| Parameter |
Value |
| Designation |
C/2015 H1 (Bressi) |
| Type |
C |
| Perihelion (tp_cal, UTC) |
2015-03-28T14:52:26.330880Z |
| Orbit solution date (soln_date, UTC) |
2021-04-15T23:33:09Z |
| Obs used |
210 |
| NEO |
- |
| M1 |
4.200 |
| K1 |
40.750 |
| PC |
0.030 |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2015-05-27.0000000 |
| e |
0.94079404 |
| q (au) |
1.926359 |
| a (au) |
32.536572 |
| i (deg) |
140.655574 |
| Ω (om, deg) |
325.804456 |
| ω (w, deg) |
21.756727 |
| M (ma, deg) |
0.315347 |
Magnitude
Scatter + Global Linear
$$
M_a = (11.248 + 6.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
11.248 |
| n |
6.000 |
| 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 |
| 2015-04-20 |
2015-07-27 |
+16.3060 |
-4.976 |
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 |
10:05:17.46 |
+15:03:04.1 |
HIP 49395 |
6.04 |
| 2026-03-26 12:00 |
10:05:12.92 |
+15:03:21.6 |
HIP 49395 |
5.24 |
| 2026-03-27 00:00 |
10:05:08.40 |
+15:03:38.9 |
HIP 49395 |
4.58 |
| 2026-03-27 12:00 |
10:05:03.92 |
+15:03:56.0 |
HIP 49395 |
4.14 |
| 2026-03-28 00:00 |
10:04:59.46 |
+15:04:12.9 |
HIP 49395 |
3.98 |
| 2026-03-28 12:00 |
10:04:55.03 |
+15:04:29.6 |
HIP 49395 |
4.12 |
| 2026-03-29 00:00 |
10:04:50.64 |
+15:04:46.1 |
HIP 49395 |
4.53 |
| 2026-03-29 12:00 |
10:04:46.27 |
+15:05:02.4 |
HIP 49395 |
5.14 |
| 2026-03-30 00:00 |
10:04:41.93 |
+15:05:18.5 |
HIP 49395 |
5.89 |
| 2026-03-30 12:00 |
10:04:37.63 |
+15:05:34.4 |
HIP 49395 |
6.72 |
| 2026-03-31 00:00 |
10:04:33.35 |
+15:05:50.2 |
HIP 49395 |
7.61 |
| 2026-03-31 12:00 |
10:04:29.11 |
+15:06:05.7 |
HIP 49395 |
8.53 |
| 2026-04-01 00:00 |
10:04:24.89 |
+15:06:21.0 |
HIP 49395 |
9.47 |
| 2026-04-01 12:00 |
10:04:20.71 |
+15:06:36.2 |
HIP 49395 |
10.42 |
| 2026-04-02 00:00 |
10:04:16.56 |
+15:06:51.1 |
HIP 49395 |
11.39 |
| 2026-04-02 12:00 |
10:04:12.45 |
+15:07:05.9 |
HIP 49395 |
12.35 |
| 2026-04-03 00:00 |
10:04:08.36 |
+15:07:20.4 |
HIP 49395 |
13.32 |
| 2026-04-03 12:00 |
10:04:04.31 |
+15:07:34.7 |
HIP 49395 |
14.29 |
| 2026-04-04 00:00 |
10:04:00.29 |
+15:07:48.9 |
HIP 49395 |
15.25 |
| 2026-04-04 12:00 |
10:03:56.30 |
+15:08:02.8 |
HIP 49395 |
16.21 |
| 2026-04-05 00:00 |
10:03:52.35 |
+15:08:16.5 |
HIP 49395 |
17.16 |
| 2026-04-05 12:00 |
10:03:48.43 |
+15:08:30.0 |
HIP 49395 |
18.11 |
| 2026-04-06 00:00 |
10:03:44.54 |
+15:08:43.3 |
HIP 49395 |
19.06 |
| 2026-04-06 12:00 |
10:03:40.69 |
+15:08:56.4 |
HIP 49395 |
19.99 |
| 2026-04-07 00:00 |
10:03:36.88 |
+15:09:09.3 |
HIP 49395 |
20.92 |
| 2026-04-07 12:00 |
10:03:33.09 |
+15:09:22.0 |
HIP 49395 |
21.85 |
| 2026-04-08 00:00 |
10:03:29.35 |
+15:09:34.5 |
HIP 49395 |
22.76 |
| 2026-04-08 12:00 |
10:03:25.63 |
+15:09:46.7 |
HIP 49168 |
23.17 |
| 2026-04-09 00:00 |
10:03:21.95 |
+15:09:58.8 |
HIP 49168 |
22.31 |
| 2026-04-09 12:00 |
10:03:18.31 |
+15:10:10.6 |
HIP 49168 |
21.46 |
| 2026-04-10 00:00 |
10:03:14.71 |
+15:10:22.3 |
HIP 49168 |
20.62 |
| 2026-04-10 12:00 |
10:03:11.14 |
+15:10:33.7 |
HIP 49168 |
19.80 |
| 2026-04-11 00:00 |
10:03:07.60 |
+15:10:44.9 |
HIP 49168 |
18.99 |
| 2026-04-11 12:00 |
10:03:04.10 |
+15:10:55.9 |
HIP 49168 |
18.20 |
| 2026-04-12 00:00 |
10:03:00.64 |
+15:11:06.6 |
HIP 49168 |
17.42 |
| 2026-04-12 12:00 |
10:02:57.22 |
+15:11:17.2 |
HIP 49168 |
16.66 |
| 2026-04-13 00:00 |
10:02:53.83 |
+15:11:27.5 |
HIP 49168 |
15.92 |
| 2026-04-13 12:00 |
10:02:50.48 |
+15:11:37.6 |
HIP 49168 |
15.19 |
| 2026-04-14 00:00 |
10:02:47.17 |
+15:11:47.5 |
HIP 49168 |
14.49 |
| 2026-04-14 12:00 |
10:02:43.89 |
+15:11:57.2 |
HIP 49168 |
13.81 |
| 2026-04-15 00:00 |
10:02:40.65 |
+15:12:06.6 |
HIP 49168 |
13.15 |
| 2026-04-15 12:00 |
10:02:37.45 |
+15:12:15.9 |
HIP 49168 |
12.51 |
| 2026-04-16 00:00 |
10:02:34.29 |
+15:12:24.9 |
HIP 49168 |
11.91 |