| 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) |
| 2026-05-12 00:00 |
10:00:45.41 |
+15:15:03.6 |
HIP 49168 |
19.86 |
| 2026-05-12 12:00 |
10:00:44.42 |
+15:15:00.7 |
HIP 49168 |
20.10 |
| 2026-05-13 00:00 |
10:00:43.46 |
+15:14:57.6 |
HIP 49168 |
20.33 |
| 2026-05-13 12:00 |
10:00:42.55 |
+15:14:54.3 |
HIP 49168 |
20.56 |
| 2026-05-14 00:00 |
10:00:41.67 |
+15:14:50.8 |
HIP 49168 |
20.78 |
| 2026-05-14 12:00 |
10:00:40.84 |
+15:14:47.1 |
HIP 49168 |
20.99 |
| 2026-05-15 00:00 |
10:00:40.06 |
+15:14:43.1 |
HIP 49168 |
21.19 |
| 2026-05-15 12:00 |
10:00:39.31 |
+15:14:38.9 |
HIP 49168 |
21.38 |
| 2026-05-16 00:00 |
10:00:38.61 |
+15:14:34.5 |
HIP 49168 |
21.57 |
| 2026-05-16 12:00 |
10:00:37.94 |
+15:14:29.9 |
HIP 49168 |
21.74 |
| 2026-05-17 00:00 |
10:00:37.32 |
+15:14:25.1 |
HIP 49168 |
21.91 |
| 2026-05-17 12:00 |
10:00:36.74 |
+15:14:20.0 |
HIP 49168 |
22.07 |
| 2026-05-18 00:00 |
10:00:36.21 |
+15:14:14.8 |
HIP 49168 |
22.22 |
| 2026-05-18 12:00 |
10:00:35.71 |
+15:14:09.3 |
HIP 49168 |
22.36 |
| 2026-05-19 00:00 |
10:00:35.26 |
+15:14:03.6 |
HIP 49168 |
22.50 |
| 2026-05-19 12:00 |
10:00:34.84 |
+15:13:57.7 |
HIP 49168 |
22.63 |
| 2026-05-20 00:00 |
10:00:34.47 |
+15:13:51.6 |
HIP 49168 |
22.75 |
| 2026-05-20 12:00 |
10:00:34.14 |
+15:13:45.3 |
HIP 49168 |
22.86 |
| 2026-05-21 00:00 |
10:00:33.85 |
+15:13:38.7 |
HIP 49168 |
22.96 |
| 2026-05-21 12:00 |
10:00:33.60 |
+15:13:32.0 |
HIP 49010 |
22.96 |
| 2026-05-22 00:00 |
10:00:33.40 |
+15:13:25.0 |
HIP 49010 |
22.84 |
| 2026-05-22 12:00 |
10:00:33.23 |
+15:13:17.8 |
HIP 49010 |
22.71 |
| 2026-05-23 00:00 |
10:00:33.11 |
+15:13:10.5 |
HIP 49010 |
22.59 |
| 2026-05-23 12:00 |
10:00:33.02 |
+15:13:02.9 |
HIP 49010 |
22.47 |
| 2026-05-24 00:00 |
10:00:32.98 |
+15:12:55.1 |
HIP 49010 |
22.34 |
| 2026-05-24 12:00 |
10:00:32.97 |
+15:12:47.1 |
HIP 49010 |
22.22 |
| 2026-05-25 00:00 |
10:00:33.01 |
+15:12:38.9 |
HIP 49010 |
22.10 |
| 2026-05-25 12:00 |
10:00:33.09 |
+15:12:30.5 |
HIP 49010 |
21.98 |
| 2026-05-26 00:00 |
10:00:33.20 |
+15:12:21.9 |
HIP 49010 |
21.87 |
| 2026-05-26 12:00 |
10:00:33.36 |
+15:12:13.1 |
HIP 49010 |
21.75 |
| 2026-05-27 00:00 |
10:00:33.56 |
+15:12:04.1 |
HIP 49010 |
21.64 |
| 2026-05-27 12:00 |
10:00:33.80 |
+15:11:54.9 |
HIP 49010 |
21.52 |
| 2026-05-28 00:00 |
10:00:34.07 |
+15:11:45.5 |
HIP 49010 |
21.41 |
| 2026-05-28 12:00 |
10:00:34.39 |
+15:11:35.9 |
HIP 49010 |
21.31 |
| 2026-05-29 00:00 |
10:00:34.74 |
+15:11:26.1 |
HIP 49010 |
21.20 |
| 2026-05-29 12:00 |
10:00:35.14 |
+15:11:16.1 |
HIP 49010 |
21.10 |
| 2026-05-30 00:00 |
10:00:35.57 |
+15:11:05.9 |
HIP 49010 |
21.00 |
| 2026-05-30 12:00 |
10:00:36.05 |
+15:10:55.5 |
HIP 49010 |
20.90 |
| 2026-05-31 00:00 |
10:00:36.56 |
+15:10:44.9 |
HIP 49010 |
20.81 |
| 2026-05-31 12:00 |
10:00:37.11 |
+15:10:34.1 |
HIP 49010 |
20.72 |
| 2026-06-01 00:00 |
10:00:37.70 |
+15:10:23.2 |
HIP 49010 |
20.63 |
| 2026-06-01 12:00 |
10:00:38.32 |
+15:10:12.0 |
HIP 49010 |
20.55 |
| 2026-06-02 00:00 |
10:00:38.99 |
+15:10:00.6 |
HIP 49010 |
20.48 |