |
14.11 |
| 2026-02-07 00:00 |
05:41:49.14 |
+52:22:14.0 |
HIP 26769 |
13.23 |
| 2026-02-07 12:00 |
05:41:44.35 |
+52:21:37.5 |
HIP 26769 |
12.37 |
| 2026-02-08 00:00 |
05:41:39.62 |
+52:21:00.9 |
HIP 26769 |
11.53 |
| 2026-02-08 12:00 |
05:41:34.97 |
+52:20:24.1 |
HIP 26769 |
10.70 |
| 2026-02-09 00:00 |
05:41:30.39 |
+52:19:47.1 |
HIP 26769 |
9.90 |
| 2026-02-09 12:00 |
05:41:25.88 |
+52:19:09.9 |
HIP 26769 |
9.11 |
| 2026-02-10 00:00 |
05:41:21.44 |
+52:18:32.5 |
HIP 26769 |
8.36 |
| 2026-02-10 12:00 |
05:41:17.08 |
+52:17:55.0 |
HIP 26769 |
7.64 |
| 2026-02-11 00:00 |
05:41:12.79 |
+52:17:17.3 |
HIP 26769 |
6.97 |
| 2026-02-11 12:00 |
05:41:08.57 |
+52:16:39.4 |
HIP 26769 |
6.35 |
| 2026-02-12 00:00 |
05:41:04.43 |
+52:16:01.4 |
HIP 26769 |
5.80 |
| 2026-02-12 12:00 |
05:41:00.36 |
+52:15:23.2 |
HIP 26769 |
5.34 |
| 2026-02-13 00:00 |
05:40:56.37 |
+52:14:44.9 |
HIP 26769 |
4.99 |
| 2026-02-13 12:00 |
05:40:52.45 |
+52:14:06.4 |
HIP 26769 |
4.78 |
| 2026-02-14 00:00 |
05:40:48.60 |
+52:13:27.8 |
HIP 26769 |
4.70 |
| 2026-02-14 12:00 |
05:40:44.83 |
+52:12:49.0 |
HIP 26769 |
4.78 |
| 2026-02-15 00:00 |
05:40:41.14 |
+52:12:10.1 |
HIP 26769 |
5.00 |
| 2026-02-15 12:00 |
05:40:37.52 |
+52:11:31.1 |
HIP 26769 |
5.34 |
| 2026-02-16 00:00 |
05:40:33.98 |
+52:10:51.9 |
HIP 26769 |
5.77 |
| 2026-02-16 12:00 |
05:40:30.52 |
+52:10:12.6 |
HIP 26769 |
6.28 |
| 2026-02-17 00:00 |
05:40:27.13 |
+52:09:33.2 |
HIP 26769 |
6.84 |
| 2026-02-17 12:00 |
05:40:23.82 |
+52:08:53.6 |
HIP 26769 |
7.45 |
| 2026-02-18 00:00 |
05:40:20.58 |
+52:08:14.0 |
HIP 26769 |
8.08 |
| 2026-02-18 12:00 |
05:40:17.42 |
+52:07:34.2 |
HIP 26769 |
8.73 |
| 2026-02-19 00:00 |
05:40:14.34 |
+52:06:54.3 |
HIP 26769 |
9.41 |
| 2026-02-19 12:00 |
05:40:11.34 |
+52:06:14.3 |
HIP 26769 |
10.09 |
| 2026-02-20 00:00 |
05:40:08.42 |
+52:05:34.3 |
HIP 26769 |
10.78 |
| 2026-02-20 12:00 |
05:40:05.57 |
+52:04:54.1 |
HIP 26769 |
11.47 |
| 2026-02-21 00:00 |
05:40:02.80 |
+52:04:13.8 |
HIP 26769 |
12.17 |
| 2026-02-21 12:00 |
05:40:00.11 |
+52:03:33.4 |
HIP 26769 |
12.87 |
| 2026-02-22 00:00 |
05:39:57.50 |
+52:02:53.0 |
HIP 26769 |
13.58 |
| 2026-02-22 12:00 |
05:39:54.96 |
+52:02:12.5 |
HIP 26769 |
14.28 |
| 2026-02-23 00:00 |
05:39:52.51 |
+52:01:31.9 |
HIP 26769 |
14.98 |
| 2026-02-23 12:00 |
05:39:50.13 |
+52:00:51.2 |
HIP 26769 |
15.68 |
| 2026-02-24 00:00 |
05:39:47.83 |
+52:00:10.5 |
HIP 26769 |
16.37 |