| 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) |
| 2026-05-12 00:00 |
05:47:57.54 |
+50:30:14.4 |
HIP 27190 |
22.16 |
| 2026-05-12 12:00 |
05:48:04.98 |
+50:29:52.9 |
HIP 27190 |
23.39 |
| 2026-05-13 00:00 |
05:48:12.47 |
+50:29:31.6 |
HIP 27190 |
24.62 |
| 2026-05-13 12:00 |
05:48:19.98 |
+50:29:10.6 |
HIP 27326 |
25.74 |
| 2026-05-14 00:00 |
05:48:27.53 |
+50:28:49.8 |
HIP 27326 |
25.90 |
| 2026-05-14 12:00 |
05:48:35.11 |
+50:28:29.3 |
HIP 27326 |
26.13 |
| 2026-05-15 00:00 |
05:48:42.73 |
+50:28:09.0 |
HIP 27326 |
26.42 |
| 2026-05-15 12:00 |
05:48:50.37 |
+50:27:48.9 |
HIP 27326 |
26.77 |
| 2026-05-16 00:00 |
05:48:58.05 |
+50:27:29.1 |
HIP 27326 |
27.19 |
| 2026-05-16 12:00 |
05:49:05.76 |
+50:27:09.5 |
HIP 27326 |
27.66 |
| 2026-05-17 00:00 |
05:49:13.51 |
+50:26:50.2 |
HIP 27326 |
28.19 |
| 2026-05-17 12:00 |
05:49:21.28 |
+50:26:31.1 |
HIP 27326 |
28.77 |
| 2026-05-18 00:00 |
05:49:29.08 |
+50:26:12.2 |
HIP 27326 |
29.40 |
| 2026-05-18 12:00 |
05:49:36.91 |
+50:25:53.6 |
HIP 27326 |
30.08 |
| 2026-05-19 00:00 |
05:49:44.77 |
+50:25:35.3 |
HIP 27326 |
30.81 |
| 2026-05-19 12:00 |
05:49:52.66 |
+50:25:17.1 |
HIP 27326 |
31.58 |
| 2026-05-20 00:00 |
05:50:00.58 |
+50:24:59.2 |
HIP 27763 |
32.17 |
| 2026-05-20 12:00 |
05:50:08.52 |
+50:24:41.6 |
HIP 27763 |
31.45 |
| 2026-05-21 00:00 |
05:50:16.49 |
+50:24:24.2 |
HIP 27763 |
30.77 |
| 2026-05-21 12:00 |
05:50:24.49 |
+50:24:07.1 |
HIP 27763 |
30.12 |
| 2026-05-22 00:00 |
05:50:32.51 |
+50:23:50.2 |
HIP 27763 |
29.50 |
| 2026-05-22 12:00 |
05:50:40.56 |
+50:23:33.5 |
HIP 27763 |
28.93 |
| 2026-05-23 00:00 |
05:50:48.63 |
+50:23:17.1 |
HIP 27763 |
28.40 |
| 2026-05-23 12:00 |
05:50:56.73 |
+50:23:00.9 |
HIP 27763 |
27.92 |
| 2026-05-24 00:00 |
05:51:04.85 |
+50:22:45.0 |
HIP 27763 |
27.48 |
| 2026-05-24 12:00 |
05:51:13.00 |
+50:22:29.3 |
HIP 27763 |
27.09 |
| 2026-05-25 00:00 |
05:51:21.17 |
+50:22:13.9 |
HIP 27763 |
26.76 |
| 2026-05-25 12:00 |
05:51:29.36 |
+50:21:58.7 |
HIP 27763 |
26.49 |
| 2026-05-26 00:00 |
05:51:37.57 |
+50:21:43.8 |
HIP 27763 |
26.28 |
| 2026-05-26 12:00 |
05:51:45.81 |
+50:21:29.1 |
HIP 27763 |
26.12 |
| 2026-05-27 00:00 |
05:51:54.06 |
+50:21:14.7 |
HIP 27763 |
26.03 |
| 2026-05-27 12:00 |
05:52:02.34 |
+50:21:00.5 |
HIP 27763 |
26.00 |
| 2026-05-28 00:00 |
05:52:10.63 |
+50:20:46.5 |
HIP 27763 |
26.04 |
| 2026-05-28 12:00 |
05:52:18.95 |
+50:20:32.8 |
HIP 27763 |
26.14 |
| 2026-05-29 00:00 |
05:52:27.29 |
+50:20:19.4 |
HIP 27763 |
26.30 |
| 2026-05-29 12:00 |
05:52:35.64 |
+50:20:06.2 |
HIP 27763 |
26.53 |
| 2026-05-30 00:00 |
05:52:44.02 |
+50:19:53.2 |
HIP 27871 |
26.53 |
| 2026-05-30 12:00 |
05:52:52.41 |
+50:19:40.5 |
HIP 27871 |
26.21 |
| 2026-05-31 00:00 |
05:53:00.82 |
+50:19:28.1 |
HIP 27871 |
25.95 |
| 2026-05-31 12:00 |
05:53:09.25 |
+50:19:15.8 |
HIP 27871 |
25.76 |
| 2026-06-01 00:00 |
05:53:17.69 |
+50:19:03.9 |
HIP 27871 |
25.64 |
| 2026-06-01 12:00 |
05:53:26.15 |
+50:18:52.2 |
HIP 27871 |
25.58 |
| 2026-06-02 00:00 |
05:53:34.63 |
+50:18:40.7 |
HIP 27871 |
25.58 |