| 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) |
| 2026-03-26 00:00 |
05:39:51.88 |
+51:19:19.5 |
HIP 26622 |
3.44 |
| 2026-03-26 12:00 |
05:39:54.24 |
+51:18:40.5 |
HIP 26622 |
3.99 |
| 2026-03-27 00:00 |
05:39:56.68 |
+51:18:01.5 |
HIP 26622 |
4.60 |
| 2026-03-27 12:00 |
05:39:59.18 |
+51:17:22.6 |
HIP 26622 |
5.26 |
| 2026-03-28 00:00 |
05:40:01.76 |
+51:16:43.9 |
HIP 26622 |
5.95 |
| 2026-03-28 12:00 |
05:40:04.41 |
+51:16:05.3 |
HIP 26622 |
6.66 |
| 2026-03-29 00:00 |
05:40:07.12 |
+51:15:26.8 |
HIP 26622 |
7.39 |
| 2026-03-29 12:00 |
05:40:09.90 |
+51:14:48.5 |
HIP 26622 |
8.14 |
| 2026-03-30 00:00 |
05:40:12.76 |
+51:14:10.2 |
HIP 26622 |
8.90 |
| 2026-03-30 12:00 |
05:40:15.68 |
+51:13:32.1 |
HIP 26622 |
9.66 |
| 2026-03-31 00:00 |
05:40:18.67 |
+51:12:54.1 |
HIP 26622 |
10.44 |
| 2026-03-31 12:00 |
05:40:21.73 |
+51:12:16.3 |
HIP 26622 |
11.22 |
| 2026-04-01 00:00 |
05:40:24.85 |
+51:11:38.6 |
HIP 26622 |
12.01 |
| 2026-04-01 12:00 |
05:40:28.04 |
+51:11:01.0 |
HIP 26622 |
12.81 |
| 2026-04-02 00:00 |
05:40:31.30 |
+51:10:23.6 |
HIP 26622 |
13.61 |
| 2026-04-02 12:00 |
05:40:34.63 |
+51:09:46.3 |
HIP 26622 |
14.42 |
| 2026-04-03 00:00 |
05:40:38.02 |
+51:09:09.1 |
HIP 26622 |
15.24 |
| 2026-04-03 12:00 |
05:40:41.48 |
+51:08:32.1 |
HIP 26622 |
16.06 |
| 2026-04-04 00:00 |
05:40:45.00 |
+51:07:55.2 |
HIP 26622 |
16.88 |
| 2026-04-04 12:00 |
05:40:48.59 |
+51:07:18.5 |
HIP 26622 |
17.71 |
| 2026-04-05 00:00 |
05:40:52.25 |
+51:06:41.9 |
HIP 26622 |
18.55 |
| 2026-04-05 12:00 |
05:40:55.97 |
+51:06:05.5 |
HIP 26622 |
19.39 |
| 2026-04-06 00:00 |
05:40:59.75 |
+51:05:29.2 |
HIP 26622 |
20.24 |
| 2026-04-06 12:00 |
05:41:03.60 |
+51:04:53.1 |
HIP 26622 |
21.09 |
| 2026-04-07 00:00 |
05:41:07.51 |
+51:04:17.2 |
HIP 26622 |
21.95 |
| 2026-04-07 12:00 |
05:41:11.49 |
+51:03:41.4 |
HIP 26622 |
22.81 |
| 2026-04-08 00:00 |
05:41:15.53 |
+51:03:05.7 |
HIP 26622 |
23.68 |
| 2026-04-08 12:00 |
05:41:19.63 |
+51:02:30.2 |
HIP 26622 |
24.56 |
| 2026-04-09 00:00 |
05:41:23.79 |
+51:01:54.9 |
HIP 26622 |
25.43 |
| 2026-04-09 12:00 |
05:41:28.02 |
+51:01:19.8 |
HIP 26622 |
26.32 |
| 2026-04-10 00:00 |
05:41:32.31 |
+51:00:44.8 |
HIP 26970 |
25.55 |
| 2026-04-10 12:00 |
05:41:36.66 |
+51:00:10.0 |
HIP 26970 |
24.66 |
| 2026-04-11 00:00 |
05:41:41.07 |
+50:59:35.3 |
HIP 26970 |
23.76 |
| 2026-04-11 12:00 |
05:41:45.55 |
+50:59:00.8 |
HIP 26970 |
22.86 |
| 2026-04-12 00:00 |
05:41:50.08 |
+50:58:26.5 |
HIP 26970 |
21.96 |
| 2026-04-12 12:00 |
05:41:54.67 |
+50:57:52.4 |
HIP 26970 |
21.05 |
| 2026-04-13 00:00 |
05:41:59.33 |
+50:57:18.4 |
HIP 26970 |
20.14 |
| 2026-04-13 12:00 |
05:42:04.04 |
+50:56:44.6 |
HIP 26970 |
19.23 |
| 2026-04-14 00:00 |
05:42:08.81 |
+50:56:11.0 |
HIP 26970 |
18.32 |
| 2026-04-14 12:00 |
05:42:13.64 |
+50:55:37.6 |
HIP 26970 |
17.40 |
| 2026-04-15 00:00 |
05:42:18.53 |
+50:55:04.4 |
HIP 26970 |
16.49 |
| 2026-04-15 12:00 |
05:42:23.48 |
+50:54:31.3 |
HIP 26970 |
15.57 |
| 2026-04-16 00:00 |
05:42:28.49 |
+50:53:58.5 |
HIP 26970 |
14.66 |